摘要
为了研究钢筋混凝土梁在服役状态下遭受火灾后承载性能的变化,对7根钢筋混凝土梁进行了高温和加载试验,测试了在250 ℃、450 ℃和650 ℃加热过程和降温过程中梁的温度、极限弯矩和极限挠度等参数;分析了温度及冷却方式对预加载梁承载性能的影响.结果表明:在预加极限弯矩的39％荷载状态下,随着温度的升高,自然冷却梁的极限弯矩逐渐降低为未受高温时梁的96.45％、93.41％和91.38％.喷水冷却梁的极限弯矩逐渐降低为未受高温时梁的96.45％、95.69％和94.68％.达到极限荷载时,自然冷却和喷水冷却梁的跨中挠度均随着所受温度的升高而逐渐增大,受250 ℃、450 ℃和650 ℃后自然冷却梁的挠度分别为10.03 mm、16.11 mm和22.32 mm;而喷水冷却梁的挠度分别为15.89 mm、16.63 mm和17.43 mm.预加载梁所经受的温度越高,则其承载性能降低的越多.
Abstract
In order to study the change of bearing capacity of reinforced concrete beams after fire in service,7 reinforced concrete(RC)beams were tested under high temperature and loading.The temperature in the beam,the ultimate bending moment,and the ultimate deflection of the beams were tested at 250 ℃,450 ℃ and 650 ℃.The influences of temperature and cooling mode on the bearing capacity of preloaded beam were analyzed.The results show that,under the pre-loading 39％ultimate bending moment,with the increase of heating temperature,the ultimate bending moment of the naturally cooled beam decreased to 96.45％,93.41％and 91.38％of that of the beam at room temperature.The ultimate bending moment of the beam cooled by water spray gradually decreases to 96.45％,95.69％and 94.68％of the beam at room temperature.When the ultimate bending moment in middle span of the beam is reached,the deflections of heated beams increase gradually with the increase of temperature,and the deflections of naturally cooling beams are 10.03 mm,16.11 mm and 22.32 mm respectively after being subjected to 250 ℃,450 ℃ and 650 ℃.The deflection of the water spraying cooling beam are 15.89 mm,16.63 mm and 17.43 mm respectively.The higher the temperature the preloaded beam is subjected to,the more their bearing capacity decreased.
维普
万方数据