Study Of Cable Damage Effect To Structural Characteristics Of The Cable-stayed Bridge

With the development of technology and economic, the structural health monitoring (SHM) of long-span bridge becomes active areas of research in recent years. The principle of the SHM system is mainly to obtain the bridge structures daily true responses on-line by sensors disposed in structures, and then deduce the state of the bridge structures by making use of those obtained information and evaluate the bridge safety and security synthetically. Study of the bridge structural characteristic is the basic of structure state identification and damage diagnosis. Background on the Runyang Yangtze River Bridge, cable damage effect to the bridge structural static and dynamic performances are analyzed.Different finite element model (FEM) should be given by different work phases and analysis purpose. Studied the strategy of modeling in different phases of SHM, it can be stated that spatial finite spar and beam element model is the appropriate model to aforementioned question. According to the related simplification modeling theory, three-dimensional finite spar and beam element model of the cable-stayed bridge of Runyang Yangtze River Bridge is given. Making use of the model updating theory based on sensitivity analysis, this model is updated pairing with the real bridge dynamic test results. Thus the academic model characterizes the real bridge well.The reasons and characteristics of cable damage occurred commonly in cable-stayed bridge are analyzed. According to the cable characteristics (uniaxial tension only) and geometrical damage theory, mainly include virtual-stress concept and equivalent-strain principle, the definition of the cable damage in FEM is proposed.Based on the bridge finite element model, the variability of structural static and dynamic properties under normal conditions and cable-damage conditions is compared. First, structural static response and dynamic properties under structure self-weight and routine traffic loading when the bridge in good conditions are calculated, and the followed damage analysis is all based on this state. Abundant numerical simulation is given to simulate the different cable damage locations and different damage grades in the same location. Based on these simulations, the variation characteristics of the structural parameters such as the beam line and the cable forces are analyzed. As to the influence of cable damage to dynamic properties of cable-stayed bridge, mode shape sensitivities to change of cable material parameters are analyzed and compared with relative parameters of beam and tower.