考虑平面弯曲变形的单跨排架结构布置规则性判定指标研究

Study on regularity indexes of single-span frame structure layout considering plane bending deformation

周期比和扭转位移比是多高层结构抗震设计常用的控制指标,但无法真实反映大跨度结构平面布置规则性及其在地震作用下的变形、内力特征。为此,以单跨排架结构为主要研究对象,考虑其屋面结构面内弯曲刚度小等特点,根据控制平面布置规则性要求的本质目的,即控制抗侧力构件侧移的均匀性,提出判断其平面布置规则性的两个指标——广义扭转位移比和剪力-刚度匹配指标。探讨了两个指标在各种参数下的变化规律,建立了两个指标的函数关系,划定了基于广义扭转位移比的结构平面布置规则性限值。结果表明:广义扭转位移比和剪力-刚度匹配指标能更合理地表征地震作用下,单跨排架结构的响应特性;按照两个指标,排架结构平面布置规则性不但取决于抗侧力构件的布置、质量分布,也取决于结构面内弯曲刚度及平面弯曲变形大小。

The period ratio and torsional displacement ratio are commonly used control indexes in seismic design of multi-story and high-rise structures,which cannot reflect the regularity of the layout of long-span structures and the deformation and internal force characteristics under earthquake excitations.Taking the single-span frame structure as the main research object,considering its characteristics of small panel stiffness,and according to the essential purpose of controlling the regularity requirement of plane layout(controlling the uniformity of lateral movement of lateral force resistant members),two new indexes were proposed to judge the regularity of plane layout,namely generalized torsional displacement ratio and shear stffness matching index.The change law of the two indexes under various parameters was discussed,the function relationship of the two indexes was established,and the regularity limit of the plane layout of long-span structures was defined based on generalized torsional displacement ratio.The results show that the generalized torsional displacement can more reasonably characterize the response characteristics of single-span frame structures under earthquake excitation than generalized torsional displacement ratio and the shear stiffness matching index.According to the above two new indicators,the regularity of plane layout of bent structure depends not only on the layout and mass distribution of lateral force resistant members,but also on the panel stiffness and plane bending deformation.