基于SSA-XGBoost的FRP筋与多种类混凝土粘结强度预测模型研究

STUDY ON PREDICTION MODEL FOR BOND STRENGTH BETWEEN FRP BARS AND MULTIPLE TYPES OF CONCRETE BASED ON SSA-XGBOOST

  • 摘要: 纤维增强复合材料(FRP)筋与混凝土间的粘结性能是影响FRP筋混凝土结构力学性能的关键因素,现阶段尚未建立一种高效准确的FRP筋与多种类混凝土粘结强度预测模型,该文提出了一种结合麻雀搜寻算法(SSA)与极限梯度提升(XGBoost)算法的FRP筋与多种类混凝土粘结强度预测模型。利用现有文献中的试验数据,建立了含348组FRP筋与多种类混凝土粘结强度数据库;将数据库按照4∶1的比例随机划分训练集与测试集,利用SSA-XGBoost算法对FRP筋与多种类混凝土的粘结强度进行预测,与随机森林(RF)、支持向量回归(SVR)、极限梯度提升(XGBoost)等常用的预测算法进行横向对比,验证该文算法模型预测结果的可靠性和准确性;利用SHAP对SSA-XGBoost模型进行可解释性分析,揭示各输入参数对模型预测结果的具体贡献程度。结果表明:相比于SVR、RF和XGBoost这三种机器学习预测模型,训练集上SSA-XGBoost模型的决定系数(R2)分别提高了1.82%、2.53%和1.31%;均方根误差(RMSE)分别降低了58.09%、44.73%和31.02%;平均绝对误差(MAE)分别降低了48.02%、52.07%和38.75%;对称平均绝对百分比误差(SMAPE)分别降低了48.30%、56.64%和47.13%。SSA-XGBoost模型在FRP筋与普通混凝土、地聚物混凝土、珊瑚混凝土、超高性能混凝土(UHPC)粘结强度预测的R2分别达到了0.980、0.985、0.956、0.981,其预测精度高。SSA-XGBoost模型中,混凝土抗压强度的SHAP值为3.79,是对粘结强度贡献最大的参数,而拔出速度的SHAP值为0.32,是贡献最小的参数。该文的SSA-XGBoost模型高效且准确预测了FRP筋与多种类混凝土的粘结强度并通过SHAP对预测模型进行了可解释分析,研究成果可为实际工程中FRP筋混凝土粘结强度设计提供参考。

     

    Abstract: The bond performance between Fiber Reinforced Plastics (FRP) bars and concrete is a key factor affecting the mechanical properties of FRP reinforced concrete structures. Currently, there is no efficient and accurate prediction model for the bond strength between FRP bars and multiple types of concrete. Based on this, this study proposes a prediction model for the bond strength between FRP bars and multiple types of concrete that combines Sparrow Search Algorithm (SSA) and Extreme Gradient Boosting (XGBoost) algorithm. A database of bond strength between 348 sets of FRP bars and various types of concrete is established using experimental data from existing literatures. The database is randomly divided into training and testing sets in a 4∶1 ratio, and the SSA-XGBoost algorithm is used to predict the bond strength between FRP reinforcement and various types of concrete. Horizontal comparisons are made with commonly used prediction algorithms such as Random Forest (RF), Support Vector Regression (SVR), and Extreme Gradient Boosting (XGBoost) to verify the reliability and accuracy of prediction results of the algorithm model. SHAP was used to conduct interpretability analysis on the SSA-XGBoost model, revealing the specific contribution of each input parameter to prediction results of the model. The results showed that compared to the three machine learning prediction models SVR, RF, and XGBoost, the SSA XGBoost model has a 1.82%, 2.53%, and 1.31% increase in coefficient of determination (R2) on the training set, respectively. The root mean square error (RMSE) has decreased by 58.09%, 44.73%, and 31.02%, respectively. The mean absolute error (MAE) has decreased by 48.02%, 52.07%, and 38.75%, respectively. The symmetric mean has absolute percentage error (SMAPE) decreased by 48.30%, 56.64%, and 47.13%, respectively. The R2 of the SSA-XGBoost model in predicting the bond strength between FRP bars and ordinary concrete, geopolymer concrete, coral concrete, and ultra-high performance concrete (UHPC) reached 0.980, 0.985, 0.956, and 0.981 respectively, indicating high prediction accuracy. In the SSA XGBoost model, the SHAP value of concrete compressive strength is 3.79. It is the parameter that contributes the most to bond strength. While the SHAP value of pull-out speed is 0.32. It is the parameter that contributes the least to bond strength. The SSA-XGBoost model efficiently and accurately predicts the bond strength between FRP bars and multiple types of concrete. And it provides interpretable analysis of the prediction model through SHAP. The research results can provide a reference for the design of bond strength between FRP bars and concrete in practical engineering.

     

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