Residual stiffness assessment of structurally failed reinforced concrete structure by dynamic testing and finite element model updating

Abstract

For a reinforced concrete (RC) beam structure subject to a mid-span point load, failure in tension is deemed to occur when steel reinforcement on the tension side has yielded. When unloaded from this post-serviceability cracking stage, the residual stiffness of the failed structure is difficult to estimate. This paper presents a new method for the residual stiffness assessment of a failed RC member such as a beam or one way narrow slab at the post-serviceability cracking stage based on dynamic testing and finite element (FE) model updating. The failed zones are simulated using damaged beam elements in an FE model of the structure and the measured modal properties i.e. frequencies and mode shapes are used as the reference data for model updating. Through a procedure of sensitivity-based updating, the stiffness distribution along the member can be obtained, leading to identification of location and extent of the damaged (failed) region.