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Around the world, many countries experience an increase in the demand for freight to be transported by road. One solution is to introduce larger heavy vehicles, which have the capability of transporting more freight. These vehicles have more trailers, more axles and are longer and heavier than existing heavy vehicle traffic. All these factors have an important influence on the dynamic amplification between the vehicle and bridge. This contribution presents the findings of the dynamic behaviour of long, multi-trailer vehicles, specifically the B-Double vehicles when crossing short to medium span bridges. The dynamic behaviour of these larger vehicles is compared to the well-known single articulated vehicles which are currently operating in many countries around the world. The effect of axle groups and their spacing on dynamic amplification is explored in depth to support the finding that the time of entry of axle groups on an excited bridge is key to the explanation of dynamic response. The relationship between midspan accelerations and dynamic amplification is introduced and explored extensively for further validation of the presented findings. There is an indication, that the commonly accepted inverse relationship between the high static load and observed low dynamic amplification is not generally true. Number of axles, along with inter-axle spacing matching with the natural frequency of the bridge are of substantial relevance to the dynamic response, yielding in some cases higher dynamic amplification of high static loads. |
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