I. Introduction:
Reinforced concrete engineering is usually referred to as reinforced concrete for short. It refers to the composite material formed by adding steel mesh, steel plate or fiber into concrete to work together with it to improve the mechanical properties of concrete. This is the most common form of reinforced concrete.
The invention of reinforced concrete appeared in modern times. It is generally believed that the French gardener Joseph maunier invented reinforced concrete in 1849, and in 1867, he obtained the patent of reinforced concrete flowerpots and reinforced concrete beams and columns applied to highway guardrails. 1872, the world's first reinforced concrete structure was completed in new york, USA, and a brand-new era in the history of human architecture began.
1928, a new reinforced concrete structure, prestressed reinforced concrete, appeared and was widely used in engineering practice after World War II. /kloc-the invention of reinforced concrete and the application of steel in the construction industry in the middle of the 0/9th century made it possible to build high-rise buildings and long-span bridges.
At present, reinforced concrete is the most widely used structural form in China, accounting for the vast majority of the total. At the same time, China is also the most used area of reinforced concrete structures in the world. Its main raw material cement output has reached18.82 million tons in 20 10, accounting for about 70% of the world's total output.
Second, the working principle:
The reason why reinforced concrete can work together is determined by its own material characteristics. First of all, the linear expansion coefficients of steel bars and concrete are almost the same, and there will be no excessive stress due to different environments. Secondly, there is a good bond between steel bars and concrete, and sometimes the surface of steel bars is processed into spacer ribs to improve the mechanical bite between concrete and steel bars.
When it is not enough to transfer the tensile force between steel bar and concrete, the end of steel bar is usually bent into a 90-degree hook. In addition, the alkaline environment provided by calcium hydroxide in concrete forms a passive protective film on the surface of steel bars, which makes steel bars less susceptible to corrosion than neutral and acidic environments.