FRP筋混凝土受弯构件最大裂缝宽度可靠度分析  

Reliability analysis of the maximum crack width of FRP bar reinforced concrete flexural members

作　　者：程凯凯 宋梅梅[1] 石韵 张煜敏[1] 代建波[1] 崔莹[1] CHENG Kaikai;SONG Meimei;SHI Yun;ZHANG Yumin;DAI Jianbo;CUI Ying(Mechanical Engineering College,Xi’an Shiyou University,Xi’an 710065,China)

机构地区：[1]西安石油大学机械工程学院,陕西西安710065

出　　处：《铁道科学与工程学报》2021年第9期2394-2399,共6页Journal of Railway Science and Engineering

基　　金：陕西省自然科学基础研究计划资助项目(2019JQ-055);陕西省教育厅专项科研计划项目(21JK0834);陕西省岩土与地下空间工程重点实验室开放基金项目(YT202008);国家自然科学基金资助项目(51808446,51908461)。

摘　　要：FRP筋因其良好的抗腐蚀性能,可替代钢筋用于强腐蚀环境或有电磁绝缘要求的混凝土结构中,但它属于非金属材料且弹性模量较低,因此,FRP筋混凝土受弯构件将产生较大的裂缝宽度。目前,我国纤维增强复合材料建设工程应用技术规范中其最大裂缝宽度的计算公式是对混凝土设计规范中计算公式的简单套改,区别在于荷载组合形式采用标准组合和最大裂缝宽度限值放宽至0.5 mm,但并未对公式进行可靠性分析,其合理性有待考证。为此,本文选取荷载效应比、配筋率、FRP筋弹性模量、FRP筋直径、截面高度、保护层厚度以及混凝土强度等作为影响因素对FRP筋构件裂缝宽度可靠度水平进行评估,分析这些因素对可靠指标的影响规律,得到可靠指标的界限值。研究结果表明:按目前规范对FRP筋最大裂缝宽度的可靠指标控制较为保守,尤其是当荷载效应比较大时,可靠指标超过2.0,明显偏高,造成不必要的浪费。因此本文建议计算FRP筋受弯构件最大裂缝时,采用荷载准永久组合,这样其可靠度控制水平更为恰当。FRP bars are always used in concrete structures with strong corrosion environments or electromagnetic insulation because of their good corrosion resistance performance.But it is a non-metallic material with low elastic modulus,which leads to larger crack width of FRP reinforced concrete members.However,the calculation formula of the maximum crack width in the current code is a simple change of that in the concrete design code.The difference is that the load combination adopts the characteristic combination and the limit of the maximum crack width is relaxed to be 0.5 mm.the rationality of the formula remains to be verified without reliability calibration.Therefore,the reliability level of crack width of FRP bars of those parameters(including the load effect ratio,the reinforcement ratio,the elastic modulus of FRP bars,the diameter of FRP bars,the section height,the thickness of the protective layer and the concrete strength)were carried out,the influence rule of these factors on the reliability index was analyzed and the limit values of the reliability index are obtained.It is shown that the current reliability index of the maximum crack width of FRP bars is relatively conservative,especially when the load effect ratio is relatively higher,the reliability index exceeds 2.0,which would cause unnecessary waste.Hence,it is suggested that the load quasi-permanent combination should be used to calculate the maximum crack of the FRP bar reinforced concrete flexural members,so that the reliability control level is more appropriate.

关 键 词：FRP筋 最大裂缝宽度 可靠度分析 

分 类 号：TU311[建筑科学—结构工程]