Predictions Of Static Load Test And Dynamic Characteristics Of A Self-anchored Suspension Bridge

It is known that a small quantity of self-anchored suspension bridges have been constructed though they do not require massive anchor blocks as the conventional suspension bridges. The main reason was the construction difficulty that the bridge deck has to be erected before erecting the main cables. The self-anchored suspension bridges can be used in the place where the geological conditions were bad and massive anchor blocks can't be constructed. The self-anchored suspension bridges were complimented because the construction was novel and the calculation methods were simple.In this paper, a self-anchored suspension bridge was investigated. Three finite element (FE) models were compared for the numerical simulation of the same bridge. Under the dead load, the calculating result was given. Predictions of static load test, the vibration character of the bridge, analysis of the bridge excitation of the seismic response were obtained.Three finite element (FE) models were compared for a self-anchored suspension bridge in order to obtain the appropriate analysis model. The shell element and two types of beam elements based on grillage method were used to simulate the steel box stiffening girder of the bridge. One of the beam elements was the element of Timoshenko beam that can consider not only the bending deflection but also shear deformation. The other was the element of Euler-Bernoulli beam that consider the bending deflection but neglect the shear deformation. The calculating results of equivalent stresses on the bottom plates were compared among the three different finite element models under the dead load. The equivalent stress on the bottom plate of the steel box and the tensile stresses of suspenders were studied for the three different finite element models. The numerical results demonstrated that the shell element model was the appropriate model for simulating steel box stiffening girder of the self-anchored suspension bridge. The beam element model was not ideal for simulating the steel box girder.The result of influence line analysis indicates that the places of No.6 suspender, No. 7 suspender and No. 11 suspender were the worst location. Heavy duty vehicles were arranged in the worst location. The equivalent stresses on the bottom plates and the top plates of the bridge deck, the suspender stresses and the connective point settlement of the bridge deck and suspender were derived. The numerical results were meet the requirement of the standards. The predicted subsidence can be used as the reference data in the practical static load test.The shell element model was analysed, solve the first 6 vibration mode shapes and frequencies. The top six natural frequencies of the self-anchored suspension bridge were range from 0.93Hz to 1.68Hz. The main form of the bridge self-vibration were main cable vibration, vertical vibration of the bridge beck, main tower bend and the twisting deformation of main girder.The 4 cases data of strong ground motion recordings was inputted along the bridge direction and transverse direction respectively. The displacement-time history curve of the main tower top, the middle steel web of No.6 suspender and No.11 suspender were given. The maximal longitudinal direction displacement of the main tower top is 6.4mm. The maximal lateral displacement of No.6 suspender was 3.3mm, and the maximal lateral displacement of No.11 suspender was 5.7mm. The seismic response analysis results of the self-anchored suspension bridge can be used in the seismic design and analysis.