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• OCR-detected characters or words in an image require line segmentation to reunite into word or sentence. • Projection based line segmentation cannot be applied to Chinese historical texts. • Columns in Chinese historical texts exhibit a sub-divided column format. • Adjacent character detection (ACD) algorithm can deal with the unique column structure. • Performance of ACD algorithm as a post-processing of OCR is discussed. In recent times, the advent of AI-based optical character recognition (OCR) has garnered significant attention in the realm of digital text conversion. However, it is imperative to note that OCR solely identifies individual characters or words, and lacks the ability to reunite them into cohesive units such as words or sentences. Consequently, the manual sorting of them to establish the appropriate reading order has emerged as a bottleneck. In this paper, we present an algorithm termed adjacent character detection (ACD), designed to serve as a post-processing of OCR, facilitating automatic digital text conversion. The algorithm involves line segmentation through a quad-ACD scan (up-down-down-up), allowing it to consecutively discern characters within a column based on their adjacency relations. Conventional projection profile analyses have struggled to effectively partition the distinct internal structure of Chinese historical text, where two annotation columns often subdivide from a single body column. In contrast, our ACD algorithm employs an approach, reuniting adjacent characters rather than fragmenting the entire text into isolated entities. Additionally, ACD algorithm enabled body/annotation classification for OCR-detected characters based on the pattern analysis of its quad scan. This cumulative information empowers the conversion of digital text in a desired reading order. To assess the efficacy of the proposed algorithm, a set of ground-truth OCR result was subjected to rigorous testing, culminating in a reading order accuracy of 98.6%. Noteworthy robustness was also demonstrated in the face of misaligned columns, experimentally induced by applying tilt, warp, and wavy noises to the original digital images. Lastly, the algorithm was integrated with two pre-developed OCR models, resulting in a reading order accuracy of 97.7%. [Display omitted] [ABSTRACT FROM AUTHOR]

Accurate identification of the failure modes of Reinforced Concrete (RC) columns based on the design parameters of the structural members is critical for earthquake-resistant design and safety evaluation of existing structures. Existing identification methods have some problems, such as high cost, incomplete consideration of influencing factors, and low precision or recall in identifying shear or flexural-shear failure. In this paper, the main factors for the failure modes of RC columns are first analyzed and studied. Then, the problem of class imbalance in data samples is investigated. To identify the failure modes of RC columns, oversampling of data (BSB-FMC), model ensembling (RFB-FMC), cost-sensitive learning (CSB-FMC) and a fusion model of three strategies (BSFCB-FMC) are proposed. And finally, the SHapley Additive exPlanations (SHAP) method is used to provide a better interpretation of the designed model. The results show that the developed strategies can improve the accuracy of identifying the failure modes of RC columns compared to the models using a single Artificial Neural Network (ANN), a Support Vector Machine (SVM), a Random Forest (RF), and Adaptive Boosting (AdaBoost). The overall accuracy of the developed BSFCB-FMC model reaches 97%, and the precision and recall for the three failure modes are both above 90%. The designed model provides a solution for fast, accurate and cost-effective identification of the failure modes of RC columns. • We develop the models for identifying the failure modes of RC columns considering class imbalance problem. • The BSFCB-FMC model is developed by considering data oversampling, model ensembling, and cost-sensitive learning. • The designed model provides engineers with an interpretable, fast and stable model for identifying failure modes. [ABSTRACT FROM AUTHOR]

Arsenic contamination, at lower concentrations (up to 500 µg L-1), is an important environmental concern but has received limited attention. Adsorption capacities, kinetics and equilibrium phenomena are concentration dependent. Previous studies focused on higher arsenic concentrations associated with industrial discharges, failing to address arsenic contamination in drinking water. This study investigates arsenic adsorption using Eleocharis dulcis biochar loaded with CuO (EDB-CuO) at lower concentrations (up to 500 µg L-1). The synthesized biochar was characterized by X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Point of Zero Charge (PZC) and Scanning Electron Microscopy (SEM). Batch adsorption experiments were conducted, varying time, concentration, temperature and pH. Results indicated that increasing temperature positively influenced arsenic adsorption onto EDB-CuO, while pH had an opposite effect, with maximum adsorption occurring at lower pH levels (2−3). The equilibrium time was established at 240 min for arsenate adsorption. Kinetic data best fitted the Ho and McKay's plot and the Langmuir model calculated a maximum adsorption capacity of 26.1 mg g-1. Thermodynamic parameters, including enthalpy, entropy and activation energy, supported the conclusion that the arsenate adsorption process was spontaneous and chemisorptive. Column studies demonstrated remarkable adsorption retention performance (>88%) of the composite for arsenate removal over 8 h. Similarly, a fixed-bed column experiment was conducted to study the adsorption mechanism of arsenate on EDB-CuO by employing the Bohart-Adams, Thomas, and Clark models. The Clark model was found to best describe the arsenate removal mechanism. Additionally, recycling studies of arsenate from the loaded EDB-CuO surface were investigated up to 4 adsorption-desorption cycles. A small decrease was observed in the second cycle, from 92.06% removal to 85.15%, which further decreased in the third cycle (62.18%), and even more in the fourth cycle (30.8%). • Efficient arsenate adsorption onto Eleocharis dulcis biochar composite with copper. • Mechanism showing the applicability of Langmuir isotherms to the adsorption data. • Kinetics is explained by Ho and Mckay's plot. • Remarkable retention capacity of the composite in column experiment. [ABSTRACT FROM AUTHOR]

• Terrestrial laser scanning of the column of Hera Lacinia Temple and its surroundings. • Polygonal modelling and survey of the column and basement. • CFD analysis of the column, subjected to the main winds in the area. The study presents the results of a multidisciplinary research that integrates terrestrial laser scanning (TLS) and computational fluid dynamics (CFD) to document and analyse an archaeological asset subject to natural hazards. The experimentation was conducted on the surviving column of the temple of Hera Lacinia, located in Capo Colonna near Crotone (Italy). The column, the fragments of the crepidoma and of the foundation constitute the most visible remains of the peripteral Doric temple (second quarter of the 5th century B.C.), belonging to the most important sanctuary of Magna Graecia. The temple, the sanctuary and the other ancient buildings, which are in the area of the Capo Colonna promontory, were destroyed over the centuries to obtain construction material. Today the column and the remains of the temple are located inside the National Archaeological Park of Capo Colonna, protected from human action, but subject to natural phenomena which are dangerous or potentially dangerous in the long term. The wind exerts a constant erosion of the surface of the column and wear of the lower part of the shaft due to the continuous oscillations to which it is subjected; moreover, the wind thrust could add up to a possible seismic action. On the other hand, the geomorphological evolution of the promontory (coastal erosion and subsidence) causes the coastline to recede, and is responsible for landslides affecting the column-basement system. Starting from the point cloud acquired by the TLS, a mesh of the column, basement and surrounding terrain was created, aimed both at documentation, graphic analysis and CFD. The survey enabled the description of the current state of the column-basement system, documenting and measuring the shapes of the column, as well as the different inclinations of the individual parts caused by instability of the ground. Furthermore, the CFD model of the Hera Lacinia column was developed. The model is based on the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations with the k-ε closure turbulence model. The oncoming wind was modelled according to the results obtained from 70 years of statistics analysis (from 1950–2021) of wind hourly data (streamwise and spanwise components). The interaction between wind flow and the Hera Lacinia column geometry shows very complex phenomenona. The adopted numerical model was able to simulate correctly the main phenomena involved such as the flow separation occurring around the column as well as the wake behind it. Particular attention was paid to investigating the most damaged areas of the column, identified by analysing recent images of the column, where the values of the time-averaged drag and lift forces were obtained. In order to obtain the erosion-based damage prediction future research will focus on the analysis of air flow erosion of the Hera-Lacinia column, starting from the measurements in situ of the main air characteristics and using the latter as the fluid for the numerical simulation, and by also considering different values of wind speed and directions. [ABSTRACT FROM AUTHOR]

We study the computational complexity of multi-stage robust optimization problems. Such problems are formulated with alternating min/max quantifiers and therefore naturally fall into a higher stage of the polynomial hierarchy. Despite this, almost no hardness results with respect to the polynomial hierarchy are known. In this work, we examine the hardness of robust two-stage adjustable and robust recoverable optimization with budgeted uncertainty sets. Our main technical contribution is the introduction of a technique tailored to prove Σ 3 p -hardness of such problems. We highlight a difference between continuous and discrete budgeted uncertainty: In the discrete case, indeed a wide range of problems becomes complete for the third stage of the polynomial hierarchy; in particular, this applies to the TSP, independent set, and vertex cover problems. However, in the continuous case this does not happen and problems remain in the first stage of the hierarchy. Finally, if we allow the uncertainty to not only affect the objective, but also multiple constraints, then this distinction disappears and even in the continuous case we encounter hardness for the third stage of the hierarchy. This shows that even robust problems which are already NP-complete can still exhibit a significant difference in computational complexity between column-wise and row-wise uncertainty. [ABSTRACT FROM AUTHOR]

This study investigated the impact of openings on the punching shear strength of 'non-coarse aggregate acrylic polymer concrete' (APC) slabs. Twelve specimens representing scaled models of a flat, with different parameters such as concrete type, opening size, and distance from the column edge. The specimens were divided into five groups, including a control group of normal strength concrete and APC specimen without openings, as well as APC specimens with various opening sizes and distances, along with APC enhancement specimens. Experimental results were validated using Abaqus finite element software, demonstrating good agreement between the experimental and simulated outcomes. The analysis encompassed several aspects, including load-deflection response, ultimate loading capacity, post-ultimate loading capacity, failure patterns, and strain distribution. The absence of coarse aggregate in APC significantly impacted its shear resistance, leading to a reduction in internal friction. Compared to ordinary concrete slabs, the ultimate capacity of APC slabs without openings was approximately 36% lower. The presence of two openings adjacent to the column further decreased the ultimate capacity by approximately 33%. The size and distance of the openings played a crucial role in determining the ultimate capacity of APC slabs. Notably, the APC specimens exceeded the design ultimate load calculated by Egyptian Code of Practice (ECP-203-2020) and ACI-318-19 codes by approximately 1.4 and 1.6, respectively. However, the study advises against relying solely on APC in shear-sensitive constructions without integrating additional enhancements for shear resistance, as the results indicate a significant reduction in the shear resistance compared to ordinary concrete slabs. [ABSTRACT FROM AUTHOR]

For any structures, Reinforced concrete (RC) columns are the utmost carping members. RC columns jacketed with CFRP membrane enhance resistance, deformation aptitude, and the auspicious confining impacts. Sundry scrutiny has been implemented about circular columns wrapping or veiled with CFRP layers. This scrutiny will manifest about Genetic Programming (GP) and Artificial Neural Networks (ANN) as soft computing models, mobbing exploited to ascertain the lateral confinement coefficient (K s) valuate of RC circular columns jacketed with CFRP membrane. For the purpose to ascertain K s value, manipulate the corresponding ambit such as the diameter of the column (b), column length (L), thickness layer of CFRP (t w), the elastic modulus of CFRP membrane (E f) along with the compressive strength of unconfined concrete (f cc). Total collection of 142 datasets for the RC circular column was employed to decipher the prediction of K s. Various statistical metrics (R2 = 0.933; RMSE = 0.054; NMBE = -0.001) compared with the ANN model and exhibits the superiority of GP in predicting the K s. Taylor diagram and Rank analysis were also carried out in this article for justification. The lucidity of the GP machine enlightenment model overtures a greater sensible and exact prediction of K s value for RC circular columns in accordance with versatile loading conditions. [ABSTRACT FROM AUTHOR]

The evaluation of the confining pressure between steel and concrete is a complex yet important issue for concrete-filled steel tube (CFT) columns. The previous study is mainly based on the finite element model (FEM) because the confining pressure cannot be measured directly in the tests. Besides, the proposed approaches to calculating the bearing capacity of CFT columns and confining pressure varied significantly as a result of the different simplification. The neural network can simulate the complex problems quickly and accurately based on the proper training and validation. This study investigates the bearing capacity of CFT columns and the confining pressure of concrete based on a newly established experimental database and the artificial neural network (ANN) models. The results can be obtained from five primary parameters of rectangular CFT columns using the ANN models. The obtained bearing capacity and confining pressure from ANN models is compared and validated with that presented in the previous literatures. The parametric studies are performed to evaluate the bearing capacity and confining pressure with the variations of the dimensions and the material strength. The result could contribute to evaluate the interaction between the steel tube and infill concrete and its effect on the bearing capacity of rectangular CFT column. [ABSTRACT FROM AUTHOR]

Reactive Dividing Wall Column (RDWC) modelling has attracted significant attention in recent years because simulations of processes containing such columns have demonstrated the potential for significant savings in energy and capital cost. Most modelling of these columns involves decomposing RDWCs into a thermodynamically equivalent flowsheet of reactive and non-reactive column sections in a sequential modular process simulation package. Such simulations of (R)DWCs can be time consuming to create and difficult to converge. It has been suggested that equation-oriented solvers can have superior numerical performance. Here, we use a CAPE-OPEN compliant equation-based parallel column model (PCM) that enables the rapid modelling of an RDWC as a single self-contained unit. Some conventionally modelled RDWCs from the literature are reproduced with the PCM to demonstrate its validity and excellent numerical performance. The ease and rapidity with which different RDWC configurations can be created is a significant advantage of our PCM. [Display omitted] • We describe an equation-oriented rate-based parallel column model for reactive distillation in Dividing Wall Columns. • The model can simulate DWCs of arbitrary configuration. • Model is easy to set up and rapid in execution. • Model is in excellent agreement with results of prior work. [ABSTRACT FROM AUTHOR]

This study investigates the stress-state- and strain-rate-dependent behavior of CeramTec ALOTEC 98% alumina ( Al 2 O 3 ) ceramic through experimentally validated finite element (FE) modeling. As the constitutive material model, a rate-dependent viscosity-regularized phenomenological model (JH2-V model) was implemented through a VUMAT subroutine in ABAQUS software. The FE model was informed and validated with the data for indirect tension and compression–shear tests under dynamic rates both quantitatively (i.e., stress–strain histories and lateral strain–axial strain curves) and qualitatively (i.e., manifestation and accumulation of damage). The validated model was leveraged to study the effect of the JH2-V model regularization parameters, mesh sensitivity, and bulking across different stress states. Additionally, by modeling the compression–shear specimen with different angles, the effect of shear on the material response was quantitatively investigated through the definition of a volumetric average damage parameter and shear strain history. Altogether, the outcomes of this study have implications for the computational design and development of ceramic-based structures in higher-scale applications (e.g., impact). [ABSTRACT FROM AUTHOR]

This paper presents experimental and numerical investigations of the seismic performance of a novel self-centering (SC) hollow-core (HC) fiber-reinforced polymer (FRP)-concrete-steel (SC-HC-FCS) bridge column. This new structure is fabricated by mounting external energy dissipators (ED) and applying unbonded post-tensioned (PT) basalt FRP (BFRP) tendon to the conventional HC-FCS column that consists of an outer FRP tube and an inner steel tube, with the space between filled with concrete. The SC-HC-FCS column combines the advantages of accelerated bridge construction and self-centering. The effects of the initial prestress force values and the configuration of the energy-dissipated aluminum bar on the column performance are studied. Based on the experimental and numerical results, it is found that the proposed SC-HC-FCS column shows adequate self-centering and energy dissipation capacities. However, it is required to properly select the configuration and material properties of the aluminum bar as energy dissipators to further refine the seismic resistance of the SC-HC-FCS column. [ABSTRACT FROM AUTHOR]

This study presents an advanced framework for modeling the lateral-torsional buckling behavior of cellular steel beams, which combines hybrid intelligent models with numerical simulation. The proposed hybrid intelligent models employ a large dataset-based finite element method (FEM) for training and validation the framework, as well as metaheuristic algorithms for optimal auto-hyper-parameters selection. A total of 1535 numerical models are examined in order to evaluate the lateral-torsional buckling behavior. Following that, the least square support vector machine (LSSVM) optimized using four metaheuristic algorithms (ME): particle swarm optimization (PSO), ant lion optimization (ALO), grey wolf optimizer (GWO), and Harris hawks optimization (HHO) algorithms, is utilized to estimate accurately the lateral-torsional buckling resistance. According to the findings of a comprehensive performance evaluation utilizing statistical and graphical comparing criteria, the suggested LSSVM-ME predicts the lateral-torsional buckling behavior with excellent accuracy. LSSVM-HHO, in particular, outperforms the other hybrid intelligence models, with an RMSE of 41.72 kN.m and an NSE of 0.99. Overall, the results indicate that the proposed framework has a great potential for use as a practical tool for estimating the lateral-torsional buckling behavior of cellular steel beams. [ABSTRACT FROM AUTHOR]

Row–column designs are widely recommended for experimental situations when there are two well-identified factors that are cross-classified representing known sources of variability. Row–column designs are expected to result a gain in accuracy of estimating treatment comparisons in an experiment as they eliminate the effects of the row and column factors. However, these designs are not readily available when the number of treatments is more than the levels of row and column blocking factors. Here, an algorithmic approach for constructing a new series of row–column​ designs with incomplete rows and columns, by amalgamating two incomplete block designs has been proposed. A wide range of incomplete block designs, viz., balanced incomplete block designs/ partially balanced incomplete block designs/t-designs, are available in the literature, which can be selected as input designs to construct the proposed series of designs. To avoid the complexity involved in the construction algorithm, an R package "iRoCoDe" has been developed for the generation of the proposed designs. A catalogue of designs has been prepared using "iRoCoDe" for ≤ 20 treatments. Further, a general form of the information matrix of these incomplete row–column​ designs has been derived, and characterization properties of component designs of the final array have been studied. The designs obtained are cost-effective and efficient as they require less experimental resources and have high canonical efficiency factors. • Incomplete row-column designs are obtained by fusing two incomplete block designs. • R package is developed to avoid the complexity involved in the construction algorithm. • The developed software is fast and user friendly. • A catalogue of generated IRC designs for v ≤ 20 is prepared for quick reference. [ABSTRACT FROM AUTHOR]

• The development and validation of a model for single-stage centrifugal compressors is presented • The influence of fluid and size on efficiency, operating range, and axial thrust on bearings is investigated • The results are presented in the form of design maps • Design maps are generated for six working fluids and different values of size parameter • The multi-objective optimization of a compressor stage for a heat pump application is documented The impact of size and working fluid on the efficiency, operating range, and axial thrust on bearings is examined for high-speed, oil-free centrifugal compressors. First, the development and validation of a reduced-order model based on scaling principles is documented. Then, the validated compressor model is used to generate design maps for stages operating with arbitrary fluid molecules, and characterized by different size. The results show that compressors operating with fluids made by heavy and complex molecules provide lower efficiency over the entire design space, if compared to their simple-molecule counterparts. However, compressors for complex-molecule fluids require lower rotational speed, and generate lower axial thrust on bearings, thus making them particularly suitable for small-scale applications. Furthermore, a decreasing value of the size parameter has a detrimental effect on the stage efficiency, as a result of manufacturing constraints. The results computed by the compressor model suggest that the efficiency penalty is more sensitive to variations of clearance gap than to surface finishing. Lastly, the reduced-order model has been used to perform a design exercise, i.e., the multi-objective optimization of the first compressor stage of the heat pump test rig being realized at Delft University of Technology. The key characteristics of the optimal compressor design has been compared to those derived from the design maps, to corroborate their validity. The optimal design has been extensively characterized by means of CFD, providing further evidence that efficient mini-compressors operating with organic fluids, and featuring pressure ratios up to five at off-design, are feasible. [ABSTRACT FROM AUTHOR]

To improve the simulation calculation accuracy of long-span composite girder bridges during construction and ensure high calculation efficiency, this paper presents a novel algorithm for analyzing internal force redistribution in steel–concrete composite girder bridges. Based on section equivalence theory, the expression describing the internal force distribution of the steel girder and the concrete deck is derived, and a new finite element model of a double-layer element, named virtual double-layer element model, is established. Based on the exponential recursive method of concrete beam element shrinkage and creep effects and the influence mechanism of concrete deck shrinkage and creep in steel–concrete composite girders, an analysis model of composite girder shrinkage and creep is established. Calculation expressions of the equivalent node force increment and fixed-end force increment of the composite girder integral element after conversion of a composite section are derived. The feasibility of the method proposed in this paper is verified through analysis of models of a continuous beam and a cable-stayed bridge. The algorithm was applied to calculate the construction process of the world's largest span cable-stayed bridge, achieving alignment with its design objectives. • An algorithm accurately simulates the continuous combination of double-layer elements and the shrinkage and creep effects. • The computational efficiency of the algorithm is enhanced using an exponential function recursion method. • The algorithm is integrated into a self-developed FEM software and its correctness has been validated. • The algorithm has been applied to calculate the construction process of several composite cable-stayed bridges. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation on the crushing behaviour of full-section pultruded glass fibre reinforced polymer (pGFRP) profiles with 11 different cross-section geometries, encompassing 6 different shapes (C, I, W, SHS, RHS, L sections). Quasi-static axial compressive tests were conducted on stub column specimens, mitigating second-order and buckling effects. The crushing phenomenon of the pGFRP profiles was investigated regarding the following aspects: (i) influence of end surface flatness, (ii) analysis of load/stress vs. strain behaviour, (iii) definition of relative slenderness thresholds to avoid buckling, (iv) determination of full-section compressive strength for various cross-sections, and (v) correlation of geometrical and mechanical experimental data. The results show that when the relative slenderness was limited to 0.7, no buckling occurred, and the load was uniformly applied across the section of the profiles. Additionally, for the different cross-section geometries, the estimates of resistance to crushing of pGFRP stub columns obtained from compressive coupon tests were non-conservative: in average, the resistance to crushing of full-section stub columns was around 60 % of those estimates. Unlike the coupon tests, the stub columns presented complex failure with multiple damage modes, which were attributed to the non-uniformity of material properties across the section walls. The correlation analysis provided insights into the linear dependency of the full-section compressive strength with geometrical and material properties. Surprisingly, shear strengths were shown to play a more relevant role in the crushing phenomenon of stub columns than compressive strength. The findings of this study will contribute to the drafting of improved design guidelines able to estimate more accurately (and likely more reliably) the compressive resistance to crushing. • Large database of experimental stub column tests along with mechanical characterization tests. • Detailed load/stress vs. strain response obtained from 2D DIC analysis. • Full-section compressive resistance significantly lower than estimates from coupon compressive tests. • Multiple failure modes in stub column tests, some of them different from those of coupon compressive tests. • Strong linear correlation between full-section compressive strength and coupon-based shear strength. [ABSTRACT FROM AUTHOR]

Concrete-filled double-skin steel tubular (CFDST) columns have been widely used in buildings and infrastructures. Therefore, the compressive behavior of CFDST columns is a subject that should be further investigated. In this paper, an efficient procedure using a Long Short-Term Memory (LSTM)-based model is proposed to predict complete axial load-displacement curves of CFDST columns under compression for the first time. Hybrid databases, including experimental data collected from the literature and numerical data generated from finite element analyses, are utilized to establish the proposed model. To augment the training data, the DoppelGANger (DGAN) algorithm is used for generating additional dummy data, which is added to the training set. After that, the Optuna framework is used to optimize the hyperparameters of the proposed model. The accuracy of the proposed model is demonstrated by comparing its predictive results with those obtained from tests and finite element results. In addition, the importance and contribution of each input variable in the proposed model are evaluated by using SHapley Additive exPlanations (SHAP) method. Finally, a cloud-based graphical user interface (GUI) is developed in the Hugging Face platform to predict and plot the complete axial load-displacement curve of CFDST columns. This GUI is a convenient tool for making predictions without requesting machine learning knowledge by the users. • A LSTM-based model is proposed to predict complete axial load-displacement curves of CFDST columns for the first time. • The proposed model performance is proven by comparing with tests and finite element results. • SHAP is used to analyze the contribution of each input variable to the output prediction. • A cloud-based GUI is made in the Hugging Face platform to provide a convenient tool for users. [ABSTRACT FROM AUTHOR]

In this work, the axial local compression of circular reinforced concrete-filled steel tube (CRCFT) stub columns is studied. Sixteen specimens, including one circular reinforced concrete stub column (CRCC) specimen and fifteen CRCFT specimens, were prepared, considering different variables, such as the local compression area ratio β , sectional steel ratio α , volume stirrup ratio ρ v , longitudinal reinforcement ratio ρ , and concrete strength f c. The axial local compression of specimens were experimentally investigated in terms of the damage process, failure mode, load-displacement relationship, ultimate bearing capacity, stiffness, deformation capacity, and strain characteristic. The finite element model of the CRCFT was also developed and validated. The parametric analysis of the local compression area ratio β , sectional steel ratio α , and volume stirrup ratio ρ v facilitated the further investigation of the axial local compression behavior of CRCFT. The results showed steel tube buckling and concrete shear failure exhibited by CRCFT specimens. With the increasing local compression area ratio β , the ultimate bearing capacity reduced by 3.6–47.9 %, whereas the local compression strength improvement coefficient β cl increased by 11.8–273.9 %. With the increase in section steel ratio α and volume stirrup ratio ρ v , the ultimate bearing capacity, stiffness, and deformation capacity were improved. Longitudinal reinforcement ratio ρ and the concrete strength f c also influenced the stiffness of CRCFT specimens. A simplified calculation method for the ultimate bearing capacity of CRCFT specimens was also presented. • Axial local compression behavior of CRCFT column was experimentally and numerically investigated. • Composite confinement effect of steel tube and stirrup was researched. • The simplified calculation method for the ultimate bearing capacity of CRCFT was presented. [ABSTRACT FROM AUTHOR]

In an attempt to alleviate the problem of growing waste glass and fully utilize the excellent material properties of fiber-reinforced polymer (FRP), a novel composite structure, waste glass aggregate concrete glass fiber reinforced polymer (GFRP)-steel double-skin tubular column (WGAC-DSTC), was proposed based on the FRP-concrete-steel double-skin tubular column (DSTC). In the present research, eight WGAC-DSTCs and four waste glass aggregate concrete-filled GFRP tubular columns (WGAC-CFFTs) were investigated to explore their mechanical performance under axial compression. Effects of diverse replacement ratio of waste glass aggregate, GFRP tube thickness, and hollow ratio of column on the mechanical performance of twelve columns were investigated. Meanwhile, this research analyzed and discussed the failure characteristics of columns, load-displacement relationship, ductility coefficient, stiffness coefficient, parameter analysis, ultimate bearing capacity, load-strain relationship and constraint factor. Besides, predicted formulae for estimating the ultimate bearing capacity of WGAC-CFFTs and WGAC-DSTCs were proposed. The research results indicated that (1) Failure mode of the WGAC-DSTCs displayed axial compression failure or shear failure and failure mode of WGAC-CFFTs exhibited mainly axial compression failure; (2) WGAC-DSTCs with 10 % replacement ratio of waste glass aggregate and hollow ratio of 0.4 indicated an increase in the ultimate bearing capacity by 17.24 % and 45.78 %, respectively, as the GFRP tube thickness increased from 1.5 mm to 2 mm and 3 mm. As the column's hollow ratio enhanced from 0.27 to 0.68, the column's ultimate bearing capacity significantly decreased by 7.08 %-60.55 %. The ultimate bearing capacity of WGAC-CFFTs showed a trend of first increasing by 8.33 %-9.41 % but then decreasing by 1.52 % when the replacement ratio of waste glass aggregate rose from 0 % to 30 %; (3) WGAC could replace natural aggregate concrete in traditional DSTC and the bearing capacity could be guaranteed. Besides, it's recommended to utilize 20 % replacement ratio of waste glass aggregate for the WGAC-DSTC whose ultimate bearing capacity enhanced by 15.17 % and possessing optimal mechanical performance; (4) The results calculated utilizing predicted formulae matched well with results of experiment. The application of waste glass aggregate concrete in DSTC can contribute to economic growth and environmental protection and meet the concept of sustainable development. • A novel composite structure for purpose of environmental protection was developed. • The mechanical performance of the WGAC-CFFTs and WGAC-DSTCs under axial load was investigated. • The effect of replacement ratio of WGA, GFRP tube thickness and hollow ratio was considered. • Predicted formulae for estimating the ultimate bearing capacity of WGAC-CFFTs and WGAC-DSTCs were proposed. [ABSTRACT FROM AUTHOR]

In recent years, a new type of composite columns called concrete-encased concrete-filled steel tube (CECFST) columns, has been developed and applied in real practice for bridges and buildings. There are a lot of experimental and numerical studies have been conducted for CECFST columns and beam-to-CECFST column joints. However, most of the previous studies only focused on conventional cast-in-situ (CIS) construction. To facilitate the construction, precast concrete (PC) technology is preferable in compression with the conventional CIS one. The outer concrete encasement and the embedded steel tube can be prefabricated together to form a precast composite column unit. After that, the precast concrete beam can be connected to the column unit on-site. To achieve the above-mentioned construction procedure, some proper and effective connection details are needed for PC beam-to-CECFST column joints. In this regard, two simple connection details were developed for connecting the precast concrete beam with the CECFST column in this paper. Cyclic tests were conducted to assess the seismic performance of the specimens with the proposed connections and the experimental results were reported. The cyclic behaviour of PC beam-to-CECFST column joints with the proposed connection details was evaluated based on several performance indices, such as ductility and energy dissipation capability. Moreover, the American standard ACI 374.1–05 was adopted to assess the effect of connection details on the seismic performance of PC beam-to-CECFST column joints. Lastly, a simplified model was developed to capture the shear force–strain relationship of the joint region. • Two simple connection details are proposed for PC beam-to-CECFST column joints. • Seismic performance of PC beam-to-CECFST column joints is evaluated. • Effects of connection details on joint cyclic behaviour are studied and analysed. • Simplified model is developed to predict the shear behaviour of concrete beam-to-CECFST column joints. [ABSTRACT FROM AUTHOR]

Box-type houses often use asymmetric cold-formed thin-walled steel columns with complex edges to meet structural requirements. However, there is a need to clarify the mechanical properties of eccentric loading in this section of the steel column. This study conducted eccentric compression tests on 24 asymmetric cold-formed thin-walled steel columns with complex edges, clarifying the specimens' ultimate load-bearing capacity and buckling mode. The results showed that the resistance to pressure provided by the corner was higher than that provided by the two crimped edges. Subsequently, a finite element model was established, and its accuracy was verified by comparing it with experimental results. Finally, based on the formula for calculating the nominal axial strength in AISI, the direct strength method formula for the stable bearing capacity of asymmetric cold-formed thin-walled steel columns with complex edges under in-plane eccentric compression was proposed. This method takes into account the local-global interactive buckling and distortional-global interactive buckling. The comparison between the theoretical calculation results and numerical simulation results demonstrated that the design method proposed in this study is effective and conservative. It can provide a reference for future engineering applications. • Conducted eccentric compression test on asymmetric angular column with complex edge. • The detailed FEM was established and validated based on the test results. • DSM formula was proposed and validated for the column section studied. [ABSTRACT FROM AUTHOR]

To tackle the challenges associated with the construction and transportation of large-scale wind turbine units, an innovative steel-concrete composite tower (SCCT) component was proposed based on the double-plate shear wall design theory. Three groups of single corrugated plate composite wall members were subjected to axial compressive performance, considering the effects of the number of corrugated plate waves, built-in vertical reinforcement, and built-in stiffening ribs. The test results indicated that the corrugated plate has better deformation ability than the flat panel. When the wave number increased from three waves to five waves, the bearing capacity increased by 4.98%. In addition, the SCCT members with built-in stiffening ribs outperformed the SCCT members with built-in vertical reinforcement bars in terms of ultimate load, stiffness, and ductility, with an increase in load-carrying capacity of 19.2%. The finite element software ABAQUS was also used to simulate and analyze the test results. These research findings can provide a theoretical and experimental basis for the optimization of wind turbine tower structures. • Axial compressive performance of steel-concrete composite tower (SCCT) component was investigated. • SCCT components with built-in stiffening ribs achieved higher bearing capacity, stiffness, and ductility than those with built-in vertical reinforcement. • The relevance and validity of the finite element model were verified by aligning the outcomes with the experimental data. [ABSTRACT FROM AUTHOR]

To explore the eccentric compressive behaviors of partially encased recycled aggregate concrete (PERAC) columns after exposure to high temperatures, 12 columns were tested in this paper, including 3 columns under axial load as controls. Factors considered in the experiment were replacement levels (r) of recycled coarse aggregate (RCA), temperature (T), and relative eccentricity (e/H). The test results show that the temperature rising of webs is effectively delayed by protection of recycled aggregate concrete (RAC). And the post-heated PREAC column has higher ductility under eccentric load due to the better deformation capacity of RAC than that of natural aggregate concrete (NAC). Similar to the effect of T , when the e/H adds from 0 to 0.2, both ultimate axial strength and initial stiffness of columns decrease significantly. When e/H adds from 0.2 to 0.4, flanges away from the loading axis are gradually changed from compression to tension. All columns eventually fail due to local buckling of flanges near loading axis. Compared with partially encased concrete (PEC) columns, the r of 50% is beneficial for PERAC columns to get better ductility and maintain stiffness. In addition, the modified method based on the code T-CECS719–2020 can be used to predict the ultimate strength of PERAC columns after exposure to high temperatures. • Compression tests are conducted on post-heated PERAC columns with different relative eccentricity. • Effects of different parameters on loading behaviors of PERAC columns were evaluated. • The presence of RAC can effectively delay the rise of web temperature during heating process of the column. • Columns exposed to higher temperatures tend to have larger deflection and lower loading capacity. • A bearing capacity calculation method for PERAC columns exposed to high temperatures is proposed. [ABSTRACT FROM AUTHOR]

To obtain superior corrosion resistance and impact resistance, as well as good economic benefits, two new types of composite structure called as steel tube internally-reinforced concrete-filled weathering steel tube (STRCFWST) and steel spiral internally-reinforced concrete-filled weathering steel (SSRCFWST) columns are proposed and compared in terms of their impact resistance in this paper. Eleven impact tests were conducted and three parameters comprising steel spiral diameter, wall thicknesses of outer and inner steel tube were considered to evaluate their influences on the lateral impact behaviors. Results show the presence of inner steel tube and reinforcement cage significantly enhances the impact resistance while slightly decreases the energy absorption capacity. Increasing inner steel tube wall thickness helps to improve the impact resistance, however the contribution is not so good as that produced by increasing the outer steel tube wall thickness, whilst varying steel spiral diameter almost has no impact. Numerical models were developed by ABAQUS/Explicit and verified via the test, based on which the full-range behaviors of STRCFWST, SSRCFWST and unreinforced concrete-filled weathering steel tube (CFWST) columns under impact loading were compared and discussed. It is demonstrated that steel tube and reinforcement cage provide little confinement on concrete infill under impact. With the same internal steel ratio, inner steel tube makes a greater contribution to sectional bending moment resistance and energy absorption as compared to the reinforcement cage. [ABSTRACT FROM AUTHOR]

• Twenty-five circular HCFHST stub columns after exposure to the heating and cooling process were tested under axial compression. • The effects of various parameters on the temperature distribution, spalling of the steel-concrete interface, failure modes, mid-height stress and strain, and post-fire mechanical performance were analyzed. • Available design methods for normal strength CFST columns were evaluated for their applicability to the unexposed and exposed HCFHST columns. The high-strength concrete-filled high-strength steel tubular (HCFHST) column is an innovative type of high-performance steel-concrete composite component, which has a broad prospect for engineering applications. To investigate the axial compressive behavior of post-fire HCFHST stub columns with circular cross-sections, twenty-five specimens were heated following ISO 834 standard fire and then loaded to failure under axial compression after being cooled. The effects of various heating durations, concrete and steel strength on the temperature distribution, spalling of the steel-concrete interface, post-fire ultimate bearing capacity and axial stiffness were analyzed. The residual ultimate capacity and axial stiffness of HCFHST stub columns experience a pronounced decrease as the heating duration increases. High strength steel has no significant contribution to the enhancement of the post-fire axial stiffness of HCFHST stub columns, and the effect level of high-strength concrete on the failure load of composite columns subjected to different heating durations is similar. Finally, the applicability of relevant equations for the residual compressive capacity of the ordinary strength CFST column to HCFHST stub columns was evaluated. The evaluation results revealed that available methods of conventional strength CFST stub columns cannot obtain accurate post-fire resistance predictions of circular HCFHST stub columns. [ABSTRACT FROM AUTHOR]

The combination of steel-FRP composite bar (SFCB) and engineered cementitious composites (ECC) in structures exposed to harsh conditions can offer benefits in mechanical performance and durability. In this study, the seismic behaviors of SFCB-reinforced ECC and concrete columns were investigated through reversed cyclic loading tests and the effects of matrix types, axial load ratios, and reinforcing bar types were discussed. The results showed that the SFCB-reinforced ECC columns experienced flexural failure characterized by SFCB fracture, whereas the SFCB-reinforced concrete columns failed owing to concrete crushing. The SFCB-reinforced ECC columns showed a 41.5 %− 116.3 % enhancement in deformation capacity and a 34.7 %− 65.2 % improvement in average energy dissipation coefficient compared with SFCB-reinforced concrete columns, which demonstrated that using ECC in SFCB-reinforced columns addressed issues of their low deformation and low energy dissipation capacity. In addition, the plastic hinge length of SFCB-reinforced columns increased substantially with the application of ECC, and the stiffness degeneration and residual deformation were reduced. • The failure mechanism of SFCB-reinforced ECC and concrete columns is comprehensively investigated through testing. • The disparities in seismic behaviors resulting from substituting concrete with ECC in SFCB-reinforced columns are discussed. • The effects of reinforcement type and axial load ratio on the seismic behaviors of SFCB-reinforced columns are analyzed. [ABSTRACT FROM AUTHOR]

A gap in current design approaches demands explicitly introducing a capacity design approach when designing steel-concrete composite reduced web section (RWS) connections. This paper addresses this gap by presenting test-validated finite element models and parametric investigations, focusing on the presence and absence of composite action over the web opening, the diameter, and the end-distance of the web opening. Additionally, the first-ever comprehensive experimental and numerical database from the literature on bare steel and composite RWS connections is compiled and thoroughly analysed to develop the capacity design assessment for such connections. Both parametric investigations and the database highlight the significance of the capacity design ratio between the connected components in achieving a desirable ductile mechanism. This is crucial, as evidenced by the results: a 15 % increase in the connection's moment capacity led to an average 21 % difference in dissipated energy, favouring the web opening with a diameter of 50 d o over 80 d o , in RWS connections with the presence of composite action. The results show that proper consideration of the capacity design approach in designing RWS connections ensures a stable yield mechanism is developed, resulting in the redistribution of global action and capping deformation demands on non-ductile elements. This enhances connections' rotational capacity and ductility by forming the Vierendeel mechanism. Lastly, the paper presents a detailing recommendation for employing RWS connections in both existing and new structures for seismic purposes. • Demountable steel-concrete composite extended end-plate RWS specimens examined under cyclic loading. • High-fidelity modelling and parametric finite element investigation. • A complete up-to-date database on steel and composite RWS connections. • Current design approaches demand an explicit introduction of the capacity design approach for prequalified RWS connections. • Vierendeel mechanism enhances the rotational capacity and the ductility of RWS connections. [ABSTRACT FROM AUTHOR]

Both wood and bamboo are natural green biomaterials with a long application history in human society. A novel bamboo-wood composite fabricated with glued laminated bamboo (glubam) and laminated veneer lumber (LVL) was developed to reduce wood resource demand and to promote bamboo utilization efficiency. Experimental and analytical investigations were conducted to study the mechanical performance of 36 bamboo-wood composite columns with different slenderness ratios under axial compression. The three-layer composite column was composed of glubam as outer layers and LVL as a core layer, with horizontal or vertical configurations respectively. The failure modes, ultimate capacity, load and deformation behaviour were evaluated. Strength failure was the typical failure mode of the short columns while buckling was commonly observed for the longer columns. Columns with vertical LVL core had overall better performed with higher compressive strength than the ones with horizontal LVL core configuration. The ultimate load of the composite columns with thin-strip glubam as outer layers were increased by 31.6 % to 45.3 % than those of thick-strip glubam as outer layers. The compressive capacity of the specimens predicted according to three standards were compared with the experimental results. An improved expression considers the material strength and column slenderness ratio was proposed, which provides a better prediction than the current design standards. • A novel bamboo-wood composite fabricated with glued laminated bamboo (glubam) and laminated veneer lumber (LVL) is proposed. • Composite columns with vertical LVL core performed better than those with transverse LVL configuration. • Thin-strip glubam outer layers provide higher ultimate load than the thick-strip ones however final damage is more severe. • Proposed expression for the compressive strength of the composite columns has a rational precision. [ABSTRACT FROM AUTHOR]

The steel–FRP composite bar (SFCB) has superior ductility and corrosion resistance, and is usually employed as longitudinal reinforcement in offshore infrastructures in harsh environments. Nevertheless, the behavior of SFCB reinforced concrete members under eccentric loading, especially in combination with FRP stirrups, remains unclear to date. To address this issue, an innovative approach is adopted in this study, wherein SFCB is employed as the longitudinal reinforcement and carbon fibre-reinforced polymer-mesh fabric (CFRP-MF) as the stirrup, fabricating an innovative corrosion-resistant reinforced concrete column. The eccentric compression performance of 12 concrete columns with different reinforcement types was profoundly investigated. Research outcomes indicated that the failure modes (namely tension and compression damage) observed in columns reinforced with longitudinal SFCBs and CFRP-MF stirrups were comparable to those of conventional steel reinforced concrete (RC) counterparts. However, notable advancements were observed in terms of effectively controlling crack development within the column. The incorporation of CFRP-MF stirrups in the column exhibited a significant confining effect, leading to enhanced compression performance under small eccentricities compared to conventional RC columns. However, in cases involving large eccentricities, the replacement of longitudinal reinforcements with equal-area SFCBs did not yield improved axial bending performance for the columns. In addition, a theoretical model was developed to predict the failure modes and capacities of columns reinforced with SFCB longitudinal reinforcement combined with CFRP-MF stirrup columns. This model exhibited a relatively high level of accuracy, underscoring its potential as a valuable tool for guiding the design of corrosion-resistant marine infrastructure and informing hybrid reinforcement schemes. A corrosion-resistant reinforcement combination has been proposed to address the issue of corrosion-prone reinforcement within the seawater and sea sand structures. The CFRP-MF stirrup columns were much better than the RC columns in terms of crack control and constraining effect. A prediction model for the axial bending capacity of longitudinal SFCB and CFRP-MF stirrup columns has been established. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive experimental programme and analysis of ultra-high-performance fibre-reinforced concrete (UHPFRC)-encased concrete-filled steel tube (CFST) columns subjected to axial and eccentric compression. Twelve short columns were tested, with six of them utilising UHPFRC encasement while the other six employing normal strength fibre-reinforced concrete (FRC) encasement for comparison purpose. The study focused on the effects of load eccentricity ratio, concrete encasement type, and steel tube configuration. Key findings from the test results including failure modes, load-deflection behaviour, moment-curvature relationships and curvature ductility were examined. The findings showed that UHPFRC-encased CFST columns exhibited significantly enhanced strength and bending capacity, while FRC-encased columns showed remarkable ductility. A notable shift in failure mode was observed with increasing load eccentricity ratio, transitioning from crushing of concrete to compression, and then to balanced failure. Furthermore, applicability of prevalent design codes such as EC4, AIJ, and ACI 318 in calculating the peak loads of UHPFRC- and FRC-encased CFST columns was assessed. The plastic stress distribution methods in EC4 and AIJ overestimated peak loads, while ACI 318's strain compatibility approach accurately predicted FRC-encased columns but not UHPFRC-encased columns. To address this, modifications of the parameters α and β were incorporated into the ACI design method to reflect the relative brittle nature of UHPFRC, resulting in accurate predictions. • Twelve short UHPFRC- and FRC-encased CFST columns were tested. • Test parameters were load eccentricity ratio, encasement type, and steel tube configuration. • Outer concrete encasement remained intact without spalling. • UHPFRC-encased CFST columns exhibited significantly enhanced strength and bending capacity. • FRC-encased columns showed remarkable ductility. [ABSTRACT FROM AUTHOR]

[Display omitted] • CSPP/ZnO NPs retains the anisotropic, biological structure from corn stalk pith. • Zn2+ adsorption behaviors affecting morphology and bactericidal action of columns. • The mechanism clarification for improving water sterilization of ZnO NPs via CSPP. • The hybrid column exhibits excellent performance to kill pathogens by filtration. The escalating demand for clean water and proliferation of microbial contamination in water have challenged ecosystems and human health safety. ZnO NPs are widely used as environmental restoration agents, but their efficacy in water decontamination is hindered by low biological toxicity. In order to enhance its sterilization efficiency, we propose a top-down strategy utilizing the unique maze structure of corn stalk pith (CSP) as a germ trapper for ZnO. The in-situ delignified CSP offers abundant active sites for the adsorption of Zn2+, exhibiting the typical behaviors of monolayer, physisorption, endothermicity, spontaneity, and randomness. This adsorption behavior exerts an influence on microscopic morphology of the composite column, consequently resulting in alterations to antibacterial properties. The results show that the hybrid column fabricated under the Zn2+ initial dosage of 1.00 mol/L at 30 h for 40 °C, possesses such optimal features as stacked grain-shaped ZnO NPs of 669.3 mg/g loading amount with adhesion coefficients of 0.73 ∼ 0.86 for bacterial microparticles. Consequently, the assembled bio-filter can eliminate E. coli and S. aureus as high as 99.7 % and 96.5 % respectively, attributed to CSPP labyrinth structure to enhance pathogen capture from water and facilitate ZnO-mediated inactivation. The collective findings emphasize the viability of agro-waste stalks as bio-filters for water purification. [ABSTRACT FROM AUTHOR]

To address corrosion problem of steel bars and shortage of freshwater and river sand in marine and offshore structures, a novel hydrophobic-modified longitudinal steel-FRP composite bars (SFCB) and FRP hoops reinforced low-alkalinity seawater sea-sand concrete (SWSSC) is developed. However, axial compressive behavior of hybrid SFCB and FRP reinforced columns is not clear and the applicability of existing design methods is low. Here, nine hybrid reinforced columns have been designed and tested. Typical failure modes of columns and axial compressive behavior of constituent materials (i.e. , hydrophobic reinforcements and low-alkalinity SWSSC) are investigated. It is found that the synergistic confining effect formed by hybrid reinforcement are significant. The mesh confinement formed by densely distributed FRP hoops and longitudinal SFCBs improves the local buckling behavior, and effectively constrains the lateral expansion of concrete core, resulting in improved compressive strength and ductility of column. The compressive contribution of single longitudinal SFCB to ultimate load capacity of column can be enhanced effectively, up to 36.3 %, by increasing steel content of SFCB. Based on this, a prediction model of hybrid reinforced columns is proposed, which can accurately evaluate the ultimate load capacity. This work provides valuable experimental observations and load capacity model for hybrid reinforced column, which promote its design and application in marine engineering. • Highly confined columns exhibit two peak loads with ductile failure mode. • Large SFCB diameter markedly enhances the load capacity of hybrid reinforced column. • A new load capacity prediction model is proposed considering synergistic confinement of SFCB and FRP hoop. • Hydrophobic SFCB and low-alkalinity SWSSC is promising for marine engineering. [ABSTRACT FROM AUTHOR]

Complex temperature fields may develop inside structural steel elements in fire, severely affecting the local and global response of the structure. However, simplified yet well-accepted design procedures allow for uniform temperature distributions in the steel elements. The second generation of Eurocodes provides advanced models for localised fires where non-negligible thermal gradients both inside the sections and along the elements are expected to influence the resistance of steel elements, especially those critical to the stability of the entire structure, such as vertical members. This paper sheds some light on the consequences of employing procedures with increasing complexity in the design of unprotected axially compressed steel columns subjected to localised fires for which the effect of the smoke layer is not significant. Five procedures were compared, considering a refinement in both the thermal and the mechanical models, culminating in the application of a procedure enabling complex temperature fields both in the section and along the column, namely the LOCAFI model, and exploiting numerical simulation in SAFIR. A parametric study was conducted, encompassing different fire scenarios and structural characteristics, resulting in 27468 analyses. It was shown that in the case of localised fire scenarios that induce significant thermal gradients in the structure advanced modelling is recommended because it better captures the thermomechanical response. Detailed considerations on relevant outcomes, such as the temperature at failure, were provided. Finally, the influence of the surrounding structure on the effectiveness of the procedures was investigated extending the parametric analysis to columns with various degrees of axial restraints. [Display omitted] • Design with simple thermal and mechanical models provides inaccurate predictions. • ISO834 leads to uneconomical consideration that fire protection is always required. • The LOCAFI model included in the 2nd generation of Eurocodes is highly recommended. • Thermal gradients become less relevant for higher axial restraints. • Failure cannot be related only to slenderness for complex thermal gradients. [ABSTRACT FROM AUTHOR]

Combining advantages of both reinforced concrete (RC) and concrete-filled steel tube (CFST), concrete-encased concrete-filled steel tube (CECFST) members demonstrate superior structural performance over pure RC or CFST counterparts. Nevertheless, current research in this domain has primarily focused on member and connection behaviour of CECFST columns, with no attention given to frame-level performance. This significantly impedes applications of this form of high-performance composite members into actual engineering practice. To bridge this research gap, a novel precast steel beam-to-CECFST column composite system is proposed in this study. This is followed by a comprehensive experimental programme, where seven precast steel beam-to-CECFST column exterior sub-assemblages were tested under cyclic loads. In the test specimens, three types of connections, including beam-to-beam (B-B), column-to-column (C-C) and beam-to-column (B-C), were incorporated to establish a precast steel beam-to-CECFST column sub-assemblage. Horizontal displacement versus shear force relationship and failure mode of the test specimens are reported, followed by a detailed analysis of test results and findings. Furthermore, a comprehensive mechanism analysis is presented, with emphasis on energy dissipation behaviour and deformation mechanism of the proposed precast composite system. The test results show that the proposed precast composite system has comparable load-carrying capacity and energy dissipation capacity in comparison with conventional cast-in-place counterparts. This indicates that despite using precast beam-to-beam and column-to-column connections, structural performance of the composite frame system would not be significantly affected, showing that this form of precast steel beam-to-CECFST column composite system has considerable potential to be adopted in actual engineering practice. • A novel fully precast steel beam-to-CECFST column composite system is proposed. • Seven precast steel beam-to-CECFST column sub-assemblages were tested under cyclic loads. • Effect of precast connections on seismic performance of the sub-assemblages were studied. • Comprehensive mechanism analyses were conducted. • The proposed fully precast system exhibited comparable resistance to cast-in-place system. [ABSTRACT FROM AUTHOR]

To utilize fully the excellent mechanical properties of bamboo, thin-walled steel, and carbon fiber-reinforced polymer (CFRP), a CFRP-confined composite member composed of bamboo strips and a thin-walled steel tube (CBSC) was proposed to design a bamboo member with high-bearing capacity and ductility. The axial compressive tests were conducted on 26 CBSC members. Based on the validated finite-element (FE) model, a parametric analysis was performed to investigate the effects of different parameters on the axial compressive mechanical behaviors of CBSC members. Finally, the predictions of the ultimate axial compressive bearing capacity derived from the unified theory of concrete-filled steel tube columns agreed well with the test and FE results. The results showed that the failure mode of short CBSC members was strength failure, including material damage in the middle of the member, and end-crushing failure. However, the slender CBSC members exhibited typical global buckling failure. CBSC members can fully utilize the mechanical characteristics of the three materials to exert their combined effects. In terms of improving the bearing capacity, the recommended number of CFRP layers for all CBSC members is one except for the short CFRP-confined bamboo strip, thin-walled, circular steel-tube composite members, which is equal to two. The critical slenderness ratios of the CBCSC specimens and CBSSC specimens for distinguishing strength failure and global buckling are 19 and 36, respectively. The proposed predicted equations can accurately estimate the ultimate bearing capacity of CBSC members under axial compression. • A composite bamboo member with high-bearing capacity and ductility was designed. • Effects of parameters on the compressive behaviors of the CBSC members were studied. • Theory-based predictions agreed with experimental and simulation FE results. [ABSTRACT FROM AUTHOR]

Concrete-filled basalt fiber reinforced polymer (BFRP) -steel composite tube (CFBCT) columns have become a highly anticipated composite structure. The lateral confinement provided by BFRP can effectively suppress the possible local buckling of the steel tube, thereby achieving the goal of optimizing axial compression performance. With the widespread application of CFBCT in engineering practice, the BFRP outer layer is likely to be affected by factors such as construction accidents or connection design, resulting in slotting and drilling damage to the BFRP outer layer. Therefore, the mechanical properties of CFBCT subjected to local damage are critical. This article examined the effects of slotting and drilling the BFRP outer layer on the axial compression performance. The non-uniform strain distribution at the damaged site was analyzed using digital image correlation (DIC) testing technology. The results show that the local damage can lead to a decrease in the bearing capacity and ductility. Compared with drilling damage, slotting has a more significant impact on axial behavior. Due to the local damage, the ultimate stress decrease by 8.1 % and 12.4 % respectively. A new computational method was introduced to predict the quantitative impact of local damage on CFBCT. • Various types of damage to the CFBCT's outer layer have been studied. • Vertical slotting has a significant impact on the axial compression performance. • A DIC system was used to investigate the evolution of strain field around the damaged area. • The ultimate stress model was modified according to a local damage impact coefficient. [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]

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]

The seismic fragility of prefabricated self-centering frame structures composed of self-centering joints is investigated for reference in their seismic design and application. In this paper, a new design of the concrete-filled double steel tubular column-RC beam joint with self-centering capability and friction energy dissipation was proposed. The joint was modeled with ABAQUS and OpenSees, and hysteretic simulation was carried out to verify the reasonableness and accuracy of the OpenSees phenomenological model. Based on the OpenSees platform, a one-bay, six-story prefabricated self-centering frame structure was modeled, and seismic fragility analysis based on the incremental dynamic analysis was performed, in which seismic fragility curves were obtained according to the probabilistic demand analysis model. The results indicated a high coincidence in hysteretic curves between the ABAQUS model and the OpenSees phenomenological model, which showed favorable self-centering and energy dissipation performance of the joint proposed in this paper. Based on FEMA 356, three kinds of performance points were defined, i.e., "Immediate Occupancy" (IO), "Life Safety" (LS), and "Collapse Prevention" (CP). The prefabricated self-centering frame in this paper tended to exceed the IO, where the stiffness and strength of the structure was susceptible to damage. However, the failure probability at the LS performance level remained low, with only 5% and 37% failure probability under moderate and rare earthquakes, respectively. The structure achieved a collapse margin ratio of 4.28, which indicated a high collapse resistance in it. • Established a phenomenological joint model based on SelfCentering Material model. • Derived lognormal distribution relationship between EDP and IM using linear regression. • Obtained failure probability of self-centering joint for CFDST under various seismic intensities through IDA. [ABSTRACT FROM AUTHOR]

This study examined the axial compressive properties of glass–fiber reinforced plastic (GFRP)–confined recycled aggregate concrete–filled steel tube (RACFST) stub columns. The differences in the failure modes, load–displacement curves, and load–strain curves of the composite columns with different parameters were analyzed, including the number of GFRP layers, steel tube thickness, recycled aggregate substitution rate, and recycled aggregate concrete compressive strength. The results revealed a bulging failure mode in the middle of the GFRP–confined RACFST stub columns. With the increasing substitution rate of recycled aggregate, the bulging deformation of the specimen increased. This eventually resulted in a reduction in the stiffness and bearing capacity but an improvement in the ductility at a later stage. The early stiffness and ultimate bearing capacity of the specimen can be increased by thickening the steel tube or strengthening the recycled aggregate concrete. However, the ductility is greatly reduced in the later stage. Based on the axial compression test of GFRP–confined RACFST stub columns, the axial compression bearing capacity formula was derived. Compared with the existing formula, the formula presented in this paper has greater accuracy. In addition, a finite element (FE) model of the composite column was established to analyze the stress development during the compression process. • The axial compression performance of GFRP–confined RACFST stub columns was studied. • The effects of different influencing factors on the mechanical properties of stub columns were investigated • A formula for calculating the bearing capacity of stub columns was obtained through the theoretical derivation. • The performance of stub columns under axial load was analyzed by the finite element method, and the accuracy was verified. [ABSTRACT FROM AUTHOR]

Precast segmental columns have various advantages as compared to traditional cast-in-place monolithic columns. Numerous studies have been conducted to investigate the behavior of precast segmental columns under earthquake and impact loadings. However, there is limited research available on the dynamic response of precast segmental columns subjected to blast loads. In this study, the dynamic behaviors of precast segmental concrete-filled double-skin steel tube (PS-CFDST) columns under blast loading were examined. Field blast tests were conducted on three large-scale columns subjected to large equivalent explosions, and a typical failure pattern of fracture of post-tensioned (PT) tendons was observed in the test. A high-fidelity finite element model was developed to study the behavior of PS-CFDST columns under blast loading. The numerical model was validated against the test results and was then used to investigate the dynamic response, failure modes, and energy dissipation mechanism. It was found that the dynamic response of PS-CFDST columns could be divided into two phases, i.e., the shear deformation and bending deformation phases. In the shear deformation phase, the PS-CFDST column dissipates a significant amount of blast energy through the slippage between segments and absorbs most of the blast energy through the damage of the concrete and the outer steel tube. The self-centering capacity of PT tendons is primarily demonstrated in the bending deformation phase. The effects of modeling techniques for PT tendons and friction coefficient between segment surfaces were also investigated. An innovative sleeve connection of CFDST segments was proposed and its effect on improving blast performance of PS-CFDST columns was analyzed. • Field blast tests were conducted on three large-scale PS-CFDST columns subjected to large equivalent explosions. • High-fidelity finite element model was developed and validated against the test results. • The dynamic response, failure modes, and energy dissipation mechanism of PS-CFDST columns were investigated. • Effects of modeling approaches of PT tendons, surface interaction friction and sleeve connections were discussed. [ABSTRACT FROM AUTHOR]

In this study, three types of socket steel beam-column corner-connections with grouting for modular integrated construction are proposed and experimentally investigated. Six grouted and two ungrouted specimens were fabricated and divided into two groups: one group underwent monotonic loading and the other was subjected to quasi-static cyclic loading. A comprehensive comparison was conducted across all these specimens. The test results show that grouted bolted socket corner-connection with diagonal stiffeners can enhance its lateral stiffness, bearing capacity, structural integrity, and energy dissipation capacity. Conversely, the absence of diagonal stiffeners and bolts connecting the flanges of the floor and the ceiling channel beams led to a significant decrease to the bearing capacity, lateral stiffness, and energy dissipation capacity of the grouted bolted socket corner-connection. This underscores the critical role of diagonal stiffeners and bolts in these connections. Notably, weld cracking or tearing was a common failure, especially at the welds connecting the beam to the column and those linking the diagonal stiffeners. This failure highlights the importance of ensuring weld quality in practical engineering applications. According to Eurocode 3, all the specimens tested could be classified as semi-rigid connection, however, only the grouted bolted socket corner-connection with diagonal stiffeners met the criteria for full-strength connections. • Propose novel grouted steel beam-column corner-connections for MiC. • Explore static and cyclic loading performance of ungrouted/grouted corner-connections. • Quantify the effect of diagonal stiffeners, grouting and bolts on static/cyclic behavior. • Perform the joint classification based on EC 3. [ABSTRACT FROM AUTHOR]

This article aims to investigate the structural response of a novel type of composite concrete columns in which the conventional steel bars are replaced in the main longitudinal direction with small circular-section steel tubes infilled with cementitious grouting material (CGM). In this study, 24 circular cross-sectional reinforced concrete columns with different transverse reinforcement configurations were tested under varied eccentric axial loads (in two series with variable slenderness ratios). The type of columns (short with a height-to-diameter ratio of 4.41 or long with a ratio of 10.29), the type of reinforcement (steel bars of 16 mm diameter, steel tubes of 16 mm outer diameter infilled with CGM or steel tubes of 25.4 mm outer diameter infilled with CGM), the spiral pitch (50 or 75 mm), and the eccentricity of the applied load (25 or 50 mm) are the main test parameters included in the experimental program. The remarkable compression and tension strengths of confined CGM in comparison to concrete inspired the idea of embedding CGM within small steel tubes. Furthermore, economic factors support replacing a portion of the conventional steel material with cementitious grouting material. To evaluate the impact of the steel reduction resulting from CGM embedment within the steel tubes, the specimens' load capacity, strain, and deformation were investigated. The outcomes demonstrated that CGM-filled steel tubes are a promising and economically feasible solution for lowering the amount of steel used in column members. The findings demonstrated that the load-carrying capability of both the short and long-tested columns reinforced with 25.4 mm diameter CGM-infilled steel tubes was marginally greater than that of the columns reinforced with 16 mm diameter steel bars by 7%. Furthermore, specimens reinforced with 16 mm outer diameter steel tubes, where the wall area of the steel tube is only 30% of the area of a steel bar with the same diameter, provide an ultimate capacity ranging from 62% to 77% of the columns reinforced with steel bars with a 16 mm diameter. The capacity of the specimens decreased as the slenderness ratio and the eccentricity of the applied load increased, while the tested column's lateral deformation increased. In the meantime, a notable enhancement in the specimen's load capacity was seen with the reduction of the spiral pitch from 75 to 50 mm. • Cementitious grouting material-filled steel tubes were proposed as an alternative to traditional steel bars in composite concrete columns. • The advantage of steel tubes is demonstrated by the higher strength gain for concrete within tubes as opposed to concrete with steel spirals alone. • The axial and lateral stiffness of all tested columns showed a considerable decrease as the eccentricity and slenderness ratio increased. [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]

• Pit-shaped defects in Cf53 rolled products due to large composite CaS-inclusions. • Large composite CaS-inclusions accumulate on the inner wall to form SEN clogging. • T.O, T.Ca, T.S content, and steel temperature affect the formation of CaS-inclusions. • Reducing Ca wire amount fed in Cf53 steel has significant industrial application. Aiming at the frequent issue of pit-shaped surface defects in S-bearing and Al-killed steel products and the related poor castability due to submerged entry nozzle (SEN) clogging, the melting and casting process of a popular auto steel Cf53 has been studied based on in-situ investigation and experimental analysis. To clarify the generation of the pit-shaped defects, the local surface chemistry, evolution of steel inclusions throughout the melting process, SEN clogging substances, and the internal relationship among them were systematically analyzed. The results show that this type of defect in the Cf53 rolled products is caused by the large-sized composite inclusions rich in CaS, which originate from the molten steel during the refining process, gradually accumulate on the inner wall of the SEN during casting, and finally lead to SEN clogging. The loose structure of clogging inclusions makes them prone to fall off into the mold and get trapped by solidifying steel shell. The formation mechanism of the inclusions was studied through FactSage software calculation. The results show that the increase in total sulfur and total calcium content, and the decrease in total oxygen content and temperature in steel will lead to CaS inclusion formation, which agrees reasonably well with experimental results. An optimized refining process to reduce calcium addition into molten steel is proposed accordingly, which achieves a remarkably alleviation in casting SEN clogging and an elimination of the pit-shaped defects on the final rolled products as well. [ABSTRACT FROM AUTHOR]

• A novel ANN method is established for probabilistic life prediction of corroded reinforced concrete. • DT is used to determine the uncertainty of fatigue life. • ANN is used to predict the fatigue life of the corresponding survival rate. • The ANN method is evaluated using the fatigue test data from corroded reinforced concrete. Corroded reinforced concrete is affected by many factors. Therefore, the effects of these uncertainties should be considered when predicting fatigue life. However, artificial neural networks cannot determine the uncertainty of fatigue life. This paper establishes a new artificial neural network method to solve this problem. First, survival rates are obtained using the minimum number of specimens method. Second, the samples are divided. Then, a decision tree is used to determine the uncertainty of the test sample using corrosion and loading conditions. Finally, an artificial neural network is used to predict the fatigue life of the test sample using the survival rate, corrosion conditions, and loading conditions. If the training samples entered the artificial neural network are small sample data, the sample data are expanded using a beta-variational autoencoder with sample division. The established method is evaluated using fatigue test data from corroded reinforced concrete. Moreover, the evaluation results show that the established method can effectively predict the survival rate and fatigue life. [ABSTRACT FROM AUTHOR]

Current prefabricated shear walls predominantly utilize grouting sleeves for connection, whereas an in-depth review and summary of the current state of research have indicated a 26.7 % construction defect rate in these sleeves due to present construction techniques. To solve the problem of defects, this study introduced a novel prefabricated shear wall design using vertical rebars connected via pressed cone sleeves (PCSs). Three reinforced concrete (RC) prefabricated shear walls with different vertical rebars connected and tested under cyclic horizontal load and constant vertical load to study the seismic performance, including cast-in-situ shear wall (specimen SW1), partial sleeve grouting defects shear wall (specimen SW2) and shear wall with vertical rebars connected via PCSs (PCSs-SW, specimen SW3). Key performance indicators such as failure modes, hysteresis curves, shear capacity, stiffness, ductility, energy dissipation capacity and stress characteristics were evaluated. The results of the tests revealed that SW1 and SW3 failures resulted from a combination of bending moment and shear force, whereas SW2 failure in the area of grout sleeve defects connection. Compared to the specimen SW2, the SW3 owns better shear bearing capacity, ductility, stiffness, energy dissipating capacity and reliable seismic performance. Meanwhile, SW3 and SW1 exhibited the similar seismic performance, can primarily achieve the effect of "equivalent cast-in-situ". Finite element (FE) model of specimen SW3 were developed by using software ABAQUS, and the precision and utility of FE models verified by testing data. Using proposed FE models, an extensive parametric study was conducted to investigate the influencing factors on the seismic performance of precast fabricated RC shear wall, including axial compression ratio, concrete strength, vertical rebar strengths and vertical rebar diameters. • Proposed a novel prefabricated concrete shear wall system connected by PCSs. • Seismic performance of the novel prefabricated shear wall was investigated. • Seismic performance of three types of concrete shear walls were compared. • Parametric analysis was conducted to investigate the influencing factors on the seismic performance. [ABSTRACT FROM AUTHOR]

• A slab-strengthening scheme is employed to mitigate the risk of progressive collapse. • Calibrated 3D nonlinear FE models are utilized for parameter analysis. • The resistance mechanism of RC structures after removing a corner column is theoretically analyzed. • A theoretical model is proposed for predicting progressive collapse resistance. Previous studies indicate that, for reinforced concrete (RC) structures, the abrupt collapse of a corner column poses a notably higher risk of progressive collapse than the loss of a middle or edge column. This is because after a corner column is lost, the restraining force from the adjacent elements is much weaker. To minimize the vulnerability of RC structures when a corner column is lost abruptly, an innovative slab-strengthening scheme (high-performance ferrocement laminate and bonded steel plate (HPFL-BSP)) was applied. Two scaled-down substructures, each at a 1/3 scale featuring identical dimensions and reinforcement details, were previously prepared. The slab of one substructure was reinforced with HPFL-BSP. The progressive collapse performance of the strengthened specimen was evaluated based on experimental results, encompassing the load–displacement relationship, ductility, and failure modes. Experimental results indicate that the slab-strengthening scheme shifted the location of the slab yield line and transformed the beams from brittle torsional failure to ductile flexural failure. The peak bearing capacity and ductility increased by 29.4% and 78.6%, respectively. Subsequently, finite element models were established and validated to further investigate the effects of the HPFL-BSP strengthening scheme on the stress distribution in slab reinforcements and the load redistribution mechanism. Additionally, the effects of different HPFL-BSP strengthening schemes, reinforcement damage, boundary conditions, and beam–slab interaction on the anti-progressive collapse performance were also investigated using the ABAQUS software. In the theoretical analysis, the resistance mechanism of RC structures subjected to corner column removal was analyzed. Moreover, a theoretical model was introduced to predict the capacity for resisting progressive collapse. [ABSTRACT FROM AUTHOR]

This research reports the results of both the implementation of innovative materials, such as composite material, and the application of the prestressing technique through appropriate tie-rods, for crane construction. The novelty lies in the introduction of both factors in order to reduce and limit the vertical deflection, while also reducing the cross section, which is the main constraint at the machine design phase. In this way, to limit the load-induced deflection of the crane, a constant external action is applied that induces a deflection opposite to that induced by the load. In particular, the object of this research is a jib crane with dimensions 4000x5000 (height and length in mm) with a load capacity of 4905 N. The research involves analytical dimensioning followed by verification of the results obtained using finite elements software (Ansys®). The parameters adopted for sizing, both the boom and the column, are the maximum displacements and safety coefficients concerning both maximum stresses and buckling phenomena. The main result is that the composite crane has the lowest weight: approximately 29 % and 21 % of the weight of the corresponding non-prestressed steel crane, for non-prestressed and prestressed composite configurations, respectively. The last part of the research concerns the construction methods for building cranes, in particular the implementation of the composite solution. [ABSTRACT FROM AUTHOR]