The Application Of Micromechanical Damage Criterion Of Structural Steel In Damage Analysis Of Steel Frame Under Extreme Loads

Failures of the steel structure caused by extreme disasters, such as earthquake andexplosion, can lead to significant loss of lives and properties, which has been a key issue inthe engineering and academic area. Under accidentally extreme loads, the macro-scaledamage of the structure often initiated from the micro-scale damage evolution of structuralsteel on the key component. Therefore, the micro-scale damage evolution mechanism ofstructure steel and its damage effect on the behaviors of the whole structures should be fullyunderstood.The micromechanical damage criterion of steel could accurately explain the failuremechanism of the structural steel under complicated stress state and, therefore, can be used asa method to forecast the macroscopic damage phenomenon of the steel structure. At present,lots of researchers had conducted a series of researches on the damage and fracturemechanism of mental materials and put forward some suitable mental micromechanicaldamage criterions. But how to apply these damage criterions into structural failure simulationanalysis is still a difficult problem.This thesis mainly aims to build a connection between micro-scale material damagecriterion and the macro-scale damage evaluation of the steel structure. At the beginning,basing on the theory of Xue-Wierzbicki damage criterion, the paper proposed a suitable microdamage initiation criterion for structural steel. Then,10tensile tests on Q235structural steelspecimen were conducted to determine the damage evolution criterion. Later, these proposedstructural steel damage criterions were applied in the following damage simulation analysis ofthe steel frame system under low-cyclic, strong seismic and the blast load. And then the paperutilized the proposed damage criterions to investigate the damage development of the steelframe under the extreme loads.The methods in this thesis provide a powerful tool for damage analysis, disasterevaluation and the optimization design of steel frames subjected to static cyclic, strongseismic and blast load.