Research On Damage Identification Method Of Highway Bridges Based On Vehicle-bridge Coupled Vibration Analysis

Highway bridge, as an important part of urban infrastructure and transport networks, once damaged, will interrupt urban transport considerably and cause huge economic losses. Early detection and diagnosis of the inherent defects or existing damages of bridges is essential to ensure the safety of bridges and avoid potential collapse. Although many damage detection methods of bridges have been proposed, most of which remain in simulation stage and they’ve never been examined by practical engineering. Among those methods, a few have been tested by practical application but proved to be ineffective with limited utilization. Therefore, it is necessary and proper to develop a novel damage identification method for bridges. Based on the existing accomplishment in the bridge damage detection, the following studies are conducted with emphasis on urban bridge structural damage detection technologies:1. The vehicle is modeled as a four-degree-of-freedom system and the vibration equations of the vehicle model are deduced by the D’Alembert principle. Then finite element method is used to discretize bridge and finite element model is set up. The vibration equations of vehicle and bridge models are coupled based on the condition of displacement and force compatibility between vehicle and bridge. A professional procedure VBAP-1 is programmed through Newmark-βalgorithm in MATLAB, which could analyze the vehicle-bridge system coupling vibration.2. Based on vehicle-bridge coupled vibration theory and the Newmark-βalgorithm, MATLAB environment and“APDL”language of ANSYS, a vehicle-bridge coupled vibration simulation program VBAP-2 is developed. The VBAP-2 is the improved version of the VBAP-1 and it is more applicable.3. Taking one concrete-filled steel tube arch bridge as an example and using vehicle-bridge coupled vibration simulation program VBAP-1, the influence of damping ratio, road roughness, the weight and velocity of vehicle on stress impact factors of the suspenders and displacement impact were analyzed.4. A method for damage identification based on dynamic response of bridge induced by moving vehicle and static test data is proposed. To locate damage of bridge, displacement energy damage index defined from the energy of the displacement response time history is adopted as the damage indicator. The displacement responses of a bridge at the healthy state are obtained from simulation of vehicle-bridge coupled vibration analysis by using VBAP-2, and the displacement responses of a damaged bridge are obtained from the sensors attached on the bridge. After damage is located by employing the displacement energy damage index, the damage extent is estimated through the least-square-method based model updating using static test data. At last, taking one simply supported bridge as an illustrative example, some damage scenarios are identified using the proposed damage identification methodology. The results indicate the proposed method to be efficient for damage localization and damage extent estimation.