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Blind bolting technology could access the inside of a closed-section column, which enables to assemble a steel beam to concrete encased CFST (CECFST) column. However, the bulge of steel tube and outer concrete were likely to appear for blind bolted normal CECFST column joints owing to the limited strength of outer concrete. Therefore, this paper adopts UHPC as outer concrete to form a UHPC encased CFST composite column, which aims to avoid the steel tube from being failed for blind bolted joints effectively. Initially, the modular construction process of UHPC encased CFST column blind bolted joints was proposed, in which the assembled joints could be divided into column and beam modular parts during construction. Afterwards, a finite element model was established by ABAQUS considering the complex interactions and material properties to validate the feasible of this modular joint. Detailed failure mechanism and contact behavior between UHPC and steel tube of the joints were discussed, indicating that the UHPC could effectively restrict the bulge of steel tube. Parametric analyses were conducted on typical UHPC encased CFST composite column blind bolted to steel beam joint. Finally, the analytical models of the joint initial stiffness and moment resistance were developed based on the component method considering the dispersal effect of outer UHPC. The comparison results declared that the proposed analytical method provided a reasonable prediction of the initial stiffness and moment resistance. The research results in this paper validated that replacing normal concrete of CECFST by UHPC could avoid column failure when using blind bolted joints and gave a proper design method for the UHPC encased CFST composite column blind bolted to steel beam joint. • Confinement between UHPC and steel tube was analyzed in assembled joints. • Failure mechanism and influence of parameters on the novel joint was discussed. • Design model on initial stiffness and moment resistance was developed. [ABSTRACT FROM AUTHOR]

This study investigates the structural performance of the corner column-to-column connection made of VectorBloc under tensile axial load, which links corner columns between two consecutive floors. Nine full-scale specimens, comprising three distinct connection types one Axial Tension Single Column (ATSC) connection and two Axial Tension Bundle Columns (ATBC-MCC and ATBC-BCC) connections were tested under axial tension load. Failure in all specimens resulted from the rupture of Socket-Head-Cap Screws (SHCSs) connecting the upper and lower blocs of the connector. Despite identical SHCSs across all specimens, variations in their positions led to different outcomes due to differing column geometries and resulting load eccentricities. Notably, the eccentricity induced bloc rotation, leading to separation on the tension face. Axial tension single column exhibited the lowest average tensile capacity, while bundle column connections, despite similar section areas, exhibited contrasting load capacities, attributed to varying load eccentricities. A subsequent parametric study, using finite element analysis, was conducted to identify parameters critical for maximizing the tensile load capacity of this column connection. • This paper presents the performance of Vectorbloc connection subjected to axial tension. • This research was completed using full-scale tests and a detailed FE-based parametric study. • The SHCSs play the most important role in the tensile capacity of the connection. • Both eccentricity and parameter d must be minimized to maximise the tensile capacity. • The parameter d is developed and introduced for the first time in this paper. [ABSTRACT FROM AUTHOR]

This paper investigates the shortcomings of the AISC 360–22 and Eurocode 3–22 provisions for calculating the plateau and lateral-torsional buckling (LTB) flexural resistance of thin-web singly-symmetric steel I-section members with the larger flange in compression. In addition, the paper proposes and evaluates corresponding newly recommended AISC 360 procedures, which eliminate the tension flange yielding (TFY) limit state check and implement a more mechanistically-based solution accounting for the inelastic reserve strength associated with flexural yielding in tension. The recommended procedures incorporate other recently proposed improvements to AISC 360, solving substantive LTB overprediction problems for certain types of built-up I-section members. The results from six large-scale experimental tests, associated finite element analysis (FEA) simulations, and parametric FEA simulation studies are considered. The results demonstrate improved accuracy and substantial gains in the predicted strengths by the recommended procedures relative to the AISC 360–22 and Eurocode 3–22 calculations for a significant range of geometries and loadings. In addition, the recommended methods address LTB overprediction problems exhibited by AISC 360–22 for a limited range of the member types studied. • Experimental evidence shows current flexure design codes can be overly conservative. • Accounting for tensile yield in flexure can result in substantial strength gains. • Codes do not calculate the true stain distribution for larger flanges in compression. • Experimental evidence shows current flexure design codes can overpredict capacity. • Improvements can be made to the design codes through simple modification. [ABSTRACT FROM AUTHOR]

The paper conducted 19 partially and 5 fully loaded tests on round-ended concrete-filled steel tubular (CFST) columns. These tests revealed that the ultimate strengths of round-ended CFST columns under partial load declined as the cross-sectional aspect ratio or partial compression area ratio increased. However, the use of a top plate effectively enhanced their ultimate strengths. In addition, a finite element model (FEM) was utilized to generate 487 large-size models to explore the confinement effect, stress distribution, and parametric effects. Since there are no specific design standards available for round-ended CFST columns, the paper has evaluated the applicability of design methods provided in Eurocode 4, AISC 360–16, and Chinese code GB50396 which are intended for circular, square, or elliptical CFST columns for round-ended CFST columns under partial load. However, these existing design techniques showed inaccurate and dispersed resistance predictions for round-ended CFST columns. Therefore, an effective simplified method for forecasting the resistance predictions of round-ended CFST columns under the partial load has been proposed based on the testing results and FEM analysis. • For the first time, partial compression tests of 19 round-ended CFST columns were conducted. • The top endplate can be used to effectively enhance its partial compression resistance. • As the cross-sectional aspect ratio increase, the load-carrying capacity falls. • Exiting design methods are not applicable to partially loaded round-ended CFST columns. • For the first time, a simplified model for their partial compression resistance was proposed. [ABSTRACT FROM AUTHOR]

Concrete-filled steel tube (CFST) columns are widely used in structures where high bearing capacity and ductility are crucial. They offer several advantages over conventional steel or concrete columns, such as a high strength-weight ratio, better ductility, and increased resistance to buckling and compression. Also, seismic damage in CFST columns primarily occurs within the plastic hinge region at their base. Therefore, by improving the ductility specifically in this plastic hinge region, the seismic resilience of CFST columns can be significantly enhanced. In this paper, the use of steel-polypropylene hybrid fiber engineered cementitious composites (HECC) in the plastic hinge region of square CFST columns is proposed to improve their hysteretic performance. This paper presents an experimental study of the hysteretic behavior with three different local HECC-enhanced CFST (LHECFST) columns. Based on the test results, modeling was performed using ABAQUS, and the reliability of the FE model was verified. Following this, FE models with smaller HECC pouring height gradients were developed, and these CFST columns were parametrically analyzed. The results show that the seismic performance of CFST columns is improved by local enhancement with HECC. The pouring of HECC will reduce the slope of the peak load descending stage of the CFST column. In addition, the formulas for calculating the peak load of LHECFST columns with different axial compression ratios and HECC pouring heights were developed and the accuracy was verified by contrasting the data. • Hysteresis tests on concrete-filled steel tube (CFST) columns were performed. • The validation data were established by finite element analysis. • Engineered cementitious composites (ECC) reduce damage in plastic hinge region. • The deterioration of peak loads in CFST columns with ECC localized pouring is slow. • Methods are proposed for calculating the peak load of two-material CFST columns. [ABSTRACT FROM AUTHOR]

Tapered concrete filled double skin tubular (CFDST) member has great potential to be employed in wind turbine structures for catering to the increasing height and output power of wind turbine. However, wind turbine was often subjected to fluctuating wind loads, causing the cyclic lateral force acted on the wind turbine tower. Currently, there is still lack of related research on tapered CFDST under lateral cyclic loading. In this paper, the finite element model (FEM) of tapered CFDST was established and verified by the test results. Detailed failure mechanism of tapered CFDST with various tapered degrees were discussed, and the contributions of sandwiched concrete, inner and outer tubes and the interactions between them were analyzed in detail. It noticed that the failure position of tapered CFDST was not always near the bottom and significantly affected by the tapered degree, which induced an appreciable effect on the hysteretic performance. Subsequently, parametric analyses were performed based on the FEM considering various parameters including slenderness ratio, tapered degree and hollow ratio. Finally, a simplified hysteretic model was proposed. Three-line model was employed to describe the skeleton curve, in which the failure position was properly considered. Typical hysteretic rules were developed to simulate the hysteretic shape of tapered CFDST under various stages. The accuracy of the proposed model was validated by the numerical results. The analytical results in this paper provide a reasonable method to predict the hysteretic performance of tapered CFDST in wind turbine structures. • Failure mechanism of tapered CFDST under cyclic loading was discussed • Parametric analyses were performed on tapered CFDST under cyclic loading. • A simplified hysteretic model was proposed and validated. [ABSTRACT FROM AUTHOR]

Assembled joints are widely recognized and applied because they are green and perfectly fit the current development trend of the construction industry. This paper proposes a composite wall-steel beam joint with crossed U-plate connection. In order to study the influence of the seismic performance of the joint, 2 experimental specimens and 13 finite element models are designed. The thickness of the U-plate, the strength of the steel of the U-plate, and the overlap length with the steel beam are changed so that the low circumferential reciprocating loading test and numerical analysis of the finite element are carried out to determine the main indexes of the seismic performances, such as hysteresis curves, skeleton curves, ductility, energy dissipation capacity, and stiffness degradation. The results show that the wall-beam joints connected with U-plate have satisfactory seismic performance. With the improvement of U-plate thickness and steel strength, the ultimate bearing capacity and ultimate displacement of the joint increase significantly, and the increase of lap length with steel connecting beams improves the ductility performance of the joint. Moreover, M U / M B ≥ 1.41 at the node domain during design can get excellent bearing capacity; the corner at the bending of the U-plate is a weak part, and it is recommended to reduce or eliminate the residual stress in the area in practice. • An experimental investigation and numerical simulations of the combined wall-steel beam joint with cross U-plate connection is presented in this paper. • The combined wall-steel beam joint with cross U-plate connection had different thickness of U-plate, steel strength of plates and lap length with steel beam, including a total of 2 experimental specimens and 13 simulation specimens. • The deformed shapes of the combined wall-steel beam joint with cross U-plate connection and the effects of different parameters on seismic performance have been observed in the tests and discussed in this paper. • Finally, comparing the test and numerical simulation results, and expanding the analysis of the effect of different parameters on the seismic performance, the problems that should be paid attention to when designing are proposed, and the recommendations on the strength and stiffness of the combined wall-steel beam joint with cross U-plate connection are given. [ABSTRACT FROM AUTHOR]

The compressive behavior of steel tube reinforced concrete (STRC) columns under eccentric loads was investigated experimentally and numerically in this paper. Primary parameters included the eccentricity ratio, the concrete-filled steel tube (CFST) area ratio, and the longitudinal rebar ratio. This paper analyzed the impacts of these parameters as well as the failure modes, the full-range compression process, and the strain development. Similar to the reinforced concrete (RC) column, the full-range compression process of STRC column under eccentric loads can be divided into three stages, i.e., elastic stage, elastic-plastic stage (cracking stage), and plastic stage (descent stage). The experimental findings showed that, on the near-load side of the STRC column, the outer concrete crushed, and the longitudinal rebars buckled in compression. Conversely, on the far-load side, the concrete exhibited cracking in tension, and the longitudinal rebars exhibited tension. Finite element (FE) analysis results demonstrated that, similar to a RC column, three distinct failure mechanisms can be identified for STRC columns under eccentric loads, i.e., compression-controlled, balanced, and tension-controlled failures. During the compression process, analyses were conducted on the contact stress between the steel tube and concrete, as well as on the load distribution between the inner CFST and the outer RC. The ultimate load of the STRC column decreased with an increase in the eccentricity ratio, while it increased with larger longitudinal rebar ratio and CFST area ratio. Based on the experimental and FE analysis results, a simplified calculation method was developed to determine the eccentricity reduction coefficient for STRC columns. • The eccentric test result of steel tube reinforced concrete (STRC) column with low CFST area ratio was presented. • The effect of eccentricity ratio, CFST area ratio and rebar ratio on the compressive behavior of STRC column were analyzed. • The failure mechanisms, load distribution and contact stress was analyzed by refined finite element analysis. • The simplified calculation method of eccentricity reduction coefficient was proposed for the ultimate load of STRC column. [ABSTRACT FROM AUTHOR]

This paper focuses on the experimental investigation of vertically-placed stiffened corrugated steel walls (VSCSWs). Quasi-static cyclic tests were conducted on three half-scale, one-story, single-bay steel shear walls with unstiffened corrugated plate, and stiffened corrugated plates with one or two pairs of horizontal stiffeners. Based on test observations, this paper elucidated the failure modes of diverse specimens and conducted a comparative analysis of their hysteresis performance. Then, the finite element models of the specimens were constructed, and their accuracy was validated using the test results. Subsequently, a series of parametric analyses were conducted to further investigate the effect of several important geometric parameters on the hysteretic behavior of VSCSWs. Both experimental and numerical results show that adding horizontal stiffeners to vertically-placed corrugated steel plate shear walls is an effective way to improve their lateral load-bearing capacity and energy dissipation performance. • Quasi-static cyclic tests were conducted on three half-scale specimens to investigate the seismic performance of VSCSWs. • The failure modes of VSCSWs were revealed based on the test observations. • The hysteretic performance of the steel shear walls with various type of steel plates was compared. • Finite element models of the specimens were developed, and parametric analyses were further conducted. [ABSTRACT FROM AUTHOR]

Bridge structures are often vulnerable to vehicle collisions, necessitating innovative solutions to enhance safety. This paper introduces a concept employing energy-absorbing crash dampers to safeguard bridge structures. The primary objective is to optimize energy dissipation while ensuring uninterrupted bridge functionality. Utilizing the finite element modeling approach, and incorporating realistic constitutive relationships and boundary conditions, simulations were performed to encompass X-shaped damper impact tests and collisions involving trucks with steel-reinforced concrete columns. The study affirms the effectiveness of the numerical model in simulating the dynamic response of steel dampers and column structures under vehicle impacts. Leveraging this modeling approach, this research compares the anti-collision performance of urban bridge structures, both with and without the proposed bridge pier. The methodology involves two key steps: first, a response surface optimization analysis is conducted for the primary energy-absorbing component, the anti-collision hollow diamond-shaped damper, determining optimal dimensions for the device at varying vehicle collision speeds. Second, a comparative study explores failure modes, collision capabilities, deflection changes, and energy absorption of bridge structures with and without the energy-absorbing crash dampers under vehicle impacts. Subsequently, this study performs an optimization design and calculation for the bridge structures. The outcomes reveal that the bridge with the pier experiences a substantial reduction in impact peak force. The damper effectively absorbs part of impact energy, with the optimized damper demonstrating superior energy absorption. • This paper presents for the first employing energy-absorbing crash dampers to safeguard bridge structures against impact. • The optimal dimensions of anti-collision hollow diamond-shaped damper is determined at varying vehicle collision speeds. • The dynamic responses of bridge structure with energy-absorbing crash dampers under lateral impact were obtained and analyzed. [ABSTRACT FROM AUTHOR]

This research paper presents a comprehensive numerical-experimental analysis of the phenomena observed during the compression of small energy absorbers (EAs) with dimensions 23 × 23 mm and a thickness of 0.6 mm. This study uses the direct impact Hopkinson (DIH) method. The locus is the detailed prediction of the strength of laser-welded joints in terms of energy absorption under both quasi-static and dynamic loading conditions. Furthermore, the paper explores the potential utility of the described methodology for modeling and predicting the failure mechanisms of small energy absorbers. This investigation delves into key factors that affect the distribution of cracks in deformed energy absorbers. These include: the detail of the reproduction of the absorber geometry, the impact of finite element formulations and modeling method (2D/3D elements) and the complexity of the material model for propagated cracks. Two material models are considered, the simplified Johnson–Cook model and the tabulated Johnson-Cook with Hockett–Shelby extrapolation model, which incorporate linear damage dependent on the stress triaxiality and Lode angle. The study also highlights the advantages and disadvantages of the DIH test method. Some features cannot be effectively observed through experimental testing alone. The experimental procedure involved initial testing and calibration of the material models for both the parent material and the welded joints at three different strain rates. Subsequently, the validated energy absorber models are subjected to static and dynamic crushing. The results are subsequently compared with the virtual results obtained using the gravity hammer method, which is a more readily accessible testing approach. Remarkably, a very high correlation between the numerical simulation and experimental data is observed, providing a comprehensive understanding of the research problem related to laser-welded absorbers. [Display omitted] • A simple constitutive model cannot predict cracking in thin-walled energy absorbers • The fully optimized material model reliably reproduces the HSS failure in a complex state of stress • The strength and ductility increase with a strain rate >1000 s−1 compared to static conditions. • The reduced number of cracks on the folds is observed in the dynamic crushing of energy absorbers. • The sensitivity of the strain rate of material is secondary to the increase of energy absorbed in dynamic crushing. [ABSTRACT FROM AUTHOR]

This paper investigates concrete-filled dual steel stiffened tubular (CFDSST) slender columns with a cold-formed stiffened outer tube, a square inner tube and concrete infill between the two steel sections and also inside the inner section. To the best of the authors' knowledge, the behaviour of these types of slender column has not previously been studied, although the behaviour of short columns has been previously explored. Accordingly, the details and development of a finite element model are presented, as well as the validation against available test data. The model is employed to conduct an extensive parametric study to examine the behaviour of CFDSST slender columns with different geometric and material properties. Based on an analysis of the strain distributions in the cross-section, a method for defining intermediate-length and long columns is proposed. It is shown that the slenderness ratio is a very important parameter in the behaviour of CFDSST columns, affecting both the capacity and the failure mode. Other important variables for intermediate-length columns are shown to be the yield strength of the outer steel tube, the strength of the sandwiched concrete and the width-to-thickness ratio of the outer tube whilst only former of these is shown to be very influential for long columns. The ultimate strengths are compared with a number of different design methods, which were suitably adapted for the section types, owing a lack of specific guidance currently available. Based on the results it was recommended that the AS/NZS 2327 design standard provides the most accurate reflection of the real behaviour for CFDSST slender columns. • This paper presents, for the first time, analysis on the behaviour of square concrete-filled dual steel-stiffened tubular slender columns. • These members are shown to behave in a efficient manner in terms of the material usage requirements. • The stiffeners improve the overall buckling response compared with members without these elements. • An advanced FE model is presented, and validated, and then used to develop a thorough understanding of the behaviour. • Detailed design guidance is also provided. [ABSTRACT FROM AUTHOR]

The paper investigates the shear mechanic performance of transformed triangular corrugated steel plates (TT-CSPs) with top stringers applied in the trestle, incorporating a comprehensive analysis of how plate dimensions and corrugation density affect both elastic and inelastic buckling capacities. By proposing and validating formulas for the ultimate shear-bearing capacity through finite element analysis (FEA), this paper advances a capacity prediction approach that accounts for the finite rigidity of top stringers by introducing a reduction factor. The results reveal that corrugation density significantly impacts both elastic buckling load and ultimate strength, with plate width playing a more crucial role than height in determining capacity. Furthermore, the inclusion of top-stringer flexural rigidity is shown to notably enhance the shear-bearing capacity of TT-CSPs, providing a vital consideration for their strength design. [Display omitted] • Proposed formula for global elastic shear buckling load of transformed triangular corrugated steel plates (TT-CSP) • Proposed a comprehensive design method to predict shear-bearing capacity of TT-CSPs, considering top stringer constraints • Study the impact of corrugated plate and corrugation dimensions on elastic and inelastic buckling capacity of TT-CSPs • Reveal the contribution of top stringers to shear resistance of built-up TT-CSPs [ABSTRACT FROM AUTHOR]

This paper presents an analytical formula for the second-order normal stresses in flanges of the imperfect I beam-columns with sinusoidal web corrugation. To deduce the analytical expression, the beam is separated into three parts. The flanges are modelled as thin-walled beam-columns and the corrugated web is modelled as a thin equivalent orthotropic plate with uniform thickness. The indispensable elastic critical loads are derived from the total potential strain energy of the imperfect beam-column using an energy method. To assess the accuracy of the proposed analytical formula, full shell finite element models were created in Abaqus software. The result of the benchmark example showed that the derived expression is accurate and applicable for geometrically nonlinear analysis of beam-columns with sinusoidal web corrugation. Based on the proposed analytical expression, the Ayrton-Perry type solutions for corrugated web columns and beams are also presented in this paper. • The proposed analytical expression has a strong mechanical background. • It is applicable for GNIA of imperfect beam-columns with sinusoidal web corrugation. • The Ayrton-Perry type solutions for columns and beams are derived. • The accuracy of the EC3-based imperfection factors is examined. [ABSTRACT FROM AUTHOR]

As a new type of connection methodology, hybrid-bonded/bolted (HBB) connections exhibit potential advantages over mechanical or pure adhesive connections in construction, aerospace, shipbuilding, machinery, and other fields. The key to designing HBB joints is reasonable load sharing between bolts and adhesive layers. An accurate analytical model could effectively and quickly help engineers perform design iterations and arrive at reasonable load-sharing predictions. The existing models usually consider HBB joints as a simple superposition of adhesive and bolted joints. This paper found through experiments that when the HBB joint is subjected to tension, the bolt hole undergoes a certain deformation, resulting in a different bolt-hole contact state than pure bolt joints. Therefore, in the HBB joint, the load transferred by the bolt calculated using the existing model is usually higher than the actual situation. In response to this situation, this paper proposes a new calculation approach for bolt shear stiffness for this particular deformation and develops an analytical model for HBB joints. By comparing with the finite element method (FEM) results, it has been proven that this model can accurately calculate the load-displacement curves of HBB joints of different materials and sizes, as well as the load distribution between bolts and adhesive layers. This provides favorable references for the design of HBB joints. • HBB joints exhibit significant hole deformation under tension, which leads to the special component's contact mode; • The special contact mode leads to the lower load-sharing of bolts in HBB joints; • The new model was derived to account for the effect of the hole deformation; [ABSTRACT FROM AUTHOR]

This paper conducts a comparative study of the tensile performance of plug-pin scaffold joints under different temperatures. The current research objects are mostly for the traditional low carbon steel scaffolding, and lack of research on the tensile performance of scaffolding joints in low temperature conditions. In this paper, based on the temporary seating facilities of the Beijing Winter Olympic Games complex, a new type of sorbite stainless steel was used. The tensile bearing capacity, damage mode and strain distribution patterns of the sorbite stainless steel joints and traditional Q355 joints under different temperature conditions were studied with finite element model and parametric analysis. The results indicated that for traditional Q355 joints, damage primarily occurs in the form of wedge bending deformation, and that decreasing temperature leads to increased tensile bearing and yield capacity. In contrast, for sorbite stainless steel joints, higher tensile bearing capacity was observed at +20 °C, but at −20 °C and − 40 °C conditions, the bend of the C-type card becomes more prone to crack. The accuracy of the ABAQUS finite element model is verified by comparing it with test results. Increasing the thickness of the U-type and C-type cards can slightly increase the tensile bearing capacity of the joint and a minimum wall thickness of 2.7 mm is recommended. Two suggestions are proposed for improving the joint design using sorbite stainless steel. The research provides a premise for further studies on the tensile performance of plug-pin scaffold joints. • A low-temperature loading test device and method for joints are proposed. It offers a test environment of −70 °C ∼ 150 °C. • The material properties of sorbite stainless steel and Q355 at −40 °C, −20 °C and room temperature are studied. • The mechanical properties of plug-pin scaffold joints using sorbite stainless steel and Q355 at low temperatures are studied. • The tensile properties of plug-pin scaffold joints at different low temperatures are investigated. • Theoretical load-displacement modeling of plug-pin scaffold joints is developed. [ABSTRACT FROM AUTHOR]

To enhance the compressive performance of steel plate shear walls, this paper proposed a new type internally stiffened double steel plate shear wall (ISD-SPSW), incorporating two outer steel plates, a number of stiffening ribs and edge members on both sides to form a closed cross-section, which significantly improves the compressive and lateral stiffness of the double steel plate shear wall. To investigate the deformation and failure modes of ISD-SPSW under vertical axial compressive loads, seven specimens were designed and fabricated in this paper, and axial compression experiments were carried out. The effects of the loading regime, number of web stiffening ribs, thickness of outer steel plates, width of edge members, and height of the wall on the compressive performance of shear walls were examined. The load-equivalent vertical strain curves, strain curves, displacement ductility coefficients, and other axial-pressure performance indices of the ISD-SPSW were obtained. The results indicated that the failure modes of ISD-SPSW under axial compressive loads primarily involve strength failure and overall bending instability. Increasing the number of stiffening ribs or the thickness of outer steel plates significantly enhances the compressive load-bearing capacity and ductility of the ISD-SPSW. When the specimen has a larger height to thickness ratio of the specimen, it is prone to overall bending instability failure, leading to lower ductility and load-bearing capacity. • Propose a double-steel plate shear wall using flat steel plate internal stiffening. • Damage under axial pressure is overall instability accompanying local buckling. • Stiffening rib can improve the steel plate's local & specimen's overall stability. • Height and thickness of specimen are important factor in compressive performance. • The finite element model is in good agreement with the test. [ABSTRACT FROM AUTHOR]

Slender webs in welded steel plate I-girders (often used for long spans or load transfer in bridges and buildings) develop initial out-of-flatness imperfections as a result of fabrication (e.g., rolling, forming, welding, and assembly). Previous research has suggested that these imperfections can reduce the shear strength of the web; therefore, various specifications since the 1960s have included out-of-flatness imperfection tolerance limits for webs in steel plate girders. The research presented in this paper (1) provides a comprehensive review of current web out-of-flatness tolerance limits and measurement approaches, (2) introduces an alternative measurement technique for the out-of-flatness of webs (which collects a wide array of equispaced measurements), and (3) presents field measurements of 23 web panels (bounded by transverse stiffeners) across 12 different girders (with depths ranging from 0.914 to 2.08 m) that were commercially fabricated for bridge applications. The peak value for the out-of-flatness of the web, averaged across all measurements for each panel, was d / 170 (where d represents the least panel dimension). However, the location of peak out-of-flatness is seldom at the middle of the panel and has a 'dimpled' shape, meaning that the peak out-of-plane bulge covers only a small portion of the panel. The measurements demonstrated in this paper provide significantly more data resolution, thus enabling a better evaluation of the true impact of realistically irregular imperfection shapes and magnitudes on the shear strength of the plate. Such an evaluation based on the measurements presented in this paper is documented in a companion paper and is performed via numerical finite element analysis. [Display omitted] • Extensive field measurements to capture the initial web out-of-flatness imperfection magnitude and shape of plate girders were conducted. • A comprehensive review of current and past web out-of-flatness tolerance limits and measurement approaches were investigated. • A new measurement technique is introduced as an alternative to improve the accuracy, repeatability, and efficiency of field measurements. • Overall, the post-fabrication magnitudes of the out-of-flatness imperfections in the web do not exceed tolerance limits prescribed by code-based specifications, the location of the peak value of the out-of-flatness in the web has dimpled shapes and is seldom at the center of the web panel. [ABSTRACT FROM AUTHOR]

In recent years, there has been a notable increase in the utilization of multi-celled corrugated-plate CFST (MC-CFST) walls. In this paper, a connection joint between a steel beam and an MC-CFST wall was proposed. The joint consisted of MC-CFST walls, end columns, horizontal diaphragms, vertical plates, and steel beams, with each steel component being interconnected through welding. To investigate its mechanical properties, a refined finite element model was developed, and the accuracy of the modeling method was validated through existing test results. The stiffness and moment capacity of the joints were analyzed, focusing on the effects of various factors, including the insertion depth of the horizontal diaphragm, beam-to-column linear stiffness ratio, width-to-thickness ratio of the end column plate, diameter of the horizontal diaphragm opening, axial compression ratio, and concrete and steel strengths. Based on numerical and theoretical analyses, a calculation method for determining the moment capacity of the joint and establishing the lower limit value for the steel tube thickness of the end columns was proposed by using the yield line analysis. The predicted value of the moment capacity of the joint was found to deviate from the finite element result by no more than 10%, suggesting that the formula exhibited excellent accuracy and applicability. The minimum steel tube thickness of the end columns was determined by considering the yield of the beam flange section. The design method presented in this paper has the potential to offer a valuable reference for practical designs of the proposed connection joint. • A novel connection joint between a steel beam and a multi-celled corrugated-plate CFST wall was proposed. • A validated FE model was established for further investigation. • A parametric analysis was conducted to investigate the influence on the stiffness of the joints. • The effect of various parameters on the moment capacity of the joints was discussed. • Based on numerical and theoretical analyses, a formula for determining the moment capacity of the joint was proposed. [ABSTRACT FROM AUTHOR]

Stainless steel exhibits strain hardening characteristics under cyclic loading, hence presenting significant potential for application in seismic design. However, the current stainless steel structural design code fails to account for this beneficial effect in the cross-section classification. Given the scarcity of research about the behavior of structural stainless steel members under cyclic stress, this paper establishes the preliminary finite element model for the austenitic stainless steel (EN 1.4301) H-section. Firstly, finite element model validation of the existing cyclic tests on stainless steel members from literature was performed, followed by numerical analyses of a total of 370 beam and beam-columns members with different axial compression ratios and plate width-thickness ratios, and subsequently evaluated the cross-section classifications specified in prEN 1993-1-4, AISC 370 and CECS 410 through extensive parametric studies. The results indicate that the current design codes are conservative in the provisions for cross-section classification because they neglect the influence of plate interactions and material strengthening effects during cyclic loading. In this paper, limit and generalized expressions for austenitic stainless steel H-section with different axial compression ratios and cross-section classes under cyclic loading about major-axis are proposed. Additionally, the effect of material strengthening on cross-section classification under cyclic loading is examined. • Classification criteria for austenitic stainless steel H-section under cyclic loading about major-axis are studies. • Cross-section classification criteria according to EC3, AISC 370 and CECS 410 design codes are evaluated. • A new cross-section classification criterion for H-section under cyclic loading is proposed. • Effect of material strain hardening on cross-section classification under cyclic loading is discussed. [ABSTRACT FROM AUTHOR]

Reported studies on T-head Square-neck One-side Bolts (TSOBs) bolted I-beam to Hollow Section Square Column (HSSC) connections demonstrated the potential of TSOB applications in terms of mechanical properties, installation construction, and cost savings [11–14]. However, existing research was limited to the connection tests and lack a systematic and complete design approach. In this paper, the method for predicting the bending moment capacities and failure modes of the connections was proposed based on the existing test researches. Besides, the Finite Element Model (FEM) of the connections was established and validated by the reported test results. A sensitive analysis on the geometric parameters of the plastic hinge line pattern for calculating the bending moment capacity of the HSSC connecting face was carried out by the validated FEM. The proposed method was compared with the numerical simulation method in terms of the predicted results of the connection structural behavior. The results show that the prediction method proposed in this paper for the connection bending moment capacities and failure modes is accurate and reliable. Moreover, the mixed patterns of Type-H bolt holes and Type-V bolt holes are recommended for the TSOBC design because of the higher bending moment capacity than the unitary bolt hole patterns. • Method for predicting the bending moment capacity of TSOBC was proposed. • Failure mode of TSOBC was predicted based on design information. • Mixed patterns of Type-H and Type-V bolt holes are recommended for TSOBC. [ABSTRACT FROM AUTHOR]

The Elliptical-head one-side bolt (EOB) is a typical representative of the third generation for one-side bolts, relying on its elliptical head and bolt hole to achieve orthogonal anchorage, and the application scenario is mainly the bolted connection of closed-section members. Studies have been reported for the shear performance of EOBs bolted lap connections and the tensile behaviour of concrete-filled steel tubes, but there is still a lack of the tensile performance of EOBs connecting Hollow section columns (HSCs), which is necessary for the application of the component method for the beam-column joints design. Therefore, numerical simulation and theoretical analysis methods were employed in this paper to demonstrate the feasibility of adopting EOBs for this type of connection, including typical failure modes, novel yield line pattern in the HSC wall, comparison with the Conventional high-strength bolt (CHB) connections, analysis of the parameters related to the elliptical bolt head and hole, and the establishment and validation of the methodology for calculating the HSC bearing capacity. The results show that: The novel trapezoidal yield line pattern tended to show in the HSC wall with the smaller bolt pitch distance and larger gauge distance; The yield strength of the EOBs bolted T-stub to HSC connections was reduced by about 15% compared to the CHBs bolted ones; Vertical layout of bolt holes, accuracy of rough assembly, rotation deviation of bolt shank within 20° and avoidance of bolt offsets in bolt hole were recommended for EOB connections; The novel yield line pattern established in this paper predicted the yield strength of the connections, and the accuracy and stability were verified by comparing with finite element modelling (FEM) results. • Tensile performance of EOBs connecting HSC was carried out. • Trapezoidal yield line pattern was found in HSC connecting wall. • Strength of EOBs bolted connections was reduced by 15% compared to CHBs bolted ones. • Equations for predicting the strength of EOBs bolted connections were established. [ABSTRACT FROM AUTHOR]

This paper presents an experimental and numerical investigation into the behaviour of cold-formed concrete-filled dual steel-stiffened tubular (CFDSST) short columns under axial compressive load. This new composite column is fabricated from four cold-formed lipped angles to make the outer steel tube and a concentrically-placed steel tube located inside with concrete filled inside both the inner and outer tubes. The lips in the outer steel section behave as longitudinal stiffeners. To investigate the axial compression behaviour of these columns, fourteen CFDSSTs were designed and fabricated as well as two concrete-filled stiffened steel tubular (CFSST) columns and two concrete-filled double steel stiffened tubular (D-CFSST) columns for comparison. The columns failed due to local buckling of the outer steel tubes. The columns were modelled using finite element analysis and the accuracy and reliability of the numerical data was determined by comparing the numerical and experimental results. The validated model was employed to conduct a parametric analysis to investigate the behaviour of CFDSST columns with different variables and properties. The results show that the ultimate strength of CFDSST columns is most significantly influenced by the presence and strength of the sandwiched concrete between the two steel sections. The paper also presents an analysis of the accuracy and reliability of different international codified methods for predicting the load-carrying capacity of CFDSSTs. • Behaviour of concrete-filled dual steel-stiffened tubular (CFDSST) short columns is provided. • A series of experimental tests are described, assessed and employed to validate FE models. • The results showed that CFDSST columns have high ultimate load and superior ductility. • The accuracy of different codified resistance methods of CFDSSTs has been assessed. [ABSTRACT FROM AUTHOR]

In this paper, a pinned scaffolding node is proposed and studied with Q355 steel and sorbite stainless steel. Twelve sets of forward and reverse bending tests were designed to study the bi-directional bending performance at temperatures of +20 °C, −20 °C, and − 40 °C. The test results show that as the temperature decreases, the initial rotational stiffness and bearing capacity of the QSJ and the SSSJ both increase. Under the same temperature conditions, the yield bearing capacity and maximum bearing capacity of the SSSJ are greater than those of the QSJ. However, the SSSJ is susceptible to cracking in the weak zone of the C-shaped member subjected to forward bending moments in low-temperature environments, which requires attention in design and use. A finite element model can accurately simulate the bi-directional bending performance of the joint. The results show that increasing the thickness of the U-shaped members by 1–1.5 mm significantly increases the maximum load capacity of the joint. The wall thickness of the pipe has no influence on the bending properties of the joint, but the initial stiffness of the joint can be increased by the depth of wedging, a wall thickness of 6 mm is recommended for C-members. The form of damage to the SSSJ can be improved by increasing the curvature of the upper edge of the C-member at the wedge. The results of this paper can provide methods and references for the engineering design of scaffolding as well as for testing in low-temperature environments. • This paper adopts the separated low temperature loading device, which is convenient for the installation and disassembly. • This study presents a low-temperature loading test device and method. It can provide a test environment of −70 °C ∼ 150 °C. • It's innovative to study the material properties of cable body stainless steel and Q355 at −40 °C, −20 °C and room temperature. • The mechanical properties of the pin-type scaffolding nodes using sorbite stainless steel and Q355 at low temperature were investigated. [ABSTRACT FROM AUTHOR]

In this paper, through on-site investigation and monitoring, the characteristics of roadway deformation and the causes of deformation and damage are analyzed. Among them, the unreasonable support system is an external factor, and the nature of rock mass, deterioration degree of surrounding rock, and high ground stress are internal factors. A simulation method of CFST considering initial defects in core concrete is proposed and utilized to analyze the mechanical properties of CFST supports. Building upon numerical simulation results, we introduce an optimized support scheme comprising annular CFST support, segmental fissure surrounding rock grouting, and bolts. Field comparison tests demonstrate that the application of the new repair technology yields remarkable enhancements in the bearing capacity of surrounding rock and supporting structures while ensuring a more uniform stress distribution within the rock mass. • Deep roadways' deformation causes are analyzed from multiple perspectives. • This paper introduces the control technology of high bearing capacity pressure equalizing support. • A simulation method of CFST considering initial defects in core concrete is proposed. • Based on the finite element model, the support scheme is further optimized and applied on site. [ABSTRACT FROM AUTHOR]

High-strength steel (HSS) welded H-section beams are increasingly used in steel structures considering their advantage of high strength, but the stability is a concern especially near the supports, where the beams are prone to buckling under the combined actions of bending and shear. In this paper, finite element method was used to analyze the mechanical performance of HSS welded H-section beams under shear and bending-shear loads. A parametrical analysis for the H-section beams under pure shear loads was conducted, and a new shear buckling coefficient calculation method considering the interaction between plates was proposed. This coefficient was then applied to calculate the shear strength, and a design method for shear buckling strength based on the direct strength method (DSM) was proposed. Finally, a new bending-shear interaction curve was developed to predict the ultimate resistance of HSS welded H-section beams under bending-shear combination, and the reliability analysis results demonstrate the feasibility and safety of the design method proposed in this paper for HSS welded H-section beams. [Display omitted] • Calculation method for elastic shear buckling coefficient of H-section beams under shear. • The Direct Strength Method for high strength steel (HSS) welded H-section beams under shear. • A new bending-shear interaction curve for HSS welded H-section beams under bending-shear combination. • Reliability analysis of the new design proposals. [ABSTRACT FROM AUTHOR]

This paper presents herein pertains the experimental and numerical investigations on axial compressive behavior of square concrete-filled stainless steel tube (CFSST) columns after high-temperature sliding. A total of 117 CFSST specimens were tested under axial compression loading. The design variables included tube thickness, temperature, duration, and concrete compressive strength. Test results indicated that the initial stiffness of square CFSST short columns was degenerated due to high-temperature sliding. CFSST specimens exhibited a 62.7% lowest residual strength at 1000 °C. The influence of high-temperature duration on the residual strength of square CFSST short columns after high-temperature sliding was limited. The residual strength of specimens was positively correlated with the thickness and concrete strength. All square CFSST columns after high-temperature sliding experienced an outward local buckling under axial compression. Finite element models of square CFSST columns after high-temperature sliding are established and validated against the experimental results. In addition, the parameter formulae of residual strength for CFSST columns after high-temperature sliding were proposed, which achieved high accuracy. This research results could provide strengthening reference for the application of CFSST columns after high-temperature sliding. • Axial compressive behavior of square CFSST columns after high-temperature sliding were investigated in this paper. • The effects of tube thickness, temperature, duration, and concrete compressive strength are analyzed. • Finite element model (FEM) of square CFSST columns after high-temperature sliding were established. • Parameter formula was proposed to estimate residual strength for square CFSST columns after high-temperature sliding. [ABSTRACT FROM AUTHOR]

This paper presents the parametric analysis and design method for the concrete-encased hexagonal concrete-filled steel tubular (CFST) column base under combined compression and biaxial bending. The corresponding experimental and numerical investigations on the seismic performance of the concrete-encased hexagonal CFST column base under combined compression and biaxial bending have been presented in the companion paper (Yang et al., 2023). The finite element model established in the companion paper is used to study the influence of key parameters on the load bearing capacity and the distribution of internal force. These parameters include those of the CFST column, the outer RC, the plate-anchor component, the axial load ratio and shear connectors. A total of six failure modes are identified, including three types of flexural failure and three types of shear failure. The ultimate capacity and ductility of the column base with flexural failure at the bottom or top of the plate are higher than that of other four failure modes, which are determined as the reasonable failure modes for practical application in the design and analysis of concrete-encased column bases. A novel design approach for the concrete-encased CFST column base is introduced. A simplified method is proposed to predict the flexural resistance of the concrete-encased CFST column base, following up with the shear strength calculation of outer RC to determine the stirrup arrangement. Some constructional recommendations are also proposed. • A parametric study is presented to investigate the effect of major parameters on the failure mode and internal force distribution of the concrete-encased column base. • A simplified strength model for concrete-encased column base under combined compression and biaxial bending is presented. • Constructional recommendations for the concrete-encased column base under combined compression and biaxial bending are proposed. [ABSTRACT FROM AUTHOR]

The bending mechanical properties of FRP-confined square concrete-filled steel tubes (CFST) reinforced with internal latticed steel angles, including the failure modes, characteristic curves and characteristic mechanical parameters of tested specimens, were investigated through experiments in this paper. The bending mechanisms were also analyzed using an established finite element model, including the analysis of the bending moment borne by each component, the distributions of contact pressure between different components at the mid-span section, and the distributions of the neutral axis under the bending capacity. The key influential parameters, including the tensile strength and thickness of the FRP, were also examined. The results indicate that the FRP has almost no influence on bending stiffness, however, it enhances the yield bending moment and bending capacity to a certain extent. It was also found that the enhancement decreases as the width of steel tube increases, and the influence of FRP is more profound before reaching the peak load. The calculation formulas for the bending capacity were developed using the superposition method and numerical fitting method. Analysis of their accuracy shows that the formulation using the superposition method yields relatively accurate and safe prediction results, with the prediction errors of less than 20 %. • The bending behavior of FRP-confined square CFST reinforced with internal latticed steel angles is investigated through experiment; • A method for characterizing the yield bending moment and bending capacity of the tested specimens is proposed; • The bending mechanisms are analyzed using an established finite element model; • The calculation formulas for the bending capacity are proposed based on the superposition method and numerical fitting method. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical investigations on web crippling behavior of hot rolled rectangular hollow section (RHS) with web holes. A total of 20 rectangular hollow sections, subjected to interior-two-flange (ITF) and end-two-flange (ETF) loading conditions undergoing web crippling, were experimentally tested. The experimental program was designed to obtain web crippling of specimen having slenderness (h/t) value of 21.32, by varying size and offset distance of web holes under two flange loading conditions. Finite element models of experimentally tested beams were developed, and results of finite element analysis showed good agreement with experimental results. A parametric study was then conducted using finite element analysis on different cross section sizes, to demonstrate the effect of size and position of web holes on web crippling capacity of rectangular hollow sections. It was demonstrated that ratio of diameter of web hole to the depth of flat portion of web (a/h) and ratio of offset distance of web hole to the flat portion of web (x/h) are the primary parameters affecting the web crippling strength. Design recommendations in the form of reduction factors for both loading conditions are proposed, that are conservative to both experimental and finite element results. To assess the reliability level of design recommendations, reliability analyses were undertaken. • Web crippling tests on rectangular hollow section with web holes were performed. • Finite element models were developed and verified against experimental results. • Parametric study involving analyses of 360 finite element models was conducted. • The effects of size and position of web holes were evaluated. • Equations of strength reduction factors were proposed. [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical studies on the fatigue performance of an innovative orthotropic steel deck (OSD) with open-ribs, apple-shaped cut-outs, and additional transverse ribs, which is employed by the Zhangjinggao Yangtze River Bridge. This bridge is set to become the world's longest suspension bridge upon completion. A full-scale section of the OSD was fabricated and subjected to fatigue loading with a total cycle of 12.3 million times. The interested cracking-prone fatigue details include rib-to-deck and rib-to-crossbeam welded joints, along with the apple-shaped cut-outs of the crossbeam. Experimental results indicated that fatigue cracks initiated separately beneath the deck plate, on the flange of the rib, and at the rib-to-crossbeam welded joint, with equivalent stress amplitudes of 159 MPa, 148 MPa, and 99 MPa at 2 million cycles, respectively. In addition, detailed finite element model of the OSD was developed using ABAQUS and validated against the experimental results. The effects of the geometry dimensions and structural details of the bridge deck, longitudinal ribs, crossbeams and transverse ribs that influence the fatigue performance of this OSD were analyzed and discussed. Parametric analyses revealed that increasing the thickness of the deck plate, the thickness or the height of the longitudinal rib, and the number of transverse ribs can effectively reduce the stress amplitudes at corresponding fatigue details, which therefore improves their fatigue performance. This study provides useful references for the fatigue evaluation and design of OSDs with open-ribs and apple-shaped cut-outs. • A full-scale section model of a new open-rib orthotropic steel deck (OSD) underwent 12.3 million cycles of fatigue testing. • Fatigue cracks at weld details were examined, and corresponding fatigue strengths were evaluated based on experimental results. • A detailed finite element model was developed using ABAQUS and validated against the experimental results. • The influence of geometric dimensions and structural details on the stress condition of the OSD was analyzed and discussed. [ABSTRACT FROM AUTHOR]

The present paper reports results of a numerical investigation of the mechanical behavior of a column base plate connection subjected to an axial compression force and a bending moment. A three-dimensional nonlinear model was developed, using the Cast3M software, and validated against experimental data. In addition, the material nonlinearity as well as contact conditions between the different components of the connection were thoughtfully considered. Based on the validated model, an extensive parametric analysis was conducted to investigate the effect of stiffeners on the forces in the anchor rods. The results clearly indicate that the design approaches that consider only the tensile strength of anchor rods while neglecting the bending moments can lead to a poor estimation of the forces applied to these rods. They also suggest that adding stiffeners provides additional strength and reduces the anchor rod bending in one direction. However, it is important to note that the stiffeners also induce an additional moment in the opposite direction. This could make the anchor rod more susceptible to biaxial bending with tension. Furthermore, this study proposes a new specific shape of stiffener is suggested (c bp5). It was concluded that the proposed shape of stiffeners allows a more uniform distribution of forces and avoids excessive stress concentrations, effectively prevents the biaxial bending in the anchor rod. [Display omitted] • 3D FE model is developed to analyze column base plate connection behavior. • Eurocode 3 overestimated anchor rod strength by neglecting bending moment. • Stiffeners induced biaxial bending on anchor bolts in stiffened connections. • Proposed stiffener shape prevented biaxial bending of anchor rods. • Compression center position influenced by the stiffeners and their shapes. [ABSTRACT FROM AUTHOR]

Concrete-filled steel tubes (CFSTs) have been extensively employed in pressurized structural members, such as high-rise buildings, large-span bridges or offshore structures. Accurately and reliably assessing the damage of CFST column subjected to explosion is helpful for designers to optimize the structural performance and construction cost. Currently, peak displacement, the damage indicator, is generally estimated via finite element method (FEM) and single degree of freedom (SDOF) oscillator model. However, the computational overhead of FEM is high, while the computational accuracy of SDOF model is low. In this paper, artificial neural network (ANN) is used to overcome the above drawbacks. A dataset of 270 experiments and numerical simulations is collected from existing literatures to develop the ANN model. The performance of this model is compared with the conventional methods, i.e., FEM and SDOF model. And its prediction accuracy and efficiency are better in the comparison by experimental results. The damage evaluation and parameter research are carried out to reveal insight into the factors on the CFST column under explosion, including the property of column and its cross-section properties, the axial compression condition, and the explosive. To support the explosion resistance design of a CFST column, an explicit equation and an excel calculation table are introduced based on the ANN model. • Proper axial compression ratio (< 0.3) is beneficial to the explosion resistance of CFST column. • Appropriate hollow ratio (6% ∼ 23%) can improve the explosion resistance of CFST columns while reducing usage of concrete. • When the hollow ratio increases, the effect of concrete properties on the anti-explosion of CFST column is weakened. • In the case of sufficient database conditions, ANN can give a more accurate peak displacement than SDOF and FE immediately. [ABSTRACT FROM AUTHOR]

To facilitate easier construction when longitudinally reinforcing cold-formed thin-walled lipped channel steel columns with steel bars, here, both ends of the steel bars used for reinforcement were cut, and the impact on the reinforcement effect was studied through experimental and numerical simulation methods. Seven groups of reinforced column specimens with different indentation lengths and one group of unreinforced specimens were designed, and axial compression tests were conducted. Parametric analyses were performed using the numerical models calibrated by tests. These numerical models included three types of specimens with typical sections and several series of specimens with different steel plate thicknesses. Using these models, the effects of the steel bar indentation length L i , steel bar diameter D , and other factors on the ultimate bearing capacity and deformation of the reinforced specimens were studied. The experimental results indicated that when the steel bar is the same length as the specimen, the compressive bearing capacity of the cold-formed thin-walled lipped channel column can be significantly improved by bonding the steel bar. Additionally, the numerical analysis results indicated that the influence of changing the steel bar diameter D on the bearing capacity of the specimens is not significant when the steel bars are indented within a certain range. As the length of the steel bar indentation increases to a certain extent, the stress concentration at the end of the steel bar becomes more significant, causing local buckling of the specimen and ultimately leading to a sharp decrease in the bearing capacity of the specimen. To achieve reinforcement, facilitate construction, and ensure structural safety, the total indentation length L i of the steel bars should not be >2 cm in practical engineering projects. Considering the economy of reinforcement engineering, it is suggested that steel bars with smaller diameters, i.e., 6 mm, should be selected. Through a comparison between the FEA and the experimental process, it was confirmed that the failure model of the numerical model is basically consistent with the experimental phenomenon, and the bearing capacity deviation was <3.3%. This indicates that the FEM established in this study was reliable. • The mechanical behaviour of the indentation length of a steel bar on the axial compression performance of a cold-formed thin-walled lipped channel column strengthened with a bonding steel bar was investigated using static axial compression experiments, numerical simulations and parameter analysis. • By using the finite element model verified by experiments, an extensive parametric study was carried out. The feasibility of cutting the two ends of the steel bars used to reinforce the column by a certain length was verified for the convenience of construction. • On the basis of meeting the requirements of reinforcement effect, convenient construction, and economy, the recommended values for the total indentation length and diameter of steel bars in this reinforcement method in actual project are provided. • The reliability of the finite element model established in this paper is verified by comparing the finite element model analysis and test process used in the study. [ABSTRACT FROM AUTHOR]

This paper focuses on the mechanical properties of bolt-fastened wedge (BFW) joints utilized in prestressed internal support under eccentric loading. The validated finite element model was established based on the full-scale test results of BFW joints subjected to eccentric loads. A series of numerical simulations were conducted to systematically investigate the bearing capacity and bending performance of the BFW joint under eccentric loads. The influence of eccentricity, web thickness, eaves thickness, base splint thickness, bolt strength, and bolt diameter on the load-bearing and bending performance of BFW joints was investigated through further parametric evaluations. A four-parameter exponential moment-rotation model was developed based on the numerical results, demonstrating its accurate representation of failure modes, load-displacement curves, and moment-rotation curves observed in full-scale tests. The load-bearing and bending performance of the BFW joint exhibited a predominantly positive correlation with parameters such as web thickness, eave thickness, bolt strength, and bolt diameter; however, the effects of these parameters were inconsistent. The influence of bolt strength and diameter was found to be the most significant, while the effect of splint thickness was minimal, indicating a considerable level of redundancy. As eccentricity increased, there was a decline in both load-bearing and bending performance of the BFW joint. Finally, a comparison between the results obtained from fitted formulas and numerical as well as experimental data revealed that the moment-rotation model accurately described the bending performance of the BFW joint under eccentric loads. • Developed and validated a finite element model of the BFW joint. • Parametric studies revealed the influence of geometrical and material parameters on BFW joint performance. • Proposed a four-parameter exponential model to represent the moment-rotation characteristics of BFW joints. • The formulas for calculating the ultimate moment resistance and initial bending stiffness of BFW joints are presented. [ABSTRACT FROM AUTHOR]

In order to ensure that the joints have excellent mechanical properties along with post-earthquake recoverability, this paper proposes the angle connected high-strength steel moment resisting beam-column joint. A total of five groups of joints were designed and the static loading tests were carried out. The study focuses on the controllable mechanism of joint concentrated damage, summarizes the calculation method of joint loading capacity, and proposes a joint finite element model considering metal ductile damage. The analyses from the perspectives of joint strain, energy dissipation, displacement cloud diagram and deformation show that the joint flange cover plate and angle have produced significant plastic deformation, and the double damage element energy dissipation mechanism has been realized. From the analysis of the deformation ratio, the proportion of beam deformation reaches 95%, and the proportion of energy consumption reaches 94%, indicating that the joint achieves the centralized damage in the damage element of the beam splice position, and the beam-column main component maintains the elasticity state; Through the research of the angle bearing mechanism, it is found that the ratio of the tensile strain to the shear strain of the angle web plate is close to 10:1, which indicates that the angle web plate is mainly subjected to bending, with shear as a supplement, and this bearing mechanism can significantly improve the loading capacity of the joint. Through finite element analysis, it is found that high strength steel beam-column members are more conducive to achieving joint concentration damage controllability when a double damage element energy dissipation mechanism is used to improve the mechanical properties of the joints. Finally, by classifying and summarizing the failure modes of the joint, a calculation method for the loading capacity of angle connected high-strength steel beam-column joints was proposed. The maximum error between theoretical calculation results and experimental results was 8.8%, demonstrating the effectiveness of the calculation method. • First, the web angle bearing mechanism and displacement distribution pattern were analyzed by VIC-3D • Secondly, clarifying the centralized plastic energy dissipation mechanism of damaged elements. • Thirdly, yielding and ultimate stage load capacity calculation methods of joint are proposed • Forth, by FE model, the role of damage elements was quantified and the advantages of high-strength steels were justified [ABSTRACT FROM AUTHOR]

This paper presents the experimental and numerical analysis of cold-formed Q1200 ultra-high-strength steel (UHSS) angle- and channel-section stub columns to elucidate their resistance performance. Initially, the mechanical property test including the flat and corner coupon specimens was conducted to quantify the effect of the cold-forming process on Q1200 UHSS. Then, the stub column test was conducted on 16 cold-formed Q1200 UHSS angle- and channel-section stub columns. Based on the experimental results, a finite element model was established to simulate the resistance performance of the cold-formed Q1200 UHSS angle- and channel-section stub columns. Subsequently, a parametric study involving 133 numerical models was performed. Then, the suitability of the design approaches in EN 1993-1-12, AISI S100, AS/NZS 4600, and the direct strength method (DSM) was evaluated. For angle-section stub columns, the design approach outlined in EN 1993-1-12 was deemed suitable and the effective cross-sectional area design approach and DSM in AISI S100 were found to be safe. However, these approaches were excessively conservative for slender cross-sections in directly predicting the ultimate resistance of angle sections. Because of unsafe predictions, the design approaches in EN 1993-1-12, AISI S100, and DSM were deemed inappropriate for channel-section stub columns. The modification suggestions were proposed for the current design approaches, where the beneficial effects from the strain hardening were included. Based on the comparisons, the revised design approaches in EN 1993-1-12, AISI S100, and DSM could be used to accurately predict the ultimate resistance of the cold-formed Q1200 UHSS angle- and channel-section stub columns. • Mechanical properties of Q1200 UHSS with cold-forming effects were studied. • Resistance of cold-formed Q1200 UHSS angle and channel sections was revealed experimentally and numerically. • Design approaches were evaluated for cold-formed Q1200 UHSS angle and channel sections under axial compressive loading. [ABSTRACT FROM AUTHOR]

This paper numerically studied the compression behaviours of ultra-high performance concrete - filled square high strength steel tubes (UFSHTs) at low temperatures. Firstly, finite element models (FEMs) were developed to simulate the ultimate strength behaviours of UFSHTs under bending and compression, which were extensively validated by bending and compression test results. Then, extensive FEM analysis were carried out to investigate the low-temperature eccentric-compression behaviours of UFSHTs at low temperatures. The studied parameters in this numerical analysis included low temperatures, eccentricities, and slenderness ratios. The FEM parametric studies showed that (1) reducing low temperatures improved the eccentric-compression capacities; (2) The load-displacement curves exhibited a more protracted hardening stage with higher eccentricity ratios; (3) the normalized N-M curves were shrunk inward with slenderness ratios increasing. Finally, modified code equations were proposed to estimate the N - M interactions of UFSHTs under low-temperature eccentric-compressions, and validations of the predictions against the test and numerical results confirmed that the modified Eurocode 4 code equations provided more reasonable estimations than AISC360 and GB50936. • FEMs on eccentric compression behaviours of UHPC-filled high-strength steel tubes (UFSHTs) at low temperatures are developed • Low temperatures improve eccentric compression behaviours of UFSHTs • Eurocode 4 predict well the N - M interactions of UFSHTs at low temperatures • Low temperatures do not affect generalized N - M interactions of UFSHTs at low temperatures [ABSTRACT FROM AUTHOR]

This paper shows the results of full-scale tests conducted to investigate the mechanical behavior of flange joints for corrugated steel plate. The observed failure mode was local buckling of the flange plate. The moment-rotation response, deformation characteristic and strain distribution are presented and analyzed. A finite element model was established and verified with the test results, and used to perform a parametric study of key parameters. The influence of the bolt diameter, flange plate thickness and axial force on the initial stiffness, yield moment and failure mode are discussed. The failure mode can be classified into three types: flange plate buckling, bolt failure, and corrugated plate yielding. Additionally, an equation for the yield moment is proposed based on the yield line mechanism and numerical results. The proposed equation provides good accuracy, whereas the yield moment is conservatively estimated by Eurocode 3. • Full-scale tests of flange joints for corrugated steel plate were conducted. • The bending behavior and failure mode were investigated. • A finite element model was established and parametric study was performed. • An equation for yield moment is proposed using yield line mechanism. [ABSTRACT FROM AUTHOR]

Designing an economical and reliable steel mold for precast concrete (PC) components can accelerate the promotion of prefabricated buildings. This paper presents an automated design framework for a steel mold of PC components to generate manufacturing information, including dimensions and location of each plate. The profile and dimensions of PC components are extracted from the shop drawings, and a finite element model of the steel mold is established and initialized. A multi-objective optimization model considering material usage and manufacturing convenience is developed to determine the geometry and quantity of plates in steel molds. The non-dominated sorting genetic algorithm II (NSGA-II) is applied to obtain a Pareto solution set for steel mold design. The production information in DXF format can be automatically generated by parsing Industry Foundation Classes (IFC) model. The cost-effectivity and practicality of the proposed framework were verified via the design case for a real PC stair mold. • An automated design framework is developed for steel mold of precast concrete components. • The mold design is modeled as multi-objective optimization model considering material and manufacturing cost. • Design parameters are extracted from shop drawings to automatically establish a parametric finite element geometric model. • The NSGA-II method performs better than MOEA/D and SPEA2 algorithms in terms of solution diversity and computing efficiency. [ABSTRACT FROM AUTHOR]

To investigate the performance of concrete-filled corrugated steel tubular (CFCST) columns under combined axial compression and bending, numerical and theoretical analyses were conducted in this paper. Firstly, a refined finite element model was established and validated against the existing test results. The stress distribution of steel and concrete with different eccentricities was then analyzed. It was found that the sectional area of concrete region under compression and the stress of corrugated steel plates decreased gradually with the increase of eccentricities. The impacts of cross-sectional dimensions, corrugation dimensions, and material strengths were studied through a parametric analysis. The results indicated that the effect of cross-sectional dimensions on the performance of CFCST columns was more significant than that of corrugation dimensions, and increasing the steel bar strength was more beneficial to improving the ultimate resistance of the CFCST column than increasing the concrete strength. Finally, a theoretical model of compression-bending performance of the CFCST column was established based on the sectional analysis method, and the N - M interaction curve was presented. The proposed N - M interaction curve could conservatively predict the load-bearing capacity of the CFCST column, and the error of 90% of the numerical examples was less than 10%, which could be used for the design of CFCST columns. • A novel CFCST column was introduced for greater load-resistant efficiency. • A refined finite element model was established and validated. • A parametric analysis was conducted to investigate the impacts of key parameters. • The combined axial and flexural behavior of CFCST columns was explored theoretically. • The N - M interaction curves were proposed with good accuracy. [ABSTRACT FROM AUTHOR]

This paper studied the behaviour of High-performance Alkali-activated slag Concrete-Filled Steel Tubular members under transverse impact along with axial compression. Combining alkali-activated slag concrete with concrete-filled steel tubes provides a novel composite material incorporating the benefits of alkali-activated slag concrete and steel tubes. Alkali-activated slag concrete, known for its environmentally beneficial traits compared to traditional concrete, improves sustainability, while concrete-filled steel tube increases structural stability. Seven specimens composed of one hollow tube and six high-performance alkali-activated slag concrete-filled steel tubular specimens were tested using a drop hammer test setup to enhance our understanding of the structural performance of high-performance alkali-activated slag concrete-filled steel tubular members. A finite element analysis model was then established to broadly compare the impact resistance of circular high-performance alkali-activated slag concrete-filled steel tubular members. The mid-span displacement and impact test durations of specimens subjected to lateral impact and axial compression were assessed using a high-speed video camera called Phantom V411. This analysis includes the examination of maximum impact load, impact plateau value, maximum displacement, residual displacement, indentation, impact duration and strain responses, and an investigation into the failure modes of the specimens. The obtained results closely align with the experimental outcomes, indicating the effectiveness of the FEA model in predicting the behaviour of circular high-performance alkali-activated slag concrete-filled steel tubular members. • Adoption of high-performance alkali-activated slag concrete (HPAASC) in concrete-filled steel tubular columns. • High-performance alkali-activated slag concrete-filled steel tubular columns (HACFST) subjected to lateral impact. • Design a finite element analysis model for HACFSTs. • Validation of designed finite element model against experimental findings of HACFSTs subjected to lateral impact. [ABSTRACT FROM AUTHOR]

Steel I-beam bridges often require strengthening due to changes in loading requirements or to increase the design life of the bridges. As the bottom flange of the I-beam is accessible most of the time, an economical option is to weld a steel cover plate to the bottom flange of the existing beam. In a continuous bridge, the bottom flange of the I-beam at the pier location is in compression. This paper presents a numerical study on preloaded steel I-beams reinforced with steel cover plates welded at the compression flanges of the beams. A series of steel I-beams are analyzed to study the effects of different parameters, such as preload level, cover plate thickness, unbraced length of the beam, material grade difference between the original I-beam and the reinforcing plate, length of the cover plate, on the behaviour of I-beams strengthened with welded cover plates at the compression flanges. Three-point loading condition was considered to simulate continuous span bridges. Finite element (FE) analyses show that adding cover plates to adjacent spans of interior support increases the ultimate capacity and the stiffness of the beam, and there is no need to extend the cover plate beyond the zero-bending moment location. Also, the reinforcement can prevent the beam from lateral torsional buckling failure. Furthermore, the preloading level has an insignificant effect, less than 3% for a preload level up to 60% of the base beam capacity, on the capacity of the steel I-beams reinforced with welded cover plates in the negative moment region. FE analysis also shows that AASHTO can reasonably predict the flexural capacities of I-beams reinforced with welded cover plates in the negative moment region. • A FE-based study is conducted on steel I-beams welded with steel cover plates in the negative moment region • There is no need to extend the cover plate beyond the zero-bending moment region when welding it at the bottom flange of I-beam • Preload has little effect on the capacity of the steel I-beams reinforced with welded cover plates in the negative moment region • Reinforcing an I-beam at the compression flange can change the failure mode of the beam from LTB to cross-section yielding [ABSTRACT FROM AUTHOR]

This paper presents an experimental and numerical study on the behavior of the high strength concrete-filled double-steel-plate composite (CDC) tower in large-span bridge under axial compression and out-of-plane bending moment. A novel rotation loading scheme with high axial load levels reaching 64000kN is proposed, which has been conducted on five full-scale specimens of the composite tower wall. Then finite element models for the tower wall specimens are established to conduct parametric analysis and calculation methods for compression-bending capacity are proposed for the CDC tower wall. Finally, a multi-scale finite element model for the whole tower is developed and design method for the tower section is proposed. The test and numerical results show that the full-scale CDC tower wall specimens exhibit excellent load-bearing capacity and ductility. The failure of the specimens is marked by localized concrete crushing and steel plates buckling on the compression side, rather than the yielding of steel plates. The effective composite performance among the concrete, steel plates, stiffeners and rebar are guaranteed by properly designed interfacial configuration including bidirectional perforated plate connectors as well as shear studs. The study provides insights into the mechanical behavior of the CDC composite structure and proposes a fiber section-based method for accurate calculation of the cross-sectional compression-bending capacity. • A novel rotation loading scheme with high axial load levels reaching 64000kN is proposed. • FE models for the tower wall specimens and multi-scale FE models for the whole tower is developed. • Failure of the specimens is marked by concrete crushing and steel buckling on the compression side. • The effective collaborative performance is guaranteed by properly designed interfacial configuration. • A fiber section-based method is proposed for the cross-sectional compression-bending capacity. [ABSTRACT FROM AUTHOR]

In this paper, the pure bending tests on six specimens were carried out with the cross-sectional forms (unstiffened, stiffened, and multi-cell) and the loading angles (0° and 45°) as the variable parameters. The failure modes, bending moment-deflection curves, deformation characteristics, flexural strength, and stiffness of the specimens were obtained. The results indicated that the flexural strength and initial flexural stiffness of stiffened and multi-cell cross-shaped CFST members can be improved compared with the unstiffened members. The loading angle has no significant effect on the flexural performance of the cross-shaped members. Finite element models of cross-shaped CFSTs under pure bending were established, considering the residual stress and cold-formed strengthening effect, and the finite element results were in good agreement with the test results. Based on the parametric analysis, the design methods of flexural strength and flexural stiffness of stiffened and multi-cell cross-shaped CFST members were proposed. • Six cross-shaped CFST members were tested under pure bending. • Stiffeners or multi-cell form can improve flexural strength and stiffness. • Finite element models of cross-shaped CFST members were established. • Design methods for flexural strength and stiffness were developed. [ABSTRACT FROM AUTHOR]

Cable clamps are crucial for connecting component and transmitting prestress in cable structures. The anti-slip performance of the cable clamp is an important factor affecting the stability and safety of the structure. This paper introduces a novel test device to evaluate the anti-slip performance of arc groove cable clamps, and anti-slip performance experiments are performed on four arc groove cable clamps and four straight groove cable clamps. Long-term high strength bolt preload loss tests are conducted to investigate the loss pattern. Furthermore, seventeen parametric finite element models are developed to analyze the effects of groove bending angle, bolt length, cable force, and pressure plate stiffness on the anti-slip performance of arc groove cable clamps. It is found that the arc groove cable clamp exhibits a higher anti-slip bearing capacity, with a friction coefficient equivalent to that of the straight groove cable clamp, both exceeding 0.2. The bolt preload stabilizes at a certain value after 96 h of screwing the bolt, while it stabilizes after 24 h of tensioning the cable. The increase in the bolt length and angel of arc groove, as well as the reduction in the stiffness of the pressure plate, have a positive impact on the anti-slip bearing capacity of the arc groove cable clamp. There is a critical cable force that results in the lowest anti-slip bearing capacity of the arc groove cable clamp. These research results provide valuable insights for the design and engineering application of arc groove cable clamps. • A test device for evaluating the anti-slip performance of arc groove cable clamps was designed. • A calculation formula for the anti-slip bearing capacity of arc groove cable clamps was proposed. • The anti-slip performance of straight and arc groove cable clamps was compared through experiments. • Long-term loss law of high-strength bolt preload was investigated. • Numerical simulations were conducted to study the factors influencing the anti-slip performance of arc groove cable clamps. [ABSTRACT FROM AUTHOR]

In this paper, a prefabricated concrete-filled square steel tube (CFSST) fully-bolted exterior diaphragm joint was proposed. To clarify the influence of axial compression ratio, beam-column linear stiffness ratio and steel tube wall thickness on the seismic performance of joints, four 1/2 scaled specimens were designed and fabricated to perform quasi-static tests. The failure characteristics, hysteresis performance, energy dissipation capacity, ductility, bearing capacity degradation, stiffness degradation of each specimen were analyzed comparatively. The findings demonstrate that the failure mode of joints was mainly characterized by significant buckling deformation of the upper flange of the beams. Increasing the axial compression ratio, steel tube wall thickness and beam-column linear stiffness ratio will improve the bearing capacity and energy dissipation capacity of the joint. The effect of axial compression ratios and beam-column linear stiffness were further discussed through finite element analysis (FEA). According to the results, the axial compression ratio and beam-to-column linear stiffness ratio had a significant effect on the bearing capacity and the axial compression ratio of 0.5 had the best seismic performance. • A prefabricated concrete-filled square steel tube (CFSST) fully-bolted exterior diaphragm joint was proposed. • The failure mode, bearing capacity, ductility and energy consumption of the new joints were obtained from the tests. • The joints were connected with full-bolts flanges, which greatly improved on-site assembly efficiency and avoided on-site welding. • The different parameters of the new joint were investigated by numerical simulations. [ABSTRACT FROM AUTHOR]

In this paper, the ductile fracture prediction method based on micromechanism of low yield point steel LY225 under cyclic loading is studied based on acoustic emission (AE) entropy. Firstly, the parameters of the cyclic void growth model (CVGM) were calibrated by a series of repeated loading tests of the circumferentially notched specimens, and then the quantitative relationship model between the cumulative AE entropy and the cyclic void growth index (CVGI) of LY225 under low-cycle fatigue load was established through reciprocating loading tests, real-time acoustic emission monitoring and finite element analysis of variable cross-section flat specimens. The cumulative AE entropy was used as the ductile fracture evaluation index to realize the prediction of ductile fracture under low-cycle fatigue load. Different from the monotonic tensile loading situation, when the material undergoes repeated loading, it will accumulate AE entropy according to the changes in VGI during the tensile and compressive cycles. Based on this, the quantitative relationship model between the cumulative AE entropy under cyclic loading and the cyclic void growth index CVGI has been revised. Finally, the micro element method was used to predict the cumulative AE entropy curve of the plastic zone of the variable cross-section flat plate specimen under repeated loading. The predicted curve was in good agreement with the experimental results, verifying the applicability and accuracy of the modified bilinear quantitative relationship model under low cycle fatigue loading. [Display omitted] • CVGM fracture parameters of LY225 steel are calibrated. • A quantitative damage evaluation method of LY225 steel under cyclic load based on AE monitoring technology is proposed. • A modified bilinear model between cumulative AE entropy and cyclic void growth index CVGI is established. • The proposed model can be used in quantitative damage evaluation and ductile fracture prediction. • The effectiveness of the model in more complex stress and strain state is verified by a series of tests. [ABSTRACT FROM AUTHOR]

This study examined the hysteretic behaviour of Square Hollow Section (SHS) T- and X-joints subjected to cyclic in-plane bending moments. A nonlinear finite element software, Abaqus, was used to investigate SHS T- and X-joint seismic performance. Prior to the parametric study, the numerical model was validated based on the available test results in the literature. A comprehensive parametric study employed validated finite element models to evaluate the influence of critical geometric parameters, including the brace-to-chord width ratio (β) and the chord width-to-thickness ratio (γ). The results of the finite element analyses regarding ductility, flexural strength, and energy dissipation behaviour of SHS T- and X-joints under quasi-static cyclic in-plane bending were evaluated. Based on the hysteretic curves, increasing β generally leaded to higher initial stiffness and moment capacity in SHS joints, considerably reducing joint rotation. Conversely, the joints with larger γ exhibited reduced initial stiffness and moment capacity. Besides, the Eurocode 3 EN1993-1-8 predictions for the ultimate flexural strength of the joints are found to be conservative compared to finite element results. The results also revealed that the SHS T- and X-joints showed satisfactory ductility levels under in-plane bending load. It was observed that the SHS T- and X-joints with high β and low γ are advantageous for absorbing energy under seismic loads. These findings offered valuable insights for the seismic-resistant design of structures incorporating SHS joints, aiding in selecting optimal configurations based on specific performance requirements. • This paper presents a numerical study of hysteretic behaviour of SHS T- and X-joints with IPBM. • An increase in β ratio generally corresponded to higher initial stiffness, moment capacity, ductility. • The joints with large γ ratio exhibited reduced initial stiffness, moment capacity and ductility. • Eurocode 3 predictions were conservative in estimating the ultimate flexural strength of the SHS T- and X-joints under IPBM. • SHS T- and X-joints with high β and low γ were advantageous for absorbing energy under seismic loads. [ABSTRACT FROM AUTHOR]

This paper investigates experimentally and numerically the axial loading behaviour of Ultra-high performance concrete (UHPC) (135 MPa)-filled double skin steel tubular columns. A total of 37 stub columns (450 mm long x 152 mm diameter) were tested, including totally filled control tubes and tubes filled with normal- and high-strength (NSC and HSC) concrete. The study examined the effects of outer tube diameter-to-thickness (D o / t o) ratio and inner-to-outer tube dimeter ratio, which reflects UHPC wall thickness, on axial strength. A nonlinear finite element model using computer program LS-DYNA was also developed and verified. The study showed that the stubs with the thinnest outer tube (D o / t o = 72) and largest inner void ratio (0.7) achieved equivalent strength to the NSC (41 MPa) totally filled thickest tube (D o / t o = 32). Failure occurred by outwards local buckling of the outer tube and inwards buckling of the inner tube, along with UHPC diagonal shear failure. The peak load reduced nonlinearly as D o / t o increased due to a transition from a class 1 to class 2 section, and the post-peak load drop increased with increasing concrete strength (f c ′) and (D o / t o) ratio. As UHPC thickness reduced to a 50% volume reduction, axial strength reduced by 20–28%. The Canadian CSA S16:19 code provisions overestimated axial strength by 12–56%. A modification factor was developed and is recommended to be introduced in the code equation. • Double-skin tubes uses thin ultra-high performance concrete (UHPC) fill in between. • Outer tube thickness and concrete wall thickness were varied in short columns. • Superior strength-to-weight ratio to normal strength concrete totally filled tubes. • A 3D nonlinear finite element model was developed and verified to assess behaviour. • A modification to CAN/CSA S16 is proposed based on multiple regression analysis. [ABSTRACT FROM AUTHOR]