Behavior Research Of Prestressed Concrete Member Based On Concrete Mechanics

Prestressed concrete structures have been widely used in many engineering areas such as building and bridge engineering. Prestressed concrete members can reduce the section dimension and lighten self-weight obviously after application of prestress. So they widely used for large span structures. Normal section strengthen calculation of the prestressed concrete member is the basement of section design. The formulas for normal section strengthen calculation in the Code are based on experiments. Although the formulas are tested by real engineering, the formula is absence of the clear mechanical concept and difficult to understand.Based on the normal section calculation assumption and applied with concrete mechanics method, normal section physical condition and geometric condition and equilibrium condition have been established. According to the different behaviors of the member strain phases, we can obtain physical values through solving the three conditions simultaneously. ANSYS has been used to simulate the prestressed concrete beam from application of prestress to damage of member, and load-deflection curve has been obtained. The thesis also compared Chinese code with US code in strengthen calculation and section design of prestressed concrete. All the results above are used for network curriculum of prestressed concrete member. Five conclusions have been obtained from the thesis as follows:1. Cracking load and ultimate load of uniaxial tensile member have been obtained. The phenomenon that incrementation of strain and stress in prestressed tendon are smaller than reinforced concrete member have been discoveryed.2. Cracking load and ultimate load of flexural member have been obtained, and the values have been compared with code.3. ANSYS has been used to simulate the prestressed concrete beam from application of prestress to damage of member, and the values below have been obtained: camber due to prestress force, reduction of deflection for self-weight, load when deflection equal zero, concrete cracking, prestress tendon yield, damage of member. All the values can be tested by theoretical values.4. By comparing Chinese code with US code in strengthen calculation and section design of prestressed concrete, the differences in quantity of material and safety level have been acknowledged.5. All the results above have been used for network curriculum of prestressed concrete member. It is based on concrete mechanics, and combined with code and finite element. It is different from traditional textbooks.