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A new type of structural element, the timber-concrete composite beam, exhibited excellent structural performance. The notched connector is widely used in timber-concrete composite systems as a result of its considerable shear capacity and stiffness. Six groups of push-out tests were performed to investigate the shear performance of the notched connectors for the timber-concrete composite beams, with consideration to the varying concrete types, the shear length of the timber, and whether the notch was reinforced. From the test results, the notched connectors that corresponded to the shear fracture of concrete or timber had a low shear capacity and poor ductility. Notched connectors that simultaneously failed at the concrete slab (via shear force), as well as at the lag screw reinforcement point during bending presented the greatest shear capacity. This was followed by the notched connectors that exhibited diagonal-compression failure at the concrete slab. Screw fasteners in the notch were shown to improve the strength, ductility, and post-peak behavior of the notched connectors. In addition, the concrete type, the shear length of the timber, and whether the notch was reinforced were found to have no major influence on the slip modulus of the notched connectors. [ABSTRACT FROM AUTHOR]

When a lag screw with a large diameter is used as the shear connector in timer-concrete composite beams, the procedure of pre-drilling is required during the construction process. In this paper, a new type of lag screw was proposed to omit the pre-drilling step. To investigate the shear behavior of the self-tapping lag screws for glulam-lightweight concrete composite beams, a total of 18 push-out tests were conducted. Based on the push-out test results, the influences of concrete type, screw diameter, and penetration length of screw into timber on the loadcarrying capacity were analyzed in detail. The push-out test results showed that the concrete type had no remarkable effect on the loadcarrying capacity. The load-carrying capacity was improved with increased screw diameter and penetration length. In addition, an analytical model for load-carrying capacity of lag screw connectors was proposed based on the push-out test results. By comparisons, it was found that the timber-timber and steel-timber models proposed in Eurocode 5 made very conservative predictions on the load-carrying capacity of lag screws. The results of the analytical method presented in this paper showed a better agreement with the experimental results. [ABSTRACT FROM AUTHOR]