Field Performance of a Composite Log-Concrete Bridge

In Brazil, composite log-concrete bridges are considered to be a viable alternative for municipal and rural use, mainly because of their low construction and maintenance costs and their high strength and stiffness. These bridges consist of a thin concrete slab over round timber beams. Materials are thus used to their best abilities, with timber under tension and concrete under compression. The two components are connected by glued steel bars. This paper presents the field performance of a composite log-concrete bridge constructed in December 2004 on the grounds of the University of São Paulo. This two-lane bridge is 12 m long, 10 m wide, and has a skew of 15 degrees. The load tests consisted of positioning fully loaded, three-axle trucks on the bridge and measuring the resulting deflections at a series of points along a transverse cross section at mid-span. In addition, an analytical assessment was made, using computer modeling to predict the response of the bridge. The field tests indicated that the composite log-concrete bridge performs adequately without structural deficiencies.