3D Nonlinear Finite-Element Modeling of Lap Splices in UHPFRC

Development in ultra-high-performance fiber-reinforced concrete (UHPFRC) structural applications that has taken place over the last two decades has generated innovative concepts that could significantly impact the concrete construction practice. The transition from conventional concrete with brittle behavior to strain-hardening behavior in direct tension allows consideration of the design of innovative structural components and offers development of new techniques for rehabilitation. Building on experimental results of internally instrumented reinforcing bars, this paper investigates the impact of tensile characteristics of UHPFRC on the performance of lap splice connections using a refined three-dimensional (3D) finite-element (FE) model at rib scale and a 3D concrete constitutive model implemented in a computer program. The results show that the model reproduces with accuracy the experimental behavior of lap splice connections in UHPFRC in terms of maximum strength, splitting failure mode, crack pattern, steel stress distribution along the splice, and eventual loss of bond. Using the validated 3D nonlinear finite-element model, the influence of splice length and UHPFRC cover thickness are highlighted in a parametric study of corner and interior lap splices. The paper illustrates the methodology that can be adopted along with experimental results to develop guidelines for designing lap splice connection in UHPFRC.