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What is the basic difference between pre tensioning and post tensioning?
Pretension is the technique in which we are imparting tension in strands before placing the concrete. Post tensioning is done by forming a duct in which strands are pulled (tensioned) after the concrete gains it’s full strength.
What are the basic types of pre stressing?
The basic types of prestressing are:
- Precompression with mostly the structure’s own weight.
- Pre-tensioning with high-strength embedded tendons.
- Post-tensioning with high-strength bonded or unbonded tendons.
What is pre stressed concrete bridge?
A concrete beam is “prestressed’ because stress is created before, or “pre,” the actual use of the beam when the working stress is applied.
What is post tensioning principle?
Working Principle of Post Tensioning When these post tensioned steel tendons are stressed, the concrete is squeezed, in other terms, the concrete is compacted which increases the compressive strength of the concrete and at the same time the steel tendons that are pulled increase the tensile strength.
What is the basic principle of prestressed concrete?
The basic principle of prestressed concrete is that to induce the internal compressive stresses by high strength steel tendons to the concrete before the load is applied so that it can counteract the tensile stresses produced in concrete due to external load.
What is the difference between pre-stressed concrete and mild concrete?
The compressive strength of concrete and tensile strength of steel is used to their fullest. Pre-stressed concrete requires high-quality dense concrete of high-strength. High strength concrete in production, placement and compaction is required. It requires high tensile steel which is 2.5 to 3.5times costlier than mild steel.
What type of wire is used for pre stressed concrete?
Pre-Stressed Concrete Materials According to AASHTO, high strength seven wire strand, high strength steel wire or alloys of grade and type (as specified by the designer) should be used in prestressed concrete. Also, stronger concrete is required in prestressed than normal RC.
What is pre-tensioning in concrete?
When using pre-tensioning, steel is stretched out before the placing of the concrete. This entails steel tendons set between two abutments, then getting stretched to roughly 80\% of their strength. The concrete then gets poured into molds around them and cured.