Experimental Study on the Progressive Collapse Resistance of Two-Storey Half-Scale Fabricated Reinforced Concrete Column-Steel Beam Composite Frame Structure

Progressive collapse behavior of case-in-place concrete and steel frame structures has been extensively investigated over the past years. However, studies on progressive collapse resistance and characteristics of prefabricated RCS composite frame structure (space frame) are limited. In this study, a half-scale prefabricated RCS space frame structure (two-storey, 1 × 2-bay) was designed and manufactured and then tested through the sudden failure of the long-side central column. The weakened part of failure column was rapidly pulled out using vehicle traction force, and displacement was obtained with a dynamic data acquisition instrument supplemented by high-speed camera to record the deformation process of the structure. Additionally, the remaining structure displacement variation and the beam-to-column connections of fem model under progressive collapse were simulated using SAP2000. The FEA results were compared with the experimental results to verify the effectiveness of the numerical analysis. Experimental results demonstrated that the prefabricated RCS composite frame structure designed in accordance with Chinese building codes shows improved resistance to progressive collapse. The dynamic effect demonstrates no significant influence on the prefabricated RCS composite frame structure, and the suggested dynamic amplification coefficient is 1.28. Steel plates (A, B, and C) of the beam-to-column connection are the weak part of the structural failure, and appropriate measures should be applied to strengthen the steel plate of the beam-to-column connection when the prefabricated RCS composite frame structure is designed to resist progressive collapse. SAP2000 FEM program verified that the numerical simulation results are basically consistent with the experimental results.

Research on the Mechanical Characteristics of H-section Steel Frame under the Action of Thermo Mechanical Coupling

The research on the mechanical characteristics of concrete-filled steel tubular composite frame under high temperature fire environment is one of the research hotspots. In this paper, the finite element simulation software is used to analyze the concrete-filled steel tubular composite frame structure. The failure mode of the flexural deformation of the composite frame structure under high temperature fire environment is introduced. The simulation results of the deformation and displacement of the single-layer single span and two-layer two-span composite frame structure are deeply studied, including the different temperature field, structural field, structural field of each beam and column The results show that: with the temperature rising, the horizontal plastic strain, vertical displacement and local plastic region of beam and column are redistributed and changed in high temperature fire environment, and the flexural effect of two-story two-span concrete-filled steel tubular composite frame under different fire positions is analyzed. The results show that: with the temperature rising, the horizontal plastic strain at the concentrated load is not the results show that the deflection and deformation redistribution are obvious, and the deflection and deformation redistribution are obvious at the joint points of beams and columns. Finally, a mechanism is formed and destroyed. The flexure effect of mode 1 is larger than that of condition 2, which indicates that the flexural effect of two-story two span CFST composite frame under full cross-section fire is larger than that of condition 2 It should be better. The research results can provide reference value for the reinforcement and repair of CFST composite frame under high temperature fire.

Seismic fragility analysis of two-story ultra-high ductile cementitious composites frame without steel reinforcement

This article numerically studies the seismic vulnerability of the frame structure made of ultra-high ductile cementitious composites without longitudinal and transverse reinforcement. A non-linear finite element model is established with the help of Open System for Earthquake Engineering Simulation and calibrated by shaking table test results on an ultra-high ductile cementitious composite-RC frame whose seismic vulnerable parts were replaced by ultra-high ductile cementitious composites without steel reinforcement. Subsequently, an analysis on the structural seismic vulnerability is performed on pure ultra-high ductile cementitious composite frame structure based on the incremental dynamic analysis method. Finally, a seismic vulnerability matrix of the ultra-high ductile cementitious composite frame under various structural limit states is obtained from seismic fragility curves. Under the major earthquake of magnitude 7.5, the probability of ultra-high ductile cementitious composite frame structure under basically intact, slight damage, moderate damage, serious damage, and collapse is 14.2%, 48.1%, 31.7%, 5.3%, and 0.7%, respectively. The achieved results also demonstrate that the ultra-high ductile cementitious composite frame can satisfy the objectivity of “No collapsed under major earthquake” at least for major earthquakes of magnitude 8. It is demonstrated that the ultra-high ductile cementitious composite frame satisfies three-level performance objectivity stipulated in GB 50011-2010 and, thus, preliminarily verifying the feasibility for constructing structures just using high-performance concrete.