ECC-NC复合梁抗弯性能试验  

Experimental Study on the Bending Performance of ECC-NC Composite Beams

作　　者：武芳文[1] 吴健辉 卞正容 马亚腾 李滋润 雷海鹏 WU Fang-wen;WU Jian-hui;BIAN Zheng-rong;MA Ya-teng;LI Zi-run;LEI Hai-peng(School of Highway,Chang'an University,Xi'an 710064,Shaanxi,China)

机构地区：[1]长安大学公路学院,陕西西安710064

出　　处：《中国公路学报》2025年第1期158-172,共15页China Journal of Highway and Transport

基　　金：国家自然科学基金项目(52378121);陕西省自然科学基础研究计划重点项目(2022JZ-32);中央高校基本科研业务费专项资金项目(300102212212)。

摘　　要：为探究配筋率和复合层厚度对ECC-NC(Engineered Cementitious Composites to Normal Concrete)复合梁抗弯性能的影响,设计了5根ECC-NC复合梁,通过四点弯曲试验,开展了ECC-NC复合梁抗弯性能研究,分析了复合梁破坏模式和裂缝发展规律,探讨了配筋率和复合层厚度对结构承载能力、韧性及延性的影响。研究结果表明:与普通混凝土梁相比,ECC-NC复合梁破坏模式不同,能有效发挥ECC材料特性,具有较好的抗弯性能;相同配筋率下,受拉区ECC层厚度增加,ECC-NC复合梁的抗弯承载力增强有限,弯剪区裂缝数量增多,延性增强,刚度退化缓慢,最佳复合层厚度为0.3h~0.5h;ECC层具有替代部分纵筋作用,受压与受拉区同时设置ECC层能极大地提高抗弯承载能力、延性及结构韧性;基于响应面法,配筋率对ECC-NC抗弯性能影响最大,最大配筋率与复合层厚度有关,0~0.5h呈负相关,0.5h~h间呈正相关,受压区设置ECC可提高界限配筋率,高配筋率有利于提高抗弯刚度,减缓裂缝扩展;弯曲荷载下,截面符合平截面假定,变形协调;基于条带法,建立了ECC-NC复合梁抗弯承载能力计算方法,与试验结果及已有文献数据校核,平均误差在6%以内,吻合度较高,可为工程应用提供理论支撑。ECC替代普通混凝土,不仅提高了结构抗弯承载力,还延缓了裂缝扩展,改善了复合梁带裂缝工作性能和抗裂性能,且抗弯性能较为优越。This research aims to clarify the failure modes and crack development patterns of engineered cementitious composite(ECC)to normal concrete(NC)composite beams.The four-point bending test was conducted on five composite beams to investigate the effects of the reinforcement ratio and layer thickness on the structural flexural performance.The research findings demonstrated that the failure modes of ECC-NC composite beams were clearly distinguished from pure NC beams,manifested by better flexural performance and effective utilization of the properties of ECC.Under a constant reinforcement rate,the increasing ECC layer thickness evidently slowed down the stiffness degradation of composite beams,thereby enhancing the flexural capacity of ECC-NC composite beams.Based on the parametric analysis,the optimal thickness of the composite layer was in the range of 0.3h-0.5h,which can effectively play a role in replacing some longitudinal bars.Combined with the response surface method,the maximum reinforcement ratio was found to be related to the thickness of the composite layer,with a negative correlation in the range of 0-0.5h and a positive correlation in the range of 0.5h-h.Therefore,setting ECC in the compression zone can increase the limit reinforcement ratio,and the high reinforcement ratio can improve flexural stiffness and slow down the crack extension.Finally,a calculation method for the bending capacity of ECC-NC composite beams was developed based on the strip method,which can be used to evaluate the capacity evolution accurately,with an error of approximately 6%.This theoretical achievement can offer underpinning for the structural design of composite beams.The comprehensive research of this paper proved that the substitution of NC with ECC not only enhances the structural flexural capacity but also retards the crack extension,and improves the cracking-control ability of composite beams.

关 键 词：桥梁工程 ECC-NC复合梁 四点弯曲试验 受弯性能 配筋率 复合层厚度 

分 类 号：U443.35[建筑科学—桥梁与隧道工程]