THE CONTACT-AND-FRICTION ELEMENT CONSIDERING NONLINEAR PERFORMANCE OF MOVABLE SUPPORTS AND RESTRAINERS

For continuous girder bridges, once the restrainer is installed at the movable pier, the seismic analysis model would be characterized by the friction nonlinearity at the movable support and conctact-and-collision nonlinearity of the restrainer. Based on the characteristics of the friction element and the contact element, finite contact-and-friction element models are presented, with the contact element being elastic and elasto-plastic, respectively. The hysteresis curve for the contact-and-friction element is given and the stiffness under unloading is derived according to various curves. The contact-and-friction element models were applied to the nonlinear time-history analysis of continuous girder bridges which contain friction-type movable supports and restrainers. The seismic dissipating effect of the restrainers on the seismic responses of the fixed pier is analyzed and it is shown that the contact-and-friction element can be used in the detailed aseismic model of continuous girder bridges which contain both restrainers and movable supports.