The difference between pre-tensioned and post-tensioned

The difference between pre-tensioned and post-tensioned
(1) pre-tensioned

     That first post-tensioned reinforced concrete pouring its main tensioning procedure as follows: In accordance with the design requirements pedestal steel sheets pulled to control the stress temporarily fixed anchorage be concrete pouring concrete to meet the design strength of more than 75% cut relax reinforced its approach is to rely on force transmission bond strength of reinforced steel and concrete to prevent elastic rebound, so get pre-stress concrete cross-section

     Methods 6.1.2 prestressed

     Pre-tensioned construction is simple, relying on bond strength of self-anchored, no need to spend a special anchorage, temporary anchorage can be reused (generally referred instrumental anchorage or fixtures), when mass production economy, stable quality, suitable for small and medium sized member factory production.

    (2) post-tensioned

     ① bonded prestressed concrete

     Before pouring concrete until the concrete to meet the design strength of more than 75%, then tensioned reinforcement (steel beam) and its main tensioning procedure is: Buried control hole pouring concrete → → → conservation wear bars pumping pipe tensioning → ​​anchor → filling (to prevent rebar rust). their approach is to rely on force transmission anchorage reinforcement to prevent elastic rebound, so get pre-stress concrete cross-section, as shown in Figure 6.2 this practice makes the whole steel and concrete became known as bonded prestressed concrete.

     Bonded prestressed concrete due to the adhesive force (resistance) effect makes prestressed steel tensile stress decreased, resulting in reduced concrete compressive stress, it should seek to reduce this bond, this method is simple and requires no tension pedestal, production of flexible, on-site construction for large components.

     ② unbonded prestressed concrete

     The main program is tensioned prestressed reinforcement brushing along the full length appearance on anti-corrosion materials such as asphalt lubricating plastic paper bag or sleeve → (prestressing steel and concrete does not establish cohesion) → poured tensioned reinforced concrete curing → ​​→ Anchorage .

    Like with ordinary concrete construction, the steel can be poured directly into the concrete design position, do not have to set aside holes, wear bars, grouting, simplifying the construction process, due to the effective pre-unbonded prestressed concrete compressive stress increases, lower cost, applicable in the span of the curve beam reinforcement.