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Movement Gauges

MODERN ENGINEERING APPROACHES TO MONITORING

Distress in Buildings, Bridges & Other Structures

Physically examing a structure does not always provide the information required to diagnose the cause of movement and sometimes a monitoring exercise is required. This can introduce an unwelcome delay and the results of the exercise are often unsatisfactory. Most Engineers that are involved in this process will have realised that the results of simple tell-tales fixed over a few cracks is unlikely to provide the necessary proof of the cause and direction of movement.

The purpose of this web site is to promote and provide new gauges that can be used by professionals to quickly and accurately indicate details of movements.

• The key recommendation is to measure vertical movements using Movement Gauges or another precise levelling technique.
• Crack widths can also be monitored, but this data should not be relied upon in isolation.

Introduction to Monitoring Foundation Movements in Buildings

A system is now available that offers the potential to cut monitoring periods down to just a few weeks. The system allows cost effective and accurate measurement of actual relative vertical movement in building foundations. The numerical results, accurate to around 0.1mm, provide Engineers with irrefutable data upon which to base foundation/structure assessments.

The gauges are simple to use; applied to the wall itself, they measure the foundation shifts and not just visible cracks. They are also relatively inconspicuous and cause no damage to the fabric of the building - ideal for historic buildings as well as residential and commercial properties.

The gauges are intended to be fixed either internally or externally to the walls around the building at convenient locations. The gauges are read to 0.1mm (or less) with the telescope of a normal automatic optical level that is set up within 5m of the gauge. Changes in relative level can then be monitored to produce graphs of foundation movement against time. Further details, Papers and Case Studies are given below (see Details of Movement Gauges).

Crack Monitoring and Moire Gauges

If it is suspected that the problems are not solely due to foundation movements, then the movement gauges should also be used in conjunction with crack monitoring so that movement from different causes can be identified. This can range from pencil marks to indicate length or widths of cracks, to surreptitious discs that are read with vernier callipers (see www.Avongard.co.uk). If access is difficult or if easy indications of movement is needed, use of Bill Harvey’s moiré gauges are recommended and details of these are given below (see Crack Monitoring section).