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Abstract This work focuses on the seismic performance of high-strength-steel frame equipped with mild-carbon-steel sacrificial beams of non-compact sections in energy dissipation bays, namely the HSSF-NCEDB structure. This work was commenced with a test program of a HSSF-NCEDB system as a feasibility study. The test results indicate that the novel structure exhibits the desirable damage-control behavior with inelastic actions locked in the sacrificial beams with non-compact sections for the expected deformation range. Even though both high-strength-steel members and sacrificial beams with non-compact sections were restricted by the limited energy dissipation, ductile manner was observed. A finite element (FE) model was established, and good agreement between the test results and the FE results was obtained. For practical applications, the concept of the buckling hinge was developed for quantifying the stable energy dissipation stage of sacrificial beams with non-compact sections. Lastly, the effectiveness of the HSSF-NCEDB system for mitigating the post-earthquake residual deformations was demonstrated by preliminary nonlinear dynamic analyses of single-degree-of-freedom oscillators with validated hysteretic models. The research findings from this work indicate that the HSSF-NCEDB structure is a promising option for structures in low-to-moderate seismic regions. Highlights • The concept of HSSF-NCEDB structure is proposed. • HSS frame is equipped with sacrificial links with non-compact sections. • A buckling-hinge model is proposed. • The potential of the structure for residual deformation mitigation is verified. [ABSTRACT FROM AUTHOR]

This paper reported an experimental and numerical study of a novel brace-type hybrid damper composed of steel slit plates enhanced by the friction mechanism. A test programme including six proof-of-concept specimens was carried out. The test results showed that the specimens exhibited multiple yielding stages, and the hysteretic response curves of the specimens were dependent on geometric configurations of the steel slit plates and the clamping force of bolts. The expected energy dissipation sequence accompanied by excellent ductility of the novel hybrid damper specimens was confirmed. The ploughing effect phenomenon between the friction interfaces as evidenced by the wear of the steel plates and increasing friction force was confirmed, which contributed to enhanced friction energy dissipation of the dampers under cyclic loadings. Then, a numerical investigation was conducted to take insights into the resisting mechanism of the specimens. The adequacy of the finite element modelling techniques was justified by a good correlation between test responses and numerical simulations. The test and numerical studies demonstrated that the energy dissipation sequence as a result of the hybrid energy dissipation mechanism contributed to improving the energy dissipation capacity and ductility of the steel slit plates. To facilitate the practical design of the novel hybrid dampers, a theoretical prediction model enabling quantification of critical mechanical quantities of the novel hybrid damper was developed, and the sufficiency of the design model was justified by comparison among the test responses, numerical results, and design predictions. • A novel brace-type hybrid damper composed of steel slit plates enhanced by the friction mechanism was proposed. • Six damper specimens were designed and physically tested. • Proposed hybrid damper can achieve excellent energy-dissipation capacity and ductility. • The resisting mechanism of the hybrid damper was comprehensively numerical studied. • A theoretical prediction model of the novel hybrid damper was developed. [ABSTRACT FROM AUTHOR]

A full-scale test programme for reinforced single-coped beams with slender web (RSCBSW) connections is reported in this paper. The test matrix included reinforcement types and coping details. The adequacy of the two reinforcement strategies was confirmed by the test results, and it was found that all specimens failed by buckling of the plate girder section away from the coped region. The test results also showed that for the reinforcement strategy with double full-depth transverse stiffeners, the decrease in the strength of the specimen in the post-ultimate stage was comparatively less significant compared with the specimens strengthened by a single full-depth transverse stiffener, and this phenomenon was more apparent in the case of a deep cope. Subsequently, finite element (FE) models of test specimens were developed to replicate the behaviour of the RSCBSW connections, based on which a parametric study covering a wider range of factors was conducted. The numerical results further confirmed the effectiveness of the reinforcement strategy, and no models experienced local web buckling in the vicinity of the cope. The available design equations to quantify the buckling resistance of the plate girders were applied to the test specimens and the numerical database. It was found that for cases with double full-depth transverse stiffeners, the design predictions were generally conservative. In contrast, unsafe predictions were obtained for several cases with a deep cope which was enhanced by a single full-depth transverse stiffener. [Display omitted] • Reinforcement strategies for enhancing single-coped beam with slender web connections were experimentally examined. • A parametric study covering a wider range of factors was conducted. • The effect of the longitudinal stiffener was confirmed. • The design equations for quantifying the resistance of the specimens were revisited. [ABSTRACT FROM AUTHOR]

We investigated the block shear performance of 16 steel angle specimens connected by double-line bolts. Among these specimens, 10 were made of S690 high-strength steel and 6 were made of normal-strength steel. The angle specimens were fabricated using two hot-rolled steel plates through groove welding. Two angle sections, i.e., 125 × 65 × 6 and 125 × 85 × 6 mm (long leg length × short leg length × thickness), were considered in the test. All angles were connected to the long leg. Apart from steel grade, the test parameters included bolt rows, parallel pitch, transverse pitch, edge distance, and unconnected leg length. Typical block shear of specimens were observed, and different fracture patterns were characterised. The test results confirmed that the block shear strength of the tension angles could be improved by increasing the tension plane area with the increase of the transverse pitch and edge distance and increasing the shear plane area with the increase of the bolt row number and parallel pitch. However, the test results showed that the block shear strength of the angles was not affected by the length of the unconnected leg. Subsequently, numerical models were built to further investigate the block shear behaviour of the double-line bolted angles, and the analysis parameters were the end distance, unconnected leg length, and connected leg length. According to the experimental and numerical results, the accuracy and adequacy of design specifications in the United States, Europe, Canada, and Japan and design equations documented in the literature for evaluating the block shear performance of double-line bolted steel angles were evaluated. • Structural performance of double-line bolted high-strength steel angles is examined. • Comparison with block shear behaviour of normal-strength steel angles is conducted. • Effects of connection dimensions are investigated. • Design recommendations are proposed. [ABSTRACT FROM AUTHOR]

This study examined the hysteretic behaviour of commercial Shape Memory Alloy (SMA) plates to promote their seismic applications in beam-to-column energy dissipation connections, and the research focus was given to the cyclic tension-release behaviour. Based on a series of SMA plate specimens, the investigation was commenced by examining the thermal characteristics, and the phase transformation behaviour of the SMA plates was characterised. Subsequently, cyclic tension-release tests of the SMA plates were conducted in the laboratory at room temperatures, and multi-phase tests considering varied loading protocols were carried out. It was observed that the self-centring capability of the SMA plates was comparatively less encouraging than bars and wires examined in the literature, whereas training cycles enabled stabilisation of the behaviour of the specimens by producing a newly recentring strain range with increased post-yield behaviour and decreasing martensite transformation stress. However, the energy dissipation of the SMA plates was reduced after experiencing the training protocols. Following the test programme, detailed numerical models of novel beam-to-column energy dissipation connection equipped with SMA plates were developed, and the feasibility of exploiting the cyclic behaviour of SMA plates was confirmed. Nonlinear spectral analyses of single-degree-of-freedom (SDF) systems representing structures were analysed to examine the influence of the structural hysteretic parameters on the structural inelastic demands quantified by strength reduction factor, and the influence of hysteretic parameters of the SMA plates on the structural seismic demand was characterised. • The cyclic tension-release behaviour of SMA plates is examined. • The thermal–mechanical behaviour of SMA plates is characterised. • Effects of the training protocol on the hysteretic behaviour are investigated. • Feasibility of applying SMA plates in beam-to-column connections is confirmed. • Strength reduction factor demand of representative systems are analysed. [ABSTRACT FROM AUTHOR]

Net section rupture is a common failure mode of bolted tension members. In particular, the net section capacity of tension angle is significantly affected by the effect of shear lag. This paper reports the tensile test results of twelve high strength steel angles and six normal steel angles of grade S690 and S275, respectively. The test parameters included steel grades, connection length (bolt number) and out-of-plane eccentricity. All the specimens were failed by net section rupture. Finite element (FE) analysis was used to simulate the structural behaviour of the test specimens and to further interpret the test results. The test and the numerical analysis results showed that the test efficiency of tension angles, which was defined by the ratio of the ultimate test load to the calculated net section resistance, was sensitive to the material ductility and the connection details (i.e. out-of-plane eccentricity and connection lengths). The effectiveness of the available design specifications for quantifying the net section resistance of S690 steel angles was evaluated. A design approach proposed by Yam and colleagues considering the influence of material mechanical characteristics and connection configurations was also revisited. It was found that the current design specifications produced inconsistent predictions of net section resistance of tension angles, whereas the method proposed by Yam and colleagues gave good predictions of net section resistance of bolted S690 steel angles. • Structural performance of bolted S690 and S275 steel angle is examined. • The influence of steel grades and connection configuration is studied. • Test observations are strengthened by finite element model results. • Design comments are proposed. [ABSTRACT FROM AUTHOR]

This paper reports a numerical study on the local web buckling strength and behaviour of single-coped beam with slender web (SCBSW). First, finite element (FE) models of SCBSW connections were developed, and the effectiveness of the modelling techniques was validated by the results of full-scale SCBSW connection tests conducted by the authors and those in the literature. Subsequently, an extensive parametric investigation covering a wide range of web slenderness ratio, cope geometries and rotational stiffness of the connection was conducted. A database of the FE results of 243 SCBSW models connected with a rotationally rigid support was developed. The analysis results show that all of the models were governed by local web buckling, and post-buckling behaviour of the SCBSW connections was confirmed. The interaction among the slender web, cope configurations and rotational stiffness of the connections on the structural behaviour and local web bucking capacity of SCBSW connections was characterised. A practical approach for evaluating the local web buckling strength of end-plate type SCBSW connecting with a rotationally rigid support was developed using the available FE results. The post-buckling behaviour and the interactive effect among the slender web and the other essential factors were considered in the proposed method. The proposed method produces reasonable predictions of the local web buckling strength of SCBSW connections with a rotationally rigid support comparing with those predicted by the FE results and the available test data, which may offer a basis for a full-fledged design guide for SCBSW. • Structural performance of single-coped beam with slender web is examined. • A parametric study is conducted using a finite element model database. • The influence of the slender web and the cope detail is studied. • The post-buckling behaviour is evident. • The strength of the single-coped beam with slender web is quantified. [ABSTRACT FROM AUTHOR]

• Novel structure self-centering cold-formed steel wall was proposed and validated using numerical method. • Lateral performance of CFSC and SC-CFSC wall were characterized by proposed theoretical model. • Residual deformation of the CFS wall was considerably optimized by SMA cables. • A few valued design recommadations were summarized to promote the partical application of the SC-CFSC wall. Cold-formed steel (CFS) structures exhibit considerable superiority in efficient and environmentally friendly building construction in high-seismic regions. The objective of this study is to develop and validate the concept of self-centering cold-formed steel composite (SC-CFSC) wall structures, and to characterize the lateral behavior of an SC-CFSC wall through numerical and theoretical analyses. Based on tests on shape memory alloy wires and CFSC walls, their hysteretic behavior is applied in ABAQUS to construct a finite element (FE) model of an SC-CFSC wall. The FE and theoretical analysis results of the SC-CFSC wall are in reasonable agreement, and valuable information regarding the design of the SC-CFSC wall is summarized. This study not only aims to provide a novel concept of self-centering CFS structures, but also to provide comprehensive explanation regarding the theoretical derivation and simulation procedures for characterizing the lateral behavior of both CFSC and SC-CFSC walls. [ABSTRACT FROM AUTHOR]

In this study, the hysteretic behaviour of shape memory alloy (SMA) plates under cyclic tension-release loadings was examined to promote their seismic applications, with an emphasis on large-size SMA plates with different geometries. Based on a series of SMA plate coupons extracted from base plates with different geometries, the thermal characteristics were investigated, and the phase transformation behaviour of the SMA plates was characterised. Subsequently, cyclic tension-release tests were conducted on the SMA plates in the laboratory, and the key mechanical performance indexes including the transformation strength, post-yield behaviour, self-centring capabilities, and energy dissipation abilities were carefully investigated. According to the results, SMA plates have a comparatively encouraging self-centring ability and moderate energy dissipation capabilities within a specified strain range. However, larger SMA plates show less satisfactory self-centring behaviour and are prone to brittle fracture at the edges. Based on the test programme, a numerical investigation was conducted to offer further insight into the potential applications of large-size SMA plates in the seismic field. A practical modelling procedure, namely the hybrid finite element (FE) modelling technique, was proposed and used to reproduce the degradation and cumulative residual deformation in the SMA plates. Moreover, nonlinear response history analyses (NL-RHAs) were performed on a prototype steel frame equipped with SMA plates in the connections to verify the feasibility of using large-size SMA plates in steel structures. • Six large-size SMA plates with various geometric dimensions were fabricated and heat-treated. • The influence of plate size on the cyclic tension-release behaviour of SMA plates was examined. • A practical FE modelling strategy and flowchart procedure for the SMA plates were proposed and verified. • The feasibility of exploiting SMA plates in seismic-resistant steel frames was explored. [ABSTRACT FROM AUTHOR]

The traditional cold-formed thin-walled (CFTW) steel sheathed walls are prone to have misalignment at the joints of wall panels and the damage of self-tapping screw connections under earthquake, resulting in obvious pinching of the hysteretic curves. In order to improve the energy dissipation and shear bearing capacity of the lateral resisting member in CFTW steel structures, an innovative structure called CFTW steel structure with braced ductile shear panel (CFTW-BSP) was proposed in this paper. Four full-scale one-story one-bay CFTW-BSP specimens containing two X-shaped and two K-shaped brace specimens were designed and tested under horizontal cyclic loads. The effects of configuration types, shear panel aspect ratios and slotted holes were investigated by comparing the lateral performance. In addition, the replaceability of the shear panel damper was analyzed. In general, the specimens performed well with a stable and plump energy dissipation capacity. The plastic deformation concentrated on the shear panel before 2% interstory drift, and then the end stud bases yielded and cracks propagated near the hold-downs at the ultimate stage. The braces always remained elastic during the tests. For X-shaped brace specimens, the slotted holes on shear panel can improve the ductility but decrease the energy dissipation capacity of the structure. For K-shaped brace specimens, the lateral resistance of the structure can be improved by decreasing the shear panel aspect ratio. • An innovative CFTW steel structure with braced shear panel (CFTW-BSP) is proposed. • Seismic performance of CFTW-BSP is studied by experimental research. • The influences of slotted holes on shear panels and shear panel aspect ratios are investigated. • The replaceability of the shear panel damper is investigated. • The proposed structures show excellent lateral resistance and the shear panel damper can be replaced at 1% interstory drift. [ABSTRACT FROM AUTHOR]

• Block shear failure of austenitic stainless steel bolted connections is studied. • The results of 15 connection tests are reported. • An extensive finite element analysis is performed to examine the block shear behaviour. • Austentic stainless steel bolted connections exhibited three distinctive block shear mechanisms. • Existing design methods are evaluated and a modified method is proposed. Austenitic stainless steel possesses very high ductility and ultimate-to-yield strength ratio, which could possibly affect the block shear failure mechanism and the corresponding ultimate capacity of bolted connections made of this material. In response to this concern, a comprehensive experimental and numerical study on the block shear behaviour of austenitic stainless steel bolted connections (ASSBCs) is conducted and reported in this paper. Based on the results of 15 experimental tests, it is found that the governing block shear mechanism of ASSBCs (for 14 out of the 15 tests) at the ultimate load corresponds to cracking of the shear sections prior to fracture of the tensile sections. This differs significantly from the conventionally accepted block shear mechanism of mild steel bolted connections, which is net section fracture of the tension area and yielding of the shear area. This observation was further confirmed by a numerical study based on validated finite element models, where three block shear mechanisms were identified for ASSBCs. A thorough parametric study was then carried out to clarify the effects of key design parameters on the block shear behaviour of ASSBCs. Finally, the experimental and numerical results are used to evaluate the applicability of existing design equations to predicting the block shear capacity of ASSBCs. An improved block shear equation is subsequently proposed based on the available data. [ABSTRACT FROM AUTHOR]

In this research, the seismic performance of a half-scaled three-storey high strength steel frame with curved knee braces (HSSF-CKB) under extreme earthquakes was investigated through shaking table tests. The test results demonstrated that the test structure maintained an encouraging recentring capacity under extreme earthquakes. By replacing the damaged curved knee braces, the structural stiffness was recovered to a certain extent. The failure mode of the test structure was governed by fracture of high strength steel beams, buckling of curved knee braces, and concrete crushing. Furthermore, a previously proposed analytical model for HSSF-CKBs was further validated by the test data. • A half-scaled, three-storey HSSF-CKB was subjected to simulated extreme earthquakes. • Encouraging recentring capacity of the test structure was observed. • Structural repair was achieved through CKB replacement. • The failure mode of the test structure was identified. • A previously proposed analytical model was further validated. [ABSTRACT FROM AUTHOR]

This study investigates the seismic behavior of an innovative cold-formed thin-walled (CFTW) steel frame with a K-shaped braced shear panel (BSPK). This new structural system is expected to improve the energy dissipation capacity of traditional CFTW steel structures. Eight full-scale one-story one-bay CFTW steel frames with BSPKs (CFTW-BSPKs) were subjected to lateral cyclic loads to examine the influence of the shear panel width-to-thickness ratio, aspect ratio, stiffening ribs, and slotted holes. The damage evolution, yield sequence, hysteresis curve, skeleton curve, load-carrying capacity, ductility, energy dissipation capacity, and stiffness degradation were analyzed. The test results demonstrated that all specimens exhibited stable hysteretic performance as well as a high load-carrying capacity. The seismic behavior consisting of energy dissipation and load-carrying capacity can be improved by increasing the shear panel width-to-thickness ratio or decreasing the aspect ratio. The stiffening ribs can significantly improve the load-carrying capacity and stiffness degradation of the specimens, while the slotted holes have a negative effect on the seismic behavior of the specimen. • Experimental studies on eight full-scale one-story one-bay CFTW steel structures with K-shaped braced shear panels (CFTW-BSP) are carried out. • The effects of shear panel dimensions, stiffening ribs, and slotted holes are investigated. • The applicability of shear stiffness equation for the shear panel are discussed. • The damage evolution processes of the structures are investigated. [ABSTRACT FROM AUTHOR]

To evaluate the seismic response of a multi-storey cold-formed thin-walled steel (CFS) structure based on the influence of nonstructural members, shake table tests were conducted on a full-scale six-storey CFS-steel plate shear wall structure (SPSWS) using bidirectional seismic inputs. The building specimen was tested at two different stages. In the first stage, the specimen mainly included structural components of walls, floors, and roofs, whereas the second stage model included all the nonstructural components. The testing program and obtained results including the observed damage, dynamic characteristics, strain response, acceleration, and displacement response were presented. Overall, this study revealed that the skin effect of lightweight wall panels, together with steel plate shear walls, resisted horizontal earthquakes and demonstrated the excellent deformation capacity and seismic performance of the CFS-SPSWS building. • The CFS-steel plate shear wall structure system was proposed. • Shake table tests on the seismic performance of the CFS-SPSWS were carried out. • The dynamic characteristics, strain response, acceleration and displacement response were obtained. • The influence of nonstructural members on the seismic response was analyzed. [ABSTRACT FROM AUTHOR]

This study experimentally investigated the mechanical properties, failure modes, and lateral resistance of oriented strand board (OSB) sheathed cold-formed steel (CFS) shear walls under monotonic loading and reversed-cyclic loading. The influences of the loading mode, vertical load, ratio and local strengthening of openings, sheathing panel, and diagonal rigid bracing on the lateral resistance of the CFS shear walls were also analyzed. The experimental results demonstrated that the loading mode exerted a significant influence on the performance of the wall panels; the shear resistance of the specimens under monotonic loading was 13% greater than that of the specimens under reversed-cyclic loading. For specimens with the identical configuration, the shear resistance decreased with the opening ratio increasing and local strengthening of openings could reduce the adverse effect. The shear bearing capacity of the single-sided (OSB) panel wall was much greater than that of the non-paneled wall. The vertical load had little influence on the wall's shear bearing capacity. Compared with ordinary CFS shear walls, the walls with V-shaped diagonal rigid bracings demonstrated greater shear bearing capacity and lateral stiffness, whereas the ductility and energy dissipation capacity were comparatively less encouraging. • Tests of OSB sheathed cold-formed steel shear walls were conducted. • Local strengthening over the opening could reduce the influence of the opening. • Diagonal rigid bracing could improve the shear bearing capacity of the wall. [ABSTRACT FROM AUTHOR]

In this paper, the seismic performance of cold-formed thin-walled steel walls with diagonal braces is studied by means of experiments and finite element analysis. In total, horizontal hysteretic loading tests were carried out on six full-scale cold-formed thin-walled steel walls. The influence of diagonal bracing, the screw spacing, wall panels and vertical loads on the seismic performance of the walls was investigated from the aspects of hysteretic curves, skeleton curves, the lateral stiffness degradation and the energy dissipation capacity. It was found that diagonal bracing could significantly improve the load-bearing capacity, stiffness, and energy dissipation capacity of the walls. However, the lateral resistance increased slightly because of premature buckling of the transverse braces at the connection between the diagonal and transverse braces. In addition, finite element models of the wall specimens were established by ABAQUS software and validated against the experimental data. A preliminary parametric study was also conducted to further examine the influence of essential parameters on the behavior of cold-formed steel walls with diagonal braces. • The hysteretic behavior of cold-formed thin-walled steel walls with diagonal braces were investigated. • Six full-scale specimens were tested under cyclic load. • Comparison between the specimens with and without diagonal braces are illustrated. • The parametric analyses were conducted by the numerical simulation. [ABSTRACT FROM AUTHOR]