损伤状态下预应力混凝土简支梁的模态挠度和模态刚度试验研究  

Test study on modal deflection and modal stiffness of prestressed concrete simply supported beams under damage state

作　　者：亓兴军 孙绪法 周广利 王珊珊 QI Xingjun;SUN Xufa;ZHOU Guangli;WANG Shanshan(School of Traffic Engineering,Shandong Jianzhu University,Jinan 250101,China;Shandong Transportation Research Institute,Jinan 250012,China;Shandong Hi-speed Co.,Ltd.,Jinan 250098,China)

机构地区：[1]山东建筑大学交通工程学院,济南250101 [2]山东省交通科学研究院,济南250012 [3]山东高速集团有限公司,济南250098

出　　处：《振动与冲击》2023年第21期227-236,262,共11页Journal of Vibration and Shock

基　　金：山东省交通运输厅科技计划项目(2020B69,2022B06);山东省企业技术创新项目(202250101726)。

摘　　要：为快速检测评估不同损伤状态现役混凝土桥梁的承载能力,以某实际高速公路改扩建工程中拆除的16 m跨径预应力混凝土单片简支空心板梁为研究对象,将模态测试技术和静力加卸载试验相结合,探讨实测模态挠度和模态刚度在实际工程中评估现役桥梁承载力的适用性和准确性。设计简支试验梁14个不同损伤程度的静载试验加卸载工况和环境激励模态测试工况,实测简支试验梁的静载挠度和各损伤程度梁体的试验模态参数,预测简支梁在逐级静力荷载下的模态挠度,对比分析不同损伤工况试验梁的荷载-位移曲线切线刚度和模态刚度。结果表明,开裂前试验梁的实测加卸载静挠度与荷载大致成线性关系,开裂后随着梁体损伤程度加重,荷载-位移曲线的线弹性阶段逐渐缩小,非线性阶段逐渐增大,表现出明显的刚度退化趋势。当试验梁处于开裂前较轻损伤状态和开裂后初始加载阶段的较大损伤状态时,实测前两阶振型预测的模态挠度与静载挠度的相对误差基本上不超过10%,模态刚度与静载试验荷载-位移曲线初始刚度的相对误差基本在10%以内,损伤程度低于较大损伤的试验梁模态刚度近似等于梁体的初始切线刚度。开裂前较轻损伤简支梁的模态刚度与设计弯矩切线刚度的相对误差均在10%以内,说明结构实测模态刚度能够比较准确地评价曾经承受4倍设计荷载而较大受损预应力混凝土简支梁的初始刚度状态,也能够准确评价曾经承受2倍设计荷载而较轻损伤未开裂简支梁桥的设计结构刚度。这对实测模态挠度和模态刚度的工程实际应用具有重要的参考指导意义,而且扩展了模态测试在桥梁健康状况技术评价中的应用范围。Here,to quickly detect and evaluate load-bearing capacity of existing concrete bridges in different damage states,a 16 m-span prestressed concrete single piece simply supported hollow plate-girder dismantled in a certain actual highway renovation and expansion project was taken as the study object,modal testing technique was combined with static loading and unloading tests to explore the applicability and correctness of measured modal deflection and modal stiffness in evaluating load-bearing capacity of existing bridges in practical engineering.Simply supported test beams' static load test loading and unloading working conditions and environmental excitation modal testing conditions with 14 different damage degrees were designed,their static load deflections and test modal parameters of beam bodies with 14 different damage degrees were measured,modal deflections of simply supported beams under static loads at different levels were predicted,and tangent stiffnesses of load-displacement curves and modal stiffnesses of test beams with different damage degrees were analyzed contrastively.The results showed that before cracking,test beams' measured loading and unloading static deflections are roughly linearly related to loads;after cracking,with increase in damage degree,linear elastic stage of load-displacement curves gradually shrinks,while nonlinear stage gradually increases to reveal an obvious trend of stiffness degradation;when test beams are in a lighter damage state before cracking and a larger damage state in initial loading stage after cracking,relative errors between predicted modal deflections of the first two measured vibration modes and static load deflections are basically not more than 10%;relative errors between modal stiffnesses and initial stiffnesses of static load-displacement curves are basically within 10%;modal stiffness of test beam with a damage degree lower than larger damage is approximately equal to initial tangent stiffness of beam body;relative error between modal stiffness of a lightly

关 键 词：损伤状态 预应力混凝土简支梁 模态挠度 模态刚度 荷载-位移曲线切线刚度 

分 类 号：U446.1[建筑科学—桥梁与隧道工程]