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Roof joint is a critical connection in space truss structures, which connects the upper steel space truss roofs and reinforced concrete structures. Because of its simple structural detailing and easy construction, a typical kind of roof joint is comprised of four embedded anchor rods, a mortar layer, a base plate, and stiffeners are popular in small- to medium-span space truss structures. Among them, base plates with slotted bolt holes are commonly used to release the deformation caused by temperature change or earthquake input. The roof joints were considered either as pinned or rigid connections in the design. In this paper, quasi-static tests investigating the influence of the applied axial force and the shape of bolt holes on the shear resistance and seismic behavior of roof joints were performed. The roof joints exhibited semi-rigid connection behavior and two types of initial resistance mechanisms, sliding and overturning, were observed. With the increase of applied axial force, the behavior of roof joint changes from sliding to overturning. Finally, effective methods to determine the initial resistance mechanism and calculate the ultimate shear strength of roof joints are proposed. These findings and analyses may provide guidelines for roof joint design practice for space truss structures. [ABSTRACT FROM AUTHOR]

Column base is one of the most important elements of steel structures. Exposed column base is commonly used in low-to-medium-rise steel moment resisting frames because of better constructability and low cost. To study the effect of exposed column base behavior on the seismic behavior of low-to-medium-rise steel moment resisting frames, a four-story, four-bay steel moment frame is studied by the nonlinear time history analysis. In the numerical analysis, two types of column base connections (rigid and semi-rigid) are considered. The width–thickness ratio of column and stiffness ratio of column base to column are chosen as the analysis parameters. The characteristics of structural responses, hysteresis loops, and the distribution of plastic energy dissipation are compared. It indicates that the collapse margin ratio is significantly increased when the exposed column base behavior is considered for the moment resisting frames with large width–thickness ratio. Moreover, if the column base connection is allowed to rotate and transfer a portion of the moment, the demand of plastic deformation capacity of steel columns is reduced, then subsequently strength deterioration caused by the local buckling at the bottom of column could be avoided. Also, the whole structure has a better ductility, the ability of plastic deformation and energy absorbance of the moment resisting frame under earthquake are therefore enhanced. The structure with the semi-rigid column base connection has larger potential to avoid the structural collapse caused by the local buckling of first-story columns. [ABSTRACT FROM AUTHOR]

This paper proposes a novel ductile linked rocking steel frame (DLRF) that relying on gravity load and rocking column base components rather than post-tensioning elements to provide the self-centering capacity. In the DLRF, rocking steel braced frames remain elastic by being permitted to uplift and rock at the rocking column bases, coupled with ductile links that act as structural fuses to dissipate energy through accommodating vertical movement between the two-rocking steel braced frames. Rocking column bases can dissipate energy through fuses that can be repaired easily by being bolted to the column. The design equations to govern the corresponding resistance mechanism of the DLRF for each limit state are presented and applied to a four-story prototype structure. Nonlinear dynamic analyses were performed to examine the behavior of the DLRF. The seismic performance of the DLRF is contrasted with a corresponding fixed-base structure, in which the column base is designed as a rigid connection. The comparison indicated that the DLRF exhibited uniformed interstory drift distribution as well as negligible residual drift subjected to DBE and MCE intensities, and thus the soft-story failure can be effectively avoided. Dynamic analyses also confirmed that the proposed design equations can predict the mechanical behavior of the DLRF with expected drift capacity and flag-shaped hysteretic response. Therefore, the proposed DLRF is a viable alternative to a seismic load-resisting system which could avoid severe and expensive damage to the structure, enhancing resilience capacity. • The ductile linked rocking steel frames (DLRF) showing flag-shaped response was introduced. • The rocking column bases can recenter the frame and ductile links can enhance energy dissipation. • The design equations based on specified performance objectives were proposed and validated. • The DLRF exhibits uniformed interstory drift distribution and reduced residual drifts. • The DLRF can perform as predicted with rocking and self-centering behavior. [ABSTRACT FROM AUTHOR]

Highlights • A novel low-rise precast wall panel structure system is proposed. • Bolt loosening is proven to be critical to the dynamic responses. • The lateral deformation mode of test structure is dominated by sliding of shear wall. • Performance design objectives and damage limit states of the system are given, and the fragility curves are performed. • The proposed novel precast structure system presents high stiffness, high load capacity and high collapse margin ratio. Abstract This paper proposes a novel low-rise precast wall panel structure with bolt connections, which has advantages of convenient and rapid assembly. To investigate seismic performance of the structure system, a shaking table test of a 1/2 scaled three-story model is conducted, by which the structural dynamic responses, damage pattern, and seismic fragility are analyzed. The results show that the proposed novel precast structure system presents high stiffness, high load capacity and high collapse margin ratio. In this novel structure system, the bolt connections are critical for the structural dynamic characteristics and responses. Damage pattern of the structure follows the sequence of bolt loosening, adjoining wall panels sliding and dislocating, structural components cracking. The seismic damage of test structure is slight, and most structural components still remain elastic in maximum considered earthquakes. Based on the test results, performance design objectives for service level earthquake, design based earthquake and maximum considered earthquake are given, and four limit states are defined. The fragility curves of the structure are developed, as well as the fragility of nonstructural components. [ABSTRACT FROM AUTHOR]

• The cyclic behavior of the corrugated steel plate (CSP) link was tested and validated. • The corrugation can provide adequate out-of-plane support to the steel plate. • The effect of geometric parameters on the seismic behavior of CSP was investigated. • Finite element simulation with ABAQUS can reliably predict CSP's nonlinear behavior. • The proposed simplified equations can effectively predict the capacity of CSP. In this paper, a novel replaceable corrugated steel plate (CSP) link is proposed. Eleven specimens with different geometries were tested. The results show that the yield lateral load and initial stiffness of the specimen were mainly affected by the aspect ratio of the CSP. On the other hand, the peak lateral load, ductility, and energy dissipation were closely related to the depth and aspect ratios of the corrugation. Robust finite element models were built to simulate the hysteretic behavior of the CSP. The result shows the finite element models were capable of simulating the cyclic response of CSP well. To facilitate design efficiency, simplified equations were proposed to predict the yield lateral load, peak lateral load, and initial stiffness of the CSP. The results show that these equations can be used efficiently to predict the capacity of CSP. Overall, this study provides a comprehensive experimental and analytical study to show that the proposed CSP link has stable seismic performance and can be used as an effective steel link for seismic applications. [ABSTRACT FROM AUTHOR]

In a full-scale seismic test conducted by the present authors on a fully prefabricated steel frame, strains on the surfaces of beams, columns, braces and slabs were monitored, and the deformations in nine bolted end-plate joints were detected. The global responses of the frame and the composite action of the slabs were analyzed and discussed in the first companion paper. The seismic behavior of members and joints in the frame test were studied in-depth in this paper. Real boundary conditions of joints assisted more accurate study of the cyclic responses of end-plate joints compared with the general experiments on T-shape joints and cruciform joints. Seismic responses of flexible braces, beams and columns were analyzed. Hysteretic performance, backbone curves, the components of story drift ratios and energy dissipation of bolted end-plate joints were discussed. Based on these previous contents, the plastic development sequences and failure modes of the frames were summarized. The results indicate that satisfactory cyclic behavior, deformation capacity and energy dissipation were exhibited in members and joints. Over 65.3% of story drifts were induced by member bending in the elastic stage, but the increments of story drift were dominated by joint deformations after the 1.44% overall drift ratio loading stage, and the cumulative story drifts caused by joint rotations reached the proportions of 57.9–83.9% at the ultimate displacement. The maximum percentages of joint cumulative energy dissipation were 69.7%, 59.0%, 56.4% and 18.2% for the first, second, and third story and the whole specimen, respectively. The plastic development sequence and the failure mode of the frame were yielding of braces (0.36–0.72% overall drift ratio), yielding of end-plate joints (0.72–2.16%), yielding of column bases (1.80–2.16%), yielding of panel zones (≥1.80%), and yielding of several beam ends and column tops (≥4.32%). [ABSTRACT FROM AUTHOR]