Effects of longitudinal reinforcement discontinuities on the seismic response of structural walls

Lap splices and bar cutoffs introduce reinforcement discontinuities in reinforced concrete structures. A two-step approach was used to investigate the effect of longitudinal reinforcement discontinuities on the seismic performance of reinforced concrete structural walls. In the first step, six cyclic tests on small-scale reinforced concrete structural walls were conducted to study the effect of bar cutoffs. Three of the six specimens had web longitudinal reinforcement cutoffs to simulate the effects of a retrofit practice used in Japan. The test results indicated that this discontinuity resulted in approximately 50% increase in the unit tensile strains in the longitudinal reinforcing bars in boundary elements. Larger unit tensile strains caused an increase in permanent strain accumulation, increasing the likelihood of bar buckling. In the second step, the mentioned test results were combined with test results from previous tests (that investigated discontinuities related to lap splices) to calibrate equations for estimating drift capacity of structural walls with and without reinforcement discontinuities.