设置三维摩擦摆支座的北京工人体育场单层网壳罩棚竖向隔震性能研究

Research on vertical isolation performance of lattice shell canopy with three-dimensional FPB of Beijing Workers’Stadium

北京工人体育场为设置三维摩擦摆隔震支座(3D-FPB)的大跨网壳高位隔震结构。由于三维摩擦摆隔震支座的竖向刚度远小于传统摩擦摆隔震支座,可减小竖向地震作用,并调节不同支座之间的不均匀抬升。在有限元软件ABAQUS中建立了包含3D-FPB的大跨网壳模型,可准确考虑滑块在滑动面上抬升。进行罕遇地震弹塑性时程分析,并与采用普通FPB的模型对比,结果表明:3D-FPB可以降低网壳的竖向地震作用及悬挑端竖向加速度,减小对竖向荷载敏感的网壳构件的应力水平,并使相邻支座之间的竖向作用力分布更加均匀;当考虑支座不均匀抬升效应后,上部网壳的竖向地震作用及悬挑端竖向加速度增大;网壳构件在加载过程中始终保持弹性,在承载能力方面有充足安全储备。

Beijing Workers’Stadium is a large-span lattice shell structure with steel roof isolated by three-dimensional friction pendulum bearings(3D-FPB)at high position.Compared with traditional FPB,3D-FPB shows much lower stiffness in vertical direction,which can reduce vertical earthquake action and adjust uneven vertical uplift between bearings.A finite element model of isolated large-span lattice shell was established in ABAQUS,which contained 3D-FPB to simulate the uplift of slider on sphere surface.The results of elastoplastic time history analysis under rare earthquake action indicate that,compared with the same lattice shell model equipped with traditional FPB,the vertical earthquake reaction force of lattice shell equipped with 3D-FPB and vertical acceleration of overhang components are reduced.Meanwhile,the stress level of components sensitive to vertical earthquake is decreased,and the vertical force of adjacent bearings distributes more evenly.Considering the non-uniform uplift of bearings during sliding,the vertical earthquake reaction force of lattice shell and vertical acceleration of overhang components are increased.The lattice shell of this project keeps elastic during loading process,thus is associated with enough sufficient safety reserve.