Importance of the Building and Construction Industry - Essay Example

PAPER MILL BUILDING Paper mill building Introduction The building and construction industry is one of the most important sectors in any nation. Building plays a pivotal role in ensuring the protection of business property as well as providing shelter to all economic activities and human being around the globe. Structural design is necessary to ensure that the erected building withstand the loads implied by the live and dead weight supported by the building. To ensure this, the structural engineer must carefully study the architect drawing and design the structural support for the building. Structural engineers are thus very important in the construction supply chain. Structural design encompasses the design of the support structure, selection of materials, computation of the member size, evaluation of the effect of the environment on the structural elements, selection of the member types and lastly the configuration of the structure in the most effective, affordable, safe and serviceable manner (Heyman, 1999). The structural designer must work according to the building standardization codes. He may have several designs of which he selects the most affective and affordable design. The design selected must not fail. To ensure proper functionality especially in the factories, the beams must not sag as this may lead to improper functioning or derailing of the cranes. Failure of the structural members results in machines drive shaft fail, machine table misalignment and burning of the bearing due to warbling. Structural materials The following structural materials are mostly used in structural design. Columns: They are erected vertically and they carry the axial loads. Beams: they are structural members subjected to pure bending. Beams are horizontally laid. Depending on their support, beams can be classified as; Cantilever beams; are usually supported at one end while the other end hangs freely. Such beams are common in balconies and verandas of storied buildings. Simply supported beams; there are supported vertically at two points. One point is fixed permanently while at the other point, an allowance is given to enable the beam to move horizontally due to expansion (Hosford, 2005). Continuous supported beams; supported at several points. There are several types of beams; these include; Universal beams; they are I shaped beams and are effective as supporting structures, they don't fail easily, they are also referred to as H section beams. Angle sections; they are 'L' shaped are mainly used for roofing where struts and ties are required to make trusses. T-sections; these are structural members that have a 'T' shape. Hollow section: there are several hollow sections that are used in structural design. These include; rectangular hollow section that have a rectangular shape, round hollow section that have a round tubular cross-section and shape, Square sections which have a square cross-section and elliptical cross-section which have an ellipse shape but are hollow inside. Trusses; they are mainly used for roofing; there are sometimes preferred in that they may span for long distances without sagging or deflecting. There are very versatile and can be redesigned easily to add more struts and ties to accommodate greater loads or span longer distances. Bars and rods; bars are rectangular while rods are circular; the are solid unlike the hollow section. Plates. Plates are metallic sheets with a thickness greater than 6mm. Concrete; One of the most widely used structural materials. It is cheap and last long as compared to all the other materials. Concrete comprise of a mix of sand, cement and aggregate in different proportions. The strength of concrete depends on the mixing ratios. Ratios with more sand and cement have greater strength and are used in industrial constructions. Nearly all concrete mixes are reinforced with steel bars. The inherent advantages of reinforcing concrete are; The composite structure resulting from the mix is more stroger and resists cracking. The steels bars are more resistant to tensile forces hence resist bending and structural failure of the concrete. The steel bars are protected from environmental corrosion. The steel bars are fire proofed. Steel weakens when it is heated but concrete is very stable even at high temperatures (Tauchert, 1974). The paper mill structural design (a)The foundation The foundation soil experienced is top soil and clay. Clay soil has some structural limitations in that it absorbs water and expands, when the soil dries up, it contracts. The repeated expansion and contraction of clay leads to the cracking of buildings materials, especially concrete. The foundation that is most suitable for this type of soil is the foundation pier. The depth of the foundation piers is 10 meters. The foundation piers are made of reinforced concrete to prevent corrosion on steel bars. The boulder clay is mixed with additives to improve its properties. Such additives include lime. The section diagram viewed along A-A is as shown below. Fig 1 showing the foundation layers of the paper mill industry The process for laying this foundation is outlined below. The site is excavated 10 meters below and the boulder clay soil is scoped out. The bounder clay near the building is then mixed with lime to improve its water absorption quality i.e. the lime prevents the expansion and contraction of clay. This layer covers a length of 5m from below. Foundation piers are sunk below into the boulder clay. A layer of stones and rocks is filled and compacted. These stones are filled to a depth of 3.8 meters. Finally the hardcore stones are filled. The hardcore depth is equal to 0.7 meters The steel rebar is laid and concrete added to form the reinforced concrete slab this fills a depth of 0.5 meters. Then another layer of concrete is added above the ground as per the design. The depth is specified as 0.2 meters Fig 2 showing the dimension of the foundation layer Fig 3 showing the foundation columns along the length of the building The pillars are erected two meters apart along the length of the wall of the paper mill. The schematic diagram above shows this. The layers of the foundation are similar to those in figure 1 and 2. Since the length of the building is 250000 mm, then, the number of pillars along one wall is equal 125. DESIGN ONE: USE OF REINFORCED CONCRETE Reinforced concrete is used for the columns that support the building. The columns are fitted two meters apart. Each wall has 125 columns along its entire length. There are four walls two of which are interior walls. The schematic diagram for the wall is as show below Fig 4 showing the columns along the length of the wall and the roofing trusses. Due to the length of the wall only a section of the wall is shown The sectional view of the building is as shown below Fig 5 showing the sectional view along A-A The structural details for section B-B are as shown below; Figure 6 showing the structural detail of section BB DESIGN TWO: USING STEEL STRUCTURE FRAME In this design the columns are made of steel beams. The framework resembles the concrete structure except that the columns and horizontally spanning beams are metallic particularly universal beams. Masonry stones are used for the walls. The structural design using steel components involves; Excavation and removing the layer of top soil and boulder clay. Erection of reinforced concrete pillars below the ground. Filling and compacting of the trench with clay mixed with lime. Filling and compacting of the excavated area with hardcore. Filling and compacting concrete slab. Erection of steel columns above the ground. Joining the whole structure to form a metallic frame of the whole building, this involves joining columns with the beams, trusses and girders Filling the gap between the columns with masonry stones Fitting of the roofing sheets The sectional view for the structure is shown below Fig 7: showing the Sectional view of the steel frame work. Section A-A Discussion The paper mill industry can be constructed using reinforced concrete or using steel structures. However the most viable design is the use of reinforced concrete. This is because; 1) In an industrial setup, there are chemical that can easily corrode the steel structures. However, concrete is not highly corroded hence last long with limited failure. 2) Reinforced concrete is cheaper than using the steel framework. 3) Due to machine vibration, the steel may suffer from creep rendering it to sag or the bolts used in joining the structural members become loose. This may lead to failure. Concrete structures on the other hand are firm and not severely affected by creep. 4) Steel softens when heated and is therefore not fire proof. Reinforced concrete resists fire and does not fail easily when heated (Charlton, 1973). Conclusion In conclusion, reinforced concrete is more viable for the paper mill building and construction as compared to the steel framework structure. References Charlton, M. 1973. Energy Principles in Theory of Structures. Oxford: Oxford University Press. Heyman, J. 1999. The Science of Structural Engineering. London: Imperial College Press. Hosford, W. 2005. Mechanical Behavior of Materials. Cambridge: Cambridge University Press. Tauchert, T. 1974. Energy Principles in Structural Mechanics. New York: McGraw-Hill. Read More