a method of measuring dynamic forces in scaffolding falsework structures

a method has been developed to measure dynamic forces in falsework arising from such sources as construction operations, movement of plant and wind effects. it uses a measuring unit which clamps easily around the tubular members of the falsework and employs strain sensitive elements to establish the mean strain developed in the member when a force is applied. these elements consist of electrical resistance strain gauges bonded to spring steel strips. by calibrating with respect to the cross sectional area of the member, the magnitude of the force can be determined. continuous recording techniques are used to monitor dynamic effects during construction operations. a change of strain of 2 microstrain can be detected, with an overall accuracy of 2 per cent. for standard mild steel scaffolding members this is equivalent to a force of approximately 0.2 kn. the overall accuracy for the measurement of force is estimated as 3 per cent. a trial during the construction of a motorway overbridge has confirmed the practical application of the method developed.(a)