COMPRESSION AND TENSION LAP SPLICES IN REINFORCED CONCRETE MEMBERS SUBJECTED TO INELASTIC CYCLIC LOADING

The research constitutes the fifth phase of a continuing investigation at Cornell University into the behavior and design of lap splices in reinforced concrete members under high intensity cyclic loads. The overall objectives of the present phase are: (1) To study the performance of compression lap splices in columns and beams, and tension lap splices in flat elements, with all splices subjected to seismic-type loading. (2) To gain more insight into the fundamental force transfer mechanisms in lap splices. (3) To include necessary modifications of the design requirements obtained from the previous phases to ensure satisfactory performance of tension lap splices in flat elements and compression lap splices in beams and columns.;The analytical investigation included: (1) a three-dimensional nonlinear finite element analysis of the bond behavior of tension lap splices under monotonic loading, and (2) a one-dimensional nonlinear finite element analysis of compression lap splices subjected to monotonic and inelastic cyclic loads.;For tension splices in flat elements, it is shown that the confinement effect of the straight transverse reinforcement is as effective in resisting bursting forces as the straight leg of stirrup-ties used for the interior splices of beams and columns. However, special attention must be given to the confinement of the edge splices, so that premature edge-splitting type failure is prevented.;It is also shown that compression lap splices can be designed to sustain high intensity cyclic loads (axial or flexural) up to at least a dozen cycles into the inelastic range, where the maximum bar strains reach 2.5 times the yield strain. Closely spaced, uniformly distributed stirrup-ties along the entire splice length plus a distance equal to d (effective depth) beyond the splice ends is recommended.;A combined experimental and analytical approach was utilized, with full-scale beams and flat elements under two point bending and full-scale columns under either concentric or eccentric loading. The main parameters studied were the amount of transverse steel, the longitudinal bar diameter and yield strength, and the splice spacing.;The research has led to modified design guidelines for detailing of tension and compression splices subjected to inelastic cyclic loads, where the actual yield strength of the reinforcement is directly considered.