Influencing factors analysis of degradation and damage and the effect on steel frame

Abstract

In order to discuss the influencing factors of damage and degradation and the effect on steel frame subject to strong earthquakes, firstly, a constitutive model was proposed for 3D finite element models to calculate the seismic behaviors of steel frame more accurately. The model was proved correct and applicable due to typical quasi-static tests. Then, based on the verified model, the damage and degradation factors were discussed by parametric analyses, including the panel zone, loading history, loading amplitude, the width to thickness ratio and yield strength. The cumulative damage phenomena of steel frame connections were further studied and the degradation distribution curve was obtained. Finally, the traditional beam element model and proposed shell element model of structure were established by ABAQUS for time history analysis. The effect of damage and degradation on seismic behaviors of steel frames were compared and discussed. The tests and analysis results revealed that: panel zone strength, loading amplitude and width-thickness ratios of plates had significant impact on damage and degradation behaviors and failure modes of connections. Premature weld cracking would lead to earlier damage and degradation under “strong to weak” earthquake, which would seriously affect the overall mechanical properties of the structure. Once local buckling caused damage, the results of the beam element model and accurate shell element model were remarkably different. Beam element model without considering damage and degradation underestimated the structural deformations, which should be paid more attention for design safety.