基于风速风向联合概率分布和动力可靠度的高层建筑抗风优化设计方法

Wind effects on tall building structures would be studied in the proposed research project. Firstly, the wind tunnel tests based on the Simultaneous Multi-Point Scanning System (SMPSS) would be conducted to obtain the along wind, crosswind and torsional wind loads acting on the tall buildings. Statistical analysis would be conducted on the long-term measured wind speed and direction datum from local metrological stations and the applicant’s field measurement results, the joint probability distribution between wind speed and direction could then be evaluated based on the measured data. The wind-induced dynamic responses and Multi-object Equivalent Static Wind Loads (MESWLs) were investigated by random vibration theory. While the simplified theoretical formula for the wind-induced acceleration response atop of the tall building was obtained and its dynamic reliability index was numerically evaluated by the dynamic reliability theory. With the seamless integrations of the Optimality Criteria method and SAP2000 Application Interface (API), the wind resistant optimized design would be conducted for the tall building structures to obtain the minimized structural weight under the MESWLs while meeting the constraint requirements in wind-induced displacement atop of the building and inter-story drifts along the building height. The additional constraint for wind-induced acceleration response atop of the building (serviceability and comfortable criteria) under the effect of joint probability distribution between wind speed and direction would also be evaluated in the structural optimization procedure. The research studies proposed in the project would be helpful to promote the wind resistant design of high-rise structures in wind engineering study.

本申请项目以高层建筑结构的风效应入手，一方面采用多点同步测压风洞实验获得作用在高层建筑结构各楼层的顺风向、横风向及扭转气动力；另一方面利用当地气象站常年观测获得的气象资料，结合课题组对高层建筑风环境的长期实测数据，对高层建筑所在地区的风速风向进行联合概率分布进行相关研究。在此基础上运用随机振动理论求解高层建筑的风致动力响应及多目标等效静力风荷载。对于结构顶部风致加速度，则通过获得其显示表达式后采用动力可靠度理论来求解其可靠度指标。再通过SAP2000 应用程序接口和最优准则优化算法的无缝集成，针对高层建筑在多目标等效水平静力风荷载情况下，研究和探讨高层建筑结构同时满足风致顶部位移、层间位移差和风速风向联合概率分布影响下的风致舒适度可靠度指标为约束条件，以结构重量最轻为优化目标的高层建筑结构抗风优化设计理论和方法。上述研究工作的开展，将大大促进风工程研究成果在高层建筑抗风优化设计中的应用。

目前国内外风荷载规范中一般均是以最不利风向法则来确定设计风速，再通过一定的折减系数来考虑风向的影响，而没有考虑风速风向的联合概率分布特征；实际上，风速和风向是密不可分的，只有将两者结合起来建立其联合概率分布函数才是对设计风速最合理、最准确的描述方式。.本项目提出了一种基于可靠度的考虑风速风向联合分布的超高层建筑结构抗风优化设计方法。（1）该方法建立了以构件材料总重或结构材料总造价为优化目标，构件截面尺寸为优化变量，结构顶部位移、最大层间位移和顶部加速度等为约束条件的超高层建筑结构抗风优化设计数学模型；从而将结构优化设计问题转换为有约束条件的函数极值问题，方便进行数值化的程序设计，无需任何人工干预即可完成优化迭代运算的全过程；（2）该方法在当地气象观测站长年积累的风速风向数据基础上，建立了其风速风向联合概率分布函数，从而可应用可靠度理论以概率的形式来描述当地不同重现期的设计风速；进而可将传统抗风优化设计中对应不同重现期/设计风速的结构顶部位移、最大层间位移和顶部加速度等确定性约束条件转化为具有概率可靠度指标的约束条件，这更符合实际情况，所获得的优化结果也将更为经济合理；在此基础上，再利用基于可靠度理论的验算点法将其转换成三类服从一定概率分布形式的随机变量（自振频率、阻尼比和风速）的显式表达，从而使抗风优化设计算法实现起来更加方便快捷；（3）本项目以CAARC标模和广州西塔为例，各种工况下的优化结果均表明：考虑风速风向联合分布要比仅考虑最不利风向，构件材料总重均有一定程度的减少，尤其是在将所有响应同时考虑时，效果更显著；这充分说明了超高层建筑结构抗风设计时考虑风速风向联合分布的必要性和本方法的实用性和有效性。.本项目所提出的方法是一种将可靠度理论、风速风向联合分布、结构抗风优化设计相结合的综合性设计方法，可进一步提高超高层建筑结构抗风优化设计的空间，有效地提高了结构设计的合理性和经济性。

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