Experimental / Theoretical Study on Strengthening effect enhancements of RC Structures with Hybrid FRP Laminates

混合 FRP 层合板增强 RC 结构加固效果的实验/理论研究

基本信息

批准号：
13650501
负责人：
WU Zhishen
金额：
$ 2.11万
依托单位：
IBARAKI UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650501/
关键词：
Fiber reinforced polymer (FRP)Hybrid Relieving of stress concentration Flexural strengthening Debonding Fracture mechanics Finite element analysis Optimum and integrated design

项目摘要

(1) Basic Hybrid Design of Different Fiber SheetsThe needs, requirements and points at issue on hybrid laminates by hybridizing different fibers are cleared up through investigating different design indices such as initial stiffness, rupture strength, ultimate strength and ductility and control indices such as strain hardening characteristics and stress drop due to successive fiber rupture. Based on these achievements, the design methods of hybrid FRP laminates by using different fibers such as three types of carbon fiber sheets with superhigh modulus, high modulus and high strength, two types of aramid fiber sheets with different moduli, PBO fiber sheet and glass fiber sheet with high rupture strain are proposed for different purposes. Moreover, the corresponding design program is also coded.(2) Experimental and Theoretical Investigations on Believing of Stress Concentrations due to Fiber Rupturing ImpactsIn order to improve above basic hybrid design, an analysis is performed to inves … More tigate how to relieve the stress concentrations induced by successive rupture of fibers. In addition, some tension tests were conducted to demonstrate the effect of PBO fibers with higher ability of energy absorption for relieving stress concentrations.(3) Experimental and Numerical Investigations on Strengthening Effects in Compressive and Flexural Concrete Members Strengthened with Hybrid Fiber SheetsThe designed hybrid fiber sheets are used to flexurally strengthen plain and reinforced concrete beams and the corresponding strengthening effects are qualitatively evaluated in terms of stiffness, strength, ductility and crack resistance. In addition, a series of concrete cylinder specimens wrapped with the proposed hybrid fiber sheets is used to investigate the confinement effects through varying different variables such as reinforcing ratios (spacing of wrapped fiber sheet strips) and concrete strength, etc.(4) Investigations on Interfacial Bond Behavior and Failure Mechanism along FRP and Concrete interfaceFirst, analytical equations are derived for predicting the bond carrying capacity in RC prisms bonded with FRP sheets. Based on a lot of experimental observations, both analytical and numerical analyzes are performed to give a clear insight into the bonding and debonding mechanisms in RC flexural members strengthened with different hybrid FRP sheets.(5) Establishments of Design Method and FE ModelThrough above analytical and numerical investigations, an existing analytical approach for predicting interfacial debonding failure is modified for evaluating the debonding behavior of strengthened structures with hybrid fiber sheets. A comprehensive design guideline is then developed to include all the possible failure modes such as steel yielding-FRP rupture, concrete crushing, shear failure and various debonding failures. Moreover, a constitutive model is established on the basis of experimental results to simulate the progressive rupture of fibers in hybrid fiber sheets and thus a nonlinear FE analysis can be implemented to evaluate both failure progresses caused by progressive rupture of fibers and cracking of concrete.(6) Optimum and integrated Design of RC Structures strengthened with Hybrid Fiber SheetsTo further develop the hybrid design concept, a series of experimental and numerical investigations is conducted to discuss countermeasures of realizing structural integrity of strengthened structures on different structural performances such as the initial stiffness, yield and ultimate loads and structural ductility under controlled load drops caused by progressive fiber ruptures. Through these investigations, an optimum design method on structures strengthened with hybrid FRP sheets is also proposed. Less

（1）通过研究不同的设计指标，例如初始刚度，破裂强度和延展性和控制折磨等不同的设计指标，从而清除了不同纤维层压板的需求，需求和点问题的基本混合设计，从而解决了杂交层压板的问题和点。基于这些成就，混合FRP层压的设计方法通过使用不同的纤维，例如具有超高模量，高模量和高强度的三种类型的碳纤维板，具有不同的Modulli，PBO纤维，PBO纤维板和玻璃纤维板，具有高爆发性应变的两种类型的芳族纤维板。此外，还对相应的设计程序进行了编码。（2）关于相信由于纤维破裂的影响，可以改善高于基本混合设计的纤维破裂的命令，进行了实验和理论研究，进行了分析以提高……更多地减轻了如何缓解纤维破裂引起的应力浓度。此外，进行了一些张力测试，以证明具有较高能量吸收能力来缓解压力浓度能力的PBO纤维的影响。（3）（3）实验和数值研究对压缩和弯曲混凝土成员增强的增强作用的实验和数值研究，与混合纤维相关的杂交纤维的效果增强了，该杂交纤维的效果具有柔韧性和强化的效果，并具有固定的术语，并具有固定的均匀效果，并具有固定的均匀效果。刚度，强度，延展性和抗裂纹性。此外，使用拟议的杂化纤维板包裹的一系列混凝土缸标本用于通过不同的变量（例如增强比（包装纤维板条的间距）和混凝土强度等不同的变量（4）来调查限制效果。 RC棱镜与FRP纸绑在一起。基于许多实验观察，进行了分析和数值分析，以清楚地深入了解RC柔性成员中的键合和剥离机制，并通过不同的混合FRP来加强。（5）设计方法的建立和FE模型的建立，以及在分析和数值研究中进行辩论，以进行辩论，以进行辩论，以进行辩论，以预测依据的依据，以进行辩论，以进行调查，以进行辩论，以进行辩论，以进行辩解，以进行辩论，以进行辩论，以进行辩论，以进行依据，以实现ISFAC型的依据。混合纤维板。然后制定了一项全面的设计指南，以包括所有可能的故障模式，例如钢铁屈服，混凝土粉碎，剪切失败和各种脱皮失败。此外，基于实验结果建立了组成模型，以模拟混合纤维板中的纤维的逐渐破裂，因此可以实施非线性FE分析，以评估纤维逐渐破裂引起的两个故障进展，并由混凝土的破裂和混凝土破裂。进行数值投资是为了讨论在不同的结构性能上实现加强结构的结构完整性的对策，例如在受控纤维破裂引起的受控负载下降下的初始刚度，产量和最终延展性和结构性延展性。通过这些投资，还提出了有关用混合FRP纸增强结构的最佳设计方法。较少的