Abstract: This paper investigates the applicability and prediction accuracy of three calculation models (Lim's model, Wei's model and Jiang's model) for ultimate stress and strain based on test database of FRP-confined seawater sea-sand concrete (SSC) cylinders. The analysis results show that the accuracy of the calculation model for predicting ultimate stress is generally higher than that of predicting ultimate strain. Among the three models for predicting ultimate stress, Lim's model and Jiang's model show similar high accuracy, with the average absolute error AAE equal to 10.7% and 11.0%, and the average mean of the ratio of the predicted value to the experimental value Mean equal to 104.3% and 105.8%. Compared with the experimental value, the predicted value of the Wei's model for ultimate stress is overall lower (Mean=81.0%), and the error is relatively large (AAE=19.6%). Among these three models, it is recommended to use Lim's model to predict the ultimate stress of FRP-confined SSC. At the same time, Jiang's model is also recommended because of similar prediction accuracy, easier computation with fewer formulas compared with Lim's model. Among the three calculation models for predicting the ultimate strain, Lim's model has the highest accuracy (AAE=27.8%, Mean=99.4%)while Wei's model and Jiang's model underestimate the ultimate strain of FRP-confined SSC, with Mean up to 74.5% and 52.2%, respectively. It is recommended to use Lim's model to predict the ultimate strain of FRP-confined SSC. To sum up, Lim's model is the best model among three calculation models for predicting the ultimate state of FRP-confined SSC since best accuracy has been achieved by Lim's model in both ultimate stress prediction and ultimate strain prediction.

Key words: FRP confinement, seawater sea-sand concrete, ultimate stress, ultimate strain, prediction accuracy