Assessment of the shear strength of existing post-tensioned bridges

The assessment of existing structures is becoming more and more important in the field of activity of a structural engineer. To get more information about the load-carrying behaviour of shear critical bridge structures an experimental campaign on large-scale post-tensioned specimen was carried out. With the aid of DIC it was possible to measure the crack kinematics of the critical shear crack during the whole test. Thus, an evaluation of different shear-transfer actions were performed. Based on these results a shear design concept – including different shear models – for post-tensioned bridge girders with a very low amount of transverse reinforcement was proposed. The approach was used to evaluate the shear strength of a real existing post-tensioned bridge. Based on the suggested concept a cost-extensive strengthening of the webs were prevented.