Behavior of Fiber Reinforced Key Joints in Precast Concrete Segmental Bridge: Experimental and Numerical Analysis

Abstract

Fiber reinforced concrete (FRC) has been gradually applied to the construction of precast segmental bridges, but due to the discontinuity of the joint structure and the existence of keys, the stress at the joint is complex. Taking the number of keys at the joint, the presence or not of reinforcement in keys, the height to width ratio of specimens and joint angle as the design parameters, 10 pairs of specimens with 2% fiber ratio and 100.1 MPa FRC dry joint matching were tested under combined bending and shear load in this study. The crack development process, failure mode, cracking load, and ultimate load were also observed. The results show that the mechanical properties of specimens with 30° and 60° joint angle are better than that of 45° for both single-keyed and double-keyed specimens. With the increase in the number of keys and the ratio of height to width, the cracking load, ultimate load, and overall stiffness of the specimens are greatly improved. The internal reinforcement in the specimen can increase the cracking load and ultimate load, change the failure mode and increase the integrity of the specimen. The reinforcement in the key has little effect on the mechanical properties and could not change the failure mode of the specimens under combined bending and shear load. In addition, a numerical analysis model was established based on a concrete damage plasticity model in ABAQUS software to investigate structural behavior of keyed dry joints under combined bending and shear load. Fortunately, the cracking evolution history and final crack pattern presented from finite element analysis results are in good agreement with the experimental results. Moreover, the average deviation of cracking load and ultimate load is only 7.3% and 2%, respectively.