A new finite joint element to model joint connections in offshore structures

In this paper, a novel approach is presented to improve the accuracy and reduce the computational time of the finite element analysis of massive lattice structures. To achieve these goals, the global structure is discretized based on the beam elements while joint connections are replaced with joint elements. Then, the proposed joint element matrices are formulated in the local model with solid elements and consequently formed according to the beam theory. The present formulation is able to impose the details of joint connections in the global matrices. To verify and evaluate the proposed model, the numerical results of various cases are compared with ANSYS and those reported in the open literature. Moreover, a special study on the real-life offshore jacket structure has been carried out subjected to static loads and free vibrations. The comparison study shows the consistency of joint elements in both mass and stiffness matrices by reducing errors significantly to 0 % and 5 % while the error of using only beam elements reaches up to 300 % in some cases. It is concluded that the present approach can be efficiently implemented for the modeling of 3D massive lattice structures with reasonable accuracy and computational time.