Experimental and analytical study on steel-concrete-ECC composite frames with URSP-S connectors

Abstract

To improve the slab crack resistance in the hogging moment region of steel-concrete composite frames, this paper proposes using Engineered Cementitious Composite (ECC) and Uplift-Restricted and Slip-Permitted Screw-type (URSP-S) connectors near the columns of the frames, the structural behavior of the innovative steel-concrete-ECC composite frames were experimentally and numerically investigated. Firstly, five 1/2-scaled steel-concrete composite frames were experimentally studied under vertical uniform slab loading and horizontal low cyclic loading. The failure mode and cracking, load-displacement relationship, stiffness and strength degradation, energy dissipating, and strain of composite frames with ECC and URSP-S connectors were analyzed, and good cooperative behavior and overall seismic performance were found. Then, it was compared with the results of the other four specimens with different slab materials and shear connector types. The experimental results showed that the use of ECC and URSP-S connectors improved slab crack resistance 55% in terms of crack width, and rarely influenced the structural performance of the composite frames. ECC played a major role in controlling the crack width while URSP-S connector played a major role in controlling the crack number. In addition, based on the test specimen with ECC and URSP-S connectors, an elaborate finite element (FE) model was developed and validated by the test results in terms of cyclic curves and failure mode. Moreover, supplementary modeling analyses with various parameters on the influence of the frame capacity were performed, where steel beam height was the most influential parameter.