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基于规范的蝶形拱桥试验冲击系数评估 被引量:2

Evaluation of Experimental Impact Coefficient of Butterfly Arch Bridge Based on Specifications
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摘要 冲击系数是衡量桥梁动力效应的重要指标。目前,各国桥梁设计规范均采用简化公式计算冲击系数,然而这通常难以准确描述复杂桥梁结构的动力效应。为了研究某蝶形拱桥的动力冲击系数,通过动力试验得到了桥梁的模态参数和关键截面的冲击系数,并结合国内外典型规范评估了试验结果。首先,介绍了桥梁的工程概况及动力试验工况。其次,利用环境振动试验得到的结构加速度响应,结合频域算法识别了桥梁的前6阶模态参数。利用行车和跳车试验数据,获得了主拱、主梁关键截面的应变冲击系数。最后,总结了国内外桥梁设计规范关于冲击系数的规定,根据冲击系数的计算依据将规范分为4类:基于跨径、基于频率、基于桥梁种类、基于车轴数量等其他方式的冲击系数计算方法。结合国内外规范评估了试验结果。结果表明:桥梁实测基频为0.586 Hz,振型特征为主拱及主桥一阶横向振动;前6阶频率和振型的实测值与计算值吻合良好;行车工况下,主拱和主梁跨中截面应变冲击系数介于1.12~1.23之间;跳车工况下,应变冲击系数介于1.21~1.74之间;不同规范对该桥冲击系数评估结果不同,并与试验值有一定差异;基于频率和跨径计算的冲击系数与试验值相对较为接近;复杂桥梁结构的冲击系数确定仍依赖于试验方法。 Impact coefficient is an important indicator to measure the dynamic effect of bridge structure.At present,the simplified equation is usually used in bridge design specifications of different countries to calculate the impact coefficient.However,this method cannot accurately describe the dynamic effects of complex bridge structure.To study the dynamic impact coefficient of a butterfly arch bridge,the modal parameters of the bridge and the impact coefficient of the key section are obtained through dynamic test,and the test result is evaluated in combination with typical specifications at home and abroad.First,the project overview and the dynamic test conditions of the bridge are introduced.Second,the structural acceleration responses are obtained by ambient vibration test,and the first 6-order modal parameters of the bridge are identified using the frequency domain algorithm.The strain impact coefficients of the key sections of the main arch and the main beam are obtained using the driving and jumping test data.Finally,the regulations regarding impact coefficients in domestic and foreign bridge design specifications are summarized.According to the calculation basis of impact coefficient,the specifications are divided into 4 categories:based on span length,based on frequency,based on bridge type and based on number of vehicle axles or other basis.The experimental result is evaluated with the domestic and foreign specifications.The result shows that(1)the measured fundamental frequency of the bridge is 0.586 Hz,the corresponding mode shape characteristic is first-order lateral vibration of main arch and main bridge;(2)the measured values of the first 6-order frequencies and mode shapes show good agreement with the analytical values;(3)under the driving condition,the strain impact coefficients of the main arch and the main beam are between 1.12 and 1.23;(4)under the jumping condition,the strain impact coefficients are between 1.21 and 1.74;(5)the evaluation results of the impact coefficient of the bridge are different by different specifications,and the evaluation results are different from the test values;(6)the calculated impact coefficients based on frequency and span are close to the experimental values;(7)The determination of the impact coefficient of complex bridge structure still depends on the experimental result.
作者 秦世强 李超 康俊涛 QIN Shi-qiang;LI Chao;KANG Jun-tao(School of Civil Engineering and Architecture,Wuhan University of Technology,Wuhan Hubei 430070,China)
出处 《公路交通科技》 CAS CSCD 北大核心 2020年第2期55-62,共8页 Journal of Highway and Transportation Research and Development
基金 国家自然科学基金项目(51608408) 中央高校基本科研业务费专项资金项目(2017IVB046).
关键词 桥梁工程 冲击系数 动力试验 钢管混凝土拱桥 蝶形拱桥 bridge engineering impact coefficient dynamic test concrete-filled steel tubular(CFST)arch bridge butterfly arch bridge
作者简介 秦世强(1987-),男,安徽肥西人,博士,副教授.(shiqiangqin@whut.edu.cn)
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