预应力FRP板加固RC梁桥结构力学性能研究

发布时间：2018-04-30 12:05

本文选题：FRP + 预应力　；参考：《浙江大学》2014年硕士论文

【摘要】：由于交通运输日益繁忙、运输车辆的吨位和轴重的增加,自然灾害的破坏、原设计标准偏低以及施工过程中存在的不足,许多服役桥梁正逐渐成为病桥、危桥,修补、补强桥梁结构已成为土木工程领域的热点问题。在不中断交通的情况下,探索高效、简捷、经济的加固技术成为研究人员的追求目标。FRP作为一种高强的新型材料,在加固工程中具有巨大的应用前景。特别是承受循环车辆荷载作用导致结构性能劣化,影响结构服役性和安全性的既有服役桥梁,FRP加固能有效提升结构承载能力,在工程中得到广泛应用。由于在循环荷载作用下加固后结构疲劳破坏往往先于承载力失效,FRP加固桥梁构件的疲劳性能研究对结构安全至关重要。然而,迄今为止国内外对预应力FRP加固技术研究相对较少,张拉锚固系统设计实施、预应力损失监测以及FRP和加固后疲劳性能评估等关键问题亟待详细专门的研究,直接影响了预应力FRP加固技术在实际工程中的应用。本文以实际工程为研究背景,设计研发工程适用的预应力FRP张拉锚固系统,通过理论分析验证了该系统的安全性并开展了参数分析；探索运用光纤光栅传感器监测CFRP板的预应力损失的精度和可行性；创新性地运用预应力CFRP板组合CFRP布对背景工程进行加固,通过数值模拟了解了加固构件的力学性能,并与非预应力加固方式进行对比研究,探讨预应力度的合理取值范围。为了明确FRP加固后结构疲劳性能,本文根据大量的FRP抗弯加固钢筋混凝土梁的疲劳试验资料,建立了FRP加固梁式构件的疲劳预测模型。现将本文主要工作简述如下： 1.运针对实际工程设计预应力CFRP板加固混凝土桥梁结构体系,通过解析及有限元分析确定预应力水平对其加固效率的影响,并通过数值分析分析所设计张拉锚固系统的关键部位,以确保其结构安全性及施工可行性。 2.运用光纤光栅传感器(FBG)监测CFRP板张拉过程以及长期的预应力损失,监测结果显示,光纤光栅传感器可以精准的测量CFRP板的应变,加固完成后,预应力有一定程度的降低,最大预应力损失值仅占设计值的4%,这说明基于FBG的监测手段不仅能满足桥梁加固过程中短期监测需求,而且可对桥梁后续运营期的预应力损失情况进行长期监测。 3.综合了预应力CFRP板加固技术和和非预应力CFRP布加固技术的优势,运行预应力CFRP板组合CFRP布对该桥进行加固,运用数值分析方法分析了未加固、非预应力CFRP板组合CFRP布加固和预应力CFRP板组合CFRP布加固三种构件的受力性能,并探讨了合理的预应力度取值范围和承载力提升率的关系。 4.根据FRP抗弯加固钢筋混凝土梁的疲劳试验资料,建立了FRP加固梁式构件疲劳寿命预测模型、钢筋峰值应变累积模型和挠度累积模型,并比较了模型与既有相关模型的预测精度。研究表明：以钢筋应变和挠度作为疲劳性能指标不仅与传统的应力指标具有相似的精度,可预测FRP加固构件承受的循环荷载次数,并可与结构监测系统信息结合,实现疲劳失效预警。
[Abstract]:With the increasing traffic of transportation , the tonnage and bearing weight of transportation vehicles , the damage of natural disasters , the low standard of original design and the shortage of the construction process , many service bridges are gradually becoming the hot spots in the field of civil engineering .

Based on the research background of practical engineering , the prestressed FRP tension anchorage system applied in R & D engineering is designed , and the safety of the system is verified by theoretical analysis and the parameter analysis is carried out .
The accuracy and feasibility of using fiber grating sensor to monitor the prestress loss of CFRP plate are explored .
In order to clarify the fatigue performance of FRP reinforced concrete beams , the fatigue prediction model of FRP strengthened beam members is established according to the fatigue test data of a large amount of FRP anti - bending reinforced concrete beams . The main work of this paper is as follows :

1 . In order to ensure the structural safety and the feasibility of construction , the concrete bridge structure system is reinforced by the prestressed CFRP plate with practical engineering design , the influence of the prestress level on the reinforcement efficiency is determined by the analysis and finite element analysis , and the key parts of the designed tension anchoring system are analyzed by numerical analysis .

2 . The fiber Bragg grating sensor ( FBG ) is used to monitor the tension process and the long - term prestress loss . The results show that the fiber grating sensor can accurately measure the strain of the CFRP plate . After the reinforcement is completed , the prestress is reduced to a certain extent . The maximum prestress loss value is only 4 % of the design value . This indicates that the FBG based monitoring means can not only meet the short - term monitoring demand in the reinforcement process of the bridge , but also can monitor the prestress loss of the subsequent operation period of the bridge .

3 . The reinforcement technology of prestressed CFRP sheets and the strengthening technology of non - prestressed CFRP sheets are combined . The prestressed CFRP sheets are used to reinforce the bridge , and the mechanical properties of three components reinforced by CFRP sheets combined with CFRP sheets and CFRP sheets are analyzed by numerical analysis , and the relationship between the reasonable prestress value range and the lifting rate of the bearing capacity is discussed .

4 . Based on the fatigue test data of FRP anti - bending reinforced concrete beam , the fatigue life prediction model , the peak strain accumulation model and the deflection accumulation model of FRP reinforcement beam are established , and the prediction accuracy of the model and the existing correlation model is compared . The results show that the strain and deflection of the steel bars are not only similar to the traditional stress index , but also can predict the number of cyclic load borne by the FRP reinforcement member , and can be combined with the information of the structural monitoring system to realize the fatigue failure warning .

【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U445.72

【参考文献】