Abstract: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.