钢筋混凝土结构加固中避免复合材料分层的理论研究

P. Firsov, B. Kaafarani
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引用次数: 0

摘要

科学工作致力于改进钢筋混凝土单元的计算方法,使用各种纤维类型的复合材料(SCM)系统加强结构时,使用FRP防止分层的验证。在用复合材料体系加固钢筋混凝土构件时,混凝土与FRP之间的粘结作用是非常重要的,因为分层(失去粘结)是破坏机制的脆弱性。粘结强度一般远高于混凝土的抗拉强度,所以分层总是从混凝土本身开始,随着不同厚度的FRP层的分离。根据承载力要求,这种破坏机制不应先于受弯或受剪构件的破坏。为了解决复合材料体系可能出现的强化分层问题,有必要考虑FRP的不同破坏模式。由于国内建筑规范的不完善,根据国外一些监管文件(ACI, CNR, FIB)的建议,对玻璃钢分层问题的解决方案进行了详细的分析。将FRP材料从混凝土基层开始剥落后的主要破坏模式系统归纳为:表面不规则性FRP材料剥落、剪切裂缝导致FRP材料分离、屈服区纵向剪应力、FRP材料过度变形(FRP断裂)、靠近FRP边缘的纵向剪应力、FRP材料锚固(固定)区破坏。提出了玻璃钢加固体系设计时需要验证的6条准则。在具体准则的制定过程中,给出了所研究节点在结构计算中应用所必需的主要理论方面。研究结果可为今后碳纤维、玻璃、芳纶等复合材料体系的结构接缝加固设计提供参考。关键词:复合材料体系,外配筋,FRP加固,钢筋混凝土,破坏模式,计算,分层
本文章由计算机程序翻译,如有差异,请以英文原文为准。
THEORETICAL ASPECTS OF AVOIDING DELAMINATION OF COMPOSITE MATERIALS DURING STRENGTHENING OF REINFORCED CONCRETE STRUCTURES
The scientific work is devoted to the improvement of the calculation methodology of reinforced concrete elements, using verification of the FRP delamination prevention, during structures strengthening with a system of composite materials (SCM) from various fibers types. During strengthening of reinforced concrete elements with composite material systems, the role of adhesion between concrete and FRP is of great importance due to the fragility of the failure mechanism due to delamination (loss of adhesion). The adhesion strength is generally much higher than the tensile strength of the concrete, so delamination always starts in concrete itself with the separation of FRP layer of different thickness. According to the load-bearing capacity requirements, such a failure mechanism should not precede the failure of the strengthened element during bending or shear. To solve the problem of possible strengthening delamination of composite materials systems, it is necessary to consider different failure modes of FRP. Due to imperfection of domestic building codes, a detailed analysis of the solution to the problem of FRP delamination was carried out in accordance with the recommendations of a number of foreign regulatory documents (ACI, CNR, FIB). The main failure modes, with subsequent initiation of delamination of FRP material from concrete base, are systematized, namely: FRP delamination due to surface irregularities, separation of FRP due to shear cracks, longitudinal shear stresses in the yield zone, excessive deformations in FRP material (FRP rupture), longitudinal shear stresses near the FRP edges, failure in anchoring (fixing) zone of FRP material. Six criterions are proposed that need to be verified during design of structures strengthening systems with FRP materials. During formulation of specified criterions, the main theoretical aspects necessary for application in structural calculations of the studied connection are given. The results of research can be used in future during the design of structures joints strengthening with systems of composite materials based on carbon fibers, glass, aramid. Keywords: system of composite materials, external reinforcement, FRP strengthening, reinforced concrete, failure mode, calculation, delamination.
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