Dynamic-Failure Study Of BSS By Considering Damage Accumulations

Based on the summary of structural material-damage study, by considering earthquake effects, the material-damage in BSS and damage contribution to structural static and dynamic behaviors were mentioned. Further, the dynamic failure forms of BSS were discussed.A new method to calculate damage variance(D) by using principle of minimum consume energy was discussed, and a new programme to detect material damage by using microhardness principle was planned. The hypothesis of stress equivalence, namely, treating the damage as the amendments of elastic modulus, was adopted when the contribution of cable damage to static and dynamic behaviors of structure were discussed. By which, the material damage was introduced into structural analysis. During analysing the form of BSS dynamic failure, beams were assumed to obey the Bilinear Kinematic Hardening Model, and the plastic development in the cross section of beams under earthquake was calculated. Then the influences of initial pre-stress, rise-span ratio, cross-section areas of beams, direction of earthquake and different types of longitudinal tension cables on dynamic failure in BSS were considered.By studying the cable damage, it was obtained that the cables-damage would cause greater influence on higher-order natural frequency while less on the first order natural frequency. And cables were damage-sensitive components, which caused great static and dynamic performance changes.By simulating the whole dynamic-failure process of structure in ANSYS, it was found that the cables were still in elastic stage when the failure occurred in normal design procedure, which could hold up the vertical displacement and made the plasticity of pipes keep on developing until failure occurred. It was indicated that the material utilization rate of BSS was very high. The effect of cables failure was discussed and found that it would lead to structural failure directly.