## 1 Introduction
[PERSON] [11] studied the seismic behavior of the frame-type underground subway station structure in loess ground. The time-history of the seismic wave was compressed according to the similarity relationship of the experimental model. In the studies mentioned above, the duration compression ratios of input motions were all determined by the time similarity ratio of a model structure in shaking table tests. In some other studies, the duration compression ratios of input motions were determined by a time similarity ratio of model soil in shaking table tests. Taking CAP1400 nuclear power plant structure as an example, [PERSON] [12] studied the suitability and seismic response characteristics of the nuclear power plants on a non-rock site, and the time similarity of input motions was adopted as the time similarity ratio of model soil. [PERSON] [13] performed shaking table tests to investigate the damage mechanisms of a subway structure in soft while experiencing strong ground motions, in which the time scaling factor was determined as the time similarity ratio of model soil. [PERSON] [14] performed a series of large-scale shaking table tests to investigate the damage mechanisms of a frame-type subway station structure in a loess site. The author considered that it was unprocurable to make all parameters meet the similitude law in the soil-structure shaking table test. The selection of the duration compression ratio of input motions is determined according to the purpose of the series of shaking table tests. Besides, some scholars chose uncompressed earthquake records as input motions to analyze the seismic responses of structures in a liquefaction site [15; 16]. To achieve the same similarity between a model structure and model soil in shaking table tests, experts conducted have relevant research. [PERSON] [17] carried out shaking table tests of shallow foundation structures in seasonal frozen soil regions. The influence of structural natural frequency, soil frozen depth, and seismic load on the seismic response of structure was studied. [PERSON] [18] studied the complex seismic soil-structure interaction phenomena by the shaking table test. The model soil and the small-scale model structure with their prototype satisfied the same physical and geometrical similarity. [PERSON] [19] investigated the seismic behavior of a shield tunnel with an ultra-large diameter of 15 m passing through a soft-hard stratum and proposed a modified similitude ratio design method. The time similitude ratios of the tunnel and soil models were consistent. In summary, experts and scholars have studied the seismic responses of structures considering SSI through a large number of shaking table tests, and made some achievements. However, there is no uniform principle for adopting the duration compression ratio of input motion on shaking table tests of a soil-structure system. It is the best choice to make the time similarity ratio of model structure consistent with that of model soil according to the similarity theory, but it is difficult to achieve this in shaking table tests due to the limitation of test conditions. Different principles and methods for determining the values of the duration compression ratio have been adopted by different researchers. While few people have considered different duration compression ratios in the shaking table tests, and there are also few comparative studies on the influence of duration compression ratio on the seismic responses of model structure and model soil. In view of the shortcomings of previous research, a small radius curved bridge was chosen as the research object in this paper, and a series of shaking table tests were performed considering soil-pile-structure interaction. Three commonly used approaches were separately chosen to determine the duration compression ratio of the input motions in the tests. The representative similarity ratios were 1/4, 1/2, and 1/1 in time, respectively.