摘要
为探究冻融以及冻融-弯曲荷载耦合作用对聚丙烯纤维水泥基复合材料(PP-ECC)梁抗弯性能的影响,设置7种试验工况,采用三分点加载方式对PP-ECC梁抗弯性能进行研究,分析冻融及冻融-弯曲荷载耦合作用下PP-ECC梁的荷载-跨中挠度曲线、抗弯承载力及裂缝发展形态差异;基于计算假定和正常环境下PP-ECC梁抗弯承载力的计算模型,结合PP-ECC材料冻融劣化机理,推导出PP-ECC梁在冻融环境下抗弯承载力计算模型;在此基础上引入持荷损伤系数γ,建立冻融-弯曲荷载耦合作用下PP-ECC梁抗弯承载力计算模型.研究结果表明:不同持荷比的PP-ECC梁极限抗弯承载力在冻融循环作用下出现不同程度降低,500次冻融循环后,持荷比为0、0.25、0.50的PP-ECC梁极限抗弯承载力分别降低了28.70%、27.09%、35.69%;受拉区PP-ECC材料开裂后不退出工作仍能协同受拉钢筋参与全截面受力;PP-ECC梁在达到极限状态时,受拉区呈多条裂缝稳态发展模式,且随冻融损伤加剧,梁体最大裂缝宽度增大,裂缝数量减少;单一冻融以及冻融-弯曲荷载耦合作用下的PP-ECC梁仍满足平截面假定;基于平截面假定建立的冻融和冻融-弯曲荷载耦合作用下PP-ECC梁的抗弯承载力计算模型吻合度分别在0.88~1.06和0.96~1.10.
To investigate the effect of freeze-thaw cycles and coupling of freeze-thaw cycles and bending loads on the flexural performance of polypropylene fiber cement-based composite(PP-ECC)beams,seven experimental working conditions were set up.In addition,the three-point loading method was adopted to explore the flexural performance of PP-ECC beams.The differences in load-span deflection curves,flexural bearing capacity,and crack development patterns of PP-ECC beams under coupling of freeze-thaw cycles and bending loads were analyzed.Based on the calculation assumptions and the calculation model of the flexural bearing capacity of PPECC beams under normal environments,combined with the freeze-thaw deterioration mechanism of PP-ECC materials,the calculation model of flexural bearing capacity of PP-ECC beams under freeze-thaw environments was deduced.Furthermore,the load-bearing damage coefficientγwas introduced on this basis.The calculation model of the flexural bearing capacity of PP-ECC beams under the coupling of freeze-thaw cycles and bending loads was established.The research results show that the ultimate flexural bearing capacity of PP-ECC beams with different load-bearing ratios decreases to varying degrees under freeze-thaw cycles.After 500 freeze-thaw cycles,the ultimate flexural bearing capacity of PP-ECC beams with load-bearing ratios of 0,0.25,and 0.5 decreases by 28.70%,27.09%,and 35.69%,respectively.After cracking under tension,the PE-ECC material can still work with the rebar under tension and participate in the stress of the whole section.When the PP-ECC beam reaches the limit state,the zone under tension develops steadily with multiple cracks.With the aggravation of freeze-thaw damage,the width of the largest crack in the beam body increases,and the number of cracks decreases.The PP-ECC beam subjected to freeze-thaw cycles and coupling of freeze-thaw cycles and bending loads still satisfies the plane section assumption.The coincidence degree of the flexural bearing capacity calculation models of PP-ECC beams under freeze-thaw cycles and coupling of freeze-thaw cycles and bending loads established based on the plane section assumption is 0.88–1.06 and 0.96–1.10,respectively.
作者
李福海
杨宗驰
刘耕园
刘梦辉
吴昊南
陈昭
李固华
LI Fuhai;YANG Zongchi;LIU Gengyuan;LIU Menghui;WU Haonan;CHEN Zhao;LI Guhua(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)
出处
《西南交通大学学报》
北大核心
2025年第1期53-62,共10页
Journal of Southwest Jiaotong University
基金
国家重点研发计划(2021YFB2600900)
四川省自然科学基金项目(2023NSFSC0025,2021YJ0545,2022NSFSC1095)。
