Design Of Precast Structural Elements

Bolted steel construction: this is when the main bulk of the construction is pre made at the workshop then bolted into place on site. This tends to be the preferred methods as it saves time and money as well having the right working conditions.

load bearing CMU, structural K joists, metal decking and a single ply roofing system. The

Higher load areas will require geopiers to be constructed under the footings to create a high load bearing capacity. The rest of the site and outbuildings will use spread footings. Structurally the building will be erected in three segmented sections separated by fire rated barriers.

Today we see different amazing and unique structures of civil engineering, it should be noted that these are not only the structures these are wonders of civil engineering.

A concrete beam is prestressed by pulling on steel rods running through the beam and then anchoring the ends of the rods to the ends of the beam. This exerts a compressive force on the concrete, offsetting tensile forces that are exerted on the beam when a load is placed on it. (A weight pressing down on a horizontal beam tends to bend the beam downward in the middle, creating compressive forces along the top of the beam and tensile forces along the bottom of the beam.) Prestressing can be applied to a concrete beam that is precast at a factory, brought to the construction site, and lifted into place by a crane; or it can be applied to cast-in-place concrete that is poured in the beam's final location. Tension can be applied to the steel wires or rods before the concrete is poured (pretensioning), or the concrete can be poured around tubes containing un tensioned steel to which tension is applied after the concrete has hardened

Aluminum roofing, doors, windows, and handrails highlight the use of wood” (Reaching the Green). The main structural support is provided by an exposed glulam timber frame. The timber frame supplies the required strength while providing the essential character and design aesthetics for the building interior provided. Ready access to dimensional lumber, structural wood by an exposed gleam timber frame. The timber frame supplies the required strength while providing the essential character and design aesthetics for the building interior. For the walls; the beam and the post frame provide the structural support needed to support the roof load. The walls are a straight light frame wood stud. The use of the wood frame, offers versatility and functionality. The floors are designed by using glulam beams and web joists. “The large open spaces provided by this assembly permitted rapid installation of electrical and mechanical services beneath the floor. The use of engineered wood trusses eliminated on-site cutting and reduced construction

Since the 1960’s prefabricated trusses have become more popular. They allow for architects to design structures with large open floor plans. They have become especially common in large metal buildings that require large spans. Prefabricated trusses are made of a variety of materials including hot rolled and cold formed steel, timber, and other metals. Prefabricated trusses’ popularity has rapidly increased because they are lightweight, stable, easy to install, and cheap (Grogan, 2007). Because they are so easy to install, the construction costs decrease because the amount of money spent on labor decreases. In addition, they have a higher chance of complying with relevant building regulations and SANS material and design specifications than trusses made by hand, on-site (Shepherd, 2006).

Pre-stressed concrete is a solid structure whereby stretched reinforcement bars surrounded by concrete. The purpose is to increase the capability of the beam to carry a much greater load with the same amount of concrete and reinforced bars.

Precast concrete is a construction method for casting concrete into a reusable mold. Recently, the number of buildings and infrastructure projects constructed using precast concrete has grown exponentially. Modern day technologies have turned precast concrete into a very durable, sustainable, and quality controlled product. Will precast and modular building systems be the future of sustainable, quality, and economical building methods?

Prior to the panels being cast to size, a concrete slab is poured to use as a base for the tilt-up panels to be cast onto.

Re-usable plastic formwork: These interlocking and modular systems are used to build widely variable, but relatively simple, concrete structures. The panels are lightweight and very robust. They are especially suited for similar structure projects and low-cost, mass housing

A layer of wire mesh is used over the galvanised iron sheet before laying the reinforcement of the framing beams which are welded to the J hooks used to anchor the sheets. This ensures that the concrete does not fill the valleys of the galvanized iron sheets and the air gap provides thermal insulation. The framing beams are then concreted to accommodate the infill material such as lean concrete or stabilized mud. This can then be clad with clay tiles, broken ceramic bars or slate depending on the availability of materials in the region. Effectively the concrete is used as a quilt over the internally secure waterproof diaphragm and assumes a secondary use. Galvalum sheets can be used in coastal regions where corrosion is a serious concern owing to

The system is based on the idea of a structural frame of reinforced concrete, built with standard elements. The ground floor is raised and there is an open plan. It consisted of a skeleton with 6 columns and slab cantilevers (Dom-ino Houses [sa]). Big opened up spaces are made use of, this emphasizes a free interior where one is able to place partitions in order to divide up different spaces. The empty shells allow for flexibility and

Pretension concrete, also known as prestressed concrete, is one of the methods to give more strength to the natural weakness of concrete through tension. The way this works is by allowing the tendons to cure in the concrete. After it has cured the tendons are released and the tension is applied. “The analysis for continuous prestressed composite beam covers: load deflection behavior, strain and stress in concrete slab and steel beam, force in shear connector, slipping between concrete and steel, and failure modes.”(Ozell) This is why they now connect the I beams with bolts to the vertical beams underneath the bridge girders, which are normally pretensioned concrete, to ensure the risk of them sidling apart and the bridge girders falling in. There are many uses for this type of concrete, some of these include floors, bridges, and beams. When looking for this type of concrete in the CSI divisions it is located under the precast section number 03-41-33. The specifications go into detail about the standards and references needed for this type of concrete. For example, there are two grades, 250 and 270, of low relaxation, seven-wire steel strands that are required in this type of concrete work. Some of the reference documents that go along with this are the ASTM Standards, U.S. Military Standards, and U.S. Federal Standards.

The lift shafts are circled by spiral staircases, constructed from precast reinforced concrete these provided the link between many of the staggered levels. The capsules composed of prefabricated residential apartment cells fitted in a spiral formation around the primary towers allowing for the interchanging between the two structures (fig.2). They are made from welded lightweight steel-truss boxes and clad in galvanised, rib-reinforced steel panels at a factory where the interiors were also fitted out (Weston 168). These capsules are also coated in a layer of rust prevention paint and a glossy spray of Kenitex, an impervious weatherproof plastic with an estimated 20 year life span. Each capsule was designed to be able to be moved from one location to another at any time by clipping onto the towers with flexible joints and was cantilevered and independent from the primary structure. However the concept of having several cells joining to form large units for larger families was never tested. Each tower is made up of 144 apartment blocks with one having nine floors while the other with 13 (Metalocus). These compartments comprise of a steel frame construction clad with sheet metal panelling closely resembling shipping containers in size and shape. The interiors were fully furnished with a permanently fitted bath, bed, seating, storage, television, air-conditioning unit and circular window (Lepik 118) (fig.3). These capsules