Experimental Study On Mechanical Properties Of Stainless Steel Reinforced Concrete Columns

The stainless steel has high strength and corrosion resistance,the application of stainless steel plays an important role in improving the durability of the whole concrete structure,studying the mechanical properties of stainless steel reinforced concrete members has important guiding significance for the design and calculation of stainless steel reinforced concrete structures.In this paper,the uniaxial eccentric compression test of 2304 stainless steel reinforced concrete short columns was carried out,the failure mechanism of stainless steel reinforced concrete eccentric compression columns was analyzed,the influence of eccentricity and reinforcement ratio on the mechanical properties of stainless steel reinforced concrete columns under eccentric compression is studied,the applicability of the constitutive model of stainless steel and the calculation method of average crack spacing and maximum crack width were discussed.The main achievements of this paper are as follows:（1）The comparison on the mechanical behavior of stainless steel reinforced concrete eccentrically pressed columns and ordinary reinforced concrete eccentrically pressed columns has been studied.The results show that the failure mode and crack development form of the stainless steel reinforced concrete eccentrically pressed column are basically consistent with the ordinary reinforced concrete eccentrically pressed column;the stainless steel reinforced concrete eccentrically pressed column has obvious deflection growth before the failure compared with the ordinary reinforced concrete column;for the calculation of stainless steel reinforced concrete eccentrically pressed column bearing capacity,the flat section assumption is still applicable.（2）The variation of lateral deflection and longitudinal reinforcement strain of stainless steel reinforced concrete eccentric compression columns with eccentric load is studied.The results show that the lateral deflection curve shape,load^span deflection curve and load^restrain strain curve of the stainless steel reinforced concrete eccentric compression column are consistent with the ordinary carbon reinforced concrete eccentric compression column,but under the same eccentric load,the lateral deflection and steel strain of the stainless steel reinforced concrete eccentric compression columns are significantly larger than those of ordinary reinforced concrete eccentric compression columns.（3）The effect of loading eccentricity on the mechanical properties of stainless steel reinforced concrete eccentric compression columns was studied.The results show that under the condition of small eccentric compression,the development of the load^strain curve of the compressed and tensioned steel bars is basically consistent with the load^strain curve of the tensioned and compressed steel bars of the large eccentric compression specimens.（4）The effect of longitudinal reinforcement ratio on the mechanical properties of stainless steel reinforced concrete eccentric compression columns has been studied.The results show that the longitudinal reinforcement ratio has no significant effect on the lateral deflection,crack development and steel strain of stainless steel reinforced concrete small eccentric compression columns.（5）According to the test results,the applicability of the stainless steel constitutive model has been discussed.The results show that the double-slash constitutive model has good applicability in the calculation of 2304 stainless steel reinforced concrete eccentric compression specimens,and has a certain safety reserve.（6）Based on the current"Code for Design of Concrete Structures",the average crack spacing and maximum crack width of stainless steel reinforced concrete eccentric compression columns are calculated and analyzed.The results show that the average crack spacing calculation formula in this code can be applied to the stainless steel reinforced concrete eccentric compression specimens;and it is recommended to multiply the member’s force characteristic coefficient α_cr in the maximum crack width calculation formula by the expansion factor of 1.3(that is,take α_cr=2.7).