为研究简支预应力钢梁在火灾高温下的耐火性能,基于实际的升温曲线,进行了2根预应力钢梁及1根非预应力钢梁的耐火性能试验,3根试验梁的截面尺寸、跨度及材料均相同。预应力拉索考虑了直线和折线2种布置方式;钢梁顶面绝热、其余3面受火、承受跨中集中荷载。最后分析了钢梁温度-时间、拉索张力-温度、挠度-温度关系。结果表明:随着炉内温度升高,预应力钢梁截面温度逐渐升高,在火灾初期,预应力钢梁跨中挠度随温度升高缓慢增加,在火灾后期挠度急剧发展;升温初期,预应力拉索张力略有降低,随着温度持续升高,拉索张力迅速降低,在临界状态时拉索完全松弛,在恢复至常温时,拉索张力也不能恢复;高温作用下预应力钢梁失效与预应力拉索张力松弛有关,在拉索张力完全消失后钢梁很快达到临界状态;高温作用下预应力钢梁的横向刚度与拉索张力存在关联,拉索一旦完全松弛,预应力钢梁挠度急剧增大并很快进入临界状态;确定拉索初始预应力对临界温度的影响时,需要综合考虑预应力拉索布置方式的影响,不同布索方式对预应力钢梁耐火性能有较大影响,其他条件相同时折线形布索的预应力钢梁比直线形布索的预应力钢梁临界温度高。 In order to study the fire resistance of simply supported prestressed steel beams under high temperature in fire, the fire resistance of two prestressed steel beams and one non-prestressed steel beam were tested based on the actual temperature rise curve. The cross-sectional dimensions , Span and material are the same. Prestressed cable considered straight line and polyline 2 kinds of arrangement; the top of the steel beam heat insulation, the other three fire, to withstand the mid-span load. Finally, the relationship between temperature and time of steel girder, tension of cable, temperature and deflection-temperature is analyzed. The results show that with the increase of furnace temperature, the cross-section temperature of prestressed steel beam gradually increases. At the initial stage of fire, the mid-span deflection of prestressed steel beam slowly increases with temperature increasing. In the early stage of fire, The tension of the cable was slightly reduced. As the temperature continued to increase, the tension of the cable decreased rapidly. When the cable was in the critical state, the cable was completely relaxed. When the cable was restored to normal temperature, the tension of the cable could not be restored. The prestressed steel beam The failure is related to the tension relaxation of the prestressed cable. The steel beam quickly reaches the critical state after the cable tension completely disappears. The transverse stiffness of the prestressed steel beam is related to the tension of the cable under high temperature. Once the cable is completely relaxed, the prestress The deflection of steel girder increases rapidly and enters the critical state quickly. When determining the influence of initial prestressing force on the critical temperature, the influence of prestressing cable arrangement mode needs to be comprehensively considered. The fire resistance of prestressed steel girders The influence of the other conditions are the same when the prestressed steel beam of the pre-stressing girder is higher than that of the prestressed steel girder of the straight-line preforming force.