Issue 30

W. Changfeng et alii, Frattura ed Integrità Strutturale, 30 (2014) 486-494; DOI: 10.3221/IGF-ESIS.30.59 493 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0 0.05 0.1 0.15 0.2 Shear deflection (m) μ Shear deflection of 1# support Model 2 Model 3 Model 4 Model 5 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0 0.05 0.1 0.15 0.2 Shear deflection (m) μ Shear deflection of 3# support Model 2 Model 3 Model 4 Model 5 (a) (b) Figure 10 : Shear deflection of movable supports under Tianjin Wave. It can be seen from Fig. 9 to 10 that: (1) The effect of restraining devices on the displacement of the girder is significant. The displacement of the girder in models with restraining devices is smaller than in models without them. The displacement of the girder in Model 3 where the friction of movable supports and elasticity of restraining devices are both considered is the smallest. (2) The restraining devices have a certain level of effect on limiting the shear deflection of the movable supports. With the existence of restraining devices, the shear deflection of movable supports is mainly related to the initial gap between the restraining devices. (3) The variation trend of displacement of the girder is similar to that of the moment of the bottom section of the fixed pier. The increase of displacement of the girder under Tianjin wave is witnessed when friction at movable supports is considered. C ONCLUSIONS he effect of nonlinearity of supports and restraining devices on the elasto-plastic seismic response of continuous girder bridge is evaluated in this study. Finite element models considering the elasto-plasticity of supports, restraining devices and bridge piers are proposed. Elaso-plastic seismic response is analysed and the following conclusions are drawn: (1) Results show that analysis ignoring the effect of friction at movable supports is not safe in some circumstances. As the friction of movable supports exists, when analysing bridge structures built on soft ground and structures with first order natural vibration period close to the predominant period of the ground when the stiffness contribution of movable supports is considered, the effect of friction at movable supports should be considered. (2) In practical design, the restrainers installed on the movable pier should be designed energy intensive to protect the movable pier from being destroyed by the violet pounding force, so model 4 was suggested to analyse the seismic distribution of the seismic force for each pier. (3) Restraining devices are effective in limiting the displacement of the girder in multi-span girder bridge, reducing the seismic response of the fixed piers and balancing the seismic distribution of each pier; for different structures, detailed finite element analysis can be conducted to modify the initial gap and stiffness of the restraining devices as well as the coefficient of friction and stiffness of the supports to reduce the seismic response of the fixed pier, balance the distribution of seismic input energy at each pier and prevent the input seismic effect from being carried by only the fixed piers. A CKNOWLEDGEMENTS his research is sponsored by project supported by national natural science foundation of china (51108220). T T