建筑覆面风致连锁损坏的概率风险评估

Probabilistic risk assessment of cascading damage for building cladding in strong wind

摘要:

日益密集的城市高层建筑群使得强风时风掷物造成的建筑覆面破坏风险大大增加,与此相关的连锁损坏问题已引起设计人员日渐重视.连锁损坏是指某一局部区域的小面积损坏导致建筑内压的极大改变,从而引发大面积覆面损坏的现象.为评估在设计过程中忽视连锁损坏现象可能带来的覆面损坏风险,本文采用同步风压时程分析与最佳线性无偏估计方法,首先计算无事故与不同程度事故性损坏下的覆面风压,然后结合超越概率方法计算覆面风压与发生概率之间的函数关系,最后得到设定事故概率下的建筑覆面设计风压.为了具体说明这一方法,本文针对一栋典型高层建筑进行案例研究,以确定考虑连锁损坏概率后的覆面设计风压.结果表明楼角区域的正风压对楼角部位的局部损坏最为敏感,其次是楼角区域的负风压.该方法可用于评估建筑表面事故性损坏对覆面设计风荷载的影响,是精细化设计的一个重要方面,同时也有助于发现对局部损坏较为敏感的区域,以便在设计中采取必要措施控制事故性损坏,从而提高设计的可靠性.

Abstract:

The increase of tall building density in large cities can potentially increase the risk of building facade damage caused by wind debris during strong winds, which has induced a major concern about cascading damage in design community. Cascading damage is a significant large area damage of cladding elements caused by small and localized facade crashes due to the increase of internal pressures. To assess the potential cascading damage, a probabilistic risk analysis method was proposed. By conducting the synchronous pressure integration and the best linear unbiased estimation (BLUE), the cladding wind pressures for undamaged configuration and various damaged configurations were calculated. The relationship between cladding wind pressures and probability of occurrence was established by using upcrossing analysis. The cladding design wind pressures were determined for a given facade accident probability. To demonstrate the method, a case study of a typical tall building was presented to determine the cladding design wind pressures by taking into account the probability of cascading damage. Results indicate that positive wind pressures in corner area were the most sensitive to local damages around building corners, followed by negative wind pressures in the corner area. The proposed method can be used to assess the impact of accidental facade damage on the cladding design wind loads, and is beneficial to identify the cladding area that is overly sensitive to accidental facade damage.