移动荷载激励下基于平均曲率模态的简支梁局部损伤识别

该文采用缺口平滑拟合技术，利用移动荷载激励下结构的响应数据，通过分析梁式结构的平均曲率模态，对结构进行局部损伤定位。该方法不需要损伤前的桥梁激振数据，受信号噪音影响较小，并且可用于多移动荷载同时激励的情况，实践性和可操作性大大提高。首先分析在质量-弹簧-阻尼体系的移动荷载激励下简支梁的动力响应，通过Newmark-β时域积分算法分析沿时间平均处理后的简支梁振动位移模态，验证了基频模态在移动荷载激励下简支梁位移响应中的支配作用，在理论上解释了平均信号处理的意义。其后，利用ANSYS生死单元技术进行质量-弹簧-阻尼体系的移动荷载仿真，构造出三角函数拟合曲线的形式用于损伤识别。数值实验取得了良好的识别效果，表明该方法在多点损伤、多移动荷载、噪音影响等情况下均具有良好的灵敏性。该文为正常通车条件下桥梁的损伤识别研究提供了一种新思路。

LOCAL DAMAGE DETECTION OF SIMPLY SUPPORTED BEAM ON THE EXCITATION OF MOVING LOAD BASED ON AVERAGE CURVATURE MODAL

Based on the average curvature modal and gapped smoothing method, a new algorithm to detect the local damage of a simply supported beam under the excitation of moving loads is proposed. Without need for the dynamic response data before a structure was damaged, this algorithm has good noise immunity, and could be used in the situation of multiple moving loads. Firstly, by calculating the dynamic response of a simply supported beam under the excitation of a mass-spring-dashpot vehicle system using Newmark-βtime domain integral algorithm, the ascendancy of a basic mode in the response is confirmed, and this explains the meaning to average the curve modal. Thereafter, an FEM model including a moving mass-spring-dashpot vehicle system on a simply supported beam is built to conduct a numerical simulation. Here a triangle fitting function is constructed to fit the average curvature modal. The numerical simulation shows that the algorithm is effective in the situation of multiply damage location, multiply moving loads, and noise environment. This algorithm provides a new research thought for the damage detection of bridges opened in normal traffic.