Movement and Monitoring

Buildings are moving all the time. They often need to in order to stay in one piece. Most of the time this movement passes unnoticed, but sometimes it can be a problem. Subsidence, settlement, heave, sway, bouncy floors, bulging walls, cracks, contraction and expansion are all forms of structural movement and may need investigation.

Monitoring the movement of structures is a key element of the structural engineer’s job. At SER we are called in when a crack appears and can then use a relatively simple method to monitor whether the crack is getting wider over time. This is done by gluing studs either side of the crack and then measuring the distance between these studs at intervals over a period of time.

More complex cases of suspected movement may require a more technical approach with remote sensors used to transmit data and provide a more precise and dynamic appraisal in which sudden changes can be detected immediately. For instance deformation monitoring measures in three dimensions and is used in settings where such measurement of bulges is crucial such as tunnels and dams. Such monitors may also measure temperature and humidity to provide an even fuller picture of how movement might be occurring.

Monitoring might be needed for structures both old and new. Whilst out walking at the weekend we saw a fine example of a simple but effective method of monitoring movement on the Grade II listed Hewenden Viaduct in West Yorkshire. Built in 1883 it is one of the highest viaducts in Britain and linked important textile towns whilst by-passing the congestion of Leeds and Bradford. Due to the instability of the ground beneath, the middle piers are wider than the others and their foundations sunk to a depth of 60 feet. As you can see from the photo, mortar was placed over a crack   in October 2017 and the fact that it remains intact indicates little movement – built for longevity, those Victorian Engineers knew what they were doing!