Fire Performance And Design Method Of Partial Encaed Concrete (PEC) Columns

Partial encaed concrete (PEC) columns is a new type of composite members consisting of welded H-shaped steel section and concrete casted between the flanges.It has distinct economic and structural advantages,such as high load bearing capacity,excellent earthquake resistance qualities.Due to the fact that steel flanges are exposed in the air ,the columns are buckling easily under fire. Leading to concrete crushing and the column strength reducing sharply. Researching on the fire resistant behavior of PEC columns is valuable for practical engineering.The main contents are as following:Based on analysis and comparison of current achievements on material behavior under high temperature, thermal properties and model of stress-strain relations for steel and concrete under high temperature were determined.A general finite element analyzing software (ABAQUS) was utilized to establish the 3D model of PEC columns. The model was used to calculate the mechanical performances of PEC columns exposed to standard ISO-834 fire from four sides. The calculated deformation curves and fire resistance of PEC columns were validated by the test results.Based on the validated model,influences of related parameters,such as sectional dimensions,load ratio,slenderness ratio,steel ratio,load eccentricity ratio,strength of steel,strength of concrete and spacing of bars on fire resistance were ananlyzed. Conclusions are as follows:the main influencing parameters are sectional dimensions,load ratio,slenderness ratio;steel ratio,load eccentricity ratio,strength of steel,strength of concrete and spacing of bars are minor factors.Based on the parametric analysis,the simplified formulas for the calculation of the fire resistance was put forward. The calculating results are in good agreement with that of numerical method.The achievements in this paper may be a reference for the fire design of PEC Columns.