高温下钢筋混凝土梁的受力性能研究

Research On the Mechanical Behavior of Reinforced Concrete Beams Under High Temperature

通过自主设计的高温加载装置,在30~300℃区间内对钢筋混凝土梁进行了四点弯曲试验,并完成了梁构件在升温和加载条件下的应变测试.采用电阻应变测试技术对钢筋混凝土梁构件的跨中截面的应变进行测试,通过原位补偿法有效分离出温度与荷载分别引起的应变.据此分析梁构件的热应力和高温下的受力性能.研究结果表明:梁中性轴的位置会受到其内部热应力的影响而发生改变;在30~75℃范围内梁的抗弯刚度无明显变化;在90~110℃范围内梁的抗弯刚度随温度的升高而增大;135℃后梁的抗弯刚度呈现出稳定下降的趋势.采用力学公式对高温下钢筋混凝土梁的应变进行计算,对比分析发现实验值与计算值有较好的吻合度.

Through the self-designed high-temperature loading device,four-point bending test was carried out on the reinforced concrete beam in the interval of 30-300℃,and the strain test of the beam member under heating and loading conditions was completed.The resistance strain test technology was used to test the strain of the mid-span section of the reinforced concrete beam member,and the strain caused by temperature and load was effectively separated by the in-situ compensation method.Based on this,the thermal stress of the beam member and the mechanical performance under high temperature were analyzed.The research results show that the position of the neutral axis of the beam will be affected by its internal thermal stress and change;the bending stiffness of the beam has no obvious change in the range of 30-75℃;the bending stiffness of the beam increases with the increase of temperature in the range of 90-110℃;after 135℃,the bending stiffness of the beam shows a steady decline.The mechanical formula is used to calculate the strain of the reinforced concrete beam at high temperature.Comparative analysis shows that the experimental value and the calculated value are in good agreement.