Construction Systems: Building Technology Report (Essay Sample)

BUILDING TECHNOLOGY REPORT
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Building Technology Report
Question 2
Budget, soil types, design loads, adjacent structures, the technology available, type of structure, conditions adjacent to the site are among the factors that are considered when selecting the type of foundation to use when constructing a building. The loading conditions (magnitude and type of loads) and the foundation material are of particular importance in the design of foundations. According to Chudley and Greeno (2013), the bearing soil at the site should be able to withstand the pressure transmitted by the specific type of foundation adopted by the structural engineer (p. 24). In this regard, the foundation material should be able to support the dead weight resulting from both the super and substructure while providing a safety margin sufficient to accommodate imposed loads from winds and building occupants.
The ground conditions at the proposed site justify the use of pile foundation in this project. According to site investigations, the subsoil is made up of mixed boulder clays extending to a depth of an average of 8 meters overlying a range of sandstones, coal, and shale deposits from the carboniferous era. The use of other types of foundations particularly pad footings will necessitate the evacuation of the entire glacial deposits which will not be economically practical. Coduto (2015) affirms that shallow types of foundations such as strip footings are adopted when the soil near the surface is capable of accommodating the ultimate loading of the structure (p. 106). In this perspective, glacial deposits fail to meet the requirements of a shallow foundation since they are characterized by high degree of consolidation especially when wet. Buildings constructed on glacial materials undergoes a significant amount of elastic and secondary settlement resulting to wide cracks on the walls and often a total failure of the structure (Chudley and Greeno, 2013, p. 40). The soil conditions on the site have low shear strengths and cohesion values, which ultimately results in low bearing capacity and thus, it is recommendable to adopt pile foundation.
The presence of mining in the locality and the adoption of a framed construction approach justifies the use of a pile foundation. Areas near deep mining sites are prone to subsidence and differential settlement of shallow foundations. According to Coduto (2015), machinery aided mining activities triggers vibration of the adjacent land making multistory buildings constructed on shallow foundations unstable (p. 120). In this light, the proposed project has three stories and is, therefore, likely to undergo wall deformation as a consequence of ground curvature attributed to the mining activities. A study conducted by Coduto (2015) on the effects of mining on the building foundations depicts that load bearing walls used in conjunction with strip footings undergoes a significant amount of cracking as a result of shock waves resulting from blasting activities and movement of heavy machinery working in mining sites (p. 132).
Pile foundations are also preferred in the construction of framed multistory buildings, where, live and dead loads are concentered at the point of application. Piles offer support to the loadings of the superstructure through either friction or endpoint bearing. Hu, Lian, and Chen (2016) ascertain that in instances where a firm foundation material is overlain by strata of compressible soils, steel, concrete or timber piles are used to transmit loadings to the bearing firm ground (p. 255). In this project the use of pile foundation can be supported by the fact that shallow footings resting on weak soils depict a relative inability to resist lateral, inclined, overturning moments, and uplifting loads (Kibert, 2016, p. 178). Some of the pile foundation approaches that can be adopted for the project include bored piles and driven piles, which are prefabricated and brought on site for construction purposes. Hu, Lian, and Chen (2016) state that driven piles are most effective in loose soils since they have a huge capacity to support anticipated design loads in competent subsurface material as consequence of friction force present and end bearing support (p. 260). Driven piles are also cheaper in comparison to bored piles, which require the use of excavating tools such as the bucket-auger-core barrel.
Raft foundations could also be adopted in place of the piles. According to Knaack, Klein, Bilow, and Auer (2014), this type of foundation is adopted with an objective of spreading the ultimate load from the structure over a significantly larger area, normally the entire proposed site (p. 234). The use of raft foundation is based on the relationship between pressure and the area it acts upon. Kibert (2016) affirms that the use of a concrete slab extending over the entire loaded area ensures that the pressure resulting from loads of the structure are minimized to a value approximately equal to the bearing capacity of the supporting soils (p. 200). Effective use of raft foundations entails stiffening the slab either by the use of ribs or cast in place beams. Coduto (2015) ascertains that raft foundations are needed on loose or soft soils with relatively low bearing capacity since they can spread the loadings on a large area and decrease the resulting pressure (p. 140). This type of foundation also ensures that differential settlements remain within the desired limits as the concrete slab resists movements between loading positions. Structural concrete with a minimum comprehensive strength of 25N/mm2 after 28 days is used in the construction of raft foundations. The slab is also reinforced with steel depending on the amount of hogging and sagging moments resulting from the weight of the building. Columns bases are then cast on the slab which acts as the footing for the piers (Knaack et al., 2014, p. 250).
Question 6
Safety is important in the construction industry owing to a wide array of parameters that can result in severe accidents in sites. In this regard, it is the duty of the contractor, designers, and project managers to ensure that the safety of the craftsmen, artisans, and laborers is guaranteed. According to Hinze, Thurman, and Wehle (2013), approximately 1.3 million people in the United Kingdom suffered from a work-related illness in 2015 (p. 25). Cooper, Junginger, and Lockwood (2013) state that one hundred and forty-four people died at work and approximately 0.6 million individuals were involved in non-fatal accidents in 2013 (p. 422). The Construction Design and Management Regulations (CDM) 2015 were introduced to govern the manner in which all constructions projects are planned, with an objective of nurturing health and safety in the sector. Walker (2015) ascertains that CDM 2015 is an update of the 2007 regulations and aims at improving safety, health, and welfare of everyone working in the construction industry (p. 302). The guidelines accord unique duties to contractors, clients, and designers, to reconsider their perception of health and safety, in order to consider them through the lifecycle of a project.
Hinze, Thurman, and Wehle (2013) affirm that the regulations fall into five broad categories, with each part having a myriad of requirements (p. 27). In this case, part four, which deals with general requirements for all constructions sites is of particular importance. According to Cooper, Junginger, and Lockwood (2013), the most critical requirement of CDM 2015 is the one that details the need for safe construction sites (p. 430). According to the guideline, a proposed workplace should provide sufficient working space that is arranged in a manner that minimizes risks to individual entering and leaving the site and also those executing tasks geared towards implementing the project. In regard to this requirement, a construction site should at all times ensure that the health of all workers is upheld by designing measures that reduce infection resulting from dust and emissions from machinery (Hinze, Thurman, and Wehle, 2013, p. 28).
Stability of a structure is another requirement of CDM 2015 that aims at minimizing accidents resulting from the collapse of elements such as columns, beams, formwork, and walls. It is the duty of the clerk of works and the site agent to ensure that all practicable steps are undertaken to ensure that any existing or new structural element doesn’t collapse as consequence of ongoing construction work (Cooper, Junginger, and Lockwood, 2013, p. 450). In this regard, it is important that structures should be used for the purpose for which they were designed for and maintained occasionally in order to reduce unforeseeable circumstances that may lead to their collapse. CDM 2015 also require demolition of structures to be executed in a way that minimizes the chances of accidents to a practical value. The process of dismantling of structures should, therefore, be planned and the arrangements for such activities recorded in writing before the demolition work begin (Walker, 2015, p. 306). This provision protects those working at the site as well as individuals adjacent to the construction project.
The provisions of CDM 2015 stresses on the need for cofferdams and caissons in all projects close to any water body. Cooper, Junginger, and Lockwood (2013) define a cofferdam as a temporary structure meant to exclude water from the working area with an objective of ensuring the element under construction gains the required strength (p. 443). For instance, conventional concrete gains comprehensive strength with time and should be protected from excessive water surges for at least 28 days after casting. The regulations ...