Concrete Frame Building and Timber Frame - Assignment Example

Question 1 The major difference between a concrete frame building and a timber frame lies in the choice of materials in use. Most of the time the outer walls in both the timber and concrete frame building will be the same where they may be found to be finished in brick, stone or by use of a skim coat. It is not easy for an onlooker to distinguish a timber frame house just by looking on the outside of the structure unless the external wall of the building is clad in timber. A masonry house building is quite different in comparison to timber frame building. It involves tradesmen working on site in all weather, with the building being erected brick by brick. A masonry house will involve various skilled tradesmen being needed to come in to complete their tasks so as to allow the next step to proceed: carpenters are required at the point when the building is at the first floor so that they can fit timber floor joists (BS 4978 ,1988).. Then the block work immediately commence at the next level. In masonry frame building all the load bearing walls will be built with concrete blocks with the internal walls and partitioning involving the use of timber. Plumbing and electrical services will be chased into the blockwork or maybe inside the stud frames. Some of the advantages associated with masonry frame building is that most of the architects happen to be familiar with the design and the building process; most of the builders have experience in constructing masonry houses and it is easy to make alterations incase of inaccurate foundations. Masonry frame structures have associated disadvantages. With masonry structure it is a challenge for the desired level of thermal insulation to be achieved. Masonry structures maybe associated with large settlement and shrinkage cracks. Masonry structures are associated with long process of building dictated by the prevailing weather conditions in addition to masonry taking a considerably long time to dry. Timber frame construction on the other hand will involve fixed panels being brought to the site and they being lifted into place by use of a crane and being positioned into the desired positions by the carpenters on concrete foundations and floors which are usually repapered in advance. By virtue of the timber frame being built off site, there is reduction of vulnerability of work schedules as a result of exposure to inclement weather (LST EN 518, 2000). By the time of arrival of panels, windows and doors will already be pre-hung and in place and this will considerably minimize errors in calculations and work onsite. A case involving a typical timber frame will take about seven days to erect and to be made watertight thereby allowing other trades to commence their work immediately (Keith F. et al, 1999). Polythene clad will be used in waterproofing exterior walls before construction of the brick or block-work. Some of the disadvantages associated with timber frame include the need to have a very accurate foundation and base; and timber frames does not allow having concrete first floor. The advantages of timber frames are The prefabricated structure associated with timber will allow quick onsite erection Timber frame ensures less time loss in the process of construction as the construction process is not dependant on weather Timber has good thermal and insulation qualities In timber structure it is easy to run services in stud wall panels Timber frame is associated with very accurate corners and edges as the components are made in the factory. Cost Difference between timber frame and concrete At the construction stage the two type of construction may not have significant difference in terms of cost. However at time of occupancy the timber frame building will prove to be much economical because of efficiency in energy consumption. Timber frames houses are sealed to ensure that the heat in the houses is not able to escape through openings. References BS 4978 (1988). Visual Strength Grading of Softwood. London. The Encyclopedia of Wood. Keith F. et al (1999).Wood Engineering and Construction Handbook, New York, McGran-Hill, Inc. LST EN 518 (2000) Structural Timber Grading – Requirements for Visual Strength Grading Standards. The Encyclopedia of Wood(1989) . New York, Sterling Publishing Co., Inc. Question 2 a) Mass of dry timber = 3.27kg Mass of wet timber = 3.87kg Mass of water = 3.87-3.27 = 0.6kg b) Hygroscopic materials have the ability of attracting and holding water molecules from the surrounding environment. This is usually achieved through either absorption or adsorption where the absorbing or adsorbing material becoming physically changed to some extent by expanding, becoming sticky or through exhibiting other physical changes as a result of the water particles being suspended inside the molecules of the material. Materials will tend to exhibit a variety of hygroscopic properties and as a result of these differences there may be detrimental effects, including stress concentration in composite materials. Coefficient of hygroscopic expansion (CHE) is a measure the extent to which a material is affected by ambient moisture. c) Timber to be used in internal application is need to have specific moisture content to ensure that treatment by preservative is satisfactory, will ensure machining is accurate and efficient fabrication thus avoiding problems due to dimension change. All this are important because internal fixtures of a house require high level of accuracy. d) The signs of dry rot are Wood that appears to shrink, split or crumble with the easiest way of detecting the dry rot being the use of a screw driver to prod the timber Detection of a growth that resembles a pancake having an arrange centre, a clear indication that dry rot is highly present as the arrange centre repenting millions of dry rot spores. The spores aid in the spreading of the dry rot in the entire building Dry rot can also be manifested in a smell similar to that of mushrooms A growth resembling cotton wool referred to as mycelium which is white in colour is another manifestation of presence of dry rot. Question 3 Sieve size (mm) Mass (g) % on sieve % passing 125 0 0 100 75 0 0 100 63 88 6.2 93.8 37.5 55 3.9 89.9 20 87 6.2 83.7 10 98 7.0 76.7 6.3 95 6.7 70.0 3.35 102 7.3 62.7 2 129 9.2 53.5 1.18 89 6.4 47.1 0.6 85 6.1 41.0 0.3 90 6.4 34.6 0.212 92 6.6 28.0 0.15 84 6.0 22 0.063 90 6.4 15.6 Figure 1 From the graph figure 1 d10, = 0.05mm d30 = 0.15 d60 = 3 Coefficient of gradation Ck = d302/d60d10 = 0.152/ (3x0.05) = 0.15 For Ck that ranges from 0.5 to 2.0 show the aggregate is well graded while for Ck value less than 0.1 will mean gap graded particles (ACI 213R-03, 2003). Read More