张军锋, 裴昊, 朱冰, 刘庆帅. 考虑材料非线性的RC双曲冷却塔风致破坏过程[J]. 工程力学, 2021, 38(3): 228-238. DOI: 10.6052/j.issn.1000-4750.2020.05.0324
引用本文: 张军锋, 裴昊, 朱冰, 刘庆帅. 考虑材料非线性的RC双曲冷却塔风致破坏过程[J]. 工程力学, 2021, 38(3): 228-238. DOI: 10.6052/j.issn.1000-4750.2020.05.0324
ZHANG Jun-feng, PEI Hao, ZHU Bing, LIU Qing-shuai. WIND-INDUCED FAILURE PROCESS OF RC HYPERBOLIC COOLING TOWERS CONSIDERING THE MATERIAL NONLINEARITY[J]. Engineering Mechanics, 2021, 38(3): 228-238. DOI: 10.6052/j.issn.1000-4750.2020.05.0324
Citation: ZHANG Jun-feng, PEI Hao, ZHU Bing, LIU Qing-shuai. WIND-INDUCED FAILURE PROCESS OF RC HYPERBOLIC COOLING TOWERS CONSIDERING THE MATERIAL NONLINEARITY[J]. Engineering Mechanics, 2021, 38(3): 228-238. DOI: 10.6052/j.issn.1000-4750.2020.05.0324

考虑材料非线性的RC双曲冷却塔风致破坏过程

WIND-INDUCED FAILURE PROCESS OF RC HYPERBOLIC COOLING TOWERS CONSIDERING THE MATERIAL NONLINEARITY

  • 摘要: 为明确RC双曲冷却塔的极限静风荷载及其风致破坏过程,以一座大型冷却塔为例,采用ABAQUS中分层壳单元模拟塔筒的混凝土和双向钢筋网,在线性计算和非线性计算验证的基础上,采用弥撒开裂模型和双线性模型模拟混凝土和钢筋的非线性受力特征,分析了自重+风荷载(工况Ⅰ)和自重+冬温+风荷载(工况Ⅱ)两种工况下的静风破坏过程,并结合荷载位移曲线、内力、应变和应力的发展和分布探究了其破坏机理。结果表明:对于工况Ⅰ,风荷载系数为λ=1.384时,首先在迎风子午线相对高度hs/Hs=0.37位置因子午向受拉出现环向裂缝且为贯通裂缝,之后整个迎风区的环向裂缝不断增加并沿环向扩展,迎风区内表面和侧风区外表面也因环向弯矩而出现子午向裂缝,开裂位置的钢筋应力迅速增加,荷载-位移曲线也由线性进入非线性并且迎风区和侧风区位移迅速增加,迎风区和侧风区内力也表现出明显的重分布特征,最后因混凝土持续开裂和喉部区域双向钢筋屈服而破坏,极限风荷载系数为λ=2.007;对于工况Ⅱ,温度效应的计入使λ=1.0时即在侧风区上部首先出现子午向裂缝,子午向裂缝开展也较工况Ⅰ略严重,但因温度的弯矩效应有限,其荷载位移曲线和工况Ⅰ基本一致,且仍以迎风区环向开裂最为显著,结构破坏依然由风荷载控制,最终的极限荷载荷载系数为λ=1.842。

     

    Abstract: To investigate the ultimate wind load and wind-induced failure process of cooling towers, a hyperbolic cooling tower was taken as an example in ABAQUS. The tower shell was modelled by layered shell elements, including the concrete and reinforcement. Based on linear and nonlinear verification calculation, the smeared crack model and bilinear model were used to represent the nonlinear behavior of the concrete and reinforcement, respectively. The failure process under the load combination of gravity and wind loads (Load Case Ⅰ) and the load combination of gravity, winter temperature and wind loads (Load Case Ⅱ) were analyzed. It was shown that when the wind load factor λ was 1.384 for Load Case Ⅰ, the circumferential cracks caused by meridian forces were initiated at hs/Hs=0.37 of the windward meridian and went through the shell. Then they continuously expanded along the circumferential direction and the meridian cracks inside the windward and outside the sideward were also caused by circumferential moment. In this process, the stress of steel at the cracks increased quickly, the load displacement curves exhibited nonlinearity, and the displacement at the windward and sideward quickly increased. There was also significant redistribution of the internal forces at these areas. The cooling tower failed as the successive concrete cracking and the yielding of the double reinforcement in the throat region when the ultimate wind load λ was 2.007. For Load Case Ⅱ, the meridian cracks first appeared at the upper area of the sideward at λ=1.0 because of the temperature effect, with a slightly greater degree than that of Load Case Ⅰ. However, the load displacement curves were almost the same for the two load cases because the effect of temperature was limited. The most significant cracking was still circumferential cracking in the windward. The failure of the structure was also controlled by the wind load, with an ultimate load factor λ of 1.842.

     

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