Stress Increment of Unbonded Prestressing Tendons in Prestressed Concrete Girders with Corrugated Steel Webs

Abstract

Experimental and finite-element studies have shown that a significant correlation exists between the stress increment of unbonded prestressing tendons and the flexural load of prestressed concrete girders with corrugated steel webs. Key parameters, which dominate the ratio of the stress increment of unbonded prestressed tendons to that of bonded nonprestressed reinforcement, have been identified in this paper, including (1) strength and the cross-sectional reinforcement ratio of bonded nonprestressed reinforcement, (2) strength and the cross-sectional area of the steel flange, (3) concrete cubic strength, and (4) ratio of the concrete flange thickness to the girder depth. Other parameters, such as the strength and thickness of the corrugated webs, initial prestressing stress and cross-sectional area of prestressing tendons, and span-depth ratio, are demonstrated with less effect. With the understanding of the parametric analysis, an analytical model of the stress increment of unbonded prestressed tendons is established in this paper for the stress increment of unbonded prestressing tendons at the yielding load of the prestressed concrete girders with corrugated steel webs. This model is able to predict tendon stress increments with good comparison with the experimental results.