荷载-硫酸盐共同作用下纤维混凝土柱受压性能

为研究在荷载-硫酸盐共同作用下聚丙烯纤维混凝土柱的偏心受压性能,对8个聚丙烯纤维混凝土柱和1个普通混凝土对照柱进行了偏心受压静力试验,获取了荷载-变形曲线、荷载-钢筋应变曲线以及截面应变,分析了应力比和腐蚀时间对试件破坏形态、延性以及峰值荷载等的影响.结果 表明:聚丙烯纤维的加入,可有效抑制硫酸盐的侵蚀作用;峰值荷载随应力比的增加呈先提高后降低趋势,随腐蚀时间增加亦呈先提高后降低趋势,150 d时承载力较120 d降低了15.83％;位移延性系数随应力比的增加而减小,随腐蚀时间增加呈先增加后降低趋势,150 d时位移延性系数较60 d降低了15.79％.同时考虑应力比及硫酸盐对混凝土的损伤,引入损伤因子,建立经历荷载和硫酸盐作用后的混凝土抗压强度计算公式;考虑聚丙烯纤维混凝土抗拉强度对受拉区的贡献,采用等效矩形应力图简化计算方法,引入受拉区等效系数,建立荷载与硫酸盐共同作用下聚丙烯纤维混凝土柱承载力计算公式;并考虑聚丙烯纤维和硫酸盐腐蚀的影响,建立了最大裂缝宽度计算公式.理论计算值与试验值吻合较好.

Compression Behavior of Fiber Concrete Column under Combined Action of Load and Sulfate Attack

In order to investigate the eccentric compression performance of polypropylene (PP) fiber reinforced concrete column under the combined action of load-sulfate attack, an eccentric compression experimental research was carried out on eight PP fiber reinforced concrete columns and one ordinary concrete column. The loaddeformation curve, load- steel strain curve, and strain of column section were obtained, and the effect of different stress ratios and corrosion time on failure modes, ductility and peak load was analyzed. The results showed that the addition of PP fiber can effectively inhibit the sulfate corrosion. The increase of stress ratio was raised at first and then reduced with the peak load. As the corrosion time increased, the peak load increased first and then decreased with the decrease rate by 15.8% for time from 120 d to 150 d. Meanwhile, the ductility coefficient increased first and then decreased with the increase in corrosion time, while decreasing with the increase in stress ratio. And the coeffi? cient at 150 d was reduced by 15.79% compared with that at 60 d. Considering the damage caused by stress ratio and sulfate attack, a damage factor was introduced to establish the calculation formula of concrete compressive strength after the combined action of load-sulfate erosion. Furthermore, considering the contribution of tensile strength of PP fi? ber, an equivalent rectangular stress diagram was used. Finally, the equivalent coefficient of tensile zone was utilized to establish the bearing capacity formula for PP fiber reinforced concrete column under the combined action of loadsulfate attack. In addition, a maximum crack width formula concerning the influence of PP fibers and sulfate corrosion was also established. The theoretical results calculated by the above formulae agreed well with the test results.