Search

This paper investigated the structural robustness of steel-framed modular buildings based on the alternative load path method using LS-DYNA. The structural responses of a reference structure were first simulated to understand typical building motion, load redistribution mechanisms and failure modes after removal of a base corner module. Based on the reference scenario, a comprehensive parametric study was then carried out to investigate the effects of structural configuration (number of modules of each floor), module posts (wall thickness and number of supporting posts) and other features (inclusion of floor slab, longitudinal wall bracing, connection stiffness and connection capacity) on the structural responses of steel modular buildings. It was found that the collapse resistance of steel modular buildings could be improved with an increase in the number of modules per floor, the number and capacity of supporting posts, higher rotational stiffness and capacity of inter-module connections, and the use of longitudinal wall bracing. Consideration of floor slabs provided a more realistic description of collapse mechanisms, due to the slab-related contact interaction and diaphragm action. Also, the structure was more vulnerable to the removal of modules (or posts) near the end corner of a building.

An innovative nodal joint system with thin-walled steel sleeve and plate is examined for development of latticed shell structures using hollow section glass fiber reinforced polymer (GFRP) members. In the proposed system, the GFRP members were connected to a steel gusset-plate space node through bolted sleeve joints (BSJs). The mechanical performance of BSJs was first examined through cantilever bending experiments. Then, the performance of the entire nodal joint system incorporating the space node was examined in bending for both in-plane and out-of-plane stiffness. Its performance was then characterized by nonlinear springs and evaluated at a structural level based on a space latticed structure configuration through finite element (FE) analysis and the resulting structural performance satisfied the ultimate limit state (ULS) and serviceability limit state (SLS) requirements as per relevant standards. A parametric study was also conducted to understand the effect of joint rotational stiffness on the overall structural performances.

This paper investigates the mechanical performance of beam-to-column connections for steel-framed building modules with RHS and SHS sections of relatively small member sizes. In the experimental program, three forms of connections are tested under static bending, including a completely welded connection (W), a bolted end plate connection (EP) and the proposed end plate–stiffener connection (ST), and the failure modes, moment–rotation behaviours and strain responses were recorded during experiments. Results show that ST connection exhibited superior connection strength, stiffness and ductility compared with the EP connection. In addition, a detailed finite element analysis was conducted to model the connection behaviours, considering bolt pretension, contact behaviours and detailed bolt geometry, showing good comparison with experiments. Furthermore, a parametric study was performed on the end plate thickness and stiffener thickness for the proposed end plate–stiffener connection. Such results finally enable a comparative study to investigate the performance of module during road transportation, highlighting the effects of connection stiffness.

This paper describes the dynamic and fatigue performances of a large-scale space frame assembled using pultruded glass fiber reinforced polymer (GFRP) composites, with reference to pedestrian bridge application. The experimental structure was assembled by circular hollow section (CHS) GFRP members with the assistance of a novel steel connection system. The results from free vibration tests were analyzed using peak-picking (PP) and stochastic subspace identification (SSI) methods to extract modal parameters, i.e. natural frequencies, damping ratios, and mode shapes. From both experimental and validated FE analysis results, the proposed space frame structure satisfied the standard requirements for pedestrian bridge application in terms of natural frequency. The torsion mode as the first order mode shape can be avoided when the contribution of a bridge deck is considered. Furthermore, the structure was examined with 2.1 million fatigue load cycles and then statically loaded up to failure. The failure load showed no decrease when compared with that of a space frame without fatigue. The structural stiffness and strain of critical compressive members measured at 0.3 million fatigue loading intervals showed no significant variations, indicating that the applied fatigue did not degrade structural components and connections.