Study On Characteristic Of Bearing Capacity About Circular Concrete With Double Ordinary Stirrups

After fully consideration of the economic factors and architectural space, in order to further enhance the bearing capacity and ductility of pillars, this paper designs 16 circular pillars of double ordinary stirrup confined concrete, including 7 columns with steel fiber 2%..Making axial compression experiment with the samples and obtain the result of the test.The experiment results showed that the higher Characteristic value of double ordinary stirrup circular column hoop inside and outside is, relatively the higher of the peak load is,meantime, the bottom half of the load-displacement curve slow down. Before and after the peak load, the deformation of double stirrup concrete circular column measured by section strain gauge coincide with the macroscopic deformation of the column. The same strength grade and reinforcement characteristic value of the double stirrup steel fiber circular concrete specimens test strength than ordinary confined concrete circular specimens increased13.2%~27.8%. What's more, the ductility is much better than that without steel fiber. The average effective stress concept is put forward, which is the bridge between single stirrups constrained and double stirrup constrained, and also provides a new way to study double stirrup effect. According to the test data of the double layer common circular column without steel fiber, the stress-strain curve formula of Popovics is modified. The model has better precision and higher safety factor, which can be used as reference for the practical engineering.