Seismic Damage Analysis of Aged Concrete Gravity Dams

Abstract

The design of a concrete gravity dam must provide the ability to withstand the seismic forces for which nonlinear behavior is expected. The nonlinear seismic response of the dam may be different due to aging, as the concrete gets degraded because of environmental factors and mechanical loadings. The present study investigates the evolution of tensile damages in aged concrete gravity dams, which is necessary to estimate the safety of existing dams towards future earthquake forces. The degraded material properties of the concrete with age, subjected to environmental factors and mechanical loadings, are determined introducing an isotropic degradation index. A concrete damaged plasticity model, which assumes both the compressive and tensile damage, is used to evaluate the nonlinear seismic response of the dam. Results show that the peak maximum principal stresses reduced at the neck due to aging effects in the concrete. It is observed that the neck region is the most vulnerable region to initiate damage for all cases of aged dams. The results show that there are severe damages to the structure at higher ages under seismic loadings. The proposed method can ensure the safety of dams during their entire design life considering the environmental factors and mechanical loadings affecting the materials as they age.

Keywords:

• Concrete Gravity Dam
• Concrete Degradation
• Damage Plasticity Model
• Earthquake Excitation
• Aged Dam
• Finite Element Method

Acknowledgments

The authors would like to acknowledge the Sponsored Research and Industrial Consultancy, Indian Institute of Technology Kharagpur, India, for funding the financial support for this research work.