Influence of strand rupture on flexural behavior of reduced-scale prestressed concrete bridge girders with different prestressing levels

Abstract

In prestressed concrete (PC) bridges, high-strength prestressing steel plays a key role in the flexural response of girders. In both pre-stressed and post-tensioned PC bridge girders, damage induced by corrosion or impact of under-passing high vehicles may led to rupture of one or more strands, significantly affecting the load-carrying capacity against dead and traffic loads. This paper presents an experimental study on the response of PC girders affected by strand rupture at different locations. Four reduced-scale post-tensioned concrete girders with different levels of initial prestressing force were tested under four-point bending. Two specimens with a different level of prestress were initially tested in undamaged configuration to provide a basis for the assessment of damage effects. The other pair of specimens were intentionally damaged - having the same initial prestressing level of their undamaged counterparts - in the lower tendon to investigate their limited flexural response under different performance levels including serviceability and collapse. Damage turned into a different critical cross section outside the loading region, i.e. both cracking and collapse were attained 1.1m away from midspan. In the last section of the paper, a cross sectional analysis of the girder was developed at cracking and ultimate conditions for the prediction of damage impact on failure mechanisms, thus validating the experimental findings.