型钢混凝土T形柱耐火性能试验
Fire resistance performance of T-shaped steel reinforced concrete columns under high temperature

为研究火灾中型钢混凝土T形柱的耐火性能和破坏机理,在高温和竖向荷载的耦合作用下,进行了4个型钢混凝土T形柱试件耐火性能试验研究,对比分析不同轴压比(0.2、0.6)和不同偏心距(0、20、40 mm)影响下型钢混凝土T形柱试件的破坏形态、温度场分布曲线、竖向变形曲线和耐火极限。试验结果表明:各试件的测点升温曲线规律基本一致; 在升温过程中,起初试件表面温度明显高于内部温度,最后内外温度趋于一致。试件中混凝土裂缝的开展对测点温度有影响,表现为裂缝出现越早或裂缝越多则测点升温速率越快; 偏心距越大,加载点一侧竖向裂缝出现越早,裂缝越多,其升温速率也较快; 试件的开裂程度随轴压比和偏心距的增大而增大; 轴心受压试件腹板部位破坏程度高于翼缘板部位,偏心受压试件裂缝主要分布在偏心一侧且多为斜裂缝; 轴压比越小,竖向膨胀越明显、膨胀时间越长; 轴压比越大,耐火极限越小,其中大轴压比试件(轴压比为0.6)的耐火极限比小轴压比试件(轴压比为0.2)降低了57%; 偏心距20、40 mm试件比2种轴压比试件的耐火极限分别降低了10.1%和17.5%。
To study the fire resistance performance and fire failure mechanisms of T-shaped steel reinforced concrete columns, four T-shaped steel reinforced concrete column specimens were tested,under the coupling effect of high temperature and vertical load. The failure modes, temperature field distributions curves, vertical deformations curves, and fire resistance limits of the specimens were analyzed,with different axial compression ratios(0.2 and 0.6)and different eccentricities(0, 20 and 40 mm). The results show that all the temperature rise curves at the measurement points are consistent. As expected, during heating, the surface temperatures of the specimens are higher than the respective internal temperatures,however, after heating, these temperatures are nearly equal. The development of cracks in the concrete specimens affects the measured points temperatures, the earlier the cracks appear or the more cracks formed,the faster the heating rate observed at the measurement points. In addition, the earlier the vertical cracks appear on the side of the load with larger eccentricity, the more cracks formed, shows the faster heating rate. Furthermore, the degree of cracking increases with both the axial compression ratio and eccentricity. The failure degree of the column web is worse than that of the flange plate under axial compression. The cracks in the specimens with eccentric compression are distributed mainly on the eccentric side, and most are inclined cracks. The axial compression ratio is smaller, the vertical expansion is more obvious, and the expansion time is longer. The fire resistance limit decreases with an increase in the axial compression ratio. The fire resistance limit of the specimen with the larger axial compression ratio of 0.6 is 57% lower than that of the specimen with the smaller axial compression ratio of 0.2. Additionally, the fire resistance limits of the specimens with eccentricities of 20 and 40 mm are 10.1% and 17.5% respectively, lower than those of the specimens with axial compression.3 tabs, 14 figs, 26 refs