Ultimate Capacity Equations of Completely Overlapped Tubular Joints

Abstract

The design of fixed offshore structures for wind turbines with a common joint configuration has been increased. A completely overlapped tubular joint (COJ) is proposed to replace the common joint in the design of fixed offshore structures as it has a higher ultimate joint capacity. However, very few detailed guidelines are specified in recommended design practices, and relative research studies on COJ in multiplanar. This study proposes the derivation of the design equation of COJ in multiplanar. The design equation in multiplanar was modified from the equation in uniplanar by multiplying it with the reduction factor. Derivation of the equation in uniplanar was based on a failure mechanic model of through-wall plastification. A quarter-circle ring was deployed in the mechanic model that postulates three hinges. The principles of energy conservation and geometric analysis were applied for derivation. The empirical study of the effective width was investigated through a parametric study of the validated finite element model. An assessment of the proposed design equation in uniplanar was closer to finite element capacity with an average percentage error of 9.48% (conservative) and standard deviation of 10.72% and more accurate than the existing equations in design codes and previous research efforts. The capacity from the equation in multiplanar was slightly decreased from the capacity in uniplanar, approximately 2.4%.??????????????????????????????????????????????????????????????????????????????????? (Common Joint Configuration) ?????????????????????????????? ?????????????????????????????????????????????????? (Completely Overlapped Joint) ????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ??????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????????????????????????????????????? ?????????????????????????????????? ???????????????????????????????????????????????????????????????????????? ???????????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????????????? ?????????????????????????? 9.48% ??????????????????????? 10.72% ???????????????????????????????????????????????????????????????????????????? ????????????????????????????????????????????????????????????????????????????????????????????????????????? 2.4% ?????????