Steel-UHPC-steel sandwich composite beams with novel enhanced C-channel connectors: Tests and analysis

Abstract

New steel-concrete-steel sandwich composite structure using novel enhanced C-channels (ECs) and ultra-high performance concrete (UHPC) was firstly proposed. The ECs offered strong tension separation resistance of faceplates from UHPC core as well as faceplate-UHPC interfacial shear resistance. Then, two-point loading tests on nine steel-UHPC-steel sandwich beams with ECs (SUSSB-ECs) were performed to study their ultimate strength behaviour. The studied parameters are thickness of steel faceplate, spacing of ECs, shear span, and strength of core. From the tests, though the shear span had quite significant influences on the ultimate strength of SUSSB-ECs, but all SUSSB-ECs failed in flexure mode even for the SUSSB-EC with short shear span ratio of 2.41, which confirms the bonding efficiency of ECs and high performance of this novel sandwich composite structures. The faceplate thickness exhibited significant, but the spacing of ECs has marginal influences on ultimate strength behaviour of SUSSB-ECs. Besides the tests, theoretical models were also developed to predict the initial stiffness, elastic stiffness, cracking load, yielding load, and ultimate load of the SUSSB-ECs. The validations of the predictions on stiffness and strength show that the developed theoretical models offer reasonable estimations on the stiffness and strength of SUSSB-ECs with limited errors.