STOCHASTIC ASSESSMENT OF NIGERIAN WOOD FOR BRIDGE DECKS

Abstract

This presentation assures the suitability of Nigerian wood using a stochastic safety evaluation method for bridge decks. A timber bridge deck is modeled in accordance to current specifications, to represent real life experiment in order to depict the structural behavior of planks when used as bridge decks. This model is then subjected to some degree of entropy using Advance Second Moment Reliability Assessment (ASMRA) method, which is then subsequently analyzed using JAVA library with the help of Flanagan polynomial. It is observed that, strength classes, timber thicknesses and stringer spacings are the major factors among others influencing the structural behavior of Nigerian timber species proposed as bridge decks material. Therefore, the major classes of the timber recommended for bridge decks are those within the strength classes N₁ to N₄and with dimensions ranging from 100 x 250mm to 150 x 300mm on stringers spaced not greater than 300mm. These strength classes with their corresponding material properties can be a source of sustainable bridge decks material over a reasonable period of time as indicated by the probability of failure as a result of damage due to load accumulation. In view of this, timber which is a locally available material can be used as supplement for bridge decks to substitute for the expensive concrete and steel which are the most commonly used materials and substantially reduce the cost of decks. Also, abandoned bridges with defects only in their decks in both rural and urban locations can be effectively rehabilitated in order to improve traffic flow, economic activities and the quality of life of the people.

http://dx.doi.org/10.4314/njt.v34i2.9