预应力混凝土梁长期预应力损失的试验测试和分析OA

Based on the concrete shrinkage and creep performance database from Northwestern University In-frastructure Technology Institute(NU-ITI),explicit expressions for concrete shrinkage and creep functions were established using genetic programming(GP)method.The simulation of concrete shrinkage and creep was implemented using Abaqus secondary development capabilities.The numerical model was calibrated based on existing long-term prestress loss experiments of prestressed concrete beams.The research results indi-cate that the GL2000 model calculation method provides the highest accuracy in shrinkage predictions.Both specifications JTG 3362-2018 and CEB-FIP Model Code 1990 underestimate shrinkage and creep compared with measured values.Direct application of specifications JTG 3362-2018 for shrinkage and creep calcula-tions lead to underestimation of prestress losses.If the shrinkage model directly modifies the ratio correction of predicted value and measured value using JTG 3362-2018,considering 95%upper and lower limits,the cor-rection ratio range is[1.195,3.048].If the creep model directly modifies the ratio correction using JTG 3362-2018,considering 95%upper and lower limits,the correction ratio range is[0.369,2.701].After apply-ing the GP-based modified JTG 3362-2018 model,the predicted values for three test samples closely match the measured values.