【作者】 程红梅；

【导师】 罗松南；

【作者基本信息】 湖南大学 ， 固体力学， 2004， 硕士

【摘要】 预应力钢筋混凝土结构在工程中得到了广泛的应用，混凝土组织构造的密实度、均匀性和组分变化，以及强度的高低，是否存在损伤或微裂纹，这些都将引起波传播路径、相位、波幅、传播时间、能量衰减以及频率成分发生变化，而接收波则综合携带了混凝土特性信息，可通过这些信息研究混凝土强度和损坏的程度。因此，在损伤的预应力钢筋混凝土结构中波传播理论的研究具有广泛的应用前景。 局部损伤混凝土介质中的波的传播理论是本文研究的基础。求出了接收波位移的时域曲线；分析了各种损伤度，损伤位置，损伤区域大小对波幅，首波延时时间等的影响。通过分析可知损伤对波传播的影响较大。因此，在无损检测时，损伤是必须考虑的因素。 伴随预应力混凝土结构中可能具有损伤，在其它外部因素作用下，混凝土结构内部也可能引起局部损伤，分析了预应力各种参数与波传播之间的定量关系。 混凝土的损伤会同时引起材料的弹性和粘性的改变，本文利用弹性和粘性双参变量来描述损伤，建立了双参数损伤理论，更能准确地描述材料损伤程度和损伤后的材料性质。分析了粘弹性混凝土介质中损伤区域长度、损伤度等对波传播的影响，给出了它们的关系曲线。 钢筋对波的传播路径、传播时间以及波幅均会产生较大的影响。本文分析了波在传播路径中的波形转换，在时域中对波型进行了叠加分析计算。进行了钢筋的直径大小，钢筋到探头的距离都对波形、波幅的定量影响分析。 本文较全面地研究了预应力钢筋混凝土结构中各种因素对波传播的影响，系统地给出了各种影响因素与波形、波幅以及传播时间之间的定量关系，为无损检测的定量化反分析提供了可靠的依据。更多还原

【Abstract】 The prestressed and reinforced concrete structures are used extensively in the engineering. The path, phase, amplitude, time, energy attenuation and frequency of wave propagation are changed by the consistency, uniformity, constituent, strength, damage and micro cracks etc. in the concrete structure. Because the characteristic information of concrete can be carried from the received wave, the strength and the damaged degree of concrete can be gained by studying this information. There are extensive prospects of application for the wave propagation theory in the prestressed and reinforced concrete structures.The theory of wave propagation in concrete media with local damage is the basis of the study in this paper. The time-displacement curve of the received wave is calculated. The strong influence of the degree, location and length of damage on the amplitude and the delaying time of the first wave are analyzed. Therefore, the damage is considered necessary in the nondestructive test of concrete structure.There may be damage in concrete structure when the prestress is loaded. The local damage may be produced in the interior of concrete structure by the other factors. The quantitative relationships between wave propagation and damage, prestress and other parameters are given.According to the experiment, the elasticity and viscosity can be changed by the damage in concrete media. A damage theory with double parameters is presented which use both elastic and viscous parameters as description of the damage, and the damaged degree and the materials properties in damaged concrete are exactly described by this theory. The influence of the damaged length and degree on the wave propagation is analyzed in the viscoelastic concrete media, and the corresponding influence curves are given.The influence of the reinforcing steel bar on the path, time and amplitude of the wave propagation are strong. The transformation of the form of wave in course of propagating is analyzed and the wave form is calculated by addition method. The quantitative influence relationships between the diameter of reinforcing steel bar, the distance (between reinforcing steel bar and the probe) and the amplitude of wave are analyzed.The influence of every factor in the prestressed and reinforced concrete structures on the wave propagation is studied in this paper. The quantitative relationships between every factors and form, amplitude, delaying time of the first wave are gained, the dependable basis is provided for further quantitative study of inversion and nondestructive test.更多还原