WEEK 6
STRUCTURAL CONCEPTS (2)
...and Ham ish’s work shop
# 640263 KATHRYN RANDALL-DZERDZ
Hamish’s workshop
Group: 2 Materials: 1200x3.9x90mm Ply Qualities: flexibility 1200x42x18mm Pine Qualities: free of knots = high structural integrity Parameters: Must span 1000mm and and resist the greatest applied force possible. Ply-wood attached with nails When the structure is loaded, the ply-wood warps revealing the tension along its upper edge as it ‘folds’ under this stress. The nails here may be pulled through the thin wood or ‘pop’ out, unable to resist the forces that are distorting the ply. Pine frame (affixed with nails) Two lengths of pine have been used to create a loadbearing frame, reinforced at intervals to distribute loads placed upon it. This type of framing is more practical under distributed loads, but failed quickly Ply-wood attached with screws (fig.1) under a live, concentrated load (fig.2) as the This wood also demonstrates distortion as it warps under stress could not be transmitted through the structure compressive and tensile forces. Unlike the nails however, the efficiently (fig.3). screws used here provide more resistance to the applied loads. The distribution and frequency of fixings determines the ability of the ply-wood to remain in contact with the pine frame, APPLIED LOAD but care must be taken not to weaken the pine structure in this COMPRESSION process (‘Hamish’ 2013, pers.comm., 6 September). FRACTURE POINT/S
TENSION
Figure 3: The forces within a structure under an applied load. Figure 1: An example of the fracture of pine and ply. Source: G. Lewis 2013.
Figure 2: An example of the concentrated loading of a structure. Source: G. Lewis 2013.
CASE STUDY - MODEL Due to the complexity of the building (Eastern Resource Centre link), a small subsection, determined to be of structural significance (fig.4) was recreated using balsa wood and card (fig.5). The end plates and the fixing of the roof spans to the existing concrete wall (fig.6) was an area of particular interest, and were recreated in detail (fig.7).
A
Figure 4: Section drawing of roofing structure.
Figure 6: Detailed section drawing of the end plate and fixings.
Existing ERC building
A Figure 7: Modelled end plate and cleats.
I-beams Figure 5: Modelled section.
Glossary Plasterboard Plasterboard is a common wall and ceiling lining material made of a gypsum (hydrated calcium sulphate (WordNet Search – 3.1 n.d.)) core surrounded by a “heavy-duty paper liner” (Boral 2012). The hydrated nature of the gypsum material helps prevent rapid fire spread, and may give up to 4 hours protection in certain applications. Plasterboard may also act to dampen noise, and may be manufactured to enhance this function. Typically, plasterboard is available in 1200mmwide sheets to suit standard 600mm stud spacing commonly found in modern housing structures. While it does not resist water, it can be sealed for use in wet-areas. Overall, plasterboard is a versatile material that can suit a number of applications depending on the manufacturing process (British Gypsum 2013). References: Boral 2002, Export Plasterboard Sheet Products, Available: http://www.boral.com.au/ plasterboardexport/export_plasterboard_sheet_products.asp [2013, 11 September]. British Gypsum 2013, 10 things you should know about plasterboard, Available: http:// www.british-gypsum.com/Technical-Advice/Installation-Guidance/10-things-youshould-know-about-plasterboard [2013, 11 September]. WordNet Search – 3.1 n.d. ‘Gypsum’, Available: http://wordnetweb.princeton.edu/ perl/webwn?s=gypsum [2013, 11 September].