Strength Evaluation of M-Beam Bridge Deck Slabs

Steel lighting columns are typically constructed from thin-walled tubes of circular or octagonal cross-section, and usually have an access hole in the region of high bending moment. The paper describes a series of tests to failure in pure bending on such tubes, some with and some without an access hole. The access hole was always at the position of extreme-fibre compression-the critical case. Twelve specimens were tested, using a purpose-built loading rig. The results give a quantitative indication of the weakening effect of an access hole, and have formed an essential basis for the development of design formulae described in a companion paper published, also in this issue of The Structural Engineer. S.A. Baban and G.H. Little

Steel lighting columns are typically constructed from thin-walled circular or octagonal tubes. The bending strength of such tubes is considered, with allowance being made for the presence of an access hole. A method of generating bending strength curves and tables is described. Because of the complexity of the problem, the method is basically empirical, using an adaptation of the Ayrton-Perry equation. The method is fully defined by the small number of simple equations given in Appendix A. The controlling parameters have been assigned values that ensure acceptable agreement with available test results. Typical design data so calculated are presented in both graphical and tabular form. G.H. Little