Mechanical performance of notched shear connections in CLT-concrete composite floor

Abstract

The results of a series of an experimental study and theoretical analysis of the shear performance of notched shear connections in CLT-concrete composite floor are presented. In total, twenty-seven specimens were prepared and tested in direct shear under monotonic loading conditions. The test variables consisted of connection type, notch depth, screw inclination and depths of CLT panel and reinforced concrete layer. Adhesive and self-tapping screws were used in the notches to enhance the stiffness and load bearing capacity of the connections. Test results indicated that direct concrete shear failure was the main failure mode of the notched connections. The screws can strengthen the shear capacity of the weakest shear plane, thereby changing the shear failure to the timber longitudinal crushing and concrete crushing failures. The specimens of a combination of a notch and an adhesive layer achieved the highest slip stiffness and load bearing capacity. The screw configuration and notch depth played an important role in the slip stiffness of the specimens of a combination of a notch and two screws. The shear capacity of the weakest shear plane was critical to the load bearing capacity of the notched specimens. The shear bearing capacity prediction model considering different failure modes achieved a good agreement with the test results. The modelling errors were less than 12%.