Seismic vulnerability assessment of concrete dam based on incremental dynamic analysis and multilayer perceptron
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Abstract:
The western region of China is rich in hydropower resources, but strong earthquakes occur frequently. Hydraulic structures may withstand strong earthquakes during their life cycle. The damage caused by earthquakes will affect the normal operation of water conservancy projects, which seriously threatens people's lives and social stability. The seismic vulnerability analysis provides the seismic basis for seismic design of hydraulic structure and earthquake prevention and disaster reduction, which is very important to ensure the expected performance of concrete gravity dam and safe operation under earthquake.The seismic vulnerability assessment of dams often requires the use of nonlinear numerical simulation methods and a huge amount of calculation work. Considering the efficiency and accuracy of seismic vulnerability assessment of dams, a way based on incremental dynamic analysis and multilayer perceptron for seismic vulnerability assessment of concrete dams is proposed. Taking a concrete gravity dam in northwest China as an example, a three-dimensional finite element model of dam body-reservoir water-foundation is established and multiple seismic response calculations are carried out. The selected ground motion records are processed by equal step amplitude modulation, and the amplitude input is carried out by three-way seismic. The peak ground acceleration is selected as the index of ground motion intensity, and the displacement of dam top along river is selected as the index of dam damage. The multilayer perceptron model was trained and tested by extracting the vibration characteristic parameters as input and the displacement of dam top along river as output. The ground motion is extended to obtain the vibration characteristic parameters. The MLP model is used to quickly predict the displacement of the dam top along the river, and the finite element results are extended. The vulnerability analysis of the concrete dam is carried out, and the vulnerability curve is drawn.The results are as follows:(1)The seismic vulnerability of concrete gravity dam is analyzed based on incremental dynamic analysis method. Incremental dynamic analysis's curve clusters of river-side displacement, transverse river flow displacement and vertical displacement of the dam crest are plotted, and seismic vulnerability curves are plotted. In summary, the earthquake damage grade of the selected gravity dam under the designed ground motion is low, and about 80% probability belongs to the basically intact state.(2)The multi-layer perceptron model is introduced into the incremental dynamic analysis method, and the seismic vulnerability analysis method of concrete gravity dam based on incremental dynamic analysis-multi-layer perceptron is proposed. After the training of the multi-layer perceptron model, the accuracy of the damage prediction index is higher. The coefficient of determination is 0.960 2, the mean square error is 0.005 6, and the mean absolute error is 0.056 1. Based on this method, more analytical data can be constructed to expand the finite element dynamic calculation results. It saves the calculation work up to 75% and reduces the nonlinear dynamic calculation time. The seismic vulnerability of dams can be predicted quickly and accurately as close as possible to the reality, and the vulnerability curve can be drawn to improve the efficiency of seismic vulnerability analysis of dams.
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