高温后无黏结预应力混凝土梁抗弯承载能力

Bending Capacity of Unbonded Prestressed Reinforced Concrete Beams After Elevated Temperature

对预加载的无黏结预应力混凝土梁的高温(火灾)性能进行了试验研究,试件的加热温度分别为250,450和650℃,加载试验分别在高温下和冷却后进行.试验表明,高温对无黏结预应力混凝土受弯构件的抗弯承载力和变形,都有较大的影响;与冷却后加载试验相比,高温下无黏结预应力混凝土受弯构件的损伤更为严重.根据受热后梁截面的温度场,采用分层法得到了高温下混凝土的平均抗压强度.在此基础上,提出了预应力混凝土梁的抗弯承载能力和变形的计算方法.计算分析表明,理论计算结果和试验结果吻合较好.

The high temperature （fire） behaviors of the preloaded unbonded prestressed reinforced concrete （RC） beams were tested to heat the samples to the temperature of 250, 450 and 650℃, respectively. The loading tests of the samples were performed under the elevated temperature and cooled conditions. The results show that high temperature has a great influence on the bending capacity and deformation of the unbonded prestressed RC flexural members. The unbonded prestressed RC flexural members under elevated temperature are damaged more seriously than that to be loaded after becoming cool. Based on the temperature field of the beam section after heated, the average compressive strength of the concrete under elevated temperature was obtained though the layer method. The calculation methods for the bending capacity and deformation of the prestressed RC beams were proposed. The numerical analyses show that the results of the new method are in good agreement with the experimental ones.