A Study of Reinforced Concrete Corner Columns

• Main Authors: Huang, Kuo-Li, 黃國立
• Other Authors: Jau, Wen-Chen
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/72768364660187065385

博士 === 國立交通大學 === 土木工程系所 === 98 === Columns are the most important members of structure. The strengths of the columns in general determine the strengths of the structure. Therefore, the study of the strengths of columns under high temperature is very important. Many studies have investigated the strength of interior (four faces fire loading) columns under high temperatures; however, there has been little research on the strength of corner (two faces fire loading) columns under high temperatures. Corner columns are usually under high biaxial eccentricity than interior columns. Furthermore, during a fire, only the interior two faces of corner columns are exposed to fire in contrast to interior columns of which all four faces are exposed. The material asymmetry of concrete after fire further complicated the behavior of the corner columns. This study investigated the behavior of corner columns under axial loading, biaxial bending and asymmetric fire loading. This study shows： (1)The corner column under the same stress ratio, the temperature distribution across the section is similar to interior columns and is not affected by concrete cover thickness, concrete strength or steel ratio. (2)The factors affecting the initiation of the cracks under high temperature on corner column in the order of importance are fire duration, concrete cover thickness, steel ratio, concrete strength and eccentricity. (3)A further examination on the residual strength rates of the corner columns after fire loading shows：(a)in the tension failure zone, the higher the eccentricity, the higher the residual strength; in the compression zone, the residual strength did not change significant, (b) the longer the fire, the less the residual strength, (c) the higher the steel ratio, the higher the residual strength, (d) the thicker the cover, the less the residual strength, and ,(e) the higher the concrete strength, the less the residual strength. (4)After the fire test, the color, crack and burst, observed from the surface are similar for both interior and corner columns. (5)After the strength test, failure surfaces are similar for both the interior and corner columns. (6)A further examination on the residual strength rates of the interior and corner columns after fire loading shows：(a) the higher the concrete strength, the less the residual strength rate, the interior and corner columns yield same trend, (b) the effect of fire duration on the residual strength rate is more prounced for interior columns, and ,(c) the effect of concrete cover is more important for exterior columns.