05.21: Bolted steel angles in compression: Influence of realistic end supports

Abstract

ABSTRACTFor compression members with primarily axial forces, steel angles with bolted connections are often used. Due to the eccentric connection on only one leg additional bending moments are acting on the member, leading to a complex load carrying behaviour with flexural and/or lateral torsional buckling phenomena. The paper mainly focuses on the presentation of the influence of realistic end support conditions at the gusset plates on the member capacity in compression.The compression capacity of steel angles with bolted connections according to various test results from literature, a large series of sophisticated numerical analyses and common code regulations are presented in a unified form, using the normalized slenderness about the weak axis as basis. Thus, a direct comparison of about 300 laboratory tests with numerical results for bolted angle members is possible, whereby limit cases for the stiffness of the end support of the gusset plate (rigid or hinged) are considered. The systematic conducted numerical calculations show (beside the well‐known influence of one‐bolt or two‐bolt connections) a very high influence of the end support of the gusset plate. The significant difference in the compression member capacity between clamped and hinged support of the gusset plate is even more pronounced than the difference between one‐bolt and two‐bolt connections – a state of affairs that is either not, or only insufficiently, reflected in current design code regulations.Even if the boundary conditions of the compression member are considered by using the corresponding ideal buckling capacity (based on a LBA calculation) for the calculation of, no single buckling curve seems to be appropriate to represent the load carrying capacity of the compressed member.