Structural performance of the Nigerian grown Abura timber bridge beam subjected to compression and shearing forces

Abstract

There is the need to subject some Nigerian timber species to reliability analysis in order to establish their structural usefulness. It is on this basis that the Nigerian grown Abura timber was studied and structurally assessed to understand its performance as timber bridge beams. This was achieved by preparing some test specimens of it from naturally seasoned samples at moisture content of 18%.and determining its strength properties, which were subjected to statistical analysis to obtain the mean, standard deviation as well as the coefficient of variation. Structural analysis, deterministic design and structural reliability analysis were performed on the Abura timber bridge beam at the Ultimate Limit State of loading. A computer programme developed in FORTRAN language and First-Order Reliability Method (FORM) were used in the reliability analysis. In order to study the effect of geometry and loading on the reliability index, sensitivity analysis was performed by altering the geometrical dimensions of the beam as well as the magnitude of the loadings on the beam. Satisfactory level of reliability indices were recorded at depth of 400 mm, breadth of 150 mm and span of 5000 mm under the ultimate limit state of loading. The Abura bridge beam depicted very low level of safety when subjected to only shearing forces under the specified design conditions. The probabilities of failure of the Abura bridge beam in compression and shear are 0.68 × 10 −5 and 0.023 respectively, under the specified design conditions.

Reliability-based Evaluation of Bending Moment Magnifiers for the Design of Reinforced Concrete Short Columns under Biaxial Bending

“…The increase of safety index () of the magnifier for the design of rectangular short column under biaxial bending implies an increase of the reliability level of the column designed employing this magnifier. This increase in safety index (β) could be attributed to the increase in EI values, which increased the rigidity of the section [32].…”

Characterisation and grading of two selected timber species grown in Kwara State Nigeria

“…Analysis of Variance (ANOVA) was used to determine if there is significance difference between the top, middle and bottom positions of the timber species. The basic bending stresses parallel to the grain for the species were determined using the failure stresses from tests by [30,31] as: 2.…”

“…Where fb par is the basic bending stress parallel to the grain, fm is the mean value of the failure stresses and σ is the standard deviation of the failure stresses The basic tensile stresses parallel to the grain for the species were determined using the failure stresses from tests by [30,31] as: 2.…”

“…The basic shear stresses parallel to the grain for the species were determined using the failure stresses from tests by [30,31] as: 2.…”

Some Physical and Mechanical Properties of <i>Daniellia Ogea</i> Harms Green Timber Species

“…By stressing interest in local and sustainable materials such as timber, a major step is being taken towards industrialisation and economic independence by the construction industry whose primary goal is to produce a structure that combines safety, economy and aesthetic flawlessly (Aguwa, 2013). Timber machined for structural use has been for centuries used in the construction industry; nevertheless, considering several factors nowadays, the interest in structural timber has been modernized; meanwhile, green timber does not refer to the colour of the specie but the timber freshly felled from tree (Negro et al, 2013).…”