复杂连体高层结构整体稳定研究

针对JGJ 3—2010《高层建筑混凝土结构技术规程》中关于高层结构整体稳定判断及刚重比限值的适用条件，明确了相关规定应用到复杂连体高层结构时存在的缺陷。在此基础上，基于欧拉临界失稳的基本原理，推导了适用于塔式刚性连体高层结构的刚重比限值，该限值主要受连接体与塔楼相对刚度的影响，并通过4个工程案例计算，表明采用规范方法将偏于保守，会放大二阶效应的不利影响。对于连接关系更加复杂的异形连体结构，通过刚重比判断结构的稳定性不再适用，应直接进行考虑二阶效应的非线性稳定分析，并建议借鉴空间结构稳定判断的方法，通过特征值屈曲分析、考虑几何非线性的直接静力稳定分析、考虑材料非线性的极限稳定破坏分析等，对结构的整体稳定进行评估。以某复杂三塔连体高层结构为例，采用所建议的方法进行稳定分析和评价。结果表明，该结构在弹性假定下稳定荷载因子大于10，考虑材料非线性时稳定承载力的安全系数超过2.0，满足安全要求。

Study on overall stability of complex high-rise connected structures

The statements in the JGJ 3—2010 ‘Technical specification for concrete structures of tall buildings’ about the overall stability of high-rise buildings were discussed. The applicability of the overall stability judgment and the limit value of stiffness-weight ratio were analyzed, and the insufficiencies of the relevant regulations when applied to complex connected high-rise structures were clarified. Based on the principle of Euler’s critical instability, the stiffness-weight ratio limit value applicable to rigid-connected-tower building were re-derived.This limit is mainly affected by the relative stiffness of the connector and the tower. Through four case studies, it is shown that the approach in the technical specification tends to be conservative, which would amplify the adverse effects of the second-order effects.For heteromorphic connected structures with more complicated connections, the stability judgment method using stiffness-weight ratio limit will not be suitable, in which case nonlinear stability analysis considering second-order effects is recommended. Similar to the design approaches used for spatial structures, the overall stability of the high-rise buildings could be evaluated through eigenvalue buckling analysis, direct static stability analysis considering geometric nonlinearity, and ultimate stability failure analysis considering material damage. Finally, taking a complex three-tower connected high-rise structure as an example, stability analysis was performed according to the above method.The results show that the stability load factor of the structure is greater than 10 under the elastic assumption, and the safety factor of the ultimate stable bearing capacity of the structure considering material failure is over 2.0, both meet the safety requirements.