Experimental and analytical studies of base pipe pin connections under direct tension

Abstract

Base pipe pin connections were developed to simulate a hinge behavior at the base of cast-in-place or precast bridge columns. Base pipe pins are composed of two steel pipes: one pipe is embedded in the column and the other in the adjoining member. Shear force is transferred through contact of the pipes and friction. The uplift force is resisted by a tension member and welded studs on the surface of the column pipe. To investigate the behavior and failure mode of base pipe pins under direct tension and to determine the ultimate tensile capacity of the pins, two scaled pipe pin connections were tested under direct tension. Elaborate nonlinear finite element (FE) studies of the pipe pins were also conducted to explore the effects of different parameters on the response of the pins. There are many possible failure modes that could occur under tension. Test results depicted that rupture of the pin tension member with no damage to the connection was the dominant failure mode in pure tension. The FE models accurately estimated the response of the test models and the observed failure mode. The analytical results showed that decreasing the pipe height alters the failure mode but does not affect the ultimate capacity of the connection significantly. Furthermore, reducing the pipe height or increasing the number of stud layers has a small effect on the ultimate capacity and stiffness of the connections.