Experimental and numerical investigation of tensile-loaded staggered bolted and hybrid pultruded composite double lap joints.

On-site construction projects typically employ staggered fastener patterns. This article describes the application of Hollo Bolts (HB). It also highlights the effectiveness of using flexible epoxy adhesive to increase the load-carrying capacity of staggered connections fastened with HB. The distribution of loads between connecting elements largely determines joint performance. Pultruded glass fiber reinforced polymer (PGFRP), bolted (B), and hybrid bolted/bonded (BB) double lap joints were subjected to a typical pulling load and numerically validated in this investigation. To simulate delamination effects, a Cohesive Zone Model with a 3D progressive damage analysis was developed. In addition, a parametric study capturing the influence of various geometrical variables such as e/d, overlap length, bolt size, adherend thickness, and the number of bolts was used to compare both categories of joints in detail. The results indicate that for staggered connections fastened with HB, an efficient load transfer can be obtained in conjunction with flexible epoxy adhesive. It is anticipated that this interaction will be even more effective as the overlap length, adherend thickness, and fastener diameter increase. The present study proves that BB connections are 43.56% stronger than B connections. [ABSTRACT FROM AUTHOR]