Adjacent Concrete Box Girders Transversely Post-Tensioned at Top Flanges Only: Experimental Investigation

Abstract

In this study, a new transverse post-tensioning (TPT) technique for box girder bridges is investigated, where TPT is applied at the top flange of the girder resulting in eliminating the intermediate transverse diaphragms. A one-third-scale bridge model consisting of four adjacent box girders with partial-depth shear keys was erected and tested. The bridge model was investigated for the optimal TPT force and spacing to ensure a uniform distribution of the clamping prestress. The efficiency of the proposed technique in transversely distributing live loads during simulated service and ultimate conditions was also investigated. Test results demonstrated that distributing the TPT force at a shorter spacing along the length of the bridge is more efficient than increasing the TPT force at discrete distant locations in producing the minimum required concrete prestress. It was observed that the effect of TPT force and spacing was insignificant during the simulated service condition, where shear keys remained intact or partially cracked. However, at failure, the presence of TPT added redundancy to the bridge model and mitigated any sudden failure when shear keys were fully cracked.