Failure modeling of sawn lumber with a fastener hole

There is a consistent reduction in member strength associated with long-ter m use of structural wood members. It is hypothesized that this reduction in strength is due to "use and aging" effects such as cracks, splits and chec ks developed from drying stresses, moisture cycling, and fastener holes ori ginating from initial construction techniques. The focus of this research e ffort was to develop an accurate model of the behavior and performance of t he recycled timbers containing fastener holes. The flexural capacity of str uctural wood joists and planks containing fastener holes was modeled utiliz ing finite element analysis (FEA) coupled with the tensor polynomial (Tsai- Wu) strength theory. Each model presented herein represents a connection de tail that is commonly used in construction. To validate the analytical appr oach, virgin timbers with drilled holes were conditioned to simulate in sit u conditions and tested to failure. Comparing the results of the analytical model to experimental behavior, the FEA results were slightly conservative with predicted strength values falling within one standard deviation from the mean value of the experimental data and thus, producing accurate result s. A critical hole location exists where the hole produces the largest redu ction in strength. Based on the results, it is recommended that the edge of the hole not be located within 6 mm from the extreme fiber in both the com pression and tension regions. If this does occur, then possibly some post p rocessing needs to be performed such as planing the member down such that t he hole is located on the edge, or the hole is completely eliminated from t he section. (C) 2000 Elsevier Science B.V. All rights reserved.