Research On Static Behavior And Design Method Of Tubed Steel Reinforced Concrete Slender Columns

In this thesis, experimental research and finite element analysis have been carried out for the behavior of tubed SRC slender columns, including axial behavior and eccentric behavior. And the Design method to calculate the flexural strength was proposed based on the test and analysis results. The main contents are as follows:1. Six circular tubed steel reinforced concrete (SRC) slender columns (L/D=6) under axial compression and6specimens with the same parameters under eccentric compression were tested. The main variable parameters of specimens were the sizes of the cross section (D=200mm,240mm), eccentricities (e=0mm,25mm), welded shear connectors or not, tube was disconnected in the middle of column or not. The failure modes, load-carrying capacity, load-midspan lateral deflection curves, load-the stress curves of tube were summarized and analyzed. The results showed that the bearing capacity of the specimens was high and the ductility was good, whether welded shear connectors or tube was disconnected in the middle of column had no effect on the bearing capacity and the failure mode of the specimens.2. Six square tubed SRC (TSRC) slender columns (L/B=6) under axial compression and6specimens with the same parameters under eccentric compression were tested. The main variable parameters of specimens were eccentricities (e=0mm,25mm), width-thickness ratio (B/t=133,100), welded shear connectors or not, tube was disconnected in the middle of column or not. Similar to the circular SRC columns, the failure modes, load-carrying capacity, load-midspan lateral deflection curves, load-the stress curves of tube were also summarized and analyzed. The results showed that the bond between steel and concrete was in good condition whether welded shear connectors or not, the ordinary specimens were better than the specimens which tube was disconnected in the middle of column on the eccentric behavior.3. The finite element method (FEM) model for TSRC slender column was established based on the test and analysis results. The FEM results show generally good agreement with test results. Based on the FEM model, the mechanism of TSRC slender column under axial and eccentric compression, the interaction between the steel tube and concrete core were analyzed and illustrated.4. The design method of TSRC slender column was explored based on experimental research and finite element analysis results. The capacity formulas of composite column on current codes were summarized. A modified EC4method has been proposed for the calculation of the capacity TSRC slender column under axial and eccentric compression. The conception of mechanics in this simplified method is distinct and the results show generally good agreement with test results.