两跨预应力混凝土连续梁抗火性能试验与分析

Experiment and analysis on fire resistance of two-span prestressed concrete continuous beams

为研究预应力混凝土连续梁的抗火性能，进行了9根两跨有粘结预应力混凝土连续梁抗火试验.通过布置于试验梁内的热电偶，获得了试验梁截面的温度场分布.布置于试验梁上的位移传感器测试结果表明，火灾下连续梁变形增长速度在受火过程中增长速度大体上是一致的.各试验梁边支座反力实测结果表明，受火10 min以内，试验梁边支座反力快速减小，受火10-40 min，边支座反力变化平缓，受火40 min以后，边支座反力又快速恢复.试验梁在受火过程中试验梁背火面经历了水分溢出、水蒸气形成和发展、溢出水干涸及水蒸气消失的过程.基于试验结果，拟合出了考虑各关键参数影响的火灾下两跨连续梁边支座反力与梁跨中变形的计算公式.

To research the fire resistance of prestressed concrete （PC） continuous beams, experiments on fire resistance of 9 two -span bounded PC continuous beams were completed. Temperature distribution along the section of beams was obtained by embedded thermoeouples in the beams. Test result measured by displacement sensors on the beams indicates that the increase speed of the deflection of beams is kept the same in fire. Test result measured by load cells at the side supports indicates that side supports reaction decreases rapidly by heating within 10 minutes ; when undergoing fire over 10 minutes till 40 minutes, side supports reaction changes slightly; after that the side supports reaction begins to recover rapidly. During the fire, the whole process of water overflowing, vapor appearing and developing, as well as water drying and vapor disappearing occurs on the unexposed surface. Calculation formula of side support reaction and deflection in the mid - span of beams subjected to fire were obtained by fitting curves of experimental data considering each key factor.