Impact Strength in Dinamic Bending as a Function of the Strength in Static Bending of Wood

Abstract

Wood is a natural, renewable and abundant material in Brazilian territory. But its use in civil construction is still commonplace. When compared to materials such as steel and concrete, it has many advantages, such as its resistance to density ratio. Where it is possible to observe a high resistance, equivalent to concrete of high performance with a much smaller density. Due to the heterogeneity of the woods, very different behaviors may occur in response to the various requests. Thus, for a better use of its capacity is essential knowledge of its properties. Among them is impact strength in bending. Impact strength in bending knowledge is fundamental in structures that will be exposed to short-lived impact loads, such as bridges. But due to some factors this is not a mechanical property that is very accessible to most research centers. The objective of this research was to use linear, exponential, logarithmic and geometric regression models to verify if it is possible to obtain a relation between the resistance modulus in the static bending, which is more easily obtained, and the impact strength in bending values. Ten Brazilian wood species were selected and static bending and impact in bending tests were performed according to ABNT NBR 7190:1997. All tests were done in the Wood and Timber Structures Laboratory (LaMEM), in the Department of Structural Engineering of the Engineering School of Sao Carlos, University of Sao Paulo. According to the results and the statistical analysis performed, it was possible to conclude that the Strength in static bending does not seem to be a good estimator of the impact strength in bending of wood.