BRB水平力分担率对高层屈曲约束支撑钢框架抗震性能影响研究

Influence of BRB horizontal force sharing rate on seismic behavior of high-rise buckling restrained braced steel frames

本文按照结构刚度相近、重量相近的思路设计了5组BRB水平力分担率β分别为20%、30%、40%、50%和60%的高层屈曲约束支撑钢框架结构模型,并对模型进行弹塑性静力推覆分析及弹塑性时程分析,研究BRB水平力分担率β对高层屈曲约束支撑钢框架抗震性能的影响。研究结果表明:(1)β=20%的结构,BRB屈服早,承载力较小,滞回耗能效果有限;β=30%~40%的结构,BRB屈服早,承载力较大,滞回耗能性能好;β=50%~60%的结构,BRB承载力大,下部楼层BRB屈服较早,滞回性能好,上部楼层BRB屈服晚,滞回性能差。(2)当结构层间位移角未超过1/50时,层间位移较大区域主要在中间楼层或中低部楼层。当结构层间位移角超过1/50时,高β值结构的下部楼层刚度迅速下降,变形增大明显。(3)罕遇地震下,随着结构β值的升高,结构上部楼层、中间楼层BRB的延性比μ及塑性延性比η会出现不同程度的下降,β值越大,楼层越高,下降越明显,而不同β值的结构下部楼层BRB的μ及η变幅较小。(4)对于高层BRB钢框架结构,工程中建议将BRB的水平率分担率β设计为30%~40%。

In order to study the influence of BRB horizontal force sharing rate on the seismic behavior of high-rise buckling restrained braced steel frames,five high rise buckling restrained braced steel frames with BRB horizontal force sharing ratio β of 20%,30%,40%,50% and 60%,respectively,are designed in accordance with the idea of similar stiffness and close weight of each structure.And elasto-plastic static analysis and time history analysis were performed on the model.The results of the study show that: First,The BRB with β of 20% installed in structures has smaller bearing capacity and limited energy dissipation effect.The BRB with β of 30% to 40% installed in structures has larger bearing capacity and well performance of hysteretic energy dissipation.The BRB with β of 50% to 60% installed in structures has large bearing capacity,and the BRB installed in lower stories yield earlier,but has better performance of hysteretic energy dissipation compared to the BRB installed in taller stories.Second,when the inter-story displacement angle of the structure is less than 1/50,the larger inter-story displacement is mainly in the middle or low-middle story.When the inter-story displacement angle of the structure is more than 1/50,stiffness decreases rapidly and deformation increases rapidly at low-rise of the structure with big value of β.Third,under infrequent earthquake,with the increase of β of the structure,the ductility ratio μ and the accumulated plastic ductility ratio η of BRB in the high rise and middle rise of the structures will decrease in varying degrees.The higher the β and the higher the floor,the more apparent the decrease is.And there is little variation of μ and η of BRB installed in lower stories with the bigger value of β and the higher height.Fourth,it is suggested that the horizontal force sharing ratio β is designed to be 30%-40% for high-rise BRB steel frame structure.