Experimental investigation on the behaviour of lap splices under uniaxial cyclic loading

Splicing of longitudinal reinforcement in the plastic hinge region of reinforced concrete (RC) members was common practice in buildings and bridges before the introduction of capacity design principles. Experimental and field observations showed that the presence of lap splices in regions where inelasticity concentrates might lead to a significant reduction of both the strength and the displacement capacity of the structural member. The behaviour of this constructional detail depends on a number of factors, which should ideally be considered when simulating the response of RC members. However, models describing the full hysteretic response of lap splices are currently lacking. Their future development, calibration, and validation depend on the existence of reliable and comprehensive experimental data. Following previous research at the École Polytechnique Fédérale de Lausanne on the seismic performance of existing, poorly detailed bridge piers, this paper describes a new experimental programme on lap splices. The goal is to investigate the influence of splice length, confining reinforcement, and loading history on the behaviour of lap splices, which are among the parameters affecting their response. The test units represent the boundary elements of bridge piers or walls and are tested under axial tension-compression cyclic loading. Their geometry, test setup, and instrumentation are herein described as well as the first preliminary results. Particular attention is drawn to the different failure modes and to the influence of confining reinforcement on the performance of lap splices.