混凝土不同应变速率下抗弯拉力学特性试验研究

发布时间：2018-06-25 06:26

本文选题：混凝土动态性能 + 荷载历史　；参考：《河北工业大学》2014年博士论文

【摘要】：混凝土材料在现代建筑材料的使用中占据着越来越重要的地位，成为用途最广的建筑材料之一，其应用的领域非常广泛，如：房屋建筑工程、道路与桥梁工程、河堤大坝工程等。混凝土作为复合型材料，实际工作中，往往是在历经荷载历史的基础上再受到动载的作用，其力学特性会受到荷载历史的影响。相对于混凝土的静态力学性能而言，混凝土的动态力学性能更为复杂，在工作过程中混凝土要受到地震、风荷载、爆炸荷载等荷载作用，故混凝土的动态力学性能对结构的安全性和稳定性起关键性作用。由于试验装置系统与试验方法的选择都会对试验结果产生很大的影响，本文结合试验设计与方案利用MTS加载装置和先进的数据采集仪，采用适当的试件制作方法和加载工艺对不同强度等级的混凝土试件进行了动态荷载作用下的弯拉试验。本文对C35、C40、C45三种强度等级的混凝土试件进行动载作用下的力学特性分析，分别在应变速率为10-6s-1、10-5s-1、10-4s-1下进行动态直接破坏、历经荷载历史以及分级加载持荷三种不同受力情况的动态弯拉破坏。通过试验数据的总结分析，研究了荷载历史、分级加载持荷与应变速率对混凝土试件的抗弯拉弹性模量、泊松比、抗弯拉峰值应变、抗弯拉强度以及弯拉应力应变曲线的影响，最后对混凝土试件的破坏机理进行了分析。基于损伤原理，本文考虑了动态应变率强化效应与损伤的弱化效应后构建了混凝土的动态抗压本构模型与动态抗拉本构模型，利用ANSYS和FORTRAN编程有限元方法得到混凝土试件的动弯拉应力应变曲线，，该结果与试验得到的结果基本吻合，进而证明了本章中提出的本构模型具有一定的参考价值。
[Abstract]:Concrete material plays an increasingly important role in the use of modern building materials and has become one of the most widely used building materials. It is widely used in many fields, such as: building engineering, road and bridge engineering, etc. A river embankment, a dam, etc. Concrete, as a composite material, is usually subjected to dynamic load on the basis of the history of load, and its mechanical properties will be affected by the history of load. Compared with the static mechanical properties of concrete, the dynamic mechanical properties of concrete are more complex. In the process of work, concrete is subjected to earthquake, wind load, explosion load and other loads. Therefore, the dynamic mechanical properties of concrete play a key role in the safety and stability of the structure. Because the choice of test equipment system and test method will have a great influence on the test results, this paper combines the test design and scheme to use MTS loading device and advanced data acquisition instrument. The flexural tensile tests of concrete specimens with different strength grades were carried out under dynamic load with proper specimen making method and loading technology. In this paper, the mechanical properties of concrete specimens with three strength grades C35- C40C45 are analyzed under dynamic loading, and dynamic direct failure is carried out at strain rate of 10-6s-1 / 10-5s-1 / 10-4s-1, respectively. Dynamic flexural failure under three different loading conditions: the history of experienced load and the load holding capacity of step loading. Through the summary and analysis of test data, the effects of load history, load holding capacity and strain rate on flexural tensile elastic modulus, Poisson's ratio, peak strain, flexural tensile strength and stress-strain curve of concrete specimens are studied. Finally, the failure mechanism of concrete specimen is analyzed. Based on the damage principle, the dynamic compressive constitutive model and the dynamic tensile constitutive model of concrete are constructed by considering the dynamic strain rate strengthening effect and the damage weakening effect. The dynamic bending stress-strain curves of concrete specimens are obtained by using ANSYS and FORTRAN programming finite element method. The results are in good agreement with the experimental results, which proves that the constitutive model proposed in this chapter has certain reference value.
【学位授予单位】：河北工业大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：TU528

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