Cable Force Identification Of Bridge Cable Structures Under Complex Boundary Condition

Due to the complexity of the boundary conditions and the uncertainty of theparameters, the cable tension test method based on the conventional string vibrationtheory cannot meet the requirement of the precision. This paper investigates the cabletension measurement of the stay cables with absorbers at two ends and the tied cablewith multi intermediate supports.1) The vibration mode information is introduced to transfer the tied cable withmulti intermediate supports into an equivalent single-span cable structure positionedbetween the two ends of the three consecutive vibration stagnation points, and themode assurance criterion (MAC) is employed to determine the equivalent boundarycondition. The study discussed the effect of dimensionless parameters on theequivalent model, and conducted theoretical error analysis and numerical simulationon the proposed regression solution of the cable force.(2) The energy principle is employed to deduce the explicit expression of thecable force for the hinged cables with two intermediate supports, and the effects ofmodal order, supporting stiffness, boundary condition and the sag effect wereconsidered. The precision of the expression is verified by finite element analysis.(3) To consider the uncertainty of the cable parameters, the frequency fittingmethod using the particle swarm optimization (PSO) techniques was presented forparameter-identification. The paper considered the determination of the solution spaceof the parameters, and conducted a comparative study on the identification accuraciesof the model-based method and the non-model based method.(4) The non-model parameter identification method based on the explicitexpression via energy principle was used to measure the cable force of the HaiyinBridge, Guangzhou. The identification results verified the applicability andhigh-efficiency of the proposed methods.