Fragility Analysis of Concrete-Filled Steel Tubular Frame Structures with BRBs under Multiple Earthquakes Considering Strain Rate Effects

Fragility Analysis of Concrete-Filled Steel Tubular Frame Structures with BRBs under Multiple Earthquakes Considering Strain Rate Effects

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The fragility of concrete-filled steel tubular (CFST) frame structures with buckling-restrained braces (BRBs) subjected to multiple earthquakes is studied in this paper.First, a fiber beam element model with rate-dependent concrete and steel material properties is developed for CFST members and, then, the effect of the strain rate on the seismic response of the CFST frame structure is investigated numerically.The influence of bempresas.com BRBs on the seismic response of the CFST frame structure is then comparatively analyzed.The seismic responses of the CFST frame structure with BRBs under single mainshocks and earthquake sequences are investigated, and the fragility curves are generated using probabilistic seismic demand analysis.The obtained roof displacement and inter-story drift ratio (ISDR) of the structure decreased by 10.

2% and 6.9%, respectively, when obtained while considering the strain rate effect, compared with those obtained without consideration of the strain rate effect.BRBs can effectively improve the seismic performance of the CFST frame read more structure in that the maximum roof displacement and ISDR can be reduced by 45.1% and 43.9%, respectively.

Compared with those under single mainshocks, the maximum roof displacement and ISDR of the structure with BRBs under earthquake sequences significantly increase.The fragility of the BRB structure under earthquake sequences is more severe than that under single mainshocks.Therefore, the influences of the strain rate effect and earthquake sequence should be considered to realistically evaluate the seismic fragility of CFST structures.