Experimental Testing and Residual Performance Evaluation of Existing Hangers with Steel Pipe Protection Taken from an In-Service Tied-Arch Bridge

Abstract

Background: Tied-arch bridges’ hangers are crucial load-bearing parts, and their excellent condition directly influences bridge safety. However, assessing in-service hangers’ continuing functional performance is irrelevant and incomplete, particularly for unique hangers covered by outer steel tubes. Objective: This research uses a case study of an under-bearing tied-arch bridge with substantial hanger damage to determine the origin of the damage and analyze the hanger’s remaining operational ability. Methodology/approach: This study presents a set of assessment methodologies and procedures for in-service hangers’ remaining functioning performance using field inspection and indoor tests. First, an appearance inspection of the full bridge hanger’s upper and lower anchor heads was carried out, and the categories of anchor head damage and distribution rules are summarized. The causes of major water damage and the lower anchor head’s water infiltration channel were explored. Then, a full interior test was performed on the disassembled sick hanger to establish its present mechanical qualities. Finally, field inspection and indoor test findings assessed the bridge hanger’s operational performance. The findings suggest that the anchor box drainage prevention system should be improved to prevent rainfall and condensation from pooling in the lower anchor box and causing anticorrosive grease failure and anchor head corrosion. Results: The hanger’s mechanical qualities have deteriorated and no longer meet usage standards. Most of the water accumulated in the anchor head of the conventional construction hanger enters from the bridge deck or rope surface, but because of the outer steel pipe, rainwater can flow into the lower anchor box through the upper anchor box along the gap between the hanger and the outer steel pipe, so the waterproof system of the upper anchor box should be checked. Conclusions: This research may be used for safety evaluation and maintenance of the same hanger in service.