Concrete-filled steel tube (CFST) columns are a composite member which mainly consists of steel tube infilled with concrete that are increasingly being used as load-carrying members these days. In construction industry, CFST columns are being preferred for the development of tall buildings and long-span bridges. This paper presents an experimental investigation on concrete-filled steel tube (CFST) columns which were post heated and were subjected to axial loading. The thickness of the casing steel was 4 mm and 5 mm and diameter was 100 mm, 125 mm and 150 mm and were infilled with concrete of grade M30 which were used in the present study. This study also represents the behavior of CFST columns for two cooling regimes (annealing and quenching) after exposure to elevated temperatures of 600 °C and 800 °C. The results obtained from experimental analysis were compared to each other in terms of load-deformation pattern, ultimate load capacity, residual strength index, secant stiffness and ductility index. The test results showed that as compared with water quenching, annealing is slightly better for post fire cooling of CFST columns. Also, the results obtained by the experimental investigation were compared with each other on the basis of two cooling regimes.

钢管混凝土（CFST）柱是一种复合构件，主要由填充有混凝土的钢管组成，如今这些钢管越来越多地用作承载构件。在建筑行业中，CFST立柱是高层建筑和大跨度桥梁开发的首选。本文对后加热并承受轴向载荷的钢管混凝土（CFST）柱进行了实验研究。套管钢的厚度为4毫米和5毫米，直径分别为100毫米，125毫米和150毫米，并填充了本研究中使用的M30级混凝土。这项研究还代表了CFST色谱柱在暴露于600°C和800°C的高温后在两种冷却方式（退火和淬火）下的行为。从实验分析获得的结果在载荷变形模式，极限载荷能力，残余强度指标，割线刚度和延性指标方面进行了比较。测试结果表明，与水淬相比，CFST柱的火后冷却退火要好一些。而且，在两种冷却方式的基础上，将通过实验研究获得的结果进行了比较。