Retrofit of Wood Bridges

Abstract

A retrofit scheme to widen and strengthen nail-laminated timber bridges was evaluated in this project. The scheme consists basically of laying a second, transverse layer of timbers above the existing deck, and casting a grout layer between the two wood ones to insure good force transfer. An old wood bridge was evaluated before and after it was retrofitted in order to investigate the effectiveness of the retrofit technique. In addition, three laboratory specimens, representing portions of the retrofitted bridge deck (ungrouted and grouted), were tested to investigate the strength and the effects of fatigue on the retrofitted bridge deck, and to evaluate the transverse load distribution of the original and retrofitted bridge deck. An analytical model of the retrofitted bridge deck was also developed utilizing the finite element method, the deflection and transverse distribution results from the model studies were compared favorably with the laboratory results.