Methods for analysing heavy transports on existing bridges

Sammanfattning: The main purpose of this thesis is to evaluate two current methods, Brokontrollen and TungTransport, used in Sweden for analysing heavy transport on existing bridges. It was investigated how the two methods compare, how bridge types affect the differences, if other variables impact the results and how, and if the methods can be improved. To answer these questions, first, a set of vehicles (which were used to analyse every bridge) were created and yielded the bridges response to varying numbers of axles and varying axle distances. Secondly, a Theoretical Method was programmed to create a reference for slab bridges. Lastly, a further evaluation of the methods was performed through varying input data and creating adjusted models in TungTransport and the Theoretical Method. It was found that the difference between the two Swedish methods was significant, ranging from Brokontrollen permitting loads 33 % lower to 50 % higher than TungTransport. Brokontrollen tends to be more conservative for tensioned structures. In addition, Brokontrollen varies less than TungTransport for changes regarding length and width. Furthermore, it was found that certain models in TungTransport, results were inconsistent; statements about Brokontrollen could generally not directly be made due to it being a “black box”. Furthermore, it was found that the axle width of permit vehicles significantly impacts the results given by TungTransport and, due to Brokontrollen not allowing axle width as input data, also the difference between the two methods. More importantly, it was found that TungTransport does not account for the prescribed range of axle widths for classification vehicles, which are used to determine the capacity of a bridge, and in so doing missing out on extra capacity of the bridge.