钢管混凝土界面状态试验研究与分析

发布时间：2018-08-04 11:35

【摘要】：钢管混凝土结构能适应现代工程向大跨、高耸、重载发展和承受恶劣条件的需要,已成为继砖石结构,混凝土结构,钢结构之后的第四种结构。其具有广阔的发展前景,成为结构工程科学的一个重要发展方向。钢管混凝土结构是由钢管与混凝土两种材料复合而成的组合结构,特殊的材料组合形式,一方面造就了限制并互补的增强作用,另一方面衍生出界面性能的复杂性。工程实践亦证明,在复杂的外界环境作用下钢管混凝土构件存在界面脱粘现象,这势必影响钢管混凝土的工作性能与结构安全。因此,研究复杂外界环境作用下的钢管混凝土界面性能及其优化方法具有重要的理论研究价值与工程实践意义。本文综合运用理论分析、试验研究与有限元法,分析了在热力耦合作用下钢管混凝土界面状态、性能与特征,主要内容包括：轴压荷载作用下界面结合状态的试验研究；界面结合状态的超声波定性试验研究；界面结合状态的自制应力盒定量试验研究；钢管混凝土膨胀性能及其界面结合性能优化试验研究；自应力钢管混凝土轴压试验研究、有限元分析及界面表征；钢管混凝土温度冲击试验、热力耦合试验及有限元对比分析等工作。主要的研究工作、结果与结论如下： 1.开展圆钢管混凝土构件轴压性能试验研究。确定钢管混凝土的截面形式、径厚比(21～42)、长径比(3)、套箍系数等为试验参数,试验研究了不同轴压荷载水平作用下,钢管混凝土界面特征及应力状态。试验结果表明：钢管自密实微膨胀混凝土具有良好的轴压承载能力和抗变形能力,在轴压作用下,可通过测定应变变化,得出钢管混凝土短柱的受力状况,可通过进一步优化界面状态,实现两种材料的最优复合。 2.进行了钢管混凝土界面结合状态的超声波定性测试方法研究。自制4组钢管混凝土试件(分别为密实基准试件、脱空试件、脱粘试件、中部空洞试件)和27个混凝土标准试块,分别测试在2d、3d、5d、7d、11d、14d、21d、28d、60d龄期下钢管混凝土试件各测点的声时、声速、振幅、频率、波形等声学参数,以及各龄期下混凝土试块波速和抗压强度。依据声波传播理论,测试分析并提出了钢管混凝土界面特征超声波综合评判法。 3.完成了界面结合状态的自制应力盒定量试验研究工作。通过自制应力盒,形成界面应力测试单元。试验研究了在不同膨胀剂掺量下(5%、8%、12%、16%、20%)钢管混凝土限制膨胀性能和混凝土试件在标准养护状态下的自由膨胀性能。同时采用解析法得到了核心混凝土限制膨胀率的合理域； 4.开展了自应力钢管混凝土轴压性能试验、有限元分析及界面表征。研究不同膨胀剂掺量下(5%、8%、12%、16%、20%)钢管混凝土试件的力学性能及受压全过程的界面特性。试验与分析结果表明：自应力钢管混凝土可以使核心混凝土从钢管混凝土构件初凝成型时即处于三向受压状态,有效确保界面紧密贴合,补偿核心混凝土收缩导致的脱空、改善钢管混凝土的延性、提高其极限承载力和抗变形能力。本次试验中,膨胀剂最佳掺量为12%,极限承载力比理论计算最大值提高了25%。 5.进行了钢管混凝土温度冲击试验、热力耦合试验及有限元对比分析。对5个钢管混凝土试件分别在20℃、40℃、60℃、80℃恒温作用下,进行了轴向全过程加载、力热耦合作用下钢管混凝土试件截面温度场分布及钢管混凝土界面应力状态等工作。同时,应用热传导理论、热弹性力学、非线性有限元和虚拟温度场等方法,研究了轴压荷载和温度冲击作用下钢管混凝土界面状态与应力分布。本文在理论研究的基础上,以组合结构界面状态、定性定量测试技术手段、核心混凝土膨胀性能合理域、热力耦合试验方法设计为重点,开展了系列试验研究和有限元分析对比,系统研究分析了热、力等因素为主的环境作用下钢管混凝土界面状态,可为钢管混凝土界面优化以及确保恶劣环境下钢管混凝土长期工作性能提供一定的理论和试验参考。
[Abstract]:The concrete filled steel tube structure can adapt to the needs of the modern engineering to large span, high rise, heavy load development and abominable conditions. It has become the fourth structure following the masonry structure, concrete structure and steel structure. It has a broad development prospect and has become an important direction of the development of structural engineering science.
The concrete filled steel tube structure is a composite structure composed of two kinds of material of steel tube and concrete. The special material combination forms the reinforcing effect of restriction and complementarity on the one hand, on the other hand, it derives the complexity of the interface performance. The engineering practice also proves that the concrete filled steel tube member exists the interface removal under the complex external environment. It is bound to affect the working performance and structural safety of the concrete filled steel tube. Therefore, it is of great theoretical and practical significance to study the performance and optimization method of the concrete filled steel tube interface under the action of complex external environment.
In this paper, the theoretical analysis, experimental study and finite element method are used to analyze the interface state, properties and characteristics of the concrete filled steel tube under the thermal coupling effect. The main contents include the experimental study on the interfacial bonding state under the axial load; the ultrasonic stability test of the interface state; the self-made stress of the interface state. Box quantitative test research; Test Research on expansion performance and interface bonding performance of concrete filled steel tube; experimental research on axial compression test of concrete filled steel tube, finite element analysis and interface characterization; temperature impact test of concrete filled steel tube, thermal coupling test and finite element analysis and other work. Below:
1. the axial compression performance test of concrete filled circular steel tube is carried out. The section form of concrete filled steel tube, the ratio of diameter to thickness (21~42), the ratio of length to diameter (3), the hoop coefficient and so on are the test parameters. The interface characteristics and stress state of the concrete filled steel tube under different axial compression loads are tested and studied. The test results show that the self compacting and micro expansion of the steel tube is mixed. The soil has good axial compression bearing capacity and anti deformation ability. Under axial pressure, the stress condition of the short column of concrete filled steel tube can be obtained by measuring the change of strain. The optimum composite of two kinds of materials can be realized by further optimizing the interface state.
2. the ultrasonic qualitative test method of the interface of concrete filled steel tube was carried out. The 4 sets of self-made concrete filled steel tube specimens were tested in 2D, 3D, 5D, 7d, 11d, 14d, 21d, 28d, and 60d age concrete-filled steel tube specimens respectively. The acoustic parameters such as sound time, sound velocity, amplitude, frequency, wave form, and the wave velocity and compressive strength of concrete specimen under each age are tested and analyzed. The ultrasonic comprehensive evaluation method for the interface characteristic of concrete filled steel tube is tested and analyzed.
3. the self-made stress box quantitative test and research work was completed. Through the self-made stress box, the interfacial stress testing unit was formed. The experimental study on the restrictive expansive properties of concrete filled steel tube under the dosage of different expansive agents (5%, 8%, 12%, 16%, 20%) and the free expansion performance of concrete specimens under the standard curing state. The reasonable area of limited expansion rate of core concrete is obtained by analysis.
4. the axial compression performance test, finite element analysis and interface characterization of self stressing concrete filled steel tube were carried out. The mechanical properties of concrete filled steel tube specimens with different expansive agents (5%, 8%, 12%, 16%, 20%) were studied. The experimental and analysis results showed that the self stressing concrete filled steel tube could make the core concrete coagulate from the steel tube. In the initial setting, the soil component is in the three direction compression state, which can effectively ensure the close bonding of the interface, compensate the void in the shrinkage of the core concrete, improve the ductility of the concrete, and improve its ultimate bearing capacity and the anti deformability. In this test, the optimum content of the expansive agent is 12%, and the ultimate bearing capacity is increased by 25%.
5. the temperature impact test of concrete filled steel tube, thermal coupling test and finite element analysis were carried out. Under the action of 5 steel tube concrete specimens at 20, 40, 60 and 80, the temperature field distribution of concrete filled steel tube specimens and the stress state of the concrete filled steel tube under the action of the coupling of force and heat were carried out. At the same time, the thermal conduction theory, thermoelastic mechanics, nonlinear finite element method and virtual temperature field are used to study the interface state and stress distribution of the concrete filled steel tube under the axial compression load and the temperature impact.
On the basis of the theoretical research, this paper takes the interface state of the composite structure, the qualitative and quantitative testing technique, the reasonable expansive field of the core concrete, the design of the thermal coupling test method as the key, the series of experimental studies and the comparison of the finite element analysis, and the systematic study and analysis of the concrete filled steel tube under the effect of the heat and the force and other factors. The interface state can provide a theoretical and experimental reference for optimizing the interface of concrete filled steel tube and ensuring the long-term performance of concrete filled steel tube in harsh environment.
【学位授予单位】：武汉理工大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU398.9

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