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AE-390
CONCRETE FRAME
GROUP 9
Contemporary USES
Now days with all the advances in concrete design, it can be used to make almost anything structural. The implementation of rebar and admixtures into concrete design has expanded the tasks that concrete framing can handle. Most structures will utilize concrete at the foundation level in the form of piles or caissons. Some applications are load bearing, but don't require a framing structure, such as: roadways, stormwater vaults, sidewalks, and retaining walls. However, concrete framing is commonly found in bridges, buildings, parking structures, and tunnels.
Figure B1: Concrete Building
Bridges
Buildings
Parking Structures
Tunnels
Concrete is a common material used to build bridges, especially arch bridges. This is because of concrete's excellent perfromance when in compression, the driving factor behind the arch design. The arch has the ability to support the forces acting normal and parallel to structure.
Concrete is the choice of many buildings, whether it be in the city or a rural community. When using steel framing, large steel members need to be hauled through the city and space needs to be found to set up a tower crane to install them. Concrete on the other hand can be driven through the city in a cement truck and then pumped vertially to create members that are cast onsite. When building in rural areas with open area around the site, this method can be used or precast members can be hauled in and placed by a tower crane.
Concrete is the most common material to make a parking garage out of. Typically parking structures are not made for aesthetics, but are simply made for function. Therefore it is acceptable for columns to be laid out in a grid pattern in order to support large loads. Among other reasons, it also does not require any of the extra fireproofing that steel does. This cuts costs tremendously, as one can imagine the amount of intumescent fireproofing it would take to cover the entire structure.
Tunnels are frequently made from concrete for the obvious reason of the arch concept. However, unlike bridges where there may only be one or two arches, tunnels are essentially one elongated arch. Compression is again the driving factor in this design but the arch has to support the weight created by the soil load that is pushing from all angles on the arch's exterior. Furthermore, it is easy to make the subtle turns of a tunnel using concrete than compared to other competing materials.
Figure B2: Concrete Bridge
Figure B3: Concrete Frame
Figure B4: Concrete Parking Garage
Figure B5: Concrete Tunnel
Contemporary Example: Burj Khalifa
Many have their doubts about the spans of concrete, however it seems the sky is the limit for concrete framing in the vertical direction. The tallest building in the world, the Burj Khalifa tower in Dubai, utilizes a concrete framing scheme.
Figure B6: Burj Khalifa
Its "Y" shape with three wings branching off of a central core is designed to reduce wind loads. Each wing is equiped with high performance concrete corridor walls and perimeter columns that meet the hexagonal core, all over flat plate concrete flooring. This produces a tower that is extremely stiff laterally and torsionally.
Figure B7: Schematic of Burj Khalifa
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