Structural Monitoring

Structural Monitoring

At various stages throughout the life of a structure, problems of movement, vibration, stability or fatigue may occur.

The simplest method of movement monitoring, with which most building professionals are familiar, is the glass tell-tale. This has the advantage of low cost and simplicity of installation but the disadvantage of low resolution. When sufficient movement occurs the glass breaks and assessment of movement must be made between the broken faces. For most purposes this information is inadequate.

Greater accuracy can be achieved by using more elaborate tell-tales or demountable gauges. The costs of staff and, possibly, access generally prevent sufficient readings being taken manually to obtain much in the way of a movement history.

Transducers are readily available for measuring stresses and deflections; rotations (both accelerations and velocities); loads (static and dynamic); temperature and humidity.

The use of 'intelligent' data logging can eliminate the gathering of data between discrete events while retaining data from the period immediately before the event. Sensitivity levels can be set to ignore minor signals. Alternatively, all data can be gathered over a continuous period and any selection or sorting carried out after the data collection is complete.

Instrumentation of a structure or component is a highly specialised task and each project will have its own solution. In addition to the basic considerations of appropriate gauging, the effects of environmental influences must be included in the submission. This can include aggressive environments, such as in a chemical plant, exposed to severe weather environments and/or large-scale wetting by seawater, or the more determined application of a destructive human mind.

Projects in which GBG Structural Services have been involved vary from long term monitoring of building movement by manually read gauges to monitoring of trunk road bridges with remote electronic reading.