Design Formula at Ultimate Stresses for Ekki (Lophira Alata) Timber Beam

Document Type : Original Article

Author

Department of Civil Engineering, University of Ilorin, Ilorin, Nigeria

Abstract

The global pursuance of design method for economic utilization of building material is the basis of this study. The ultimate stress design method proposed in this study is in line with this pursuit as it encourages full utilization of material section and thus brings in economy in material application. This is the focus of this study on appropriate design procedure for Ekki (Lophira alata ) timber beam. This new method can replace the conventional design which is based only on modulus of rupture that has been reported not a rational method because it relies only on the extreme thin fibre tensile strength of the beam in flexure, whereas, for such a beam, it is subjected to both tension stress (below the neutral axis ) and compression stress (above the neutral axis). Based on this fact, the method generated two stress expressions, one for axial tension and the other for axial compression, represented by their typical stress-strain equations for loaded Ekki specimens. To develop the beam design equations, the axial typical stress-strain equations were converted to bending expressions of the stress-neutral axis depth relationships for the Ekki beam section. These relationships were further simplified and tested to give theoretical results that compare well with the experimental values.

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