PLT44 - What do we miss when we analyze and design radial gates for spillways? – A case study of the Pyramid Dam Headworks structure.

Abstract Description: The state-of-practice for the seismic analysis of existing and new radial gates is to apply the earthquake in the stream direction. This method does not account for the vertical component of the earthquake and the flexibility of the gate. Due to the curved geometry of the radial gate, the vertical component of the earthquake could have a notable impact on its performance. Additionally, as a common practice, hydrodynamic loads are calculated using the Westergaard method and assuming an incompressible fluid material. Several studies have indicated that this method is not appropriate for seismic analysis of curved structures such as radial gates. This paper presents the effects of the vertical component of the earthquake and compressibility of water on the seismic performance of the Pyramid Dam Headworks structure, which is located in a high-seismic zone. The paper compares the pseudo-static method using the closed-form solution with dynamic time-history finite element analyses results using the Westergaard method and compressible fluid material. The paper provides an insight into what structural engineers may miss when designing new radial gates or checking existing ones. Further, the risks to the safety of dams caused by these assumptions will be discussed.