Study On Bearing Capacity Of Micro Steel Fiber Reinforced Cementitious Composites Columns With High Strength Stirrups

With the rapid development of economy and population,people demand more and more for buildings.And in modern society,the number of buildings is increasing,and the height of the building is also increasing.Therefore,the light and high strength is one of the goals of the present building.So this paper presents a new viewpoint of improving the strength,ductility and deformation of the column by two aspects:structure and material,which reflected by the micro steel fiber reinforced cement composite square columns with the high strength multiple stirrup.This paper designed a total of 18 square columns.There are several ways to compare groups,for example,according to the volume fraction of micro steel fiber,the volume can be divided into 0%,1%and 2%,respectively,accounting for 1/3;the spacing of stirrups can be divided into 100mm,70mm and 40mm,each accounting for 1/3;According to the strength grade of cement-based composite materials;,they can be divided into C30 and C40,each accounting for 1/2.According to the axial compression tests of square column specimens,this paper analyzes the influence of micro steel fiber reinforced cementitious composite columns with high strength composite stirrups on the bearing capacity and deformation properties of specimens by the spacing of high strength composite stirrups,the content of micro steel fiber and the strength grade of cement matrix composites.The axial compression test of micro steel fiber reinforced cement composite column with high strength composite stirrups shows:The micro steel fiber can effectively improve the deformation performance of cement matrix composites,and can greatly improve the damage of the protective layer;The strength,deformation and ductility of the columns can be improved effectively by reducing the spacing between high strength stirrups;When the peak load is reached,the micro steel fiber reinforced cement matrix composite material begins to destroy,the longitudinal reinforcement reaches the yield strength,and the strength of the composite stirrups can not reach the yield strength;The strength of the column with high strength grade of cement matrix composite is higher,but the ductility,deformation performance and the situation of the stirrups play are lower than that with low strength grade of the cement matrix composite;It is more convenient to observe the effect of the change of each factor on the performance of the column specimens by using the low strength grade of cement matrix composites.By analyzing the experimental data and the empirical formula,it is derived from theoretical formula as follows:bearing capacity formula of micro steel fiber reinforced cement composite column with high strength composite stirrups,strength formula of micro steel fiber cement matrix composites,the constraint force formula of high strength composite stirrups for steel fiber reinforced cement composites,the longitudinal reinforcement stress-strain formula,the stirrup stress-strain formula.