Investigation of the buckling behaviour of thin-walled hollow concrete piers

Tall hollow concrete piers with high width-to-thickness ratios are commonly used in long-span box girder bridges. Such thin-walled structures present the possibility of failure due to local buckling. So, in common practice, diaphragms are usually included in hollow piers to improve the local stability; however, is that necessary? Although experimental research on the buckling behaviour of hollow piers has been conducted extensively, few analytical attempts have been performed to reveal the effects of the width-to-thickness ratio on local buckling behaviour. To this end, an analytical model has been proposed to investigate the local buckling behaviour of hollow piers. Following the Ritz-Timoshenko method, an analytical formula for critical local buckling stress has been developed and verified to have good accuracy compared with finite element analyses. Based on the buckling failure mode of a hollow pier with a slenderness ratio >6, it can be reasonably postulated that the strength of the hollow pier will be unaffected by local compression flange buckling when the wall width-to-thickness ratio is< 24, and it is entirely unnecessary to include diaphragms in hollow piers for stability. Additionally, it is equally interesting that the critical width-to-thickness ratio of a hollow pier with a slenderness ratio >4 derived using the proposed model is the same as the value given by the current AASHTO-LRFD Bridge Design Specifications.