基于弹性约束支承梁转角影响线的梁结构损伤诊断

针对现有桥梁结构损伤诊断研究中，对实际主梁结构的边界支承条件不理想与截面参数不确定性考虑不充分的问题，提出考虑弹性转动与竖向约束的梁结构模型，引入截面不确定系数与局部损伤来模拟既有桥梁主梁. 推导得到主梁模型转角影响线解析式，提出基于弹性约束支承梁与转角影响线指标的损伤诊断方法与加载实施方案. 结合算例，研究测点位置、损伤程度、测试噪声对损伤诊断结果的影响，提出边界等效子结构模型试验验证所提方法. 研究表明，转角影响线差值曲率能精确定位、定量弹性约束支承梁的局部损伤，在损伤程度定量试验各工况中，最大相对误差为25%. 算例表明，在5%测试噪声时，仍可以定位梁结构局部损伤，且在梁端转动约束较弱时，损伤诊断敏感性较高.

Beam structure damage detection based on rotational-angle-influence-lines of elastic-constrained-support beam

The consideration of non-ideal supporting boundary and uncertainty of section parameters in actual bridge structure are insufficient in the research of beam bridge structure damage identification. Thus a beam structural model considering elastic rotation and vertical restraint was proposed, and the uncertainty coefficient of section parameters and local damage were introduced to simulate the existing beam structure. The analytical expression of the rotational-angle-influence-lines of elastic-constrained-support beam and the damage identification indicator based on that were derived, and the loading implementation scheme was proposed. The influence of measuring point, damage degree and measuring noise on the damage identification was investigated combined with the simulation cases. The experiment of the boundary equivalent substructure model was carried out to verify the proposed method. Research show that the curvature of rotational-angle-influence-lines difference can be used to accurately locate the local damage and effectively calculate the degree of existing beam structural damage, and the maximum relative errors of the damage degree solution are 25%. Simulation cases show that the proposed method can locate the damage positions under the condition of 5% test noise. The susceptibility of damage diagnosis is high when the rotation constraint is weak.