Fixed Cross Section Prestressed Concrete
Prestressed concrete is versatile to a wide assortment of basic frameworks. These incorporate pre-tensioned and post-tensioned structures, both cast set up and precast, and other prestressed elements related to regularly reinforced concrete. While there is no broad arrangement for precast and prestressed concrete, it is valuable to amass certain elements and structures to clarify how prestressed and precast concrete is designed and built.
Prestressed and precast concrete might be considered in four general classes:
1. Standardized Elements
2. Fixed Cross Section Elements
3. Fully Engineered Elements
4. Precast Non-prestressed Elements
While there is some cover, each gathering has its own special attributes. We will discuss the Fixed Cross Section Elements of prestressed concrete today.
Fixed Cross Section Elements
The design engineer is required to decide the prestressing forces and tendon areas in fixed cross section circumstances. Two regular fixed section design conditions are post-tensioned pillars and slabs for building or parking structure development, and girders for bridge development. Different utilizations of fixed section elements incorporate structures, for example, water tanks and post-tensioned slabs on-ground.
Flat plate and flat slab floor frameworks are undeniably appropriate for the utilization of post-tensioning tendons. Another well known framework is single direction slab and pillar floor frameworks that are thrown set up. The design engineer determines a tendon profile geometry and a normal viable post-tensioning force important to fulfill the design necessities.
The specialty engineer for the post-tensioning organization at that point takes this prerequisite and produces a nitty gritty design with tendon sizes and dispersing alongside port and graft areas. Pour strips and other enumerating prerequisites important to disengage the post-tensioned component from different elements in the structure ought to be nitty gritty by the engineer.
Determination of the tendon area is controlled by the thickness of the slab. The most extreme tendon unusualness accessible to the engineer is controlled by least spread prerequisites for erosion and fire security over the top and base of the tendon. Hence, in these applications, the section shape doesn't fluctuate, yet rather the design is constrained by the determination of the prestressed force and tendon separating.
Another mainstream fixed section are two-way slab frameworks utilized as podium slabs. Podium slabs are regularly a solitary story post-tensioned concrete floor framework upheld by sections that help a lighter superstructure above, which is generally wood or metal stud dividers with a light floor framework.
These are mainstream for use in private development where the upper stories fill in as the living zones and the region underneath the podium slab fills in as stopping. The podium slab is generally designed as a different structure from that of the wood or metal stud superstructures. The individual structures may have two separate auxiliary engineers.
Spliced bridge girders are a case of design to a fixed section utilizing halfway standardized precast, pretensioned elements that are additionally post-tensioned during the last phase of get together. State divisions of transportation and AASHTO determine standard pillar sections.
Precast plants have structures for bridge girder sections utilized in their market zone. The section choice is reliant on the state practice and is additionally impacted by the separation that the girders are dispatched.
The variety and the greatness of burdens, load situation on the bridge, the girder dispersing in the bridge, and the bridge deck design, block characterizing standard prestressing tendon forces and areas.
The design engineer chooses from a few decisions with respect to the format and stacking of the bridge before design of the prestressing force and area. In contrast to standardized items, the design engineer determines all subtleties of the bridge girder.
Another case of spliced fragmented precast development utilizing standardized shapes includes the utilization of plant-created evenly bended, precast concrete U-girders (Hamilton and Dolan, 2016). These U-girders utilize standardized shapes and geometry alongside present tensioning to encourage design and development effectiveness.
Engineer's Role with fixed cross section elements
The engineer's job with fixed cross section component structures changes with the customer and venture. A few models include the following.
Building design engineers indicate the ideal last prestress force. The temporary worker or post-tensioning organization specialty engineer finishes the design by deciding the tendon dividing and focusing on forces. The design engineer at that point affirms the temporary worker's shop drawing submission.
Building design engineers indicate the last prestress force, tendon area, and equipment itemizing. Post-tensioning organization engineer builds up the tendon format, jetty area, and focuses on succession.
Bridge design engineers set up the total pillar design, including point by point assurance of prestress forces, tendon area, and development arrangement.
Tasks, for example, tanks are regularly acquired on a design?assemble premise. The contractual worker and either the temporary worker's in-house engineering staff or a counseling engineer readies the design to meet undertaking prerequisites and the contractual worker's favored development practice.
Read More: Fully Engineered & Precast Nonprestressed Concrete
