Mechanical and Bonded Connections
A common method for increasing the strength and durability of a traditional mechanical connection is to use adhesives. Epoxy resins are known for their bonding capabilities to many materials, therefore epoxy adhesives are often used in connections between composites and between composites and other materials assembled with bolts and adhesives. Two-part urethane adhesives are available with reliable results as well. The adhesives are applied to the prepared mating surfaces, and the connection is assembled with the completing step being permanent installation of the mechanical fasteners. Strength capacities of this connection are generally higher than mechanical connections because the load is transferred from one member to the next over a greater area.
A less common method for connecting pultruded shapes is to bond the parts together using epoxy resins or similar resins. Reliability of bonded connections is more difficult to achieve in the field due to variability in ambient conditions. It can be successfully performed, and interest and experience in this method is increasing.
Pultrusion manufacturers and molded fabricators have information available for performing each of these connection types: You can call them, purchase a professional publication or download a well-tested guide. Their recommendations will most often include years of successful practice and details supported by laboratory test data.