Damage identification and bearing capacity evaluation of bridges based on distributed long-gauge strain envelope line under moving vehicle loads

In this article, a new method to identify damage and assess the bearing capacity of a bridge is put forward, and the long-gauge strain influence line coefficient is chosen as the damage index. First, the relationship between the local element bending stiffness and long-gauge strain was studied according to the theory of the strain influence line under moving vehicle loads. Then, the static strain response is extracted from the long-gauge strain history using empirical mode decomposition method, and the maximum value is used to construct the strain envelope coefficient curve. A series of studies on damage identification and bearing capacity assessment based on the long-gauge strain envelope coefficient index are conducted, and a real bridge test is carried out on a continuous box girder bridge. The numerical analysis and practical bridge test results show that the method exhibits good performance in locating and quantifying damage, and that it has engineering significance in bearing capacity evaluation and post-bridge structure reinforcement design.