Prediction Equations for the Fundamental Period and Mode Shape of Roller Compacted Concrete Gravity Dams considering Three Dimensional Geometry Effects

ABSTARCT

Dams are important structures both for energy production and irrigation. The design and assessment of dams require special attention due to their vital functions and also the severity of the consequences in the event of collapse. The prediction of the target fundamental period range is necessary to develop site specific response spectra. In this study, a new fundamental period prediction equation is proposed for roller compacted concrete gravity dams on the basis of over 19,000 3D finite element analyses. The parameters for 3D models included the upstream and downstream slopes of the dam body, the modulus of elasticity of the dam and foundation, the height of the dam, the length of the valley and the length of the sloped portions of the valley geometry. Numerical models corresponding to all possible combinations of these parameters were generated and the modal properties of the system were determined. Next, a nonlinear regression analysis was conducted to determine a period prediction equation. The proposed prediction equation had a coefficient of determination value of 0.93. Finally, equations to determine the first mode shape for the deepest sections of the dams constructed on trapezoidal, rectangular and triangular valleys were developed for use in the preliminary design and/or assessment stages.

KEYWORDS:

• Period Prediction
• 3d Valley
• Nonlinear Regression
• Mode Shape
• Gravity Dams

Acknowledgement

This study was supported by Scientific Research Coordination Unit of Hacettepe University under the grant number FBB-2017-16271.