Analysing the Shear Behavior of Old Post-tensioned Bridges with Real Sized Beam Elements

The shear strength of prestressed concrete girders, especially those with limited shear reinforcement, is a subject of continuous research. Due to the lack of tests with realistic construction details and realistic heights, experimental investigations of various aspects of the shear bearing behaviour have been intensified in recent years in large collaborative research projects. This paper presents three series of experiments on different aspects of this problem. When old concrete bridges are recalculated, it is often found that their shear reinforcement is of a type that is no longer permitted. In test series 1 it is shown that they nevertheless make a significant contribution to the shear capacity. The analytical approach developed to consider them as an additive contribution is also presented. In contrast to conventional representative scaled test series, the experiments in test series 2 deliberately reduce the amount of longitudinal reinforcement to match efficiently designed bridge cross-sections and investigate the influence of longitudinal deformations on the shear capacity. Test series 3 investigates the effect of prestressing on the shear capacity with variations in the level of prestressing as well as the initial utilisation of the yield strength of the tendons on scaled cross-sections (h=1.2 m) to further analyse realistically designed beam elements. A comparison of the failure loads with the existing recalculation guideline and its forthcoming update provides further insight.      «

The shear strength of prestressed concrete girders, especially those with limited shear reinforcement, is a subject of continuous research. Due to the lack of tests with realistic construction details and realistic heights, experimental investigations of various aspects of the shear bearing behaviour have been intensified in recent years in large collaborative research projects. This paper presents three series of experiments on different aspects of this problem. When old concrete bridges are re...     »