易江, 莫金生, 李建中. 强震作用下独塔斜拉桥拉索松弛现象研究[J]. 工程力学, 2018, 35(6): 97-104,114. DOI: 10.6052/j.issn.1000-4750.2017.02.0143
引用本文: 易江, 莫金生, 李建中. 强震作用下独塔斜拉桥拉索松弛现象研究[J]. 工程力学, 2018, 35(6): 97-104,114. DOI: 10.6052/j.issn.1000-4750.2017.02.0143
YI Jiang, MO Jin-sheng, LI Jian-zhong. STUDY ON CABLE RELAXATION OF SIGNLE-TOWER CABLE-STAYED BRIDGE DUE TO STRONG EARTHQUAKES[J]. Engineering Mechanics, 2018, 35(6): 97-104,114. DOI: 10.6052/j.issn.1000-4750.2017.02.0143
Citation: YI Jiang, MO Jin-sheng, LI Jian-zhong. STUDY ON CABLE RELAXATION OF SIGNLE-TOWER CABLE-STAYED BRIDGE DUE TO STRONG EARTHQUAKES[J]. Engineering Mechanics, 2018, 35(6): 97-104,114. DOI: 10.6052/j.issn.1000-4750.2017.02.0143

强震作用下独塔斜拉桥拉索松弛现象研究

STUDY ON CABLE RELAXATION OF SIGNLE-TOWER CABLE-STAYED BRIDGE DUE TO STRONG EARTHQUAKES

  • 摘要: 为考虑地震作用下斜拉桥拉索的垂度效应,常规方法是将拉索模拟为弹性单元,根据恒载索力修正单元材料的弹性模量;但该方法忽略了索力变化对拉索轴向刚度的影响,也未考虑强震中可能出现的拉索松弛现象。该文先给出了三种不同的拉索应力-应变方程,然后以一座独塔斜拉桥为背景,通过赋予拉索不同的应力-应变关系建立了三个非线性有限元模型,研究了强震作用下拉索的地震响应和拉索松弛现象。结果表明:在近场地震作用下,拉索索力变化幅度较大,部分拉索有可能出现松弛现象;拉索松弛后,出现松弛的拉索最小索力不再减小,最大索力继续增加;对于整个结构而言,拉索松弛只是局部响应的变化,对梁体位移和塔柱受力等地震响应的影响有限;但地震中不考虑索力变化对拉索轴向刚度的影响可能低估结构的地震响应,最大偏差可达到20%。

     

    Abstract: To consider cables' sag effects of cable-stayed bridges due to earthquakes, the common approach is to model cables as elastic elements by modifying its elastic modulus according to the cable force under dead load. However, this approach ignored the influence of the cable force on the variation of cables' axial stiffness and that cable relaxation might occur under strong earthquake. This paper firstly presented three different formulations of stress-strain relationship for cables. Based on a single-tower cable-stayed bridge, three nonlinear finite element models were then established by applying different stress-strain relationships of cables. The seismic response of cables and cable relaxation were then studied under near-fault ground motions. Analytical results revealed that large varying cable forces were detected under strong earthquakes and some of the cables experienced cable relaxation. After cable relaxation, the minimum cable force of the cables with cable relaxation no longer decreased while the maximum cable force continued to increase. For the whole structure, cable relaxation was restricted to influence local response and limitedly affected the deck displacement and tower force. However, the seismic response of the structure might be underestimated if the changing axial stiffness from a varying cable force was not considered, with the maximum error reaching 20%.

     

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