下部框架结构的协同工作对张弦桁架抗震性能的影响

Effect of seismic responses of truss string structure with cooperative work of the base frame structure

采用时程分析法对广州国际会展中心张弦桁架结构进行地震响应分析,详细对比了有无下部框架结构协同工作下,结构的自振特性、下弦跨中节点的水平加速度和竖向位移的地震响应、上下弦杆轴力和拉索应力的地震响应.结果表明:下部框架结构的协同工作使结构的自振频率减小,但对张弦桁架低阶振型的影响不大;大幅度地改变了张弦桁架的水平加速度地震响应峰值;下部结构的协同工作使张弦桁架的竖向位移地震响应明显减小,但位移响应的衰减速度变慢;下部框架结构的协同工作对张弦桁架边跨和跨中弦杆轴力地震响应的影响各不相同,对索应力地震响应的影响极小.

This paper analyzes seismic responses of truss string structure of Guangzhou Convention and Exhibition Centre using time history analysis method. Its natural vibration characteristics, seismic responses of horizontal and vertical accelerations and vertical displacements of nodes of bottom chord members at midspan, seismic responses of height difference of parallel upper chord member at midspan, response of axial pressure of bottom and upper chord members and stresses of cable are calculated and compared whether the cooperative work of the base frame structure is considered or not. The results show that. With cooperative work of base frame structure, low natural frequencies of vibration of structure decreases, but the effect on the low modes of truss string structure are small. Seismic peak response of horizontal accelerations are greatly changed. Seismic responses of vertical displacements is reduced greatly, but the rate of decay of displacements slows down. Effect of base frame structure to seismic response of chord member at the support and midspan of truss string structure is different.