Experimental study on the withdrawal performance of mortar-glulam hybrid anchored screws

In steel-timber composite floors, the screw connection between the H-steel and timber slab is vitally important, and the accurate calculation of the withdrawal performance of screws is one of the keys to accurately evaluating the shear performance of screw connections. In this paper, 20 groups of pull-out experiments were performed for mortar-glulam hybrid anchored screws. The differences in the withdrawal performance of glulam-anchored screws, mortar-anchored screws and mortar-glulam hybrid anchored screws were evaluated, and the effects of the screw diameter, effective anchorage length, and mortar anchorage ratio on the withdrawal performance of screws were analyzed. First, compared with glulam anchorage, the withdrawal strength and withdrawal stiffness of mortar anchorage increased by 54.7% and 33.0%, respectively. Second, when the total effective anchorage length was constant, as the mortar anchorage length increased, the withdrawal stiffness and withdrawal resistance of mortar-glulam hybrid anchored screws increased linearly. Finally, the calculation method of the modified effective anchorage length for mortar-glulam hybrid anchored screws was proposed, which improved the accuracy of the standards for calculating the withdrawal resistance of hybrid anchored screws by approximately 20%.