酸雨环境下钢筋混凝土框架梁抗震性能试验研究

Experimental study on seismic behaviors of reinforced concrete frame beams in simulated acid environment

为研究酸雨侵蚀环境中RC框架梁的抗震性能,设计了3组不同剪跨比(剪跨比分别为5.0、4.2、3.4)的RC框架梁,采用人工气候盐雾箱对其进行酸雨环境(pH值为3.0)加速侵蚀试验,随后对其进行拟静力试验,分析了不同酸雨酸化深度下的钢筋锈蚀程度和剪跨比对RC框架梁抗震性能的影响。结果表明:在酸雨溶液中的H^+和SO_4^(2-)的共同侵蚀作用下,RC框架梁混凝土表面出现坑蚀小洞,且蚀洞随着侵蚀程度的增加而逐渐加重;当酸化深度小于混凝土保护层厚度时,RC框架梁的承载力和延性略有增加;随着酸雨侵蚀程度的加深,相同剪跨比的试件,其破坏状态由弯曲破坏转变为以弯曲变形为主的弯剪破坏,当纵筋锈蚀率为6.5%时,承载力下降了17.6%,延性降低了5.24%,累积耗能减少30.87%;当钢筋锈蚀程度相近时,试件的弯剪破坏形态随着剪跨比的减小逐渐明显,承载力增大,延性和耗能能力随之减小。

To investigate seismic behaviors of RC frame beams corroded in the environment of acid rain, 3 groups of RC frame beam specimens with shear span ratios of 5.0, 4.2 and 3.4 respectively were subjected to accelerated corrosion in simulated acid environment （ pH = 3.0）. After that, quasi-static tests on the specimens were carried out to investigate the influence of both corrosion degree and shear span ratio on seismic behavious of RC frame beams with different acidulated depth, including strength, stiffness degradation, energy-dissipating capacity, etc. The results reveal that, some holes appear on the surface of RC frame beam concrete due to the combined erosion of H＋ and SO42- in the simulated acid solution, and get more severe with the prolongation of corrosion. When acidulated depth is less than concrete cover, both the bearing capacity and ductility of RC frame beams show an increase. With the increasing of acidulated depth, the failure patterns of test beams change from flexure failure to flexure-shear failure. Compared with non-corroded specimen, the load bearing capacity of the corroded specimen is decreased by 17.6%, the ductility is dropped by 5.24% , and the cumulative energy dissipation is dropped by 30.87% when the mass loss of longitudinal steel is 6.5 %. With the similar degree of reinforcement corrosion, the flexure-shear behavior becomes obvious with the reduction of shear span ratio, and the load bearing capacity of specimens shows an increase, but the ductility as well as the energy dissipation capacity decreases.