Experimental study on shaped steel shear connectors used in large-scale composite structures

Steel-concrete-steel (SCS) composite structures are used in immersed tunnels and are superior in capacity, constructional facility, etc. in comparison with traditional structures. Land T-shaped shear connectors are two typical types of shear connectors used in the composite structures. To investigate the mechanical performances of the connectors, 12 groups of push-out tests were conducted. Interfacial slip, bending deformation of the connector web, and strains on the concrete, were measured. Failure modes of concrete crushing were observed in all tested specimens. Evoked outcomes indicated that the performances of the Land T-shaped connectors were controlled by the non-reinforced concrete. The strain measured in the tests indicated that stress concentration and concrete crushing were mainly located at the root regions. The shear-force-slip relationship, strain distribution, etc., were further analyzed and discussed. Accordingly, the currently available methods used to evaluate the ultimate strength are discussed. These methods were found to be accurate in the case of the L-shaped shear connectors but too conservative for T-shaped shear connectors. A scaling factor was proposed for modification. Finally, 122 groups testing data was collected for validation, which proved that the modified method has adequate accuracy and can be used in various design applications. The experiment data of the L-shape and T shape shear connectors with different experimental methods were studied which shows the push-out specimens and beam specimens have similar performance. The results of the experimental study and theoretical analyses indicate that the L-shape and T-shape shear connectors have similar mechanical properties while the T-shape shear connectors have better performance concerning the shear stiffness and the ultimate shear strength. (c) 2020 Elsevier Ltd. All rights reserved.