预应力简支钢梁高温性能试验研究

发布时间：2018-03-03 12:32

本文选题：桥梁工程　切入点：预应力钢梁　出处：《中国公路学报》2016年08期 　论文类型：期刊论文

【摘要】：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。
[Abstract]:In order to study the fire resistance of simply supported prestressed steel beams under high temperature, based on the actual heating curves, the section sizes of 2 prestressed steel beams and 1 unprestressed steel beam were tested. The span and material are the same. The prestressed cable takes into account the straight line and the broken line. The top surface of the steel beam is adiabatic, the other three sides are under fire, and bear the concentrated load in the span. Finally, the temperature and time of the steel beam, the tension of the cable and the temperature are analyzed. The results show that the cross section temperature of prestressed steel beam increases gradually with the increase of furnace temperature. In the early stage of fire, the mid-span deflection of prestressed steel beam increases slowly with the increase of temperature, and the deflection develops rapidly in the later stage of fire. At the early stage of heating, the tension of prestressed cable decreases slightly, and with the temperature rising, the tension of cable decreases rapidly, and the cable tension is completely relaxed at critical state, and the tension of cable can not be restored when the temperature is restored to normal temperature. The failure of prestressed steel beam under high temperature is related to the tension relaxation of the prestressed cable, and the steel beam reaches the critical state soon after the cable tension disappears completely, and the transverse stiffness of the prestressed steel beam is related to the cable tension under the high temperature. Once the cable is completely relaxed, the deflection of the prestressed steel beam increases sharply and rapidly enters the critical state, and the influence of the initial prestress of the cable on the critical temperature should be considered synthetically when determining the effect of the initial prestress on the critical temperature. The fire resistance of prestressed steel beams is greatly affected by different cabling modes, and the critical temperature of prestressed steel beams with folded linear cables is higher than that of prestressed steel beams with linear cables under the same conditions.
【作者单位】：武汉理工大学土木工程与建筑学院;武汉地铁集团有限公司;广州杰赛科技股份有限公司;同济大学土木工程防灾国家重点实验室;
【基金】：国家自然科学基金项目(51278394)
【分类号】：U446

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