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to the prototype according to the similarity law of gravity. This conclusion can be drawn based on water fall model tests under different scales (Fig. 1), and analysis of the prototype observation data from the Ertan hydropower station, Yalong river, China [10] (Fig. 2). -10 0 10 20 30 40 50 60 70 0.0 1.5 3.0 4.5 6.0 7.5 X=L/h Fr=6.30 The scale is 1:1 The scale is 1:2 The scale is 1:5 0 1 2 3 4 5 6 7 8 0 1 2 3 4 Prototype observation data Frequency (Hz) Experimental data Fig. 1 Strength coefficient distribution of water fall fluctuating pressure Fig. 2 Comparison between the prototype and model data of the fluctuating pressure frequency of the plunge pool in Ertan hydropower station (convert to prototype by gravity law) The structural dynamic similarity, including geometric similarity, movement similarity and boundary similarity, refers to the similarity of the dynamic response of the structural system. This similarity is related to the frequency, vibration mode and damping of the structure. According to the principle that the hydraulic similarity conditions is compatible with the structural dynamic similarity conditions, the hydroelastic model must adhere to the conditions of large density (λρ = 1), a low elasticity modulus (λE=λL), an equal damping ratio (λξ = 1), and an equal Poisson’s ratio (λν = 1) [11]. 3. RESEARCH BACKGROUND The high concrete gravity dam at Jinsha River, China, was selected to be the study dam for our investigation. This dam has a crest elevation of 384.00 m and a crest length of 909.26 m; the maximum height of the dam is 162.00 m. The dam body consists of 12 surface holes and 10 mid-level outlets which are alternatively arranged and divided into two symmetrical energy dissipation zones by the middle guide wall. This arrangement form is a typical layout for a high dam with energy dissipation via a hydraulic jump. The minimum and maximum distance between the hydropower station and the nearest urban area downstream is 0.5 km and 2.5 km, respectively. According 724