Experimental and numerical investigations on the T joint of jack-up platform laterally punched by a knife edge indenter

Experimental and numerical studies are performed to investigate the performance of T joints in a jack-up structure under lateral impact loading. The dynamic response is studied in a drop weight impact testing machine with three different falling heights, and the failure mode and local damages of the specimens are investigated. The experimental results indicate that the force-time curves corresponding to the three falling heights have similar tendencies during the plastic deformation process, and three stages are observed in each force-time curve. The failure mode of the T joints is commonly concave at the impacted area of the chord member and is buckled at the section near the mid-span of the brace member. When both ends are fixed, the chord member displays the conventional plastic failure mechanism due to bending. Numerical simulations that consider the material nonlinearity are conducted to investigate the performance of the T-joints, and various lateral impact loadings are addressed. Coupon tests of the steel are conducted to obtain the mechanical properties under both quasi-static and dynamic conditions, and these test results are input as the material properties for numerical simulation. Good agreement was attained between the FEM responses and the experimental results.