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An experimental study was performed to investigate the effect of external prestressed truss steel-bar units installed on an unreinforced masonry (URM) wall under out-of-plane loadings. The key components of this new retrofitting method are prestressed vertical and diagonal bars. The prestressed vertical bars induce a prestressing force onto the horizontal section of the URM wall and the diagonal bars resist lateral loadings. Reverse cyclic tests were conducted on a full-scale URM wall as a control specimen and URM walls retrofitted in-plane and/or out-of-plane (parallel to short intersecting walls). The test results showed that the specimen strengthened using the new technique was superior to the control specimen in terms of seismic performance, including lateral load resistance, stiffness, energy dissipation and restrained slip of the entire specimen. Two units installed on short intersecting walls exhibited the same shear strength as four units installed on the in-plane and in-plane retrofitted masonry walls. The out-of-plane masonry specimen demonstrated the best performance. It was confirmed that aligning the retrofitting method based on the loading direction was effective, despite the lower axial load level.

This paper investigates the dynamic response and assesses the safety of a propylene tower subjected to blasting vibrations. A group of monitoring experiments on the response of the tower to blasting vibrations was carried out to this end. A model of a cantilever beam was used for the response along the horizontal direction and that of a strut for along the vertical direction. The theoretical and measured displacements were consistent in terms of time history curves and peak values. The design spectrum of the tower suitable for sustaining blasting vibrations was then proposed and verified, and its safety was assessed in combination with local requirements on seismic design. The results show that the first six modes of response should be considered under blasting vibrations in the horizontal direction, instead of the first three modes as in the case of an earthquake. The first three modes should be considered under blasting vibrations in the vertical direction. Owing to the importance higher modes in this scenario, the shear should be taken as the primary object of evaluation when assessing the safety of a tall propylene tower subjected to blasting vibrations.

It has recently been shown that the ever-increasing complexity and inability of methods used for the design of reinforced concrete (RC) structures to consistently safeguard against brittle types of failure is the outcome of the conflict between the assumptions of the underlying theory and the fundamental concrete material characteristics. This paper demonstrates that these drawbacks can be eliminated through a coherent alternative theory developed on the basis of simplified beam theory modified to account for true concrete behaviour. Through the use of experimental information obtained from the literature, the proposed theory shows that, in contrast with widely held views, a structural member's load-carrying capacity depends solely on the strength of the compressive zone, which was found to be significantly larger than what it is widely considered to be. Moreover, load transfer is accomplished by the bending action of the concrete cantilevers formed between consecutive inclined or flexural cracks in the tensile zone. The above findings essentially underline the development of an alternative design method – the compressive force path method – and this is an indication of the suitability of the proposed theory to open up new possibilities for improving RC design.

Past bridge failures due to earthquakes have been found to be due to inadequate seismic design of the bridge piers. It is thus essential to investigate the effect of lateral confinement on the seismic behaviour of bridge piers. The aim of this study was to evaluate, experimentally and numerically, the seismic performance of reinforced concrete bridge piers with various types of transverse reinforcement. For this purpose, three scaled-down (1 : 4) circular bridge pier specimens were tested under constant axial and quasi-static cyclic loading (QSCL). A control specimen was made with spiral lateral reinforcement, while the other two specimens were made with stirrups with cross-ties and strips with cross-ties. The hysteresis loops, envelope curves, energy dissipation and stiffness degradation of all three specimens were determined in order to evaluate their seismic behaviour. Compared with the control specimen, the specimen with strips and cross-ties showed increased lateral load capacity, cumulative energy dissipation and higher initial stiffness due to the effect of increased confinement. The results of finite-element analysis showed good agreement with the experimental results. The findings of this study indicate that strips with cross-ties can be used in bridge piers when a high lateral load carrying capacity and energy dissipation are required.

The ‘rope effect’ is a positive effect caused by the failure of fasteners of dowel-type connections. A similar mechanism can be found in connections with screw reinforcement. For self-tapping screws used as reinforcement for connections, bending of the self-tapping screws tends to close developed cracks. Utilising the withdrawal resistance provided by the threads on the pointed end of the screw and the pull-through resistance from the screw head, screw reinforcement enhances the embedment strength and splitting resistance of the wood and increases the ductility of the connection. The influence of different thread lengths and locations on reinforcement effectiveness regarding the embedment strength of the timber was investigated in this study. For cases with threads located only on the pointed end, the splitting resistance increased with longer thread length, indicating that the rope effect was progressively enhanced. It was also found that screws with halved thread length demonstrated similar reinforcement effectiveness to fully threaded screws while the partial threads reduced the risk of damaging the screw during installation. A calculation method to predict the load-carrying capacity of screw-reinforced dowel-type connections was also formulated.

Modal analysis of concrete arch dam–reservoir–foundation rock systems is a challenging task. The complexities arise mainly due to computing mode shapes encountered when solving an eigenvalue problem with asymmetric generalized mass and stiffness matrices. Moreover, the problem becomes complicated when wave propagation is occurring due to the inclusion of water compressibility and foundation rock mass. In the present study, a computational tool is especially developed for this purpose. The theoretical background is explained initially. Subsequently, dynamic analysis of the Morrow Point arch dam–reservoir–foundation rock system is carried out with different values of reservoir bottom absorption coefficient. In addition, some of the modal characteristics of such systems, including resonant frequencies and natural periods, are discussed. The main objective is to perform these analyses by modal analysis. However, the direct method of analysis is also carried out in each case as a basis for comparison from the perspectives of accuracy and efficiency.

Stress concentrations in a new type of reduced-beam-section (RBS) connection were investigated. Experimental and numerical results of RBS connections with semilunar web (SW) and holed tubular webs (HTW) were compared with connections with tubular webs (TW). For the SW, two semi-circular plates were used in place of a flat web in the beam. For the HTW, a steel tube was used instead of part of the beam web and holes were created in the beam web. For the TW, a steel tube was used instead of part of the beam web but without holes. The connections had adequate shear capacity but made little contribution to flexural stiffness and capacity. Semi-deep beam specimens were fabricated and tested under cyclic loading. The results showed that the beam connections with SWs and HTWs had 30% and 20% less fatigue damage respectively than those with TWs. The story drift capacity was also increased to 7%, much more than that stipulated by current seismic codes. The specimens were modelled using finite-element software to validate the experimental results.

This paper presents the results of both experimental and numerical investigations on the overall structural performance of two-equal-span reinforced concrete perforated (castellated) beams subjected to external pre-stressing. First, the effects of providing castellated openings along with the application of external pre-stressing on both the ultimate capacity and the percentage of moment redistribution were investigated experimentally. Then, after validation of the numerical modelling, the effects of controlling the parameters on the percentage of moment redistribution were investigated numerically. Experimental results showed that providing castellated openings accelerated the appearance of both flexural and shear cracks, and decreased the ultimate capacity by about 24% compared to that of a solid beam. Moreover, application of external pre-stressing on the castellated beam compensated for the reduction in ultimate capacity and outperformed it by about 9% compared to that of a solid beam. Based on the numerical results, it appears to be better to increase the amount of main tensile steel and strand eccentricity at the hogging moment zone, as well as increase the effective pre-stressing force, to reduce the percentage of moment redistribution at both sagging and hogging moments.

The aim of this study was to develop an efficient probability-based seismic fragility assessment method for steel moment-resisting frames (MRFs). In this method, Bayes estimators are used to improve the accuracy of the results based on new analyses or experimental observations. The efficiency of Bayes estimators in the updating process of fragility curves is demonstrated based on the results of incremental dynamic analysis of three-, five- and seven-storey steel MRFs under a set of 40 spectrum-compatible earthquake ground motions. The results indicate that the constant-hazard-level (engineering demand parameter based) fragility analysis approach leads to less than 6% error in the prediction of performance levels and therefore can be considered a competent alternative to the more computationally expensive constant-performance (intensity measure based) approach. While the earthquake duration can considerably affect the results of fragility analysis, the prediction errors can be reduced to an acceptable level through selection of four different time intervals with at least three records in each group. It is also concluded that Bayes estimators can generally provide a very good level of accuracy in updating fragility curves by reducing the maximum errors to less than 2.5% compared with the exact values.

A finite-element (FE) investigation into the response of integral abutment bridges (IABs) to seismic loading in the longitudinal direction was conducted. An example multi-span reinforced concrete solid-slab bridge was designed and analysed using an elasto-plastic two-dimensional FE model. The bridge abutment was taken as supported on steel H-piles. The proposed FE model was found to have the capability of simulating both the bridge construction and the backfilling process using a multi-step numerical process. The bridge was examined considering various lengths and different backfill materials, and was subjected to earthquake loading. The analyses showed that the seismic response of IABs is notably affected by the bridge length. Longer bridges may be subject to higher pressures on the abutments and internal forces in the bridge structure. The stiffness and strength parameters of the backfill material may also markedly influence dynamic pressures on the abutments and internal forces in the structure. Backfill materials with greater stiffness and strength parameters may cause significant reductions in the seismic flexural stresses in both the abutments and the deck. Coupling seismic and thermal loads could be suggested for the design of IABs.

The performance of integral bridges subjected to a multi-component earthquake has not been thoroughly investigated. Here, the responses of an integral bridge subjected to three-component far- and near-field earthquakes are determined to evaluate its relative structural advantages and disadvantages over a conventional bridge. Further, the effect of the interaction between the internal forces in the three directions on the total responses or yielding due to simultaneous application of the three components of an earthquake is investigated. For this purpose, two geometrically comparable bridges, one integral and other conventional, are analysed under far- and near-field earthquakes using SAP2000. The parameters varied are the type of ground motion, peak ground acceleration and orientation of the major horizontal component of the ground motion. Seismic demand parameters include the maximum bending moment in the girders, maximum moments at the top and bottom of piers, displacements in three directions and the plastic hinges formed. The results of the analysis show that the deck of the integral bridge has smaller displacements when compared with the conventional bridge. A greater number of plastic hinges are formed in the integral bridge, but the degree of damage shown by the hinge rotations in the conventional bridge is greater.

The effects of high-strength steel (HSS) on the damage indices (DIs) of four special moment frames and three beam–column connection (BCC) specimens under cyclical loading were experimentally studied. The specimens with HSS rebars (with yield strengths of 500 MPa and 580 MPa) were designed and constructed based on the special seismic provisions of ACI 318-19. Several types of DIs (from single DIs to combined DIs based on parameters such as displacement, absorbed energy and stiffness) were calculated according to the experimental results. The results showed that the application of the higher strength steel expedited the failure process of the specimens. Moreover, the DIs indicated that the specimen fitted with HSS for both the longitudinal and transverse rebars had the greatest damage propagation speed of the frames. For the BCCs, the specimen with HSS as just the longitudinal rebars showed the greatest damage propagation speed. The results also showed that the displacement-based DIs were less accurate than the other types of DIs for studying the damage behaviour of both the frame and the BCC specimens. The combined DIs were found to be more accurate than the other DIs.

An investigation was carried out to improve the seismic performance of concrete columns reinforced with high-strength steel bars and subsequently retrofitted with vertical and horizontal carbon-fibre-reinforced polymer (CFRP) strips. Seven columns were constructed and tested under constant axial and cyclic lateral loading. The results showed that attaching CFRP vertical strips in or over grooves outperformed conventional externally bonded reinforcement, as evidenced by greater energy dissipation and strength. Furthermore, the use of corner strip–battens for the horizontal CFRP strips was found to outperform conventional wrapping, as evidenced by greater ductility and energy dissipation. Confining stresses were also more uniformly distributed and strip rupture shifted from the edges to the mid-sides of the section.

The assessment of the structural safety of buildings, with the related outcomes and other structural information, is typically reported in un-structured sets of documents (tables, drawings, reports, etc.). This happens even if Building Information Modelling (BIM) workflows, platforms, and standards are adopted. Generally, the BIM database provides input data for the structural design, but most of the data produced by structural designers, according to the structural codes, do not fully integrate into the BIM database along with other context-related information. These data are not easily recorded, especially in openBIM standard file formats such as Industry Foundation Classes (IFC). In the context of digital procedures for permit applications pertaining to seismic structural engineering, the authors propose an openBIM approach for the integration of structural information to support the activities of building authorities’ bodies (BABs). The proposed framework has led to the development of an Information Delivery Manual (IDM) and a Model View Definition (MVD), considering the IFC schema, for the integration and exchange of information within a BIM-based environment. Successively, the authors implemented the proposed IDM/MVD solution in a case study that provided an effective workflow for innovative future delivery of necessary information to building authorities to obtain seismic authorization permits.

This paper reports on a numerical study into the crack-dependent behaviour of a steel-plate girder bridge strengthened with carbon-fibre-reinforced polymer sheets. Progressive cracking, which represented fatigue-induced damage, was simulated from up to 10% of the girder depth. Finite-element analysis was used to evaluate the performance of the control, damaged and strengthened cases subject to standard US highway fatigue loading. The efficacy of polymer strengthening was also examined from a strength perspective, using the load factor rating method and the load and resistance factor rating method. Localised fatigue cracking caused a stress concentration along the girder and its progression rate was related to the degree of web fracture. The damage of the tensile flange was more influential in reducing the flexural capacity of the girder relative to damage of the web. The strengthening decreased the stress ranges, thereby increasing the fatigue life of the girder, and enhanced the maximum average daily traffic capacity. Reliability modelling indicated a transition in failure rates before and after 3% cracking in the girder, supporting the extended functional time resulting from strengthening.

To resolve the problem of ductile fracturing of beam flanges in traditional connections with concrete-filled steel tube columns using site-welded side plates, an alternative connection design requiring minimal site welding was designed and studied. An explicit analysis method, considering the fracture strain criterion developed by the stress triaxiality path, was adopted to study the seismic performance and fracture resistance of the proposed connection. The results of a verified finite-element model indicated that the steel beam flange in the connection never fractured. The connection exhibited a notably higher maximum bending moment and ductility than the traditional connection. The side plates in the proposed connection were tension-bending or compression-bending elements, unlike in the traditional connection. The failure modes, maximum bending moment, ductility and stress distribution of the side plates were compared and analysed parametrically. Based on the stress distribution of the side plates according to the finite-element results, a fitting formula related to the width and thickness of the side plates was obtained. A formula to calculate the flexural capacity was also developed according to the force model of the proposed connection. The calculations and finite-element results were in good agreement.

Most performance prediction models for asphalt pavements are either based on laboratory data or numerical distress data collected from field surveys. However, these models do not fully reflect the true performance of pavements in different traffic and environmental conditions. In the study reported in this paper, a multi-input unified prediction model based on an artificial neural network was developed by using a mixture of numerical and categorical features for in-service pavement test sections in the USA. Pavement age, cracking length and area, cumulative traffic loading, two functional classes of roads, four climatic zones and maintenance effects were considered as input variables while changes in the pavement condition index (PCI) were determined as the output. The developed model was found to be efficient in terms of processing time and accuracy in dealing with the complexity and non-linearity of multiple input parameters. The results showed that the model provided a high correlation between observed and predicted deterioration at the training stage. The testing and validation results also yielded high accuracy in predicting the PCI and could be combined with a pavement management system to plan timely and accurate maintenance strategies.

The distribution of earthquake-induced energy in a 42-storey reinforced concrete dual-system building at three ground shaking intensities was investigated. The earthquake-induced energy response of the building was obtained in terms of elastic energy (kinetic energy and strain energy) and inelastic energy (hysteretic energy and structural damping energy) components for each structural member. Hysteretic energy is an indicator of inelastic deformations (i.e. potential damage) and is considered particularly important as it leads to high irrecoverable energy demands in a building and identifies critical members that require higher energy absorption capacity. The ratio of hysteretic energy to input energy was assessed among different structural members as well as along the building height. The results showed that the hysteretic energy constituted less than 10% of the total input energy and was mostly dissipated in the frame members for low-intensity events, whereas 75% of the input energy was dissipated in the hysteretic mechanism, prominently by the beams. In terms of hysteretic energy demands, the critical floor levels were found to be the 12th and 26th floors. The findings of this research will help engineers obtain a reasonable estimate of the expected hysteretic energy demand once the input energy is known.

This paper deals with the experimental investigation of hygrothermal behavior of wooden-frame building envelope. The experiment was based on in-situ monitoring of a full size experimental monozone house built at the University of Lorraine. Variations in temperature and relative humidity inside and outside the envelope were logged simultaneously with local meteorological data. Results showed the high coupling between temperature and relative humidity variations within the envelope materials. An overall hygrothermal response of the wall highlighted an interesting hygrothermal dynamic behavior of the envelope which may contribute to mitigate variations of relative humidity inside the building. Nevertheless, relative humidity evolves within a range of values ​​that can lead to mold growth at a certain position which may alter wooden envelope life.

This paper presents a practical optimum design solution of prismatic simply supported prestressed concrete girders that are subjected to uniformly distributed static loads. While assuming linear elastic behaviour and employing working stresses method, the optimum values of two design variables, namely the cross-sectional dimensions and the prestressing force, are formulated as a nonlinear optimization model. Optimum values of the design variables are computed to satisfy either a minimum weight or a minimum cost objective function. To solve the nonlinear programming models, a program named Non-Linear Programming Prestressed Concrete Optimizer (NLPRECO) was coded in MATLAB® programming environment. Some illustrative design problems were solved using NLPRECO and their results are demonstrated herein. Sensitivity analysis of the optimized design variables, to variations in design parameters, was also investigated and the results are presented. Results show substantial improvement over the regular un-optimized solutions and moderate improvement over a linear programming optimization solutions.

Thin-walled shell structures are characterised by a lightweight structural form with high strength. The importance of using cylinders and cones has long been known to engineers and designers in various engineering disciplines and they are widely used in shell form. In this work, the buckling and post-buckling behaviour of thin-walled cylindrical shells with geometric imperfections was investigated under vacuum-type pressure loads. Ten shell models with dents of two depths and lengths were designed for experimental tests: the dents were the thickness or twice the thickness of the shell, while their lengths were half or one-third of the height of the model. Carbon-fibre-reinforced polymer (CFRP) was used to retrofit some of the dented models. Test results from the CFRP specimens and the non-CFRP specimens were then compared with each other and with theoretical calculations.

The aim of the present paper is to compare the current design codes’ predictions for reinforced concrete (RC) T-beams with the alternative physical methods – namely, the compressive force path (CFP) method and artificial neural networks (ANNs). Therefore, two databases, for T-beams without stirrups and with stirrups, are developed using the available experimental studies. The comparative study on prediction (obtained from the American Concrete Institute and Eurocode 2, CFP and ANN models) shows that the predictions of the ANN model provide a closer fit to the experimental results; after ANN the predictions of the CFP method are close to the experimental results when compared with the counterpart physical model. Comparative studies are also conducted on the critical parameters for the behaviour of RC T-beams. Furthermore, a non-linear finite-element tool (i.e. Abaqus) is used to validate the prediction of the ANN and CFP model. The crack pattern from Abaqus exhibited the same mechanics, on which the CFP models are based.

A case study of the steel–concrete composite structure in the Pidie Jaya Regency Multipurpose Hall which experienced substantial permanent lateral deformation due to the effect of an earthquake is presented in this study. Therefore, it is important to assess the response of the structure to earthquake load and propose the strengthening strategies to make the buildings useful again. The purpose was to evaluate the causes of large deformations and the behavior of structure in resisting earthquake loads. The building structure model used in this study is a space frame with two-column base support conditions which are fixed and hinged supports after which a non-linear time history analysis was conducted. The time history analysis was conducted using five ground motion acceleration data recorded during earthquakes to determine the deformation and it was found that the large structure permanent deformation was due to the small structure stiffness in the direction of the deformation due to the use of only one column row in front of the building. Moreover, hinged support was observed to have caused a greater deformation than fixed support but was found not to be the main cause of large permanent deformation of the structure. The building structure was further strengthened by adding 4 columns while the oblique columns remained in a sloping condition. Meanwhile, the response spectrum analysis showed the strengthening structure was able to withstand earthquake loads with less deformation than the required standard.

To understand the influence of the layout and geometric parameters of the lining concrete on the mechanical properties of multi-cell single-box girder bridges with corrugated steel webs, the Fenghua River Bridge is taken as an example. This is a single-box three-cell continuous girder bridge with corrugated steel webs that is the largest of its kind in China. It was used to establish the finite-element model in this paper. The results of this study suggest that the lining concrete single-side arrangement has good economic and mechanical properties. The influence of the geometric parameters of the lining concrete on the mechanical properties of the structure was studied using the finite-element model, and the length and thickness range of the lining concrete of the single-box multi-cell composite girder bridge with corrugated steel webs are provided. The research results provide useful suggestions for the design of lining concrete in real bridge projects, and thereby make up the gap in the existing code.

Self-tapping screws have the potential to reinforce timber elements. However, their application is restricted due to a lack of design guidance. Compared with fully threaded screws, partially threaded screws with a shorter thread length have less drive-in torque, enabling easier installation. This study showed that partially threaded screws are as effective as fully threaded screws in enhancing the mechanical properties of single-dowel timber connections with artificial cracks. A total of 120 embedment tests were conducted, using screws with two thread lengths (33% and 100%) on single-dowel connections. The connections were also prepared with three different widths of artificial crack to represent splitting of the wood due to moisture variation. The results showed that the screws with 33% thread length were as effective as screws with 100% thread length at reinforcing the connections when the crack width was 1.5 mm or 4.5 mm. However, for a crack width of 6 mm, the embedment strength of the connections reinforced with screws with a 33% thread length was significantly lower (about 15.7%) than the connections reinforced with screws with a 100% thread length. This research demonstrates the potential of using self-tapping screws with a partial thread to reinforce existing timber elements with cracks.

This study addresses performances and behaviors of the multi-cross-section HAWT blade design with and without fences. The FX66-S-196 V, FX63-137 S and SG6043, supercritical airfoils were used and distributed along the blade radius; further, the NACA4412 single-cross-section HAWT blade having the same dimensions was used to compare the behaviors and overall performances of all the blades. Analyses were then performed numerically using blade elements momentum BEM theory with a self-code (F.90) and CFD as well as experimentally with three multi-cross-section blades designed using SOLIDWORKS and 3D- printed with polylactic acid. the multi-cross-section HAWT blades show good performance compared with the single- cross-section blade, with an approximately 8% increase in power coefficient, i.e., 40 W, for a miniature wind turbine (127 cm diameter 500 W output power) and greater improvements for wind turbines with large diameters. The fences were designed using boundary layer theory and installed on multi-cross-section blades in experimentally determined positions. The fences showed high performance, with a 16% increase in total power coefficient and high flutter stability.

In order to promote the application and development of steel–concrete composite beams in bridges, the fatigue performance of corroded studs was investigated. Based on fatigue crack propagation theory and the fatigue failure mechanism of corroded studs, a fatigue life prediction model for corroded studs was proposed. The values of key parameters in the fatigue life prediction model of corroded studs were obtained. Moreover, the fatigue life of corroded studs was analysed. Results show that the error between the calculated value and the test value of the fatigue life of corroded studs is less than 10%, and the fatigue life prediction model for corroded studs is sufficiently accurate. As the corrosion rate of a stud increases, its fatigue life rapidly decreases. When the corrosion rate of the stud increases from 5 to 50%, the fatigue life of the stud decreases from 20 to 90%, respectively; thus corrosion greatly reduces the fatigue life of the stud.

Different methodologies have been suggested in the literature to simulate the adverse impact of reinforcement corrosion on the non-linear structural behaviour of deteriorated reinforced concrete (RC) structures. The modelling methodology used, however, can significantly bias the predicted time-dependent structural behaviour of deteriorated structures. Considering the critical importance of numerical modelling in bridge maintenance scheduling and effective decision making, the influence of different modelling strategies on the anticipated time-variant structural performance of corroded concrete bridge columns is investigated. To this end, various simple and advanced modelling methodologies are evaluated. The effect of the considered modelling scenarios on the estimation of damage limit states, the sequence of multiple failure modes, structural capacity (both ductility and strength) and energy dissipation capacity of a benchmark circular RC column is evaluated over its service life. The results show that the modelling strategy significantly affects the predicted time-variant structural performance of the deteriorated structure.

Cold-formed steel members are usually used as purlins in buildings to support roof cladding and thus they can be treated as beams restrained fully or partially in the lateral and torsional directions. However, when these beams are subjected to wind suction loading, their free flange is in compression, which may cause web–flange distortional buckling (WFDB). This paper presents an analytical study on the WFDB of zed-section purlins when subjected to uplift bending. A simplified model is proposed to describe the WFDB of partially restrained purlins, from which the formula for calculating the critical stress of the WFDB is derived. The present model is validated by the results obtained from the finite strip analysis.

Reliable column–column connection contributes to a reduction in waste materials and enables structures to be demountable after their service life. This paper demonstrates the feasibility of using a bolted-flange connection with concrete-filled steel tube (CFST) columns subjected to axial compression load. Compression capacity, ductility, axial stiffness and toughness, as well as failure modes are discussed. The specimens are grouped into two categories: group I—connection without stiffeners and group II—connections supported by stiffeners. Three thicknesses of 2, 4 and 6 mm were used to manufacture the bolted flanges and stiffeners. The results showed that the proposed connection was effective to avoid a reduction in compression capacity. The various thicknesses of bolted flanges in group I specimens had a slight influence on the axial stiffness value and that influence was doubled in group II specimens. The stiffeners played a significant role in the toughness value and this was reduced with a reduction in the thickness of the stiffeners. In addition, an improvement in ductility was noticeable in stiffened specimens. Consequently, it can be inferred that bolted-flange joints have the potential to produce reliable and economical designs for CFST columns.

Generally, in reinforced concrete (RC) core wall buildings, the formation of one plastic hinge at the base is preferred; this is called the single plastic hinge (SPH) approach. During a severe earthquake, this approach results in significant moment demand in the upper regions of the wall due to the effect of higher modes of vibration. This study considered RC core walls of 30-, 40- and 50-storey buildings, designed using a response spectrum analysis. The SPH, dual plastic hinge (DPH), triple plastic hinge (TPH) and extended plastic hinge (EPH) approaches were examined using fibre element models and non-linear time history analysis. The DPH and TPH approaches respectively contain one and two plastic hinges at the upper levels of the wall in addition to the base plastic hinge. The effect of the locations of the upper plastic hinges on the seismic response of the core wall was investigated. The results showed that there is not a distinct level for the upper plastic hinge location to minimise the envelope of different demand quantities simultaneously. The curvature demand of the middle plastic hinge in the TPH case was higher than the base curvature demands. Reducing the resistant moment at the wall base by reducing the reinforcement ratio can help to balance curvature demands along the height of the TPH model.

Vibration properties of civil structures, which are commonly analysed for damage detection, are affected by changing environmental and operational conditions, and most notably are subjected to bilinear effects from changing ambient temperature conditions. Therefore, damage detection in structures during the past decade has focused on eliminating the effects of these changing environments that affect the vibration properties of the structures. Several methods have been proposed in the literature to tackle the non-linear effects from changing environments. However, these methods can only analyse systems (e.g. natural frequency–environmental and operational system) that have an incremental change in relationship; they cannot model the bilinear effects from the changing temperature conditions, which may lead to false alerts. Hence, a damage detection method is proposed in this paper to tackle the piecewise effects from changing temperature conditions. The method makes use of a Gaussian mixture model to separate the different effects acting on the structures and uses principal component analysis for data processing. The method is applied to the Z24 Bridge, in Switzerland, which was subjected to bilinear effects from changing temperature conditions. The results obtained demonstrate that the proposed method successfully takes into account the piecewise effects to indicate the presence of damage.

Seismic responses of utility tunnel-soil system were studied via shaking table model tests with considerations of two kinds of double box utility tunnels: with and without joint connections. These two testing utility tunnel models were made of galvanized iron wire and micro-concrete, and the ground was simulated by the dry standard sand through layered tamping treatment. The utility tunnel-soil system was subjected to horizontal vibration in uniaxial direction perpendicular to the longitudinal direction of tunnel model. Via instrumentations of earth pressure gauges, accelerometers and strain gauges, the earth pressure response, acceleration response and bending moment response were measured. The testing results show that the joint connections in the utility tunnel along the longitudinal direction play an important role in determining the characteristic of earth pressure response and bending moment response, whereas the effect of joint connections on acceleration response is less significant. In addition, the partition wall exhibits the consistent acceleration response with the side-wall of double box utility tunnel model under seismic condition. Based on the testing results, it is suggested that the joint connection should be taken reasonably into consideration during design and construction for engineering practice.

Probabilistic analysis is an important step in assessing the reliability of geosynthetic reinforced slopes. In this paper, a practical procedure is developed to implement probabilistic stability analysis for reinforced slope considering both the spatial variability of soil strength and the uncertainty of geosynthetics. In the proposed procedure, the random limit equilibrium method (RLEM) is used to calculate the factor of safety (FOS) and the simple genetic algorithm (SGA) is used to find the non-circular critical slip surface. A comparison is elaborately conducted between the procedure and random finite difference method (RFDM), verifying the feasibility of the proposed procedure in probabilistic stability analysis of reinforced soil slopes. Based on the proposed procedure, a series of probabilistic analyses are performed to study the effects of uncertainties of some key parameters on FOS and slip mass volume. The results show that the soil variability, correlation length and geosynthetic length are significant factors, while geosynthetic variability shows limited effect on FOS. The geosynthetic length plays an important role within the statistical characteristics of FOS and slip mass volume by differentiating the failure mechanism into internal failure mode and external failure mode.

Shear and flexural failure are commonly known as the highest catastrophic failure mode as it never gives any earlier notice before the collapse. The most common shape in the structure of beams and girders is T-section. Therefore it will be more necessary to investigate the condition of these structures. In this research, the flexural behaviour of RC T-beams is investigated experimentally and analytically strengthened with Basalt Fiber Reinforced Polymer (BFRP). A symmetrical one-point static loading system is applied on RC T-beams superficially bonded with 45° degree, and 90° wrapping up to failure. The effects of both wrapping patterns of BFRP on RC T-beams were investigated for ultimate load carrying capacity, deflection, strain, and failure modes. The experimental results demonstrate that superficially bonded BFRP can enhance the flexural capacity and reduce the deflection of the beam significantly. Further, the results show that the most effective wrapping pattern was a 45° degree than 90°wrapping and without wrapping. Then the RC T- beam was modeled by using ABAQUS to validate the present experimental and analytical results. After a series of comparative studies, the analytical results fairly admit with the experimental results. In the end, this study surmised showing different cracking patterns and yield points of the beam with and without strengthening. It is hoped that the results of this study will be of considerable help for the strengthening of T- beams and structures.

The structural behaviour of concrete-filled steel tubular columns subjected to full and local compression loads was investigated. Experiments were performed on 18 columns with different cross-sectional slenderness ratios. The experimental parameters were the local compression area ratio and the slenderness ratio. The strength index, stiffness and ductility index of the columns were obtained through experimental tests. The results revealed that the local compression area ratio and slenderness ratio are key parameters that considerably affect the strength capacity of columns subjected to full and local compression loads. Design models provided in various international codes and various studies were used to validate the experimental results. Furthermore, the suitability of these design models for predicting the strength capacity of columns subjected to full and local compression loads was examined. Finally, through regression analysis, a simplified design model was developed for predicting the strength capacity of columns under full and local compression loads.

Cross-sectional analyses of circular and square reinforced concrete (RC) columns strengthened with reactive powder concrete jacketing and fibre-reinforced polymer (FRP) wrapping were undertaken. The stress block method was used to determine theoretical axial load–bending moment (AL–BM) interactions of the columns. These were then compared with experimental results and found to be in very good agreement. A parametric study was also undertaken to investigate the most important factors that influence the AL–BM capacity of circular and square strengthened columns. Finally, a group of theoretical AL–BM interactions for circular and square strengthened columns was produced. These can be used in a wide range of applications for strengthening RC columns with high-performance concrete jackets and FRP wraps.

In order to study the effects of a steel spring floating slab track (SSFST) on the vibration and noise of rail transit overhead box-girders, a train–track system coupling model in the frequency domain was established. Two numerical models – a finite-element model to analyse the vibration and a boundary-element model for predicting structure-borne noise – were then built. Based on a field test of one 30 m long simply supported box-girder paved with ordinary slab track (OST) in an urban rail transit system, the models were verified to be effective at predicting the vibration and noise of the box-girder. Meanwhile, both the vibration- and noise-reduction effects of SSFST were assessed in comparison with OST. After substituting SSFST for OST, the maximum reductions of the overall vibration acceleration level and overall sound pressure level of the box-girder were 34·7 dB and 25 dB, respectively. Finally, the effects of the SSFST's parameters on the noise of the box-girder were investigated. The results showed that the isolator stiffness is the primary factor that affects the noise characteristics of the box-girder, followed by the floating slab thickness. However, the floating slab length and fastener stiffness were found to have little influence on the noise radiation.

Ultra-high-performance concrete (UHPC) has been regarded as promising alternative to provide reliable connections between difference segments (e.g., columns and pier footing/cap) during accelerated bridge construction (ABC) procedures. This paper proposes an innovative layered-UHPC connection for the pre-fabricated segmental (PFS) pier, whose seismic performance was validated through quasi-static experiment. The corresponding design procedure for PFS pier with this type of connections is presented based on the test results. The layered-UHPC connection ensures the emulative performance of pre-fabricated bridge as cast-in-place (CIP) ones, as well as provides greater economic efficiency than traditional UHPC connections. Based on experimental results, key issues concerning this connection, including the tensile behavior of UHPC, height of connection region, thickness of UHPC layer and steel bars in grouting bed, are presented and discussed. Then a seismic design procedure is proposed utilizing the capacity protection philosophy widely adopted in design specifications. The layered-UHPC connection is expected as capacity-protected component without damage, since it provides anchorage for steels extended from columns and pier cap/footing. While the pre-fabricated region is designed as ductile component undergoing nonlinearity during strong earthquakes. Following the detailed elaborations about the design philosophy, requirement and implementation steps, this procedure is further presented through illustration examples using PFS piers with various heights. The results show that PFS piers designed according to this procedure could meet the requirement under both frequent and rare earthquakes. Note that the PFS piers with this layered-UHPC connections could be designed similar to and emulative as CIP ones, which is believed friendly to designers in engineering practice.

Unstiffened steel plate shear walls (SPSWs) are one of the most efficient lateral resisting systems in conventional steel structures. The essential characteristics of SPSWs, including high initial stiffness, great ductility and low compression resistance, make them desirable for implementation in self-centring structures that aim to eliminate or effectively reduce residual drift under earthquake load. In this work, a numerical simulation of a self-centring SPSW based on the strip model published by the American Institute of Steel Construction was conducted and an attempt was made to modify the method to match experimental results more accurately. It was found that the compression resistance of shear wall strips, realistic pinching behaviour and energy dissipation of bolts in post-tensioned connections are key aspects for developing a reliable simulation of a self-centring frames with SPSWs. Neglecting any of these issues can distort evaluation of the self-centring capability and the dissipated energy in the frame. In addition, deterioration in the shear wall material due to web plate tearing needs to be considered in the modelling to achieve more realistic assessments of the ultimate stiffness and strength of the system under significant seismic loads.

Seismic isolation has been used to improve the seismic performance of buildings for the last decades. However, it has been shown that the code-based displacement capacity of isolation members does not provide adequate collapse probabilities for different Risk Categories of ASCE 7–16. Seismic design codes stipulate to determine maximum isolator displacement at the Risk-Targeted Maximum Considered Earthquake (MCER) level. Although the code-based isolator displacement capacity is checked with the mean displacement of the MCER level nonlinear time history analysis results, extreme event effects and incorporating uncertainties into fragility curves create additional displacement demands. Therefore, there is a need to amplify the code-based displacement capacity of isolators to obtain sufficient collapse performance. A previous study, assumed elastic behavior and rigid mass model for the superstructure, proposes an iterative probabilistic approach. In the present study, seven different seismically isolated buildings are modeled, and the nonlinear behavior of isolators and superstructures is considered in the incremental dynamic analyses achieved for all models to obtain fragility curves. Although the seismic isolation considerably decreases the spectral accelerations of the superstructure, it is shown that the R-μ-T relations for diaphragm level accelerations, transferred accelerations from base to superstructure, become more sensitive to nonlinear behavior at the superstructure mode periods. The fragility curves of five case study buildings are obtained using the FEMA P695 procedure, and it is figured out that the collapse probability of isolation units is highly correlated with the required isolator displacement to code-based maximum isolator displacement (D/DM) ratio. Then, two simple equations with high correlation coefficients are acquired to estimate the required displacement capacity for prescribed risk-target levels. Further, the obtained equations are verified for two different isolated building models, and their results are compared with the Incremental Dynamic Analysis (IDA) results. The verification results show that the given equations can be used in the preliminary design phase of seismically isolated mid-rise reinforced concrete buildings.

This study deals with the behaviour of duplex stainless steel bolted connections. The aim of the study is to respond to the question if the current stainless steel design specifications are able to predict the behaviour of such connections. Firstly, the net cross-section capacity of duplex stainless steel plates subjected to tensile loading are presented. They were conducted to obtain the stress–strain curves and tensile fracture behaviour used to support the finite element (FE) fracture simulations. Secondly, nonlinear FE models are developed for duplex stainless steel bolted connections subjected to tensile loading. The FE models are validated against experimental data in terms of load–displacement curves, failure modes and ultimate loads. Then, a numerical parametric study that consists of 133 duplex stainless steel grade EN 1.4162 bolted connection specimens is carried out. The failure modes of bolted connections are carefully examined, including combined tear out and bearing, bearing and net section, looking at the influence of parameters such as end distance, edge distance and spacing between the bolts in the connections. The results are compared to the design rules prescribed in the current stainless steel design specifications. Generally, it is found that the Australian/New Zealand (AS/NZS), American (SEI/ASCE) Specification and European codes conservatively predict the ultimate strengths of the bolted connections, whereas the strengths predicted by the AS/NZS and SEI/ASCE specifications are overall more accurate and less scattered.

Light-gauge Steel Framed (LSF) floor panels are commonly employed in conventional and modular building constructions on the basis of their lightweight nature. Previous research studies on the fire performance of LSF floor panels have been limited to Cold-Formed Steel (CFS) lipped channel and hollow flange joists. Therefore, there is a need for research on the fire performance of the LSF floor panels designed with optimised CFS joists in conventional floor panels and modular floor panels. This paper focuses on the fire performance of LSF conventional and modular floor panels made of optimised CFS joists found in the literature, using Finite Element (FE) analyses. Heat transfer FE models of LSF floor panels were developed and validated against the data available in the literature. Subsequently, the validated FE models were extended to investigate the LSF conventional and modular floor panels made of optimised CFS joists. In total 32 different LSF modular and conventional panels were analysed. A load ratio-critical average joist temperature relationship was derived based on the past test results and extensive FE results. The established relationship in conjunction with time-temperature profiles from the FE analysis was used to predict the Fire Resistance Rating (FRR) of the LSF conventional and modular floor panels made of optimised CFS joists. The results showed that modular floor panels withstand significant standard fire loading compared to the conventional floor panels while optimised CFS joists can also be used to enhance the fire performance.

This paper presents outcome of a research which investigates the fatigue behaviour of duplex stainless steel grade (EN 1.4162) via cyclic tests on welded cruciform joints and base plates. A database of experimental tests for similar high-strength steel details was also collated from the literature. The obtained experimental S-N curve was then compared to the current European design ones and re-evaluated according to the hot spot stress method. A good agreement was observed between the studied detail performance and the collated reference data. Improvement to the fatigue design rules for the studied duplex and similar high-strength steel details is then proposed. ispartof: Engineering Structures vol:247 status: Published online

Nowadays, the semi-probabilistic design approach using partial safety factors is by far the most widely used technique for the design of new industrial buildings. It is believed that the method delivers a safe design with respect to a minimum degree of reliability as prescribed by EN1990. This paper aims at describing the behaviour of single-bay portal frames at a system level based on analytical reliability approach with dominant failure modes. In the case of extreme loading where cross-sections attain their ultimate resistances, the failure modes of single-bay portal frames can be described using a limited number of critical sections. The limit state or performance function is hence reduced to the assessment of those critical sections. Through the use of the well-known force-based method, an analytical matrix formulation of the problem can be proposed and can be easily implemented. For each variable included in the performance resistance of the system, probability density functions can be calculated (Monte Carlo method) and their influence on the system’s reliability level investigated. Comparison can then be made with the results obtained with the partial safety factor method. As a case-study, the influence of the building shape (height-to-span) and load ratio on the reliability of single-bay portal frames is investigated.

In this paper, the Difference of Seismic Response across Different Spans (DSR) in the longitudinal distribution of High-Speed Railway Multi-spans Simply Supported Bridge (HSRSB) under longitudinal earthquake excitation is investigated, and an evaluation method which can intuitively reflect the difference of seismic response is proposed. A feasible way to strengthen the connection stiffness between adjacent girders is proposed to control DSR. The rationality of the finite element model used is verified by comparing the numerical results with the experimental ones, showing a satisfactory agreement. Comparing the seismic response of a bridge model considering the subgrade-track constraints (BCTM) and a bridge model without subgrade-track constraints (BWTM), it is found that the DSR in the longitudinal distribution causes some new disadvantages, which are neglected in BWTM. The BCTM considering DLC generates a model called BCDM. The effect of the number of span on DSR are studied based on BCDM. The analysis of this model showed that DLC suppresses the DSR and reduces the seismic response of most bridge components. It also transfers the seismic disadvantage from the bridge part to the subgrade-track structure. As it is more convenient and cost-effective to repair the base plate of the subgrade than the bridge components after earthquake seismic event, this disadvantage transfer is in favor of forming a new anti-seismic system that subgrade-track structure is used to protect the bridge part.

Long-term in-service monitoring has been heralded as having the potential to radically reshape the design and operation of civil structures and infrastructure. However, in order for civil and structural engineers to extract the greatest value from in situ structural monitoring there are a range of practical, cultural and social barriers which must be overcome. To explore current perceptions of long-term monitoring in civil and structural engineering, a multi-national survey of 146 participants was conducted to understand perceived uncertainties within the existing civil/structural engineering design process, perceptions of long-term monitoring, and the potential for the future integration and use of long-term monitoring in the civil/structural engineering design process. This study highlights that while views of long-term monitoring as a tool within the engineering design process are broadly positive, there is a wide disparity on its current implementation in practice, little agreement on how it may offer the greatest benefit to civil and structural engineering design, and a current lack of direct financial incentive to prompt its use within industry.

Buckling-restrained steel plate shear walls have been developed that can markedly alleviate the shortcomings of ordinary steel plate shear wall systems. A parametric study was carried out on finite-element models of buckling-restrained steel plate shear walls, to which cyclic and non-linear static analyses in accordance with the ATC-24 loading protocol were applied. Based on the results acquired from the hysteretic curves, an increase in concrete compressive strength does not markedly affect the ductility and energy dissipation capacity. Moreover, it was observed that as the width of the gap between the concrete panel and steel plate grew, energy dissipation and the response modification factor were reduced. In addition, the results indicated that an increase in the concrete compressive strength improved both shear capacity and initial stiffness. Accordingly, based on a comparison between the rate of improvement in shear capacity arising from an increase in strength of the concrete panels, frame and steel plate, it is concluded that it would be much more rational to increase the concrete strength so that greater shear capacity could be achieved.

Enhancing the torsional capacity of reinforced concrete (RC) beams while maintaining reasonably economic and efficient cross-sections poses a practical challenge in the design of such elements. Thus, developing and testing economically viable reinforcing techniques for enhancing the torsional capacity of RC beams is a significant aspect. Among these techniques is the continuous spiral reinforcement system that has shown promising results in enhancing the torsional capacity of rectangular RC elements. In this study, the role of continuous rectangular spiral stirrups, as a transverse reinforcement with a controllable pitch (P) and inclination angle (θ), in enhancing the torsional behavior of rectangular solid and hollow RC beams has been investigated experimentally. The applied torque was directed to lock the spirals for all specimens. The experimental program of this investigation included testing of ten specimens of normal strength RC beams; two of which were solid with closed and spiral rectangular stirrups. While the rest of specimens were hollow specimens included one beam reinforced by closed stirrups and seven beams reinforced by rectangular spiral stirrups with different reinforcing ratios. Different variables were considered to develop a wide range of the beams’ reinforcing scenarios. This includes stirrups type (conventional closed stirrups and rectangular spiral stirrups), inclined stirrups ratio, pitch, inclination angle and finally the longitudinal reinforcement ratio. In addition, a three-dimensional finite element model using ANSYS-15.0 was developed to examine the capability of the model to capture the observed torsional behavior of the experimentally tested beams. The obtained results showed that using inclined spiral rectangular stirrups in reinforcing RC solid and hollow beams greatly enhanced the torsional capacity by about 16% and 18%, respectively compared to using the conventional closed stirrups. Moreover, the results showed that using that technique leads to higher twist- angles, more ductile failure and increased strain energy by about 27% and 16% for solid and hollow beams, respectively. Lastly, the comparison between the results obtained from numerical model and experimental results showed good agreement and thus the numerical model can be used to extend the experimental work for investigating different reinforcing schemes.

Based on field measurement data of the Fuyingzi Tunnel on the Zhangtang Railway, we analyzed a ballastless slab track, which is commonly used in the track structures of heavy-haul railway tunnels. In accordance with the measured data, the dynamic load thresholds and distributions on the surface and bottom of the ballastless slab track were analyzed. In this study, a fatigue damage analysis of the ballastless slab track was performed based on the dynamic load time–history curve. The results show that the ballastless slab track could accomplish train load attenuation and reduce the dynamic load from heavy-haul trains by 47.22% from the surface to the bottom. In addition, the distribution at the bottom of the ballastless slab track exhibited a “triangular” shape, and the dynamic load threshold at the line center accounted for 78.67% of that at the track position. Meanwhile, the distribution at the surface was “saddle-shaped,” and the dynamic load threshold at the track position accounted for 79.55% of that at the line center position. Combining the measured data and linear fatigue damage theory, the fatigue damage of the ballastless slab track was analyzed effectively. Additionally, according to the measured dynamic stress of the ballastless slab track structure, the accuracy of the calculation results was verified. The dynamic action of the train load led to a more concentrated damage of the track bed, and the damage occurred earlier than that in the ordinary line. The axle load was the primary influencing factor for the track bed fatigue damage, and the damage mainly occurred in the track position. These results provide a theoretical basis for performing stress analysis and designing parameters for ballastless slab tracks in heavy-haul railway tunnels.