pree tenssion of steel

Pree tenssion of steel

In various work we are use the steel with concrete that are called rcc*reinforcement cement concret if steel will be used before using the concrete then tahat are called pree tenssion steel  they are under stress-pre-tensioned concrete, steel rods or cables around-the tendons are inserted. This treatment, and the tension is released when the compression of static friction is transmitted to solid tendons as a solid bond. Imposed on the concrete stress is transmitted directly to the tendons.

Pre-tensioning the tendons are stretched between a strong, stable anchoring points is required. Thus, pre-tensioned concrete elements than the prefabricated and which may limit their size are transported to the construction site. Pre-tensioned beam elements, balconies, lintels, floor slabs or can be added to the pile. The emphasis on a modern bridge design is stressed ribbon bridge.

Bonded post-tensioned concrete after pouring concrete (in situ) during the curing process, a method for applying compression is a descriptive term. Concrete would otherwise be located in an area where tension concrete element to follow, a plastic, steel or aluminum is poured around the curved duct.

A set of tendons are pulled through the duct and the concrete is poured. Once the concrete has hardened, tendons of the concrete member is a reaction against the hydraulic jacks (push) are tensioned by.

Transfer pressure for concrete, tendons of the (see Hooke's law) according to design specifications, have grown, they are wedged in position and maintain tension after Jack is removed. Duct then grouted to protect the tendons from corrosion is in.

This method generally frame the issues for the Foundation's extensive land (sometimes called Adobe dirt) for construction of places where I create monolithic slabs are used to produce. Seasonal expansion and contraction of the soil supports all the stresses throughout the building without significant flexure-tensioned slabs, taken in.

Post-tensioning of concrete segmental bridge as well, falsework supported by the assembly of prefabricated parts and is treated by both used in the construction of various bridges.

unbonded post-tensioning the advantages of this system include:

traditional reinforcement requirements as tendons reduction in accidents can not destress.
the tendons allow a more efficient design approach "woven" could easily be.
Higher on the ultimate strength of the bond between the strand and concrete.
To build bridges in Europe this form of prestressing anchor / dead end.The maintain the integrity of popularity in the 1950s and 60s with no long-term problems surrounding increased significantly. However, a history of problems with long-term stability of such structures have been more skeptical have been encountered.

Poor workmanship or quality control during construction, sometimes consisting of prestressing tendons ducts are not fully protected from corrosion on steel, leaving voids in the grout, are not filled. Highway and water (from de icing salts) chloride are able to penetrate into the voids if the situation becomes serious.

Notable events are listed below:

West Glamorgan, post-tensioning particularly vulnerable to defects in post-tensioned segmental structure of Wales, in 1985 the Ynys-Y- Gwas bridge collapsed without warning system.
Melle bridge built during the 1950s in Belgium, the following members of the tendon corrosion failure of the post-tensioned tie demolished in 1992.
Tendon corrosion in England after the discovery of several bridges, highways agency in New internal grouted post-tensioned bridges issued on post-tensioned bridge stock and its current 5-year program of inspection work.
Charlotte Motor Speedway, USA, part of a footbridge gave way and he dropped to the ground in 2000, a number of people were injured. In this case, the de-icing salts sodium chloride corrosion addition, as a concrete mix that was used was exacerbated by calcium chloride.
Errors discovered in post-tensioning system since 2011, London, England, at the Hammersmith flyover was subject to an emergency closure.