DETERMINATION OF COST-EFFECTIVE OPTIMAL TARGET RELIABILITY FOR SEISMIC DESIGN AND UPGRADING OF LONG SPAN PC BRIDGES

Abstract

A systematic approach is proposed for the development of the reliability-based seismic safety and cost-effective performance criteria for design and upgrading of long-span segmental PC box-girder bridges. Following the procedure of the Korean Standard Bridge Design Code(KSBDC), the model bridge would be designed for varying levels of safety or reliability under specified earthquake loadings. The cost functions which consist of the initial cost, maintenance cost, direct damage cost, and indirect losses are formulated as functions of structural damage probability and Park-Ang damage index. The Park-Ang damage index is used for the quantification of structural damage under possible earthquake loadings. The system failure probability of example bridges is considered for the development of the target reliability for seismic design and upgrading of bridges. Structural component models are used for the 2-D/3-D dynamic analysis of whole structure. A seismic hazard curve for Seoul area, which is applied to probabilistic seismic hazard analysis and a stochastic ground input motion generated considering site effects, is used for non-linear damage assessment of the model bridge. The aforementioned procedure is developed as a new computer code for bridges, especially including a simulation algorithm, a Monte Carlo simulation-based reliability analysis program, and nonlinear dynamic analysis program, DRAIN-2DX/3DX.