by In order to avoid premature occurrence of cracks in reinforced concrete structures and fully utilize their high-strength steel bars and high-strength concrete, it is possible to generate pre pressure on the structural components before they bear the load to reduce or offset the tensile stress caused by the load on the concrete, so that the tensile stress of the structural components is not large, and even in a compressed state, thus producing prestressed concrete..
In ordinary reinforced concrete tensile or bending components, due to the low tensile strength and ultimate tensile strain of concrete, even if the concrete undergoes volume changes without external constraints, there are already micro cracks inside the concrete. Under the action of load, it usually works with cracks. The root cause of cracks caused by deformation (such as temperature changes, shrinkage, expansion, uneven settlement, cracks caused by external loads, cracks caused by chemical reactions, etc.) that occur over time after the final setting of concrete is due to the volume change of concrete being constrained, causing excessive tensile stress (or strain) inside. In order to avoid premature occurrence of cracks in reinforced concrete structures and fully utilize their high-strength steel bars and high-strength concrete, it is possible to generate pre pressure on the structural components before they bear the load to reduce or offset the tensile stress caused by the load on the concrete, so that the tensile stress of the structural components is not large, and even in a compressed state, thus producing prestressed concrete..
The pre-stressed concrete structure has a small cross-section, high stiffness, good crack resistance and durability, and is widely used in the construction field around the world today, promoting the development of concrete structures. Therefore, in the face of the current situation, it is necessary to conduct in-depth and detailed research and analysis on it, fully understand and play to the advantages of pre-stressed concrete, so as to further improve the application of pre-stressed concrete in engineering and extend its service life, Improve comprehensive benefits..
Due to insufficient strength and stiffness of the pedestal, its stability is poor, resulting in deformation, overturning, and sliding of the pedestal, leading to loss of prestress. Due to the poor self-locking and self anchoring capabilities of the fixture itself, the strength and hardness of the cone pin are lower than those of the prestressed reinforcement, resulting in loss of prestress..
Due to the low strength of concrete, the preload is greater than the compressive stress of concrete, causing it to be crushed and resulting in loss of prestress. Due to the inherent characteristics of shrinkage and creep in concrete, excessive shrinkage and creep can cause loss of prestress. Due to the improper size of coarse aggregate particles, there is a loss of prestress. The low strength of steel bars (steel wires) causes loss of prestress. Poor plasticity of steel bars (steel wires) leads to loss of prestress. Insufficient surface roughness of steel bars (steel wires) leads to loss of prestress..
The value of tension control stress directly affects the effectiveness of prestressed concrete. If the value of tension control stress is too low, the pre compression stress generated by the prestressed steel bars after several losses on the concrete is too small, which cannot effectively improve the crack resistance and stiffness of prestressed concrete components..
The loss of prestress caused by the temperature difference between the prestressed steel bars under tension and the equipment under tension during concrete heating and curing. Due to the fact that the temperature of the steel bars and the pedestal during tensioning is the same as t1, the concrete is heated and cured.
