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This study reported an experimental study of hybrid-self-centering connections (HSCCs) employing energy dissipation sequences. The dual self-centering mechanism of the connection consisting of post-tensioned (PT) steel strands and shape memory alloy (SMA) bolts provided the self-centering driving force, and the energy dissipation sequences can be realized by friction dampers and SMA bolts. An experimental program employing five proof-of-concept connections was tested under the cyclic loading scenarios. The test results including hysteretic responses, strain gauge readings, force evolution in PT steel strands, strength and stiffness, energy dissipation capability, and self-centering ability were examined and discussed. The obvious trilinear hysteretic feature of the test connection accompanied by excellent self-centering ability, moderate energy dissipation capability, and satisfactory ductility was confirmed. In addition, the encouraging repairability of the test connection was verified by retests of repaired specimens. Subsequently, finite element (FE) models verified by the experimental results were developed to further examine the behavior of the proposed connection. A design model was developed enabling the quantification of the multilinear behavior of moment-rotation responses of the proposed connection. The good agreement between the stiffness and strength of the connection from the test data confirmed the rationality of the proposed design model. The analysis results of nonlinear spectral analyses confirmed the effectiveness of structures equipped with the HSCC in reducing acceleration response. [ABSTRACT FROM AUTHOR]

A noteworthy feature of the hybrid steel moment resisting frames (MRFs) with energy dissipation bays (EDBs) is the damage-control behaviour characterised by concentration of plastic damages in the energy dissipation bay (EDB) under earthquakes. This paper presents a design methodology for conducting the damage-control design of hybrid steel MRFs with EDBs. First, the structural damage-control behaviour quantified by the classical bilinear kinematic hysteretic model with significant post-yielding stiffness ratio is clarified utilising the test results extracted from a large-scale quasi-static test programme. Then, based on the seismic energy balance of single-degree-of-freedom systems incorporating significant post-yielding stiffness ratios, the design philosophy and governing energy balance equations featuring the damage-control behaviour of low-to-medium rise hybrid steel MRFs with EDBs under earthquake ground motions are presented. Subsequently, a stepwise design procedure that can be used to search for a design strategy of a hybrid steel MRF with EDBs under expected ground motions is developed. Three low-to-medium rise prototype structures are designed by the proposed methodology, and the seismic responses of the systems are evaluated by pushover analyses and nonlinear response history analyses based on numerical models validated by the test results. The results indicate that all the prototype hybrid steel MRFs with EDBs can achieve the damage-control behaviour with the prescribed drift threshold, and hence the post-earthquake residual deformations are also mitigated. Since the proposed method is a direct-iterative design procedure, it also retains practical attractiveness and will facilitate the seismic design of hybrid steel MRFs with EDBs. [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]

• The hysteretic behaviour of shape memory alloy (SMA) plates with superelastic effect under cyclic tension–compression loading was investigated. • We designed and tested 33 SMA plates with buckling-restrained devices to examine the mechanical properties of SMA plates subjected to cyclic tension–compression loading. • The test parameters are the specimen thickness, loading protocols, and test temperatures. • The failure mode, stress–strain responses, strength, and self-centring capability of the specimens were analysed and discussed. Shape memory alloys (SMAs) have garnered significant attention for their potential in earthquake-resistant structures, primarily due to their superelastic effect and exceptional self-centring capabilities. However, the mechanical properties of SMA plates, especially under cyclic tension–compression loading, remain underexplored. This research aims to bridge this gap by designing and testing 33 SMA plates equipped with buckling-restrained devices. The study varied parameters such as specimen thickness (4 mm, 6 mm, and 8 mm), loading protocols (seven in total), and test temperatures (25 °C and 0 °C). The findings reveal that the stress–strain curves under cyclic tension–compression loading exhibited asymmetric characteristics. For instance, at 25℃, a 4 mm thick specimen at 4% strain had a compressive peak stress that was 22.2% higher than its tensile counterpart, and its compressive residual strain exceeded the tensile residual strain by 99.0%. Furthermore, when compared to SMA plates under cyclic tension-release loading, those under cyclic tension–compression loading had reduced tensile residual strains. At 0 °C, the peak stress saw a decrease ranging from 2.4 to 43.1%, while the residual strain surged by 11.9–591.4% compared to the tests at 25℃. This study provides novel insights into the behavior of SMA plates under varied conditions, emphasizing their potential for seismic applications. [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]

• The hysteretic response curves of the fuse connections subjected to cyclic loading were plump. • The fuse angles can concentrate the inelasticity effectively in a wide deformation range. • The retest with replaced angles exhibited a similar performance to the initial test. • The fuse connection achieved an initial stiffness close to that of a typical welded beam-to-column connection. In this study, an innovative replaceable fuse connection for beam members in moment resisting steel frames was proposed. Steel angles are designed as fuse elements for energy dissipation and post-earthquake replacement. The load carrying mechanism of the connection was explored. In order to examine the feasibility of the notion, a total of six full-scale subassemblies of beam-to-column connections were tested. The test parameters that affect the performance of the fuse connection were studied, and the repairability was validated by a retest specimen with replaced fuse angles. Test results demonstrated that the hysteretic response curves of the test connections subjected to cyclic loading were plump, and the fuse angles can concentrate the inelasticity effectively in a wide deformation range. The novel connections equipped with fuse angles can achieve an initial elastic stiffness close to that of a conventional welded beam-to-column connection. In addition, theoretical equations for predicting the elastic stiffness and resistance of the connection were developed, and their sufficiency was validated by test results. [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]

A composite wall is the primary lateral force-resisting system in a cold-formed thin-walled steel structural system. The shear force between the upper and lower walls is transmitted through an inter-story connection in the cold-formed thin-walled steel platform framing system. In this study, the 16 platform framing inter-story connection specimens were subjected to cyclic loading to study the shear resistance, the failure modes, deformation, and the influence of stiffeners, lateral rigid blocking, X-shaped straps, and vertical. Hysteretic curves, skeleton curves, shear bearing capacity, and lateral stiffness values were obtained from the testing. The results showed that the specimens with only stiffeners had a lower shear capacity and lateral stiffness, which were significantly affected by the vertical force. Further, short stiffeners were not fully effective. The highest shear capacity and lateral stiffness values were characterized for the specimens with rigid blocking. Increasing the rigid blocking improved the shear resistance of the specimens, and rigid blocking with the same height as the floor joists contributed to excellent shear capacity and lateral stiffness of the specimens under vertical loading. The lateral stiffness of the inter-story connection was also significantly increased by using X-shaped straps, and the vertical force resulted in substantial decrease of the lateral stiffness. Based on the test results and a comparison of the nominal shear strength values required by current specifications, this study proposed improvements to the design of cold-formed thin-walled steel platform framing inter-story connections. [Display omitted] • Low cyclic loading tests were performed on 16 inter-story connection specimens. • Hysteretic curves, skeleton curves, shear bearing capacity, and lateral stiffness values were obtained. • It deals with the impacts of stiffeners, lateral rigid blocking, X-shaped straps, vertical forces, amount and height. • It provides improvements to the design of cold-formed thin-walled steel inter-story connections. [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]