Reinforcement Analysis of Rigid Hangers for Existing Old Arch Bridges: A Case Study of Ling Bridge

Abstract

Ling Bridge, built in 1936, is an old half-through riveted steel arch bridge with rigid hangers and a floating deck system. The effects of various factors, such as temperature, vehicle load, and crowd load, have caused large additional stresses on the rigid hangers. According to the inspection in 2011, the bridge was in a dangerous state. Therefore, improving the structural strength of the bridge and prolonging the service life for another 40 years while protecting the cultural relic were major problems. This study analyzes rigid hangers on the premise that the reinforcement schemes of other bridge components have been determined. First, the damage situation, material properties and mechanical behaviors of old hangers are evaluated. Second, an appropriate reinforcement method is proposed. Third, mechanical and fatigue analyses are conducted on the new structures to prove the rationality of the reinforcement method. For the undemolished old structures, a fracture assessment of existing damage is performed to obtain the evolution laws and ensure safety. Finite element calculations and fatigue fracture analyses show that the proposed reinforcement method for the hanger system can reduce all hangers’ stresses effectively to prolong service life and protect the cultural relic.