Stress strain response of pre-damaged concrete confined with recycled steel straps- a green confining material.

Abstract

When an engineer is determining the restoration strategy for a deteriorated concrete building, a precise design model is particularly essential. Although many design models have been proposed previously for various confining techniques, these models are not suitable for confinement using pre-tensioned recycled steel straps. This because pre-tensioned steel straps confinement has larger confining pressure at the onset of loading stage compared to other existing confining techniques. In this study, stress-strain responses of concrete repaired using pre-tensioned steel straps are assessed through experimental tests. Concrete cylinders were prepared and pre-damaged to a certain damaged degree to resemble damaged structures. They were then confined by using pre-tensioned steel straps. This acts as a repairing technique to restore the loading capacity of the damaged concrete. The experimental results showed that the confining volumetric ratio and pre-damaged degrees are two most important parameters that affects the stress-strain response. For this reason, previously developed design models are unable to capture the experimental test results in this study. Hence, confining volumetric ratio and pre-damaged degrees should be included in the development of the design model in future. In this study, a new design model is proposed by calibrating these two parameters into previous models. This proposed model is shown to be able to capture the stress-strain behaviour and is in good agreement with the experimental results. It is believed that engineers can apply this model in the design of repair works for a deteriorated concrete building.