## 1 Introduction  
Reinforced concrete (RC) columns are fundamental structural components that are widely used in civil infrastructures such as buildings and bridges. In seismic-prone regions, the seismic performance of such structural components significantly affects structural safety in seismic events. However, due to the nonlinearity of structural materials and the uncertainty of earthquake excitations, there are still some difficulties exists for researchers and engineers in some fields, e.g., the rapid seismic evaluation of a regional transport network, including a number of bridges [1]. Therefore, it is still necessary to develop a rapid and reliable model for the main components of structures, e.g., RC columns and piers. Researchers and engineers in seismic engineering have conducted many laboratory experiments, including pseudo-static and shaking table tests, to investigate the mechanical properties of RC columns. Based on them, several explicit formulas have also been established, founded upon a theoretical analysis and regression analysis of experimental data [2; 3] for structural design in seismic engineering. [PERSON] et al. [4] examined existing design equations related to shear strength, and observed significant differences in the predicted results. [PERSON] and [PERSON] [5] and [PERSON] and [PERSON] [6] also found significant inaccuracies in the predicted deformation capacity of RC columns obtained from existing methods. The reason for the differences is that RC material exhibits strong uncertainties and nonlinearity. Moreover, under the combination of constant vertical and lateral dynamic loads, the seismic performance of RC columns is affected by many other properties of structural components, such as the shear span ratio [7], longitudinal and transverse reinforcement ratio [8; 9] and the axial compression ratio [10]. Besides, finite element analysis (FEA) is an alternative and useful tool that can be used to analyze the nonlinear mechanical properties of the RC structure [11; 12]. For RC columns, the lumped plasticity (LP) hinge method and distributed plasticity (DP) hinge method are typical methods to model the nonlinear characteristics of the structures [13; 14]. However, the LP method is relatively coarse, while the DP method is often time-consuming, and the results significantly depend upon the setup of the model parameters and boundary conditions [15]. This may lead to large estimation errors during the seismic performance prediction of RC structures. [PERSON] et al. [16] organized an open competition to predict the hysteretic response of a 3-storey frame, which was initially tested in the laboratory. Although detailed information of the structural configuration and material properties was provided to the competitors, most of the FEA results of 30 research groups were far from the test results, no matter what types of FEA model they used. This may result from the complicated damage mechanism of the material and the unclear boundaries and connections in the real RC structures. To overcome these drawbacks, [PERSON] et al. [17] developed a relatively simple LP model including the effective stiffness, pre and post-peak inelastic deformations, etc. It has been demonstrated that this model can simulate the seismic performance of RC structures with proper model parameters [18; 19]. In practice, the accurate analysis is not only dependent upon the tools used, but also the experience of the analysts (mainly from the disaster lessons or the laboratory test results). The experience, which is generally related to the model parameter determination, may vary greatly among different groups. Therefore, essential model parameters considering the historical experience are needed for the accurate simulation of RC columns. In this study, a model-free and data-driven method is deduced for the determination of the key parameters of the commonly-used LP model. It is expected that more test results can overcome subjective errors and model uncertainties, improving the LP model.