Have you ever watched construction crews building a parking garage or skyscraper and wondered how they were able to raise and attach huge concrete panels like they were building blocks? You never see them actually fill concrete into a form to make the panels, so how do they do it? The key is actually a construction system called post tensioning and it has allowed for a few serious miracles in urban construction since its creation.
What is Post Tensioning? Put simply, this is a way of Anchorhead, so they are stronger and a lot more immune to cracking and breaking under environmental conditions. Concrete, when created and formed, can be quite strong in its compressed form yet it is still relatively weak in other places. By bonding the concrete block during creation with stainless-steel wires or rods, it improves its tensile strength, making the complete more durable to extreme changes.
The main benefit to creating concrete construction panels in this fashion is that it decreases the maintenance needed to keep your structure in general fully operational. Whether the finished item is a slab foundation or a nuclear containment wall, it is going to hold the flexibility it must have to resist temperature and environmental changes, less material will likely be required to cover the identical area, a lighter structure weight overall as well as a more impressive range of structural integrity using a marked boost in deflection and vibration control. This technique has become a boon to the people areas which can be regularly plagued by earthquakes, and hurricanes.
How Is It Done? Tensioning strands of stainless-steel wire, usually grouped into bundles, are stretched along the length of an empty concrete form prior to pouring. Since the concrete hardens, the strands are tightened, “stressing” them throughout the hardening concrete. The strands are anchored by adjustable chucks, which is often loosened or tightened during installing of the finished panel.
There are 2 methods widely used today in making a post tensioned slab of concrete: wedge anchor. Inside the bonded method, a bonding grout is included in each channel whereby the tensioning wires happen to be strung. This technique enhances the stability in the whole, further reducing maintenance costs in construction. Architecture designs which require greater flexibility, like those used in earthquake zones, will use the unbonded method, since they require greater flexibility, as opposed to additional reinforcement.
Typical steel strands used in post-tensioning possess a tensile strength of 270,000 pounds/in². Compared, a normal non-prestressed part of reinforcing features a tensile strength of 60,000 psi. Strands routinely have a diameter of 1/2 in., and are stressed to a force of 33,000 pounds. The stresses brought to the concrete counterbalance the expected external loads the concrete is going to be put through.
In post-tensioning the steel is held in a duct, which stops the steel and concrete from binding right after the concrete solidifies. The steel may then be stressed after the concrete sets. This is usually carried out in two stages. The initial prestress applied is up to 50% from the final force and this is achieved if the compressive strength reaches 12-15N/mm².
The next stage happens when the post stressed accessories occurs and this is accomplished when the concrete meets its design strength. The strands and bars are tensioned by stretching these with a hydraulic jack. They are then fixed set up with the anchoring component, which holds the force inside them for your life of the building. Post-tensioning allows the engineer to have each of the benefits rwkhni using prestressed concrete and keep the freedom of constructing on location.
Probably the most prominent markets for concrete which has been created through post tensioning represent the majority of installations that are available in the average city’s infrastructure. Airports, stadiums, parking garages, nuclear plants and roadways all incorporate these intricately created and durable slabs to their design. Inside the private sector, constructions like hotels, universities, offices and condominiums have likewise taken advantage of this flexible alternative to traditional concrete installations. Want to find out much more about post tensioning processes and what types of forms can be produced for construction purposes?