Flexural response of continuous unbonded post-tensioned beams strengthened with CFRP laminates

Abstract

The sudden brittle rupture of carbon fiber-reinforced polymer (CFRP) materials is often confused with the redistribution capacity of statically indeterminate CFRP-strengthened structures. Few investigations have been carried out regarding the flexural behavior of continuous CFRP-strengthened unbonded post-tensioned (UPT) beams, despite such beams having been extensively applied in practice, owing to retrofitting alternatives. This study emphasizes the flexural response of continuous UPT beams strengthened with CFRP laminates subjected to monotonic loading to failure. Progressive fracture of the CFRP laminates appears in the hogging and sagging regions, accompanied by concrete crushing in the sagging regions. The degree of moment redistribution (MR) and ductility generally increase with decreasing compressive zone depth of the critical section over the inner support. When the ratio of the global reinforcement index of the inner support to that of the mid-span increases, the MR and ductility decrease.