Studies on Impact Behavior and Design Method of the Seismic Bridge Restrainers

点击翻译按钮获取中文摘要

The design load of seismic restrainer for a road bridge differs greatly depending on the design philosophy and may be either : (1) ROO<2> times a half of the dead load (Rd) of a girder. This design load is based on the assumption due to liquefaction moves and inclines the pier or causes the pier to hit another as occurred in the 1995 Hyogoken-Nanbu Earthquake. (2) the design seismic coefficient (0.2) x dead load (2Rd) =0.4Rd : This design load is introduced to prevent a girder end from falling off a pier top in an earthquake.The other subjects should be approached from the following two viewpoints : (i) Trilateral effects of the structures that prevent bridge fall, such as drift limiting devices, overlap length of girder end and pier top, and bridge-fall preventing devices, (ii) Impact on the girder coupling device in the worst case scenario that the bridge should fall.The purpose of the present study is to examine these two points by clarifying the impact response characteristics of a … More n seismic coupling plate used as a bridge-fall preventing device and obtaining fundamental reference data on the design forces using adynamic response analysis in a gravity field.In the first fiscal year of this grant, this research funds were used to purchase the application software Dyna2e for dynamic analysis of a framed structure and the impact response analysis software LS-DYNA3D.In an attempt to address (i) above, preliminary studies of the mutual effects of bridge-fall preventing structures were performed by dynamic analysis of the response characteristics of the pier-bridge girder coupling system. With respect to (ii) above, a prototype model was analyzed with respect to impact on a girder coupling device when a bridge falls.However, prior to the completion of these stdies, the 1995 Hyogoken-Nanbu Earthqake occurred, which provided a good qpportunilty to directly observe the real movement of piers and girders in an intracoastal earthqake.Using the data obtained from the earthquake, impact response analysis was performed last fiscal year in order to study the impact response that a bridge fall may produce on a girder coupling device. This study also developed a method that enables easy calculation of kinematic energy using geometric conditions and considering the drop of a rigid bar. Thus, the ROO<2>Rd method, which is one of the current design methods, and discussed more efficient design method using energy criteria. Less