a super-element based on finite element method for latticed columns

latticed columns are frequently used in industrial steel structures. in some countries these built-up columns might be even used in other types of steel structures such as residential and commercial buildings. besides, latticed columns are parts of skeletons of many historic buildings all around the world. to analyze a steel structure with latticed columns a more accurate numerical model for such a column seems to be essential. the lay-out and connectivity of constructing main profiles of a latticed column leads to formation of many shear zones along the length of a column. therefore, considering shear effects on the behavior of a lattice column is inevitable. this paper proposed a new super-element with twelve degrees of freedom to be used in finite element modeling of latticed columns. the cross sectional area, moments of inertia, shear coefficient and torsional rigidity of the developed new element are derived. to compute these parameters with less complexity a model using only beam elements is also introduced. a general purpose finite element program named lace is developed. this fe program is capable of performing linear and nonlinear analysis of 3d-frames with latticed columns, considering shear deformation. to show the accuracy of the proposed element, several cases are studied. the outcome of these investigations revealed that the current-in-practice model for latticed columns suffers from some major shortcomings which to some extends are resolved by the proposed super-element. the developed element showed the capability of modeling a lattice column with good accuracy and less computational cost.