Experimental and Numerical Study of Curved SFRC and ECC composite beams with Various Connectors

Abstract

In order to investigate the cracking behavior of curved steel-concrete composite mechanical behavior under a hogging moment, two composite box girders with a central angle of 9° were designed and tested under static loads. In the reported test program, the CCB-1 was designed with steel fiber reinforced concrete (SFRC) slab and shear studs. In contrast, the CCB-2 was designed with Engineered Cementitious Composites (ECC) and Uplift-Restricted and Slip-Permitted (URSP) connectors for enhanced crack resistance. The load-displacement curve, strength and displacement ductility, failure mode, and strain distribution were reported in detail. For the tests of small curvature beams loaded under the hogging moment, the flexural critical failure mode was observed for both specimens, which was governed by compressive yielding of the top steel plate and tensile yielding of the concrete slab. The URSP connectors in CCB-2 effectively released the interface slip of composite girders, enhanced the interface slip capacity, and reduced the crack width of concrete compared with traditional shear studs in CCB-1. Besides, the nonlinear elaborate finite element (FE) models of two specimens were developed, and the modeling scheme and the material constitutive model were reported in detail. The developed nonlinear FE model well predicted the test results in terms of load-displacement curve, initial stiffness, failure mode, and strain distribution of concrete slab and steel beam. Both test results and FE results showed that the shear lag behavior of the concrete slab was insignificant, while the steel flange plates showed a notable shear lag effect. Therefore, the performance of the URSP connectors is well validated.