Effects of roof geometry on tornado-induced structural actions of a low-rise building
Effects of roof geometry on tornado-induced structural actions of a low-rise building
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屋顶几何形状对龙卷风引起的低层建筑结构作用的影响
DOI：
10.1016/j.engstruct.2020.111367
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发表时间：
2021
影响因子：
5.5
通讯作者：
P. Sarkar
中科院分区：
文献类型：
--
作者：
Alireza Razavi;P. Sarkar
龙卷风中持续的财产和生命损失，包括2019年3月3日李县龙卷风造成的23人死亡，反映了社区对龙卷风的脆弱性，并需要改进建筑标准，以更准确地预测这种极端负荷。本文研究了三种屋顶几何形状：平屋顶、山墙屋顶和屋脊屋顶，在龙卷风平移作用下，对低层建筑物的最大整体和局部风致上抬、剪力和弯矩的影响。为了探索局部结构作用，考虑了沿每栋建筑较长水平尺寸的最多五个框架沿着。最大的结构动作，独立于建筑物的方向和它的距离的龙卷风轨道的中心进行了计算，结果表明，一个平屋顶的建筑物经历了最大量的整体隆起，整体剪切，局部隆起，和时刻。对于相同的框架位置，只有四坡屋顶建筑的局部剪力等于或大于平屋顶建筑的剪力。这项研究还表明，山形屋顶和四坡屋顶建筑物的经验的时刻类似的幅度，而山形屋顶表现更好地防止剪切和四坡屋顶表现更好地防止隆起。实验计算的结构动作与ASCE 7 -16的预测进行了比较，结果表明，ASCE 7 -16预测整体和局部隆起，和时刻，而过度预测剪切的所有屋顶几何形状。采用ASCE 7 -16程序对一个双坡屋顶建筑的整体和局部隆起的最大预测误差分别为41%和55%。内部框架经历了最大的隆起预测不足，这使得它们成为符合ASCE 7 -16建筑标准的低层建筑物的脆弱位置。最后，通过引入修正因子，对ASCE 7 -16进行修正，提高了其在不同屋面结构作用下的预测精度。
Continued loss of property and lives in tornadoes including the 23-person death toll resulting from the Lee County AL tornado on March 3rd 2019 reflects the ever-present vulnerability of the community to tornadoes, and necessitates improvement in building standards for more accurately predicting such extreme loads. This article investigates effects of three roof geometries: flat, gable, and hip, on maximum overall and local wind-induced uplift, shear and moment on low-rise buildings by a translating tornado. To explore local structural actions, maximum of five frames along the longer horizontal dimension of each building were considered. Maximum structural actions, independent of building orientation and its distance to the center of the tornado-track were calculated, with results showing that a flat roof building experiences the largest amount of overall uplift, overall shear, local uplift, and moment. Only local shears on a hip roof building were equal to or larger than those of a flat roof building for same frame locations. This study also showed that gable and hip roof buildings experience moments of similar magnitudes, whereas a gable roof performs better against shear and a hip roof performs better against uplift. Experimentally-calculated structural actions were compared with predictions of ASCE7-16, with results showing that ASCE7-16 under-predicts overall and local uplifts, and moments, while over-predicts shear for all roof geometries. The maximum under-prediction of overall and local uplifts using ASCE7-16′s procedure were 41% and 55%, respectively, both for a gable roof building. Internal frames experienced maximum under-prediction of uplifts, which makes them a vulnerable location of low-rise buildings that are built in compliance with ASCE7-16 building standard. Finally, correction factors were introduced to modify and improve accuracy of ASCE7-16 in prediction of structural actions on low-rise buildings with different roof geometries.