Performance of prestressed concrete girder in ultimate bending for AS5100:2004 and AS5100:2017

In 2017, AS5100, the Australian standard for bridge design and assessment, underwent significant updates from the previous 2004 edition. While the assessment methods remain similar, the design methods for prestressed concrete bridge components, which are required for their assessment, have significantly changed. It is then of interest to determine the implications of the changes. To do this, the performance of an already-constructed Super-T girder is assessed for ultimate strength in bending. Using the deterministic method prescribed by the code, the performance requirement is not met using the current code, whereas it is met using the 2004 superseded code (the code used for its design). From this, it is apparent that reliability analysis could play a very useful role in assessing such bridges. Consequently, a reliability analysis is conducted and it is found that both codes give indices significantly higher than an accepted target reliability index. It is concluded that the level of conservatism of AS5100 should be further investigated.