Experiment on bearing capacity of bolted joints for pultruded composite square profile

Composite profiles produced by industrial pultrusion process have consistent cross-section shape (such as square, Ⅰ-shaped, grooved, etc), stable performance and continuous length. The technique of joint connection is difficult. The experimental and theoretical analysis of mechanical bolted joints were carried out. The effects of parameters such as aperture, end distance and wall thickness on bearing capacity of bolted joints were researched. The enhancement technology of unidirectional fiber profiles bolted hole wall by metal gasket around the neck was proposed. Then the design formula of joint connection for pultruded composites was fitted. The results show that when the failure mode of pultruded composite square profiles is local crush of joint on tube, the relationship between the ultimate bearing capacity and the product of pore size and thickness (d·t) is linear. Meanwhile, the failure modes of joints are related with the ratio of end distance to pore diameter. Under the mode of crushing rupture, when the thickness of the joint plate is constant, the increment of the ultimate bearing capacity decreases with increasing pore diameter. The ultimate bearing capacity of bolted joints can be significantly enhanced by 63% using metal gasket reinforced technology.