Kwang-Min Lee

PRACTICAL APPLICATION OF LIFE-CYCLE COST EFFECTIVE DESIGN AND REHABILITATION OF CIVIL INFRASTRUCTURES

The demand on the practical application of life-cycle cost effectiveness for design and rehabilitation of civil infrastructure is rapidly growing in civil engineering practice. In the 21st century it is almost obvious that life-cycle costs together with value engineering will become a new paradigm for all engineering decision problems in practice. However, in spite of impressive progress in the research on LLC, most of the research has focused on the theoretical point and has not fully incorporated the critical issues for the practical implementation. This paper intended to suggest a systematic integrated approach to the practical application of various LLC methodologies for the design and rehabilitation of civil infrastructure.

LIFE-CYCLE COST EFFECTIVE OPTIMAL SEISMIC DESIGN FOR CONTINUOUS PSC BRIDGES

A systematic procedure is developed for the reliability-based seismic safety level for bridge life-cycle cost design criteria of continuous PC bridges. The paper proposes a set of cost function models for life-cycle cost analysis of bridges. The total life cycle cost function consist of initial coast and direct/indirect damage costs considering repair/replacement costs, human losses, property damage costs, road user costs, and indirect regional economic losses. The damage costs are successfully expressed in terms of Park-Ang median global damage indices and damage probabilities. To computer Park-Ang median global damage indices and damage probabilities, SMART-IDARC-BRIDGE, a modified version of the well-known IDARC-BRIDGE, incorporating simplified Monte Carlo simulations and system reliability for multi-unit PC bridges is used. Earthquake ground motions used to simulate the realistic loading condition are obtained from non-stationary filtered Gaussian processes with both frequency and amplitude modulations based on the Yen-Wen stochastic ground input motion model. The proposed approach is applied to model bridges of moth moderate seismicity regions like Korea and high seismicity regions like Japan and various sensitivity analyses are performed to identify governing parameters. From the results of the numerical investigation, the proposed approach can be effectively utilized for optimal seismic safety levels for bridge life-cycle costs design criteria.

PRACTICAL LIFE-CYCLE COST EFFECTIVE OPTIMUM DESIGN OF STEEL BRIDGES

A practical Life-Cycle Cost (LCC) formulation and procedure for the LCC-effective optimum of steel bridges is presented in this paper. A general LCC model for optimum design of steel bridges consists of initial cost and direct/indirect rehabilitation costs of steel bridges including repair/replacement costs, loss of contents or fatality and injury losses, road user costs, and indirect socio-economic losses. This paper focuses on the presentation of a general formulation of LCC models and LCC effective design system models for steel bridges suitable for practical implementation.