【作者】 李颖；

【导师】 易志坚；

【作者基本信息】 重庆交通大学 ， 桥梁与隧道工程， 2009， 硕士

【摘要】 现行混凝土结构理论仅考虑“破坏”状态时的极限平衡来计算结构的承载力,这种处理问题的方式对评价结构的承载力性能虽然有效,但却忽略了结构从开裂到破坏的全过程分析。钢筋混凝土结构在正常使用情况下是带裂纹工作的,结构从开裂到破坏有一个漫长的带裂纹工作的过程,其裂纹的发生发展规律以及裂纹的发生发展对结构性能的影响需要全面、深入、科学的描述和分析。而高强钢筋混凝土与普通钢筋混凝土受弯构件的裂纹发展规律是否有所区别,钢筋混凝土结构的设计能否有新的思路都需要我们来研究、探讨。本文基于断裂力学基本原理分析了钢筋混凝土结构中钢筋的阻裂机理;并用有限元软件进行了建模计算,进行了高强钢筋混凝土梁和普通钢筋混凝土梁的裂纹发展规律试验。首先对钢筋混凝土结构的阻裂机理进行了认真深入的分析表明,钢筋以闭合力的方式发挥作用,钢筋的闭合力减小了裂纹尖端的应力强度因子;然后利用有限元软件MSC.Marc对素混凝土小梁和钢筋混凝土小梁进行了断裂力学有限元建模计算,验证了钢筋优越的阻裂性能,由于钢筋闭合力的作用,裂纹尖端应力强度因子随裂纹高度先缓慢增大后急速下降,得出了钢筋的作用将使混凝土梁的裂纹在0.75倍左右梁高止裂的重要结论;最后通过对高强钢筋混凝土梁和普通钢筋混凝土梁的试验,验证了有限元计算的钢筋止裂结论,并且分析了加载过程中裂纹间距、高度及宽度情况,总结得出了高强钢筋混凝土梁和普通钢筋混凝土梁的裂纹发展的四个阶段,对比了高强钢筋混凝土梁和普通钢筋混凝土梁裂纹发展规律的不同点。本文通过有限元计算和高强钢筋混凝土结构、普通钢筋混凝土结构的试验,揭示了钢筋的阻裂规律,通过对比两种钢筋混凝土受弯构件的裂纹发展规律提出了基于裂纹发展阶段论的钢筋混凝土结构设计新构想。更多还原

【Abstract】 The existing concrete structure theory only considers the limit equilibrium state destroyed to calculate the bearing capacity of the structure. The way to deal with the problem may be effective for bearing capacity of the structure, but it ignores the entire process of analysis of the structure from cracking to damage.The reinforced concrete structure works with cracks under the normal usage status. Structure goes through a long process from cracking to damage working with cracks. It needs a comprehensive, in-depth and scientific description and analysis for the law of the crack occurrence and development and the occurrence and development of cracks on structural properties. Whether the laws of the development of the cracks are different between the high-strength reinforced concrete and ordinary reinforced concrete flexural members, and it is also need to study that the design of reinforced concrete structures could have new ideas.This article analyzes the resistance mechanism of crack in reinforced concrete structure bases on the basic principles of fracture mechanics; and It uses finite element model to calculate. It does tests of flexural members about the high-strength reinforced concrete and the ordinary reinforced concrete. First, it does a depth analysis about the resistance mechanism of reinforced concrete structure. It shows that the closure force of reinforced steel bars in order to play a role in the way, reinforced edge of the closure of the crack tip reduces the stress intensity factor; then use finite element software MSC. Marc to build the fracture mechanics finite element modeling to analyze plain concrete beam and reinforced concrete beam, It verifies that steel has a superior performance to resistance the crack, Because the steel had closed force, stress intensity factor at crack tip with crack height is first slowly increasing and then rapidly declining. The crack will not develop when it develop to the beam’s height of about 0.75 times with the effect of the steel. Through the test of high-strength reinforced concrete and ordinary reinforced concrete beam, it verifies that the finite element calculation of preventing crack of steel is right. It analyzes the process of crack spacing, height and width of the situation in loading process. It summed up to draw the four stages of development of the crack about the high-strength reinforced concrete beam and ordinary reinforced concrete beam. It gets the different law of crack development between the high-strength reinforced concrete beams and reinforced concrete beam. In this paper, the laws of resistance crack of steel have been revealed by the finite element analysis and the test of high-strength reinforced concrete structure and reinforced concrete structure. By summing up the law of development of crack about two reinforced concrete flexural members, the new design ideas of reinforced concrete structures are received.更多还原