ABSTRACT
The structure must neither overturn nor uplift at the supports. For bridges on flexible piers, it is important that the piers are not excessively flexible, as this could lead to bridge instability as a result of longitudinal movement of the superstructure. Therefore, the designer must verify that under those actions that have an unfavourable effect, the structure resists any movements with a sufficient margin of safety against instability. This must be the case both during construction and in service.
