Dynamic load amplification on short an medium span bridges

Goal of this study was to analyze amount of dynamic load amplification on short and medium span road bridges. Parameters taken into account are truck weight and velocity, surface condition and bridge type. The study was limited to passage of single truck; multiple events were not analyzed. Dynamic load amplification was calculated using transient dynamic finite element analysis with full vehicle-structure interaction. Two truck types were modeled: mid-European 5 axle semi-trailer (40 tons) and north-European 7 axle semi-trailer (60 tons). Velocity was varied between 40 and 120 km/h, while trailer weight was varied between empty trailer and maximal load. Results show that the analyzed steel bridge produced significantly higher load amplification values than for example composite bridges. Tendencies that have been observed are: heavier vehicles produce lower amplification values; faster vehicle velocities give higher dynamic amplification; shorter-span bridges have higher dynamic amplification. However, these are tendencies and not rules; they have exceptions. Highest calculated load amplification was 1.65, which was achieved on a 30 m steel bridge by an empty truck at 90 km/h; lowest calculated DAF was close to 1.0.