冻融循环作用后圆钢管混凝土界面粘结性能试验研究

为研究冻融循环作用后圆钢管混凝土界面粘结滑移性能，以冻融循环次数、钢管壁厚、混凝土强度为变量，设计21个试件进行推出试验，分析冻融损伤后圆钢管混凝土柱粘结强度、荷载—滑移及钢管应变的变化规律。结果表明：经冻融循环作用后圆钢管混凝土柱的荷载—滑移曲线与未经冻融试件趋势相似，均可分为上升段、下降段、残余段；受冻融循环作用影响的圆钢管混凝土柱界面粘结性能下降，粘结强度与冻融循环次数成反比，界面滑移量总体呈上升趋势；增大套箍系数可增大试件界面粘结强度，提高圆钢管混凝土柱抗冻性能。根据试验结果，提出考虑冻融循环次数和套箍系数的圆钢管混凝土柱粘结强度计算表达式，计算结果与试验结果吻合良好。

Experimental study on interfacial bonding properties of circular steel tube concrete columns after freeze-thaw cycles

In order to study the bond slip behavior of round steel tube concrete column after freeze-thaw cycle, a total of 21 specimens were designed to carry out the push test, taking the number of freeze-thaw cycles, steel tube wall thickness and strength of concrete as variables. The variation laws of bond strength, load-slip and strain of round steel tube concrete column under freeze-thaw damage were analyzed. The test results show that the load-slip curves of the circular steel tube concrete columns subjected to freeze-thaw cycles are similar to those of the specimens without freeze-thaw cycles, which can be divided into ascending section, descending section and residual section. Under the influence of freeze-thaw cycles, the interfacial bond performance of concrete column with round steel tube decreases, the bond strength is inversely proportional to the number of freeze-thaw cycles, and the interfacial slip generally increases. The increase of the hoop coefficient can increase the interfacial bond strength and improve the frost resistance of the concrete column of round steel tube. According to the test results, a formula for calculating the bond strength of concrete column with round steel tube considering the number of freeze-thaw cycles and the hoop coefficient is proposed, and the calculated results are in good agreement with the test results.