| Partial encased concrete(PEC)columns make full use of the advantages of concrete and steel,is a new combined structure,having a higher load bearing and a better ductile,especially the outside steel as nature formwork powerfully support the structure.However,the fire resistance of steel is rather poor.Under fire,the performance of the exposed steel flange is drastically reduced.Its own buckling deformation will squeeze internal concrete,increasing the stress of the column,reducing the strength and stiffness of the entire structure.However,there are few research on local buckling of PEC columns in high temperature.So,it is necessary to do some research about the buckling of the steel flange in high temperature.Specific content as follows:(1)By comparing the research results at home and abroad to determine the thermal parameters of steel and concrete with PEC columns in high temperature.By using the software ABAQUS,a sequentially coupled thermal-mechanical analysis model was established.(2)The model was validated by the data of PEC column fire resistance test and local stability test of H-shaped steel short column under high temperature,in order to prove the model’s accuracy.(3)The factors affecting the buckling were studied in detail.The effects of the parameters such as width-to-thickness ratio,slenderness-to-eccentricity ratio,and the strength of steel on the buckling stress and buckling deformation were analyzed.(4)The flange’s buckling performance of H-shaped steel column without concrete was analyzed and compared with PEC column to obtain the effect of out-of-plane confinement on the buckling performance of steel flange due to the existence of concrete was analyzed.(5)The critical temperature of the buckling of the PEC column and the fire resistance of the column were analyzed at the established stress ratio.On the basis of this,the reason of the difference of the critical temperature and the fire resistance at different stress ratios was discussed. |
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