桥梁预应力混凝土梁纵向与横向应力波特征及其应用

发布时间：2018-01-20 22:56

本文关键词： 预应力混凝土梁桥预应力孔道应力波有限元法分数阶傅里叶变换　出处：《湘潭大学》2015年硕士论文　论文类型：学位论文

【摘要】：预应力混凝土结构有着刚度大、抗疲劳效果好、重量轻以及能有效控制结构挠度的优点而被广泛的应用于现代桥梁工程中。预应力管道注浆质量直接影响混凝土梁桥结构耐久性和承载能力,因此对预应力管道注浆质量进行检测是预防和消除结构安全隐患的重要步骤。应力波方法是预应力结构主要的无损检测方法,研究应力波在预应力管道结构中的传播特性、影响因素和应力波信号处理方法有助于优化检测方案和修正检测结果。本文研究了桥梁预应力混凝土结构中纵向和横向应力波特性,首先利用有限元方法进行仿真模拟分析,然后进行实验测试分析,主要目的是通过应力波法识别预应力混凝土结构中的注浆缺陷,本文的主要研究内容及结果如下:(1)研究了预应力管道注浆结构纵向透射应力波特性和混凝土强度对应力波的影响。首先用ANSYS/LS-DYNA有限元软件建立无管道结构混凝土有限元模型和预应力管道结构有限元模型,然后求解并分析空浆长度和脱空度对固结波速的影响,以及混凝土强度对应力波首波时间和幅度的影响。结果表明,随着空浆长度从0m增加到0.2m,固结波速从4037m/s增加到4914m/s;固结波速随着注浆脱空度的增大而增大;随着混凝土型号的增加,应力波首波到达时间从63.89μs减小到51.78μs;应力波信号幅度随混凝土强度的增加而减小。(2)研究预应力管道注浆结构检测的横向反射应力波特性,并通过分数阶傅立叶变换对预应力管道结构注浆缺陷进行识别分析。首先用ANSYS/LSDYNA有限元软件建立注浆密实度分别为0%、30%、50%、70%、100%的预应力管道结构有限元模型,求解并分析,利用分数阶傅立叶变换处理应力波数据,计算得到信号分数阶域幅值比。结果表明,管道反射波随着注浆密实度增加而减小,有缺陷处的分数阶傅里叶域幅值比不相等,通过激发点两侧信号的分数阶域幅值比能够识别出注浆缺陷。(3)对分数阶傅立叶域幅值比识别预应力管道结构注浆缺陷的方法进行了实验模型上的验证分析。通过建立实际模型,利用TH402型桥梁注浆密实度检测仪进行数据采集,实验模型中注浆脱空度为80%,缺陷长度分为四组,分别是5cm、10cm、15cm、20cm,对采集数据进行分数阶傅里叶变换,计算出分数阶域幅值比,实验测试结果为,在注浆不密实处的激发点两侧信号分数阶傅里叶域幅值比不相等,这与模拟结果相吻合。
[Abstract]:Prestressed concrete structure has a large stiffness and good anti-fatigue effect. The advantages of light weight and the ability to effectively control the deflection of the structure are widely used in modern bridge engineering. The grouting quality of prestressed pipe directly affects the durability and bearing capacity of concrete beam bridge. Therefore, it is an important step to prevent and eliminate the hidden danger of structural safety by testing the grouting quality of prestressed pipeline. The stress wave method is the main nondestructive testing method of prestressed structure. The propagation characteristics of stress waves in prestressed pipeline structures are studied. The influence factors and the signal processing method of stress wave are helpful to optimize the detection scheme and revise the test results. This paper studies the longitudinal and transverse stress wave characteristics of prestressed concrete structure. First, the finite element method is used to simulate and analyze, then the experimental test is carried out. The main purpose is to identify the grouting defects in prestressed concrete structures by the stress wave method. The main contents and results of this thesis are as follows: 1). The influence of longitudinal transmission stress wave characteristics of prestressed pipeline grouting structure and concrete strength corresponding force wave is studied. Firstly, the finite element model of concrete without pipeline structure is established by using ANSYS/LS-DYNA finite element software. And the finite element model of prestressing pipe structure. Then, the effects of slurry length and degree of void removal on the consolidation velocity, and the effect of concrete strength on the time and amplitude of the first wave of the force wave are solved and analyzed. The results show that with the increase of the length of the slurry from 0 m to 0.2 m. The consolidation velocity increased from 4037m / s to 4914m / s; The consolidation velocity increases with the increase of grouting void degree. With the increase of concrete type, the arrival time of the first wave of the stress wave decreases from 63.89 渭 s to 51.78 渭 s. The amplitude of stress wave signal decreases with the increase of concrete strength. And through fractional Fourier transform to identify the grouting defects of prestressed pipeline structure. Firstly, the grouting density is 0 ~ 30% by using ANSYS/LSDYNA finite element software. The finite element model of 100% prestressing pipe structure is solved and analyzed. The stress wave data are processed by fractional Fourier transform and the amplitude-to-value ratio of signal fractional order domain is calculated. The results show that. The reflected wave of pipeline decreases with the increase of grouting compactness, and the fractional Fourier domain amplitude ratio is not equal. The grouting defect can be identified by the fractional order amplitude ratio of the signals on both sides of the excitation point.). The method of identifying grouting defects in prestressed pipeline structure by fractional Fourier domain amplitude ratio is verified and analyzed on the experimental model. The actual model is established. The TH402 bridge grouting compactness detector was used to collect data. In the experimental model, the grouting void degree was 80 and the defect length was divided into four groups, which were 5cm / 10cm / 15cm respectively. At 20 cm, the fractional Fourier transform is used to calculate the amplitude-to-value ratio in fractional order domain. The experimental results show that the amplitude-to-value ratio of the two sides of the signal at the firing point is not equal. This agrees with the simulation results.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441;U446

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