Issue 30

W. Changfeng et alii, Frattura ed Integrità Strutturale, 30 (2014) 486-494; DOI: 10.3221/IGF-ESIS.30.59 490 Figure 5 : Numerical FE model. (2) Model 2: The friction of the movable supports is considered with coefficient of friction taken as 0.02, 0.05, 0.10, 0.15, 0.20. No restraining devices are provided. As the stiffness of the supports is large before slipping occurs, the initial stiffness of the middle movable supports is taken as 1e6 kN/m and side movable supports, 4e5 kN/m during the analysis. (3) Model 3: The elastic effect of the restraining devices is considered. When slipping occurs for a certain distance, the relative displacement of the girder and piers is restrained by the restraining devices. The restraining devices are considered elastic with a stiffness of 1e6 kN/m. The failure of the restraining devices is not considered. (4) Model 4: The nonlinearity of the restraining devices is considered and the initial stiffness of the restraining devices is set identical as in Model 3. On the basis that the horizontal sliding force of the supports is considered, the critical yield force of the restraining devices is taken as 30% of the horizontal sliding force of the supports. In actual engineering, the critical yield force of the restraining devices can be determined by its mechanism. The analytical model of Model 4 is given in Fig. 6. (5) Model 5: No longitudinal restraining devices are provided for side piers and only the friction of side movable supports is considered. The movable supports are identical as in Model 4. Both the friction of support and the nonlinearity of the restraining devices are considered. During the time history analysis, three rare artificial seismic waves and Tianjin wave are incorporated with the peak value of the seismic wave adjusted to 0.4g. Takeda Model coupled degree of freedom hysteretic model Pier #1 Pier(#2) movable supports restrainers movable pier Pier #3 Pier #4 Takeda Model Takeda Model Takeda Model fixed pier movable pier movable pier fixed bearing movable supports restrainers hysteretic model hysteretic model Figure 6 : Calculation Diagram for Model 4. E FFECT OF NONLINEARITY OF SUPPORTS AND RESTRAINING DEVICES ON THE ELASTO - PLASTIC SEISMIC RESPONSE OF BRIDGE STRUCTURE Comparison of calculated moment and curvature of the bottom section of the fixed pier hen the nonlinearity of the movable supports and restraining devices is considered, the hysteretic energy dissipation of movable supports affects the energy dissipating mechanism of the bridge structure. The existence of restraining devices results in the redistribution of seismic effect on each pier and thus the seismic W