Full-Scale Ultimate-Load Test of a Stress-Laminated-Timber Bridge Deck

Abstract

A general assumption reported in the literature is that the structural response of a stress-laminated-timber (SLT) bridge deck is linear until failure. However, few studies of ultimate-load tests (ULTs) on timber bridges have been reported. A full-scale test of a SLT deck (span, 4.9 m; thickness, 270 mm) was performed to obtain the deformations at various prestress levels as well as at the ultimate-load capacity of such a structure. Prior to the ULT, nondestructive tests (NDT) were performed at three different prestress levels. The load was applied as an axle load positioned both centrically and eccentrically. The deflections were about 10% larger at a prestress level of 300 kPa compared with a prestress level of 600 and 900 kPa. For applied loads larger than 150–250 kN, the deflection of the deck was nonlinear at certain positions. This was most likely owing to large concentrated shear forces that resulted in interlaminar slip between the laminates. The limit for linearity seems to be dependent on the applied prestress. A prestress of 600 kPa and an eccentrically positioned load was used for the ULT. Failure occurred at a load level of 900 kN. The existing design codes and new procedures in development may be verified and calibrated against the results in this paper.