复杂体型高层建筑结构稳定性验算

Stability checking of the complicated-shape tall building structure

高烈度区结构刚度一般由水平荷载控制,而在低烈度区则往往由整体稳定决定。结构侧向刚度和重力荷载是影响结构整体稳定和P-Δ效应的主要因素,《高层建筑混凝土结构技术规程》(JGJ 3—2010)采用刚重比作为控制指标。基于结构楼层荷载沿竖向均匀分布,规范给出了刚重比的限值指标。对于体型复杂的高层建筑,不同建筑之间质量沿高度分布差异很大,采用同样的控制参数,结构实际稳定性无法保证。根据实际体型和水平荷载分布情况,引入楼层竖向荷载分布系数β,通过控制结构在风荷载和地震作用下的P-Δ效应,计算了结构合理刚重比,对规范指标进行了修正;同时根据实际荷载分布提出了任意水平荷载分布下的等效侧向刚度的计算公式。

The stiffness of the structure in high seismic zones is controlled by the horizontal loads while it is often controlled by the overall stability in low seismic zones. The key factors,determining the overall structure stability and P-Δ effect,are lateral stiffness and gravity loads of the structure. In technical specification for concrete structures of tall building（ JGJ 3—2010）,the rigidity-gravity ratio is chosen as the control parameter in the seismic design. Based on the assumption that the structural floor loads are uniformly distributed along the vertical direction,the design guideline gives the limit values for the rigidity-gravity ratio. However,for the high rise building with complex geometry,whose masses are not necessarily uniformly distributed along the vertical direction,the structural stability could not be guaranteed if the same limit values for the rigidity-gravity ratios are applied. To this end,the vertical floor load distribution factor β is firstly introduced based on the geometry of the structure and distribution of the horizontal loads acting on the structure; by controlling the P-Δ effect of the structure under wind and earthquake loads,reasonable structural rigidity-gravity ratios are obtained and the design recommendations in the code are modified. In addition,the design formulae to calculate the equivalent lateral structure stiffness for arbitrary horizontal load distribution are proposed.