长周期超高层建筑三维稳定设计及其扭转屈曲因子

3D stability design and torsional buckling factor of long-period super high-rise buildings

讨论了长周期超高层钢筋混凝土建筑的三维稳定设计。以巨型框架-核心筒结构体系为背景,对15个案例进行弹性屈曲和地震反应分析。所有案例的扭转屈曲均为第一扭转模态,与收集到的8个工程实例的屈曲性能基本一致。弯矩作用平面内的P-Δ效应仍是重力二阶效应的主要表现形式。但是,5%偶然偏心的计入对于偏心明显的长周期超高层建筑而言,P-Δ,θ效应会进一步放大构件的变形,导致配筋的增加。典型工程实例的推覆分析表明,P-Δ,θ效应对结构整体的抗倾覆能力也许不会产生实质性的影响。另外,由于屈曲分析与自由振动分析微分方程的一致性,对于长周期超高层建筑,推荐使用扭转屈曲因子λt cr替代周期比作为控制抗扭刚度的指标。

3D stability design of long-period super high-rise RC buildings was discussed. The elastic buckling and seismic responses of 15 cases were studied, the background of which is the long-period super high-rise RC buildings framed with the mega-columns and concrete core structure. The torsional buckling of all cases is the first buckling mode, which is the same as the buckling behaviour of 8 engineering projects collected. P-A effects in the moment acted plane remain to be primary in the second order theory. However, for the long-period super high-rise buildings with large eccentricity, the deformation of members would be amplified due to P-A, 0 effects with 5% accidental eccentric distance, leading to increase the reinforcement contents. The performance of one typical illustration was estimated by the Pushover analysis, and the results show that P-△ θ effects may have not significant influences on the collapse capacity of the structure. Furthermore, depending on both differential equations of buckling and free vibration being mathematically equivalent, we strongly recommend that the reasonable torsional stiffness of the long-period super high-rise buildings would be measured by using the torsional buckling factor At, replacing the period-ratio defined in the current China code.