1886, German engineer M. Knut put forward the calculation method of reinforced concrete slab. At the same time, the British W.D. Wilkinson put forward the patent of reinforced concrete floor; T. Hai Ete, an American, experimented with concrete beams; Frenchman f kvani published a monograph on the application of reinforced concrete.
The design methods adopted in the design codes of reinforced concrete structures in various countries include allowable stress design method, failure strength design method and limit state design method. In early reinforced concrete, the allowable stress design method based on elastic theory was mostly adopted.
In the late 1930s, the Soviet Union began to adopt the failure strength design method considering the plasticity of reinforced concrete in the failure stage. 1950 is further improved to the limit state design method, which integrates the advantages of the first two design methods, not only checking the allowable stress, allowable crack width and deflection in the use stage, but also checking the bearing capacity in the failure stage, and the concept is clear.
Reinforced concrete technology was first applied to China in Shanghai and Guangzhou at the beginning of last century. South Tower is the first high-rise building with reinforced concrete structure in Guangzhou. The first reinforced concrete building in Guangzhou, South Building, was started on 19 18 and completed on 1922. The building is 65 meters high, 12 floors. Operating department stores, tourism and hotels, the rooftop is a sky garden playground, with elevators for transporting guests and spiral trapezoidal ramps for cars to get on and off. 1June, 938, the building was burned down, leaving only the charred skeleton. 1954 was rebuilt and strengthened in March, and it was renamed as the South Building, which is still in use today and its appearance remains the same.
Concrete structure refers to the structure made of reinforced concrete. The main load-bearing members are made of reinforced concrete. Including thin shell structure, large formwork cast-in-place structure and reinforced concrete structure building built by sliding mode and lifting plate. A building made of steel and concrete. Steel bars bear tension and concrete bears pressure.
Advantages of reinforced concrete structure:
1. Good durability and fire resistance (compared with steel structure), reinforced concrete structure has good durability. Under normal use conditions, it generally does not need regular maintenance and repair, and it also has strong fire resistance. 2, the integrity is good, giving people the feeling that the whole is integrated; 3, good formability, fresh concrete is plastic, and can be designed and made into structures or components of various shapes and sizes according to needs. 4, save steel than steel structure, concrete structure is generally reinforced with concrete, so save a lot of steel than general steel structure.
Second, the reinforced concrete structure shortcomings:
1, self-weight, the gravity density of reinforced concrete is about 25kn/m 3, which is greater than that of masonry and wood. Although it is lighter than steel, the cross-sectional size of the structure is larger, so its own weight far exceeds that of the steel structure with the same span or height.
2. The tensile strength of concrete is low, and it is easy to crack. The tensile strength of concrete is very low. Therefore, ordinary reinforced concrete structures often work with cracks. Although the existence of cracks does not necessarily mean that the structure is destroyed, it affects the durability and aesthetics of the structure.
3, the template cycle is long.
4. The construction is influenced by seasons and easily restricted by rainy days.
5. It is difficult to reinforce and repair, and it is even more difficult to repair once problems occur.