板柱-支撑结构抗震设计关键问题分析

Key issues on seismic design of slab-column structure strengthened by buckling restrained braces

板柱结构具有可利用空间大、布局灵活、显著降低层高等优势,但是存在结构水平刚度较弱、位移大、抗震承载力较差等问题。为解决上述问题,在板柱结构中设置屈曲约束支撑,以提高结构的抗侧刚度,增强其抗震承载力。通过对3个高度不同和2个大面积的板柱-支撑结构的计算表明,板柱结构抗侧刚度和承载力较弱的问题可通过设置适当数量的屈曲约束支撑解决。为研究板柱-支撑结构的变形、层间剪力、倾覆弯矩、支撑布置等问题,通过PKPM建模分析,结果表明:多遇地震作用下,板柱-支撑结构可采用框架结构的弹性层间位移角(1/550)来控制结构变形;板柱-支撑结构中支撑承担的楼层剪力建议不低于楼层剪力的40%;通过对比GB 50011—2010《建筑抗震设计规范》和力学概念计算得到楼层倾覆力矩的结果,认为采用规范建议的方法较为合理;支撑的竖向居中布置会减小支撑倾覆力矩占比,而对支撑剪力占比影响较小。

Slab-column structures have advantages of large available space,flexible layout and significantly reducing height.However,their disadvantages include weak horizontal stiffness,large displacement,and poor seismic resisting capacity.In order to solve the problems,buckling-restrained braces are applied in the slab-column structures to increase the lateral stiffness and to enhance the seismic resisting capacity.Based on the calculation of three models with different heights and two models with large area,it is found that the shortcomings of weak lateral stiffness and bearing capacity of slab-column structures can be solved by installing an appropriate amount of buckling-restraint braces.To investigate the issues of drift ratio,shear force,overturning moment and brace layout,PKPM models were established.The results show that under frequent earthquakes,the slab-column structures strengthened by bucklingrestrained braces can be designed by the code provisions of the maximum elastic interstory drift ratio of frame structures(1/550)to control the structural deformation.The proportion of the shear force contributed by the braces is suggested to be no less than 40%.The overturning moment calculated by the codified method is more reasonable than the results given by mechanical concept methods.Placing the braces vertically along the central bay tends to reduce the overturning moment contributed by the braces,while having little influence on the shear force contributed by the braces.