Wooden bridges with deck of sawn board and round beams: main orientations

The county of Itapeva–SP, Brazil, has a great territorial extension, with many vicinal roads and, consequently, many wooden bridges with some type of problem. This research had the purpose of analysing 34 wooden bridges, with decks formed by natural longitudinal beams connected to the sawn transverse boards, to identify the main problems presented and proposition of solutions. The great majority of the analysed bridges (82.35%) presented a small span (up to 15 m), and the analysed spans ranged from 5 m to 44 m approximately. The lack of of preservative treatment was a problem for all analyzed bridges and this is a great factor that contributes to the reduction of the lifetime of the bridges. As a result of this work, the main construction and calculation recommendations for wooden bridges are presented. Two pre-sizing tables are also presented to guide builders and other interested parties in the construction of wooden bridges, in order to obtain secure structures, low cost and with guaranteed durability.