earthquakes have frequently happened through the world, a number of countries have modified and enhanced the seismic design regluations. Similarly our government modified and revised the Highway Design Specifications in early 2000, and then the part o...
earthquakes have frequently happened through the world, a number of countries have modified and enhanced the seismic design regluations. Similarly our government modified and revised the Highway Design Specifications in early 2000, and then the part of seismic design was revised also. Korea Highway Corporation needs the revision of the Guide Specifications of Seismic Design according to the revised design specifications and requires the counterplans for existing bridges against earthquake attack. In fact the existing bridges constructed 10 to 30 years ago have experienced no or less earfhquake and have no satisfaction to the safety and integrity during earthquake. Therefore, this study is intended to revise the guide specifications concretely and determine the priority rating method. In addition, the examining method of seismic performance of existing bridges should be established on the basis of the verification by experimental and theoritical approach. This study is continual project through two years and this year is the first year. The results of this study is summarized as following. Firstly, the revision plan of guide specification is plotted in this study. To reflect the contents of highway design specification, U.S regulations, Japanese design pecifications and Eurocode are investigated thoroughly. The seismic isolation guidelines are proposed, where the applicable methods, manipulations, quality control and erection guidelines are introduced. On the basis of first-year study results, the detailed revision will be continued. Secondly, the provisions for the priority rating of seismic performance is established. In our country, this approach has not been applied before. In this study the three factors have been considered. These factors contain the seismicity indicating the earthquake probability and site characteristics, the structural vulnerability of existing bridges which shows the weakness of structure and irregularity, and the social and economic impact which the failure of the bridges may give to the society. This study establishes the decision making process, for priority ranking and the process is verified by applying 20 bridges which are the representitives of each highway route. Thirdly, the experimental and theoretical study is performed. The ductility factor for the existing bridges may be verified by experiment only. For this, the draft of each bridge is investigated and the design details are examined. Through this examination, the representative of experimental model is determined. The experiment will be performed in two ways. One is the quasi static test, and the other pseudo-dynamic test. These tests are to use the same model. Each model is varied according to the aspect ratio, transverse reinforcement, and lap splice. Besides, the multi-column and theoritical approach will be carried out. Until now, the test model and theoritical way using demand-capacity Performance spectrum are determined and the further study will be continued. Fourthly, the development of the device against falling down of superstructure is carried out. When the superstructure is destroyed, the impact to the lifeline is critical. Until now, the minimum seats width is regulated, but the device to solve this problem is required and partly,the devices to protect the collapse of superstructure such as restrainers and wedge, etc. are permitted. In this study, the new method to protect the collapse of bridges and distribution of seismic forces is cultivated. For this the basic drawing is made and the experimlental way to verify the applicability of new device is proposed. Next year, the detailed study will be carried out to confirm this device. As mentioned, the themes performed by this study will enlarge the variability of seismic plans for highway bridges, and will be helpful to the decision making to enhance aseismatic behavior of new and existing bridges.