LOAD MODEL FOR BRIDGE DESIGN CODE

The paper deals with the development of load model for the Ontario Highway Bridge Design Code. Three components of dead load are considered: weight of factory-made elements, weight of cast-in-place concrete, and bituminous surface (asphalt). The live load model is based on the truck survey data. The maximum live load moments and shears are calculated for one-lane and two-lane bridges. For spans up to about 40 m, one truck per lane governs; for longer spans, two trucks following behind the other provide the largest live load effect. For two lanes, two fully correlated trucks govern. The dynamic load is modeled on the basis of simulations. The results of calculations indicate that dynamic load depends not only on the span but also on road surface roughness and vehicle dynamics. Load combination including dead load, live load, dynamic load, wind, and earthquake is modeled using Turkstra's rule. The maximum effect is determined as a sum of the extreme value of one load component plus the average values of other simultaneous load components. The developed load models can be used in the calculation of load and resistance factors for the design and evaluation code.