Ass 5 4011B.docx - INFORMATION REPORT CONCRETE FRAME...

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Unformatted text preview: INFORMATION REPORT- CONCRETE FRAME BUILDING Report on Warehouse Construction. Table of Contents Introduction.......................................................................................................................................3 Background.......................................................................................................................................3 Footing System..................................................................................................................................4 Structural System...............................................................................................................................8 1st Floor.........................................................................................................................................8 Basement Floor..............................................................................................................................8 Basement Wall...............................................................................................................................8 Column Bracket.............................................................................................................................8 Drop Panels...................................................................................................................................8 Exterior Columns...........................................................................................................................9 Flat Plate........................................................................................................................................9 Flat Slab.........................................................................................................................................9 Interior Columns............................................................................................................................9 Pedestal..........................................................................................................................................9 Roof...............................................................................................................................................9 Spread Footing.............................................................................................................................10 Upturned Beam............................................................................................................................10 Floor System....................................................................................................................................12 Slab Design..................................................................................................................................12 Slab Thickness.............................................................................................................................13 Wall System.....................................................................................................................................14 Roof System....................................................................................................................................15 Roof System Structure.................................................................................................................15 Roof Cladding.............................................................................................................................16 Specification product of Roof cladding......................................................................................16 Gutter Details...............................................................................................................................17 Services System...............................................................................................................................17 Storm Water Control....................................................................................................................17 Electricity....................................................................................................................................19 Water and Sewage........................................................................................................................19 Fire Protection.............................................................................................................................21 Conclusion.......................................................................................................................................23 References.......................................................................................................................................23 Page 2 of 24 Introduction Concrete frame structures are a very common - or perhaps the most common- type of modern building. As the name suggests, this type of building consists of a frame or skeleton of concrete. Horizontal members of this frame are called beams, and vertical members are called columns. Humans walk on flat planes of concrete called slabs. Of these, the column is the most important, as it is the primary load-carrying element of the building. If you damage a beam in a building, it will usually affect only one floor, but damage to a column could bring down the entire building. The worldwide use of reinforced concrete construction stems from the wide availability of reinforcing steel as well as the concrete ingredients. Unlike steel, concrete production does not require expensive manufacturing mills. Concrete construction, does, however, require a certain level of technology, expertise, and workmanship, particularly in the field during construction. In some cases, single-family houses or simple low-rise residential buildings are constructed without any engineering assistance (ATC, 1996). The purpose of this report is to outline the technical aspects involved in installing and erecting a Reinforced concrete building. There are six systems which will be the main points of discussion that will be outlines throughout this report. These systems are footing, structural, floor, wall, services and roofing systems. The information that will be collated in this report is based on an existing Reinforce Concrete framed building which will include photographs and sketches to support this discussion. given that following a building from start to finish will take some time to complete, this will be supplemented by images from the internet that will be consistent with the building used for the body of the report. Background This report outlines the structural design of a five story reinforced concrete office building. The framing arrangement and column locations of the building were provided based on architectural and structural requirements. The structure system of the office building is a reinforced concrete tilt up frame with a one way slab and beam floor system. Page 3 of 24 The framing plan of the five story reinforced concrete building was provided and can be seen in Figure 1. As shown in the framing plan, the building is six bays by three bays. The outer bays along the six bay side are 14 feet centre to center while the inner bays along the six bay side are 16 feet centre to center. The outer bays along the three bay side are 25 feet center to center while the inner bay along the three bay side is 30 feet center to center. The framing plan also denotes one way slabs with T beams that run along the six bay columns. Footing System Footings are an important part of foundation construction. They are typically made of concrete with rebar reinforcement that has been poured into an excavated trench. The purpose of footings is to support the foundation, prevent settling and transfers the load from the building to this very foundation. Each site is unique, the slope, soil type and rock position will all affect the design of the footings. If there is any slope to the site, some cut and fill excavation may be needed. Page 4 of 24 Footings need to have even bearing on solid ground, this means that the concrete needs to sit on rock or very hard compacted earth. All these circumstances may be difficult to predict until excavation has begun, but a few holes dug nearby and a talk with your engineer of architect will help you to know what to expect. The type of soil also plays an integral role in determining which type of footing to use. the wrong type of footing used in a volatile soil can cause lengthily costs and extreme damages to the structure of the building. However, a properly designed footing suitable to the soil type will eliminate settlement occurring when the soil is stressed by the imposed weight of the Reinforced concrete building. Determining the type of ground conditions which the site may have is done by a professional Geotechnical Engineer. The engineer has completed his assessment, he will issue a geotechnical report outlining the soil type for the site. For the purpose of the report, we can assume that the geotechnical report has outline that the sites foundation material consists mainly of solid sand and stiff clays with hard shale beneath the clay, which extends beyond 3 metres deep. With these results we can assume there will be some soil movement within the first layers of the foundation material and that the footing is best place on the shale material to provide a strong base with high bearing pressure. This will enable the slab to eliminate or dramatically decrease and movement that can result in cracks in the structural membrane. Based on these findings, the Geotechnical Engineer has suggested 2 types of footing systems that can be used in these conditions that is most appropriate for the Reinforced concrete building. The first suggested is Pad footings. Pad footings are generally used in good soil conditions where footings do not have to be deep and structural loads from the building are isolated in columns and not continuous as in load bearing walls (Tafe NSW). Due to the point loads applied to the foundation, Pad footings are respectably the most suitable in long-span portal frame construction and the simplest and cost effective footing used for vertical support and the transfer of building loads to the ground. Also in achieving a workable surface and the distribution of loads to the foundation, combined concrete slab would be used along with the Pad footing. The reinforcements and metal dowels also play a big part in the sufficient footings behaviour. Below is a sketch and a picture to depict how a pad footing is constructed and connected to the frame of the portal building. Page 5 of 24 Image above (Tafe NSW) The Pad footing section above shows How HD Bolt cast is placed into the concrete pad before drying. Once the concrete has dried, the steel column is bolted into the pad footing, then finally the floor slab is then poured. The second type of footing is known as a strip footing. A Strip Footing is a relatively small strip of concrete placed into a trench and reinforced with steel. The footing supports the load of the exterior walls and any interior wall that is load bearing or supports a slab such as the tilt up wall construction as used in this report. Strip footings are one of the most common footings used in Australia (Abis) Page 6 of 24 Reinforced strip of concrete laid in trench in ground. Used to support continuous brick walls. Typically 300mmm deep x 300 - 400mm wide. Process: Dig trench with backhoe or by hand. Tie up reinforcing cage. Lay reinforcing (reo) in trench. Support reo cage to ensure required concrete cover all round. Pour concrete and allow to cure before loading. Reo requires 40mm concrete cover. Lapping of bars min. 500mm or full width at T and L intersections. Stepping techniques - see As 2870 Clause 5.4.3 Suitable for A, S, M, H class sites. The images below depicts what's involved in installing strip footing. (Raters). Page 7 of 24 Structural System A reinforced concrete building is made up of a few components that essentially work together to make up and support the concrete building. This section aims to discuss each component of the structural system and describe how the frame supports the load of the building, and discuss in detail the types of connections utilised between the structural members. 1st Floor This is simply the floor that has 1 storey height above ground Basement Floor The floor of the basement of the building. The basement floor is either completely or partially below the ground floor. A basement can be used in almost exactly the same manner as an additional above-ground floor of a house or other building. The concrete floor in most basements is structurally not part of the foundation; only the basement walls are. Basement Wall The wall surrounding the basement floor is called the basement wall. The basement walls can be regarded structurally as part of the foundation. The basement walls are shear walls which can resist lateral loads as well. Moreover, these walls are meant to be highly non-porous and water resistant. This wall is a crucial component which contributes to the stability of the frame (Jones, 2003) Column Bracket Column Bracket is protrusion from the column also used for hanging or attaching lamps, bulbs or other accessories to it like road signs. Drop Panels Drop panels are used to thicken the slab around the column in flat slabs to avoid punching shear. Since flat slabs have no stirrups shear is resisted by thickening the slab around the column to increase the concrete in shear. Beams can also be used, but generally drop panels are preferred to avoid conflicts with the electromechanical works of the structure. Page 8 of 24 Exterior Columns The columns supporting the main structure of the building. This is the main component in concrete frame structures as the exterior columns are of extreme importance and bear the load of the building as well as resist environmental factors like wind, rain, and other physical factors. Flat Plate Slabs connecting to columns directly. Flat plate system is widely adopted by engineers as it provides many advantages . The system can reduce the height of the building, provide more flexible spatial planning due to no beams present, and further reduce the material cost. However, the main problem in practice is the brittle failure of flat plate under punching shear. Flat Slab The flat plate is a two-way reinforced concrete framing system utilizing a slab of uniform thickness, the simplest of structural shapes. The flat slab is a two-way reinforced structural system that includes either drop panels or column capitals at columns to resist heavier loads and thus permit longer spans. Interior Columns Interior columns in a frame structure support the slab and beams internally. They are not as susceptible to buckling and environmental effects as the external ones but still are extremely important considering the safety and stability of the building. Interior columns can also serve aesthetic and architectural purposes. Pedestal An architectural support or base, as for a column or statue. Roof A roof is the covering on the uppermost part of a building. A roof protects the building and its contents from the effects of weather and the elements. The elements in the design of a roof are: the material Page 9 of 24 the construction the durability & Serviceability Spread Footing To distribute the load of the foundation on the soil, spread footings are installed below the building's foundation. This type of footing is continuous below the perimeter of the house walls and may be thickened or widened at the points where concentrated loads are applied e.g. columns. These components are constructed from concrete and are reinforced with rebar or steel to add additional support. This type of footer design is highly beneficial to use as with pad and strip footings. Since they transfer the weight of the building over a large area, they have little risk of failure Upturned Beam Through the use of upturned concrete T-beams, designers created a naturally ventilated workspace that employs the thermal mass of an exposed concrete ceiling. This concrete absorbs heat during the day and is purged at night by cool breezes. This also works well in concrete buildings as rather than have a large beam under the floor, the beam is cast above and below the floors, acts as bearing and shear tension and compression face reinforcement will be somewhat different, but beam cross section area will stay the same (Jones, 2003). Page 10 of 24 A sketch depicting the components of the structural Concrete frame. Page 11 of 24 Above: A sketch depicting the components of the structural Concrete frame. Construction of Basement walls depicting the reinforcement for the concrete. Floor System This section of the report aims to identify the methodology and design requirements for heavily loaded slab on ground construction. With domestic concrete slabs, the imposed loads result only from pedestrian traffic and therefore are not considered. In industrial buildings however, greater imposed loads are encountered and must be considered. These loads include Trucks and forklifts imposing rolling loads Storage units imposing static loads (Tafe NSW). This means the slab must be designed to support these loads. This means that the finished flooring system should be structurally sound and be able to behave well under the future service conditions, easily to install building services and easy to maintain and also obtain an attractive finish. Slab Design The slabs were primarily designed with reinforcing steel parallel to the numerical grid lines. This is because the floor system is a one way slab, which means that bending will occur between the two supporting beams in a parabolic shape, with the largest moments being at the top of the slab near the supports and at the bottom of the slabs at the mid spans. Steel was also provided in the transverse direction to provide resistance to the temperature and shrinkage cracks in the tension regions. The first ground floor slab was the common raft slab, with the additional slabs being suspended concrete slabs. The stiffened raft configuration is in accordance of an effective structural design to support all types of loads within the warehouse. The raft slab of this warehouse consist of: 175 mm thick concrete slab edge beams internal beams steel reinforcement throughout. Page 12 of 24 The image depicts the stiffened raft is a slab on the ground with edge beans and internal beams which are poured as an integral part of the slab. Slab Thickness The slab thickness was determined to be 175mm. The exterior spans required 175mm slab thickness, which was slightly larger than the slab thickness requirement for the interior spans. For ease of construction and economical purposes, a slab thickness of 175mm was used throughout the entire building. For the floors, the dead loads included the load from the mechanical equipment and the ceiling (15 psf) and the load from the slab (87.5 psf). The live load for the floors was 50 psf while the partition loading (which was also considered a live load) was 20 psf. The dead loads for the roof included the load from the mechanical equipment and the ceiling (15 psf), the load from the roofing material (7 psf) and load from the slab (87.5 psf). The live load for the roof was comprised of the snow load only (30 psf). The load for the slabs was calculated by multiplying the slab thickness by the unit weight of concrete (150 psf). Sample design drawings of the floor slabs are shown in Figures 3-4. Page 13 of 24 Wall System The external walls of this building is made up from the 'Ritek pre fabricated concrete panel' wall system. These systems consist of pre-fabricated panels using a composite stud assembly, providing a permanent formwork for reinforced concrete walls (...
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