Non Linear Damage Accumulation Based Fatigue Life Estimation of Reinforced Concrete Bridges Considering Overloading Effects

Abstract

This thesis presents an attempt to determine fatigue life of reinforced concrete bridges by adopting a non-linear damage accumulation method subjected to different amplitude loading due to passing of vehicles in Nepal. The bridge was modeled in finite element software and static analysis was carried out to determine the stresses acting on a bridge deck. The corresponding stresses in reinforcement bars is determined using limit state method and the stresses are incorporated in sequential law to carry out the fatigue life. Since S-N curves available in different codes represents stresses corresponding to more than hundred thousand cycles of failure, a full range S-N curve is developed to carry out sequential law. The material properties of the modeled bridges are taken from design data. The thesis concludes that the fatigue damage due to sequential law is low in previous years; however, there is exponential increase in damage in later years. Although the updated linear method seems to yield almost comparable result as sequential law, the fatigue progress is best represented by sequential law. In addition, the fatigue life for various overloading conditions is determined, and change in damage for respective overloading is analyzed.