Research On Axial Compression Performance Of Seawater Mixing Coral Aggregate Concrete Under Stirrup Constraint

With the proposal of China’s maritime power strategy and the acceleration of the construction of islands and reefs in the South China Sea,it is necessary to study a kind of building material with local materials,convenient construction and better economy.The experiment,theoretical research and application of coral aggregate concrete need to be improved constantly.Based on experiments and theoretical analysis,this paper studies the axial compression performance of Marine coral-mixed aggregate concrete under different constraint conditions.The main research contents are as follows:First of all,the axial compression test was carried out on 45 specimens with the size of 150 mm × 150 mm × 450 mm with the strength grade of concrete,different forms of stirrups and different spacing of stirrups as the change parameters.The test results showed that the failure form of coral aggregate concrete was different from that of natural aggregate concrete,and the failure interface ran through coral coarse aggregate.With the increase of strength grade,the brittleness of coral aggregate concrete increases,and the failure form changes from "H" type to "X" type to penetrating oblique crack.Stirrup constraints can effectively improve the axial compression performance of coral aggregate concrete and increase the peak stress and strain of coral aggregate concrete in the core area.Different stirrup forms have different constraint effects on concrete in the core area,rectangular stirrup is the worst,rhombus composite stirrup and spiral stirrup have better constraint effects.Secondly,in the stirrup restraint coral aggregate concrete,on the basis of the stress-strain curve of reinforcement is developed,with the consideration of the form,stirrup spacing and coral stirrup restraint coral aggregate concrete strength grade of concrete damage constitutive model for stress-strain curve,the curve considering the damage in the process of loading,also taking into account the form of reinforcement and stirrup spacing and the coupling relationship between concrete strength grade,can better predict stirrup restraint coral aggregate concrete stress-strain curve;At the same time,the damage curve with strain development is given: with the decrease of stirrup spacing,the damage development is relatively slow;The damage control of diamond and spiral clamps is better than that of rectangular clamps.Finally,coral in 36 stirrup constraints on the basis of concrete axial compression test,according to the existing concrete octahedral strength theory,established the coral aggregate concrete in stirrup strength theory and under the restriction of verification,the results show that the proposed stirrup coral aggregate concrete strength theory under the restriction of calculated values and measured values coincide degree is higher;On the basis of strength theory combined with reinforced concrete design specification proposed coral aggregate concrete column bearing capacity calculation formula,and with the Chinese standard,American standard,European standard comparison,found that,the bearing capacity calculation formula in this paper,considering the form of reinforcement and stirrup spacing,calculated value more consistent and it is safe to be more scientific and the measured values can be used as a constraint coral aggregate concrete column stirrup bearing capacity calculation.