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Title: Environmental effects on a suspension bridge's performance
Author: Westgate, Robert
ISNI:       0000 0004 2723 2717
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2012
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Current Structural Health Monitoring (SHM) research uses changes in a bridge’s behaviour to locate and quantify the damage in a structure. However the structural responses are also linked to environmental effects, such as its temperature and the traffic load. In order to understand a typical suspension bridge’s behaviour to environmental conditions, studies on the Tamar Suspension Bridge’s response to temperature and traffic are contained in this thesis. This was achieved by observing data collected from long-term monitoring systems installed on the structure, and simulated responses derived from a three-dimensional finite element model of the bridge. The data of the bridge have shown that the profile of the suspension bridge reconfigures when the temperature of its structure increases, causing the deck to sag and expand. The natural frequencies of the bridge were noted to drop during the day. Transient thermal responses were also indentified; the differing rates of warming up between the deck, towers and cables manifested in the structural responses of the bridge. Phenomena caused by the temperature differential across the bridge’s surface were also studied. Investigations on the effect of traffic demonstrated its additional mass causes the natural frequencies to decrease for certain modes. This was identifiable in the time series data, where the largest reduction in frequencies is during rush hours. The investigations have shown that the changes the modal frequencies and modal mass are dependent on the eccentricity of the traffic flow on the bridge, which may increase or decrease depending on the mode shape. The loading of an abnormally heavy trailer on the bridge has also demonstrated the deformation to the bridge’s quasi-static shape as the vehicle travelled across. The location of the vehicle on the bridge was also able to affect the modal properties of the suspension bridge, according to simulated results.
Supervisor: Brownjohn, James Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available