钢筋混凝土梁开裂弯矩不同计算方法对比分析

Contrastive Analysis of Different Calculation Methods of Cracking Moment for Reinforced Concrete Beams

基于试验、理论及仿真分析研究了钢筋混凝土梁开裂弯矩不同计算方法的适用性.利用自主研制的反向加载试验设备完成了7根梁的受弯开裂试验;推导了双筋截面梁开裂弯矩求解的理论表达式;分析了梁开裂弯矩不同近似计算方法的异同;采用ABAQUS构建了试验梁的仿真分析模型,得到了梁开裂弯矩的仿真解.将不同计算方法得到的结果与试验值进行对比分析,结果表明:钢筋混凝土梁开裂弯矩不同算法的结果较实测值均偏大,其中仿真值误差最小;横向受力裂缝出现时,梁刚度并不发生突变,仅当裂缝贯通保护层且发展到一定程度时其刚度才降低;现有梁开裂弯矩近似计算公式更适宜于估算梁刚度第一个突变点对应的弯矩值.

The applicability of different calculation methods of cracking moment for reinforced concrete beams is studied based on experiments, theories and simulation analysis. The experiments of seven reinforced con- crete beams are conducted based on the invention of reverse loading test equipment. The theoretical expres- sion of cracking moment of beam with compression steel is derived; and the similarities and differences be- tween the different approximate formulas of cracking moment for reinforced concrete beams are analyzed. The simulation analysis model of the beam is established by ABAQUS software; and the simulation value of cracking moment of beam is obtained. The results of different calculation methods are compared with the experimental results. The results show that： the values of different calculation methods of cracking moment for re- inforced concrete beams are larger than the measured ones; and the error of simulation is the smallest. When the transverse stress cracks appear, the rigidity of beam does not mutate. Only when the cracks through the protective layer and develop to a certain extent, it is reduced. The existing approximate calculation formulas of cracking moment for reinforced concrete beams are more suitable for estimating the load value which corre- sponds to the first mutation point of the beam rigidity.