Investigation on the Behaviour of Floodway Structures Under Extreme Flood Loading

Investigation on the Behaviour of Floodway Structures Under Extreme Flood Loading

Floodways are infrastructure used in road design to enable safe vehicular passage across waterways susceptible to flooding at relatively low average recurrence intervals. During the significant flood events of the past decade, repeat structural damage and consistent failure mechanisms have been observed, compromising the reliability of the rural road network and thus the resilience of communities. These failures are a result of the flood loadings encountered during extreme flood events, which are not currently considered in floodway design guidelines that typically rely upon hydraulic design principles.

The primary objective of this research was to evaluate the principal structural failure mechanisms of concrete floodways. To achieve this, an industry based survey and an experimental program were conducted, and a scaled finite element model created to compare findings. This enables the typical failure mechanisms for floodways to be determined. A numerical finite element model of a full scale standard engineering floodway type was then developed and parameters applied to simulate extreme flood conditions. Modelling was then expanded to cover five standard engineering floodway types enabling a refined structural design methodology to be deduced. The finite element models were then used to determine the worst case loading scenario, and to develop a floodway design guideline with an incorporated structural design methodology.

Limited research into the structural adequacy of concrete floodways had been undertaken; the key discovery of this research was the vulnerability of concrete floodway structures to impact loading during extreme flood events. The key research outcome was the conclusive design guideline which collated the research and subsequent investigations and provided a practical end-user outcome. Through the implementation of this design guideline more resilient floodway structures will result, thus improving the reliability of the rural road network as well as community resilience and safety.

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