Plastic hinge models for the displacement-based assessment of wall-type bridge piers with poor detailing

This paper presents a plastic hinge modelling approach for wall-type bridge piers with detailing deficiencies such as low transverse reinforcement ratios and lap splices in potential plastic hinge regions. Currently available plastic hinge length estimates and strain limits are validated against a series of seven large scale tests, representing poorly detailed bridge piers. Besides the flexural deformations, which are predicted with the plastic hinge approach, the shear deformations need to be taken into account due to the geometry and detailing of the considered piers. Shear-flexure interaction is accounted for by relating the shear distortion to the axial strains in the plastic hinge. Lap splices in potential plastic hinge regions have a significant influence on the displacement capacity of the structure as their degradation may lead to a nearly instant loss of lateral load bearing capacity. Hence, strain limits defining the onset of splice degradation are assessed using the experimental data.