Damage evaluation and ultra-low-cycle fatigue analysis of high-rise steel frame with mesoscopic fracture models

摘要

In this study, a straightforward method for evaluating damage and ultra-low-cycle fatigue (ULCF) life of high-rise steel frame structures under strong seismic loading at the material level was newly proposed on basis of interstory drift measurement and mesoscopic fracture models. A mesoscopic ULCF model for cyclic loading was improved by considering both effects of strain amplitude and loading sequence, which was implemented into finite element software. Since elastic loading and unloading processes do not affect damage accumulation, four filtering methods for inter-story displacement data were proposed to improve computing efficiency without impeding simulation accuracy. An improved fracture model was integrated into ABAQUS using a user-defined subroutine, and a hybrid finite element analysis using both shell and beam elements was conducted, where filtered displacement was employed as input data. Experimental results of a shaking table test on a 1/3-scale 18-story steel frame conducted at E-Defense were employed to prove validity of the analysis method and fracture models. Comparison results show that the improved mesoscopic ULCF model can evaluate crack initiation of steel structures with acceptable accuracy.