非金属纤维编织网增强超高韧性水泥基复合材料抗剪加固研究

Ultra high toughness cementitious composite (UHTCC) overlays can be used for durability repair of deteriorated concrete structures since they have a strain hardening property and multiple cracking behaviors. Textile can be applied for the improvement of bearing of concrete structures since they have a light weight, high tensile strength and better corrosion resistance. The project aims to develop a new composite system, textile reinforced ultra high toughness cementitious composite (TRU), and evaluate the mechanical behavior of TRU and shear strengthening of RC beams with TRU. The detailed contents of this project are as follows: (1) mechanical property tests of TRU, including mechanical tests of textile, bond tests of the interface between the textile and UHTCC substrates, direct tension tests; (2) single shear tests between TRU and old concrete substrates; (3) shear bearing capacity tests and durability tests of RC beams reinforced with TRU. Three methods could be used, including test method, finite element method and formula method. And then, two models could be determined, including bond-slip model for textile/UHTCC and constitutive model for TRU. Two formulae would be derived, including bond-slip formulae for TRU/concrete and shear formulae for RC beams reinforced with TRU. In this project, attempts are made to solve some limitation problems for traditional reinforced materials and develop shear design theories to facilitate the practical implementation of such a new TRU strengthening system.

本项目利用超高韧性水泥基复合材料（简称UHTCC）显著的应变硬化特性和优异的裂缝控制能力，与轻质、高强度、耐腐蚀的非金属纤维编织网结合，开展了非金属纤维编织网增强超高韧性水泥基复合材料（简称TRU）抗剪加固研究。具体内容包括：（1）开展TRU基本力学性能研究：非金属纤维编织网基本力学性能试验研究、非金属纤维编织网与UHTCC基体粘结性能研究、TRU拉伸性能研究；（2）采用单剪试验研究纤维编织网与UHTCC之间、TRU层与老混凝土之间的界面粘结性能；（3）开展TRU加固RC梁的抗剪受力性能和耐久性研究。研究采用试验与有限元模拟、理论推导相结合的方法，建立纤维束与UHTCC基体粘结滑动模型、TRU材料本构模型、TRU与老混凝土之间的粘结强度计算公式和TRU增强RC梁的抗剪承载力计算公式。本项目旨在解决传统加固材料一些局限性问题，为指导TRU加固钢筋混凝土结构的抗剪设计奠定理论和设计基础。

本项目利用超高韧性水泥基复合材料（简称UHTCC）显著的应变硬化特性和优异的裂缝控制能力，与轻质、高强度、耐腐蚀的非金属纤维编织网结合，开展了非金属纤维编织网增强UHTCC（简称TRU）抗剪加固研究。开展了TRU基本力学性能研究、TRU与老混凝土单剪试验研究、TRU加固RC梁的抗剪受力性能和耐久性研究。研究结果表明：（1）经过聚合物处理的纤维编织网，其力学性能优于未经过聚合物处理的纤维编织网；纤维编织网的屈曲特性造成纤维束的拉伸强度低于单丝抗拉强度，纤维利用率低，工程中应考虑纤维束的应力损失。（2）调节纤维束埋长、经向纤维（非受力纤维）、纤维掺量、环氧浸渍粘砂等因素能有效提高非金属纤维编织网与UHTCC基体的粘结强度。（3）项目通过考虑纤维编织网配网率、纤维掺量、纤维束类型等因素评估了TRU材料的极限拉伸强度，基于试验结果建立了TRU材料的本构模型。（4）项目通过单剪试验分析了纤维编织网与UHTCC、TRU层与老混凝土双界面的粘结滑移破坏机理，给出了界面最小粘结长度，建立了TRU与老混凝土之间的粘结强度拟合公式。（5）项目采用TRU材料加固RC梁，分析多种因素对受剪梁承载力的影响，依据UHTCC材料的应变硬化特性对RC梁“桁架-拱”的抗剪计算模型进行修正，建立了TRU加固RC梁的抗剪计算方法。（6）在TRU加固RC梁耐久性试验中，UHTCC优异的裂缝控制能力和非金属纤维编织网超强的耐腐蚀特性，有效地提高了结构的耐久性。本项目的研究成果可以解决传统加固材料一些局限性问题，为指导TRU加固钢筋混凝土结构的抗剪设计奠定理论和设计基础。