Experimental evaluation of a steel bubble expansion joint

In order to accommodate large lateral movements, the authors recently developed a new type of steel expansion joint by introducing a bubble in the center of the expansion joint. The lateral movement capacity of the joint was investigated by finite element simulation taking into account both material and geometric non-linearities. The results of the numerical simulations show that the innovative steel bubble joint can accommodate substantially more lateral movements than the conventional steel expansion joint. In this article, the results of the experimental evaluation of the bubble joint are reported. Full scale experiments were carried on three bubble expansion joints: a 2-ft wide joint with a 3-ft high bubble, a 3-ft wide joint with a 3-ft high bubble, and a 3-ft wide joint with a 4.5-ft high bubble. The effectiveness of the new steel bubble expansion joint to undergo large lateral displacements was confirmed by experimental investigations. The experimental results are compared with non-linear finite element simulation results. It is observed that the experimental results agree with the finite element results reasonably well.