The application of prestress in concrete components is mainly to overcome the weakness of low concrete tensile strength and make full use of high-strength steel. For steel-stranded concrete tension and bending members, because the tensile strength of concrete is very low, its ultimate tensile strength is generally about 1/10 of its compressive strength.
Therefore, in normal use, concrete members are usually For components that work with cracks, the stress of the tensile steel bars can only reach 20-30 MPa for components that are not allowed to crack. For components that allow cracking, usually, when the tensile steel bar stress reaches 250MPa, the crack width has reached 0.2-0.3m. At this time, the durability of the component has been reduced, and it is not suitable for high-humidity or corrosive work. surroundings.
The function of the prestressed steel strand is to make the structural members generate pre-compression stress to reduce or offset the concrete tensile stress caused by the load before the structural members are loaded, so as to control the tensile stress level of the structural members, and even make the members in a compressed state, So as to avoid the premature appearance of cracks in reinforced concrete components, make full use of high-strength steel bars and high-strength concrete to improve its performance and durability.
(1) Prestressed concrete steel strands can be made into a slender load-bearing structure with a larger span and a smaller deadweight than ordinary reinforced concrete due to the effective use of high-strength steel strands and concrete.
(2) Prestress can improve the performance of the concrete structure, thereby preventing concrete from cracking, or at least limiting the width of the crack to a harmless degree, which improves the durability of the structure.
(3) Even if it is partially prestressed under the use of load, the deformation of the structure can be controlled to a small state.
(4) The prestressed concrete steel strand structure has high fatigue resistance. Even if partial prestress technology is adopted, the change range of the stress of the steel bar is relatively small.
(5) In prestressed concrete members, as long as the strain of the steel bar is below 0.01%, the cracks caused by the overload may reclose after the load is removed.
The main characteristics of prestressed steel strands are high strength and good relaxation performance and are often used in construction projects. If you want to know more about prestressed steel strands after reading the above content, you can get a comprehensive solution by contacting us.
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