What is pre-stressed concrete?

PRE-STRESSED CONCRETE PART 1

Pre-stressing is a way of counteracting the effect of external loads on structure by imposing a state of stresses contrary to the load effects

Pre-stressing has two parts

Pre-Tensioning

Usually straight or harped profiles, mostly used in the precast industry some example would be hollow core slabs, precast beams, Girder beams

Post Tensioning

Any type of profile, can be precast or cast in place
The only basic difference between pre-tensioning and post tensioning is the state of the structural element while the stressing activities are done. In pretension the stressing is applied prior to concreting while in post tensioning the stressing is applied after the concrete is poured and hardened

Further, Post Tensioning is divided in to bonded and unbonded systems; we will get in to this in later days.
Pre-stressing a concrete element has two effect axial and transversal based on the tendon profile and anchorage selected.
We can have one of the three,
Axial (pure pre compression), Eccentrical axial effect, or axial/transversal effect. The later effect is difficult to utilize in pre-tension system

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