Study On Law Of Crack Development Of Reinforced Concrete Flexural Member

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.