Joint Movement Models for the A.L. Macdonald Suspension Bridge

摘要

The Angus L. Macdonald (ALM) and the A. Murray MacKay (AMM) are two suspension bridges that span the Halifax Harbour linking the Halifax Peninsula with Dartmouth, Nova Scotia. The ALM and AMM were first opened in 1955 and 1970, respectively. As with any aging infrastructure the need for maintenance and rehabilitation exists, which requires adequate engineering knowledge of the structure. This study will investigate the expansion joint movement of both the ALM and AMM. Halifax Harbour Bridges (HHB) wishes to understand the range of the expansion joint movement and thereby minimize the cost of future joints. The bridge code suggests a range of movement that is believed to be conservative for a long span structure. The purpose of the expansion joints study is to use structural monitoring to assist in the selection of an appropriate range of movement for the new expansion joints on the ALM. In late June of 2012, a field-monitoring program was developed to monitor the joint movement. The objective was to obtain a better understanding of the bridges' response to thermal, wind, and live load variations. The deck at each tower of the ALM and the AMM was instrumented with displacement transducers to measure and record longitudinal movement of the main and side spans with respect to the main towers. Weather conditions were also recorded by two weather stations located at the midpoint of each bridge. This paper will discuss the details of the monitoring program, analysis techniques used, as well as preliminary results and conclusions.