Đập bê tông trọng lực thường được xây dựng trong các khối cách nhau bằng các khớp co lại theo chiều dọc. Các thiết kế của các đập trọng lực bê tông thẳng truyền thống được thực hiện bằng cách giả sử mỗi khối để được độc lập. | Appl ication SDOF mode l to seismic base s l iding ana lysis of concrete gravity dams subjected to earthquake l oad Quoc Cong Prof. Dr. Zhang LiaoJun MEng. Gong Cunyan College of Water Conservancy and Hydropower Engineering Hohai University Nanjing China 1. Introduction Concrete gravity dams are typically constructed in blocks separated by vertical contraction joints. The design of straight concrete gravity dams is traditionally performed by assuming each block to be independent. Understanding the 2-D behaviour of individual monoliths is thus considered relevant and 2-D models are usually employed in safety evaluations of existing dams. During a strong seismic event low to medium height concrete gravity dams tend to crack at the base which attract high stresses. The state-of-the-practice in the seismic evaluation of concrete gravity dams requires that the failure mode of the dam monolith sliding at its base must be considered. It is well recognized that the pseudo-static loads determined on the basis of a seismic coefficient are very small when compared to the actual forces expected in a gravity dam during a strong earthquake 1 . Therefore it is highly unlikely that the traditional safety criteria 2 for sliding stability can be satisfied if the pseudo-static lateral forces were to represent the true dynamic forces acting on a dam during a moderate to intense earthquake. However the evaluation of seismic sliding safety on the basis of static loads has little meaning in the context of the oscillatory nature of earthquake loading and the corresponding dam response. Therefore the normal criteria for evaluating static stability may not be appropriate to evaluate the seismic stability of concrete gravity dams. During an earthquake as the forces acting on the dam change with time it is desirable to assess the stability criteria at various time instants during the entire duration of the earthquake. Of particular importance is the evaluation of the critical .
