Measurement of reinforcement strains caused by blast loading

摘要

The ability to measure reinforcement strain distributions in reinforced concrete structural elements is an important tool in the understanding of structural behaviour. A knowledge of strain values enables bar stresses and forces to be determined and, from stress distributions, bond stresses can be calculated. Measurement of reinforcement strains is complicated by the need to ensure that the bond characteristic between the bar and the surrounding concrete is undisturbed by the measurement technique. Mains [1] was the first to use a procedure which achieved this by installing electric resistance strain gauges in a longitudinal duct positioned centrally in the cross-section, with the wires from the gauges passing along the duct and exiting at the bar ends. This avoided the disturbance caused by mounting the gauges on the surface of the bar and routing their wires through the surrounding concrete, a procedure which, as well as affecting the bond characteristic, has a strong tendency to initiate cracking when specimens are loaded.