超大型钢筋混凝土冷却塔模型地震模拟振动台试验研究
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摘要
研究原型结构为即将要在抗震设防烈度8度区建设的高度为220 m的1 000 MW级热力发电厂超大型间接空气冷却塔,设计并实现了缩尺比为1∶30模型的地震模拟振动台试验.试验工况涵盖I～IV类场地条件下,冷却塔模型分别在7度、8度设防多遇地震、偶遇地震和罕遇地震对应的72组三向地震动激励,观察检验模型结构在不同场地条件不同地震动激励水平下的反应性态.同时,在每个级别的地震模拟试验工况前后,进行模型振动模态特性试验,实时监控模型结构在经历每个阶段地震动工况后的振动特性变化情况.试验结果表明,该冷却塔结构基本能够满足7度、8度设防条件下的抗震要求,但冷却塔下部的X型支腿两端与其喉部以上的壳体属于抗震薄弱部位,受较为密集的多个相邻高阶振型耦合振动影响,上部壳体厚度最薄处出现较为严重的环向破坏.
The 1/30 scaled model of a cooling tower was designed and tested in a shaking table in this study,whose prototype structure is a 220 m high super huge indirect dry cooling tower(1 000 MW grade) of an electric power project which will be constructed in an area of fortify intensity 8.The test contained 72 cases that the model structure was orderly excited by minor earthquake,moderate earthquake and major earthquake under seismic fortify intensities of 7 and 8 in four different site conditions(I～IV).Meanwhile,white noise excitation tests were inserted before and after each condition to real-time monitor changes of model structure’s natural vibration characteristics.The results show that,the cooling tower can basically satisfy anti-seismic requirements under the fortifying intensity 7 and 8,but the two ends of the X-pillar and the shell above the throat of the tower are both the weak parts.In addition,due to the influence of multiple adjacent high modes’ coupled vibration,severe hoop damage may appear at the thinnest shell of the tower.
The 1/30 scaled model of a cooling tower was designed and tested in a shaking table in this study,whose prototype structure is a 220 m high super huge indirect dry cooling tower(1 000 MW grade) of an electric power project which will be constructed in an area of fortify intensity 8.The test contained 72 cases that the model structure was orderly excited by minor earthquake,moderate earthquake and major earthquake under seismic fortify intensities of 7 and 8 in four different site conditions(I～IV).Meanwhile,white noise excitation tests were inserted before and after each condition to real-time monitor changes of model structure’s natural vibration characteristics.The results show that,the cooling tower can basically satisfy anti-seismic requirements under the fortifying intensity 7 and 8,but the two ends of the X-pillar and the shell above the throat of the tower are both the weak parts.In addition,due to the influence of multiple adjacent high modes’ coupled vibration,severe hoop damage may appear at the thinnest shell of the tower.
引文
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[2]薛文,白国良,姚有成,等.超大型双曲冷却塔考虑不同场地类型的地震性能研究[J].水利与建筑工程学报,2010,8(4):224-226.
[3]于敏,刘晋超,吴波,等.竖向地震作用对超大型冷却塔结构的影响分析[J].工程抗震与加固改造,2012,34(3):44-49.
[4]张敏政.地震模拟实验中相似律应用的若干问题[J].地震工程与工程振动,1997,17(2):52-58.
[5]CECS160:2004建筑工程抗震性态设计通则[S].
[6]GB 5001-2010建筑抗震设计规范[S].
[7]杨耀锋,程玉琢.冷却塔在地基固有频率和振型的试验研究[J].西安矿业学院学报,1995,15:9-12.
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