| At present,the diversification of building structure and the development of intelligent construction assembly are the general trend.In this paper,a double C light steel partially wrapped fiber self-compacting lightweight aggregate concrete（DCPSLC）structure system is proposed by pouring fiber reinforced self-compacting lightweight aggregate（FRSCLC）,inside the cold-formed thin-walled steel frame.The structural system not only has the structural characteristics of concrete-filled steel tube,but also can give full play to the characteristics of lightweight materials,and the cross-sectional characteristics of structural members are also conducive to the connection between members and prefabricated assembly production.In this paper,the axial compression mechanical properties of DCPSLC columns are studied.The main contents are as follows:In this paper,11 DCPSLC short columns and 4 DCPSLC medium-long columns are designed and made.the experimental design parameters are section steel thickness（2mm,3mm,4mm）,concrete strength grade（LC45,LC55,LC65）,plate spacing（100mm,150 mm,200mm）and slenderness ratio（20,30,40,50,60）.The effects of different design parameters on the mechanical properties of DCPSLC columns are investigated.The finite element models of five DCPSLC short columns are established,and the formula for calculating the axial compressive bearing capacity of DCPSLC columns is established by combining the test results with the numerical simulation results.The main results are as follows: local crushing of concrete,local buckling of section steel flange and separation of web joint occur in DCPSLC columns during failure.With the increase of slenderness ratio,the specimen will develop from strength failure to local instability failure.The cooperative working ability of section steel skeleton and internal concrete mainly depends on the thickness of section steel.The transverse restraint effect of flange on concrete will increase with the increase of section steel thickness,but the growth rate will decrease with the increase of concrete strength grade.Changing the spacing between panels will not significantly affect the transverse restraint of concrete.According to the numerical simulation analysis,the stress value of concrete in the middle of the section steel web and the corner of the flange is larger,and the stress value of concrete will gradually decrease from the middle of the section steel to all around with the change of the restraint action of the section steel.Based on the experimental and numerical simulation results,the strength improvement coefficients of the model based on Mader constraint and the model of dividing different constraint regions are calculated respectively,in which the former is higher than the latter because of overestimating the influence of the change of plate spacing on the constraint effect.Finally,the formula of axial compression bearing capacity is established,and the effects of local buckling of section steel flange,overall failure of web and concrete strength improvement coefficient on bearing capacity are considered.the calculated values of the formula are in good agreement with the experimental values.however,the increase of slenderness ratio will lead to the increase of second-order effect,and the bearing capacity decreases by 10.1%,15.5%,17.3% and 33.3% compared with the same period last year,so the relationship between stability coefficient and slenderness ratio is established.It is found that the stability coefficient can be effectively applied to the bearing capacity formula. |
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