Model development and seismic performance evaluation of rectangular reinforced concrete columns with short lap splices in existing building frames

Abstract Numerous existing building structures around the world were constructed without seismic provisions. Reinforced concrete columns in these buildings feature shortcomings (e.g., shorter lap splices, splices located in the plastic hinge zone, and minimal confinement) which increase their seismic vulnerabilities. To assess the seismic risk associated with these structures, this study proposes a numerical model to capture the nonlinear behavior of bar-slip in lap splices and applies the model to non-ductile building frames. To this end, an experimental database consisting of 28 rectangular specimens exhibiting lap-splice failure prior to yielding is constructed and then used to calibrate the numerical model to optimize the model parameters. The proposed model correlates strongly with the existing experimental data. The seismic damage potential of non-ductile frames is evaluated by developing their fragility curves. The selected building frames feature three stories with different lap-splice lengths and continuous longitudinal reinforcement in the plastic hinge zone. Fragility results indicate that increasing the lap-splice length in the plastic hinge zone decreases the frame vulnerability.