CFRP筋与珊瑚海砂海水混凝土的黏结性能研究

Bond behavior between CFRP bars and coral seawater concrete

  • 摘要: 为研究珊瑚海砂海水混凝土(CSSC)与碳纤维增强复合材料(CFRP)筋之间的黏结性能,以黏结长度、保护层厚度、混凝土强度、混凝土种类及箍筋约束为试验参数,对21组共63个中心拉拔试件进行了拔出试验。结果表明:试件的破坏可区分为两类,混凝土是否开裂和损伤主要出现在何处;试件的黏结强度随黏结长度的增加而逐渐降低;当保护层厚度较小时(小于5dc),增大保护层厚度对提高其黏结强度有显著效果,但保护层厚度大于 5dc 后增强效果大幅减弱;一定范围内增大混凝土强度,有助于提高 CFRP 筋与CSSC的黏结性能;与未加固的试件相比,箍筋的约束平均提高了CSSC 试件7.7%的黏结强度;与CSSC试件相比,碎石海砂海水混凝土(SWSCC)的黏结强度平均增大了8.2%.。基于试验结果及收集到的同类研究结果,建立了CSSC 与CFRP筋间黏结强度计算式,并通过确定界面黏结系数K的取值范围,确定了基本锚固长度计算式。通过与试验结果对比,验证了所建公式能够合理预测CSSC与CFRP筋的黏结性能。

     

    Abstract: In order to study the bonding properties between coral sand seawater concrete (CSSC) and carbon fiber reinforced composite (CFRP) bars, 21 groups of 63 center-drawn specimens were pulled out with bonding length, protective layer thickness, concrete strength, concrete type and stir-bar constraint as test parameters. The results showed that the failure modes of the specimens could be categorized into two types, primarily depending on whether cracking occurred and where the damage was localized. Bond strength was observed to decrease progressively with increasing bond length. When the concrete cover thickness was relatively small (less than 5dc), increasing the cover significantly enhanced bond strength; however, this enhancement diminished substantially when the cover exceeded 5dc. Within a certain range, increasing concrete strength improved the bond performance between CFRP bars and CSSC. Compared to unconfined specimens, stirrup confinement increased the bond strength of CSSC specimens by an average of 7.7%. In addition, replacing CSSC with seawater sea-sand crushed stone concrete (SWSCC) led to an average increase of 8.2% in bond strength. Based on the experimental findings and supplemented by data from related studies, a bond strength prediction model for CFRP bars embedded in CSSC was developed. A bond coefficient K was introduced to characterize the bond interface, and a formula for the basic anchorage length was established. The proposed equations demonstrated good agreement with the test results and proved effective in predicting the bond performance between CFRP bars and CSSC.

     

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