Seismic Fragility Analysis of the Reinforced Concrete Continuous Bridge Piers Based on Machine Learning and Symbolic Regression Fusion Algorithms

Table 8

The comparison of fitness evaluation index of single IM and various multivariate IMs.

Direction	IMs	Goodness of fit	Correlation coefficient	MSE	MAE	Fitting complexity	Number of parameters
Transverse	Machine learning and symbolic regression fusion algorithms	0.984	0.993	0.100	0.234	30	5
	Single	0.701	0.837	1.880	1.070	2	2
	Kiani	0.711	0.843	1.816	1.156	5	5
	Lv Dagang	0.564	0.751	2.736	1.200	3	3
	Liu Tingting	0.715	0.846	1.790	1.071	7	7
Longitudinal	Machine learning and symbolic regression fusion algorithms	0.997	0.998	0.012	0.084	30	5
	Single	0.796	0.892	0.755	0.731	2	2
	Kiani	0.763	0.874	0.875	0.788	5	5
	Lv Dagang	0.624	0.791	1.387	0.891	3	3
	Liu Tingting	0.793	0.891	0.765	0.697	7	7

MSE is the mean square error; MAE is the mean absolute error.