Usage and Importance of Construction Technology - Term Paper Example

Construction Technology Introduction In the Construction Technology, the type of foundation that is going to be used is important in ensuring safety and longevity of a structure. This paper shows the design, usage and importance of four (4) types of foundation being studied namely: (1) strip foundation, (2) deep strip foundation, (3) trench fill foundation, and (4) raft foundation. It also illustrates some features of the external envelope of the traditional form of construction. Also, this paper provides additional information regarding the English bond, Flemish bond and stretcher bond. Traditional Form of Construction Traditional Construction is part of the banking industry’s informal sector which is approved without professional involvement of builders. This type of construction share three (3) characteristics: (1) the use of local materials, (2) have evolved through the years to cope with local conditions, and (3) strong built. Walls The traditional form of construction has cavity outer walls or recomposed stone containing inner walls of brick or block. Another characteristic pertaining to the walls is the timber framed property with brick outer walls and reconstituted stone that was built in 1970 or later. Wall made of solid stone are also seen in traditional constructions. Roofs For the roofs, the tiles are made of concrete. It also has a slate, and uses thatch which is a straw. It can also be made from asphalt or felt and may contain copper or lead. Foundation Functions and Driving Forces A foundation is a dimension of a structure whose task is to support the loads super-imposed to it by the transmitting elements like columns. Raymond Wong (2002) presents several functions of a foundation: 1. Foundation averts settlement, which includes differential settlement, of a structure. 2. Foundation avoids the probable movement of a structure because of periodic shrinkage and swelling of the subsoil. 3. Foundation permits over water or water-logged ground buildings 4. Foundation resists wind power that can result to uplifting and overturning. 5. Foundation also prevents lateral movements because of the movement of the soil. 6. Foundation strengthens the existing or unbalanced structures. Wong (2002) also cites several factors that affect the choice and performance of foundations: (1) nature of the sub-soil, (2) foundation materials, (3) economical consideration in using the proper foundation, (4) layout of the structure which includes the building and floor plans, positioning loads and the like, and (5) site condition with respect to location and workspace. Classification of Foundation Foundation can be sub-divided into four (4) different categories which will be discussed in this paper: (1) Strip Foundation (see Figure 1i), (2) Deep Strip Foundation (see Figure 4ii), (3) Trench Fill Foundation (see Figure 3iii), and (4) Raft Foundation.(see Figure 2iv) Wong (2002) classifies the strip and raft foundations (aside from pad foundations) as examples of a single kind of foundation known as the shallow foundation. This type of foundation is rested on a stratum with sufficient capacity of the bearing and placed in 3m (at most) below the ground level. In selecting or choosing whether a shallow foundation is going to be used, Wong (2002) dictates that shallow foundation depends on the size and the disposition of the structural loads and also the bearing capacity of the subsoil. According to the author, the combination of either two or three types of shallow foundation on a single structure is common. The Strip Foundation is the most common foundation used in domestic works according to the ‘Building Approval Foundations’ in United Kingdom. The width of the foundation is dependent on the soil type. For single storey buildings, the width is around 450 mm wide while for two-storey buildings, the width is around 600 mm wide. Both have a thickness of at least 200 mm. Strip Foundations are used in transferring long and continuous loads such as walls. As mentioned above the width and depth of this foundation is dependent on two (2) factors: (1) nature of the ground, and (2) building loads. The Raft Foundation is a big thick slab combined that is designed to accommodate and support a large portion or the whole structure itself. Raft foundations are used when the subsoil is weak or the columns are placed very near each other and with diverged loadings. The foundation also serves as a transfer block to put together and tie-up all the vertical load elements to the plate-form foundation. (Wong 2002) Trench Fill foundation is another example of shallow foundation. This type of foundation is used when the concrete of more than 500 mm in depth filled the trench. The recommended is that the concrete infill is done to a minimum of 150mm below the ground level. It ensures the vertical alignment from the sides up to the top section and do not form the mushroom head. It other cases, lining of trenches may be required. Trench fill can also reduce labour costs and simplify operations below the ground level. (Building Approval Foundations) The Deep Strip Foundation is an example of deep foundation. Similar with strip foundation, deep strip foundation is ideal for continuous loads carried by walls. The depth of the foundation is increased to make a stronger load bearing strata on the base or to a depth where the ground’s moisture content is not affected by the seasonal variation. The upper layer of soil or clay is weak and thus susceptible to expansion and contraction brought by the changes in moisture content. In order to avoid this, compressible sheeting is used in order to prevent clay soils from exerting pressure in the deep strip foundation. Brickworks English Bond English bond (see Figure 5) contains alternating tracks of headers and stretchers, with the alternative headers placed in the centre, over and under the vertical joints of stretchers. English bond brick walls are ideal for garden walls. It observes a rule on building a wall made of brick that no two adjacent vertical lines should be in line. Flemish Bond Flemish bond (see Figure 6) consists also of alternating headers and stretchers with headers centred above and below the headers. It also observes the principle that no two adjacent vertical lines must be in line. Stretcher Bond The stretcher bond (see Figure 7) is the most commonly used bond today. The walls built using this kind of bond is a half brick wide. Similar with the first two bond types, no two adjacent vertical joints should be in line. List of References ‘Building Approval Foundations, Foundations to meet Swale’s soil conditions’. Swale.gov. (accessed 07 December 2008) Available from: http://www.swale.gov.uk/media/adobepdf/building_approval_foundations.pdf ‘The Characteristics of Traditional Construction’. Icomos.org (accessed 07 December 2008) Available from: http://www.icomos.org/iiwc/seismic/Yeomans.pdf. Wong, Raymond. ‘Foundation’. University of Hong Kong. 2002: 1-116. (accessed 07 December 2008) Available from: http://www.scribd.com/doc/3776571/Construction-Technology-series-Foundation. Endnotes: Read More