中空夹层钢管混凝土叠合短柱长期变形计算方法

In order to provide references for the design and engineering application of the concrete-encased concrete-filled double-skin steel tube (CECFDST) stub column, the long-term performance of the composite column was studied. Based on the moisture distribution model of concrete, the non-uniform shrinkage and creep prediction models suitable for outer concrete were derived. A theoretical analysis method for long-term deformation was proposed using the step-by-step integration method. On the basis of the anastomosis between theoretical calculation and experimental results,the influences of the concrete-filled double-skin steel tube ratio,hollow ratio, reinforcement ratio, and steel content of the CECFDST stub columns on long-term deformation were analyzed. The accuracy of the age-adjusted effective modulus method was calibrated with the step-by-step integration method in the long-term analysis of the CECFDST stub columns. The concrete-filled double-skin steel tube ratio and the steel content of outer steel tube are the main factors affecting the long-term deformation of the CECFDST stub columns. When the concrete-filled double-skin steel tube ratio increases from 0. 5 to 0. 7,the aging deformation after 10 years of loading decreases by 21%. The calculation deviation of the age-adjusted effective modulus method gradually increases with the decrease of the concrete-filled double-skin steel tube ratio. The modified effective modulus of outer concrete can significantly improve prediction accuracy of simplified calculation methods.