Evaluation of the efficiency of UHP-SHCC beams in flexure under external prestressing (comparative study)

Externally prestressed beams are structural concrete members in which prestressing tendons are placed outside the concrete section. Design provisions of many international codes for external prestressed beams are limited to ordinary concrete (OC). However, the main advantage of using an ultra high performance strain hardening cementitious composite (UHP-SHCC) is to increase the flexural load-carrying capacity for concrete members. The aim of this research was, therefore, to find the coupling effect of external prestressing and the use of UHP-SHCC. To achieve this objective, three prototype beams were tested to evaluate the effect of prestressing on the behaviour of UHP-SHCC beams. The experimental results were also compared with those of an OC beam. Basic section analysis was carried out on uncracked, cracked elastic and ultimate strength conditions. The analytical model was verified and validated against experimental tests. An extensive parametric study using a basic analysis was carried out for prestressed UHP-SHCC beams under quasi-static monotonic loading. Comparative studies were conducted to achieve the efficiency of UHP-SHCC beams under external prestressing as compared with ordinary and high-strength concrete (HSC) beams with and without reinforcement. The test results indicate the efficiency of using UHP-SHCC material with external prestressing to improve the failure loads and ductility of beams relative to ordinary and HSC beams.