Determination of dynamic amplification factors for small- and medium-span highway bridges considering the effect of automated truck platooning loads

Abstract

Automated truck platooning (ATP) has a good potential in energy conservation and carbon emissions reduction, yet it has raised a wide concern to the safety and performance of highway bridges. Accurately estimating ATP-induced load effects on highway bridges is necessary since it plays a crucial role in both bridge safety evaluation and traffic/ATP decision-making. Conventionally, the dynamic load effects induced by ATP on highway bridges are simplified by multiplying the static load effects with the code-specified dynamic amplification factor (DAF) which has not taken the ATP into consideration. This approach may need improvements as the actual DAFs of a bridge can be significantly affected by ATP loads. In this study, the DAFs of highway bridges under ATP loads are investigated via both theoretical analyses and numerical simulations. Several standard highway bridges with different cross-sections and span lengths and probable ATP loading scenarios are considered, and the influences of multiple factors are investigated, including the truck mass, the number of platooned trucks, and the road surface condition. Both theoretical and simulation results show that highway bridges are at risk of two types of resonance due to ATP loads. The resonance types can be roughly identified by the span length of the bridge. Specifically, bridges with span lengths shorter than 15 m are mainly affected by steady resonance while bridges with longer span lengths are at high risk of transient resonance. Both types of resonance can lead to increased DAFs of highway bridges, which may exceed the DAFs specified in bridge design codes. To accommodate ATP loads, proper DAFs are proposed as a supplement to the current bridge design codes.