Double shear connection of Shorea Compression member using combined double-sided adhesive tapes and lag screws

Abstract

The use of double-sided adhesive tapes to resist shear force in a connection of wood compression member has the advantage of less construction time than the use of mechanical fastener such as lag screw because it is not necessary to make holes in connection with double-sided adhesive tapes. However, connection with mechanical fastener is more ductile compared to connection with double-sided adhesive tapes. To resist the same force, a connection with combined double adhesive tapes and lag screws needs shorter connection length compared to a connection with lag screws only. In this paper, three types of compression member connections are studied, namely connection with double adhesive tapes only (type 1), connection with lag screws only (type 2), and connection with combined double adhesive tapes and lag screws (type 3). The performance of each type of connections in terms of strength, initial stiffness, and ductility are studied experimentally. The thickness, width, and length of double adhesive tape are 1.1 mm, 20 mm, and 300 mm, respectively. The diameter of lag screw is 9.53 mm (3/8 in.). Four specimens for each connection type were laterally loaded on universal testing machine (UTM) until failure occurred. Load-deflection curve of each specimen were recorded. The average strength of the first, second, and third types of connections are 15.60 kN, 27.71 kN, and 31.22 kN, respectively. The average initial stiffness of the first, second, and third types of connections are 1.58 kN/mm, 4.32 kN/mm, and 4.33 kN/mm, respectively. The average ductility of the first, second, and third types of connections are 1.41, 5.60, and 4.63, respectively. It can be concluded that connection that utilizes combined double-sided adhesive tapes and lag screws has the highest performance in terms of strength and initial stiffness. Although the ductility of wooden connection that utilizes combined double-sided adhesive tapes and lag screws is lower than that of wooden connection that utilizes lag screw, it is much higher (3.3 times) than that of wooden connection that utilizes double-sided adhesive tape only.