Contents
Table of Contents
Introduction 2
1. LO 1 Understanding the properties and uses of materials in construction: 2
1.1 The Properties of Construction Materials 5
1.2 Properties of materials: 6
1.3 Uses of materials: construction, refurbishment, maintenance, replacement,
energy efficiency:………………………………………………………………………………………………….…9
2. LO2 Understanding the structural behavior of construction materials……………………………………..10
2.1 The Effects of Loading Structural materials……………………………………………………….10
2.2 Comparison of Timber, Steel and Reinforced Concrete Structural Members under Load…….11
3. LO3 Relation of Scientific Principles to Human Comfort Levels………………………………………………..14
3.1 Factors affecting human comfort……………………………………………………………………….14
3.2 Methods used to integrate building services into the overall building design……………………..15
4. Conclusion ……………………………………………………………………………………………………………………………..18
5. References………………………………………………………………………………………………………………………………19
Introduction:
Mathematical techniques can be applied to practical engineering problems to make optimum use of resources by evaluating a number of different options which may be available in terms of material and their relative affordability and effectiveness, keeping in mind the ecology friendly features that each of these possess. This gives all concerned options to consider when looking towards executing a particular construction project.
LO 1 Understanding the properties and uses of materials in construction:
1.1 The Properties of Construction Materials
Materials Used Uses In Structures Young’s Modulus (E) Locally Available Alternative Materials
Aggregates (Gravel) (1) Clay (Soft to hard) Used as sub base support for concrete slabs for foundation, underground drainage fill and basic ingredient for concrete. 10-200 MPa Yes Glass cullet, crushed recycled concrete, granulated coal ash, blast furnace slag
(2) Sandy (loose to compact) As above 10-50 MPa Yes As above
(3) Gravel Soil (loose to compact) As above 70-170 MPa Yes As above
Clay products (1) Bricks Used for masonry work, they are the smallest unit held together by mortar 3 .00– 5..66 MPa Yes Fly ash, aerocon (autoclaved aerated concrete)
(2) Tiles
(i) Panels
Also used as a masonry unit 67-68 GPa Yes Concrete, acrylic, decra, bitumen
(ii) Porcelain Stoneware Also used as a masonry unit 50 – 80 GPa Yes As above
(3) Cement It is a binder, essential for the preparation of mortar mix for masonry and for preparing concrete. GPa Yes Geopolymer, lime mixed with pozzola (slag, fly ash, calcinated clay), sulphur, gypsum
(4) Concrete It is a composite material made from aggregate, water and cement and used for preparing the foundation and structure of the building. 17 GPa Yes Wood, cold formed steel, structural concrete insulated panel, cross laminated wood
(5) Concrete, High Strength (compression) As above 30 GPa Yes As above
Metals And Alloys (1) Iron Used mostly for reinforcement of concrete in foundation and structure of the building and for other miscellaneous items likes latches, hinges etc. 210 GPa Yes Steel, aluminium
(2) Steel, Structural ASTM-A36 As above 200 GPa Yes Reinforced concrete, cross laminated wood
(3) Copper Used in roofing, exterior cladding, electrical wiring, heating systems, plumbing etc 117 GPa Yes Brass, Crossed linked polythelene (PEX)
(4) Brass Used for making pipes, tubes, weather stripping etc 102-125 GPA Yes unplasticised PVC or HDPE products
(5) Aluminium Used for window frames, roofing, siding, door handles, window catches, air conditioning and heating systems, etc. 69 GPa Yes unplasticised PVC or HDPE products, steel
(6) Lead Used in pipes for plumbing and materials like paint, solder, coating etc. 13.79 GPa Yes R.C.C., uPVC, G.I., C.I.
Timber and timber products (1) Timber Used for wall paneling, thermal insulation, scaffolding etc 9-13 GPa Yes Fibre Reinforced Polymer Board, gypsum plaster board
(2) Plywood Used for wall paneling, thermal insulation etc 12.4 GPa Yes Use phenol bonded instead of urea bonded, Fibre Reinforced Polymer Board, Gypsum board
Plastics and other artificial materials (1) Carbon fiber reinforced Used for strengthening and increasing flexure of structure of the building, replaces steel as in structure 150 GPa Yes Steel
(2) HDPE Used for plumbing pipes and storage tanks mostly 0.8 GPa Yes R.C.C., uPVC, G.I., C.I.
(3) Gypsum plaster board Decorative and protective uses mostly on ceiling and wall linings and partitions. 2.01 GPa Yes Magnesium Oxide, Wood
(4) Ceramic tiles Used for decorative and protective purposes on floors, roofs, walls etc. 38.78 GPa Yes Hardwood, laminated tiles, marble, bamboo
(5) Glass (96% silica) Used for decorative purposes and for thermal and fire insulation and interior fittings. 46.2 GPa Yes Brick, wood, brick
1.2 Properties of materials:
a. Important characteristics of materials to be used in providing main supporting structure of the building:
1. Concrete: The effective properties of concrete would depend on the cementitious mixture of cement and water with aggregates. A lower cementitious ratio makes a stronger concrete, this ratio would also determine the density, shrinkage, resistance to abrasion and water demand. It has considerably less tensile and shear strength (5MPa) as compared to compressive strength (14-42 MPa), concrete is therefore reinforced with steel to compensate for that. Elasticity of concrete is constant 17 GPa, except under high stress levels. Its co-efficient for thermal expansion is very low and concrete subject to long term compression has a tendency to creep. Its natural advantages of high compressive strength, low elasticity, low co-efficient of thermal expansion makes it the perfect choice as a foundation material, its weaknesses compensated to a certain extent by reinforcing it.
2. Steel: Steel has a high strength to weight ratio, combined with that its comparatively high fatigue strength, ductility, ability to be prefabricated, speed and ease of erection and repair, make it the material of choice for reinforcing concrete and for making the structure of a building. The disadvantages of steel is that it has a high elasticity (200 GPa) and a tendency to buckle along with a low co-efficient of thermal expansion which is compensated by using more material and fireproofing the material.
3. Cement: It is essential for the preparation of concrete. It acts as a binder. It offers a high compressive strength which increases gradually after it sets. It has a high ability to absorb water and low elasticity both of which decreases when it sets. Combines with fly ash or other pozzolanas it binds the concrete to the aggregates.
4. Aggregates: Aggregates are gravel, either clay or sandy used to make the concrete admixture. Their water absorption capacity, elasticity, hardness depends on the kind of aggregate used.
b. Important characteristics of materials to be used for minimizing the amount of energy needed to maintain a comfortable thermal environment:
1. Aluminium: Polished aluminium has a reflectivity of 0.80 and an emissivity of 0.05 and thus makes the perfect material for maintaining a comfortable thermal environment inside the building.
2. White washing the exterior of the building is another way of maintaining the thermal environment, as it has a reflectivity of 0.70 and an emisivity of 0.90.
3. Glass: In a damp and cold external environment, large glass windows offer the option of letting the sunlight in while preventing the heat inside from escaping and are therefore a suitable material. It has a reflectivity of 0.08 and emissivity of 0.90.
If so desired, extended sunshades can be provided on windows to prevent the summer sun while allowing the winter sun to penetrate into the building through glass windows. This is particularly useful during exceptionally hot summers.
Another eco-friendly approach would be to have a roof garden which will prevent radiation at night while absorbing heat during the day.
4. Gypsum plaster boards: These are poor conductors and natural insulators, therefore they prevent heat from escaping the rooms and prevents the cold winds from entering inside and thus helps maintain the thermal environment.
c. Important characteristics of materials to be used for providing a dry and hard-wearing and smooth ground floor of the building: For a floor of these characteristics, the best materials to use are marble, Terrazzo, concrete, mosaic etc. These materials have a few characteristics in common. They are cost effective, durable and attractive in appearance, non-absorbent, resistant to staining and easily cleanable. They are smooth (except concrete floors).
d. Important characteristics of materials to be used for prevention of rising damp: Rising damps are caused by the rise of ground water through capillaries in mortar and concrete. To prevent this houses include synthetic damp proof course. Low porosity slate bricks are used for the first few courses around 15 cm above ground level through which water cannot pass
e. Important characteristics of materials to be used for producing fire doors: Fire doors are usually made of glass, gypsum, timber, steel, vermiculite or aluminum. The thermal co-efficient of these materials are very low compared to other materials. They are non-conductors.
f. Important characteristics of materials to be used for covering the play area for young children: The most common ones would be sand, pea gravel, wood chips, Bark Mulch, engineered wood fiber, shredded tires, mats or tiles, poured in place. The area should be properly fenced in for the protection of the child. Common property of the materials is they are highly elastic and porous in nature. These materials have a low density.
1.3 Uses of materials: construction, refurbishment, maintenance, replacement, energy efficiency:
Comparison between cross laminated wood materials such as Glulam with steel and concrete for the main structure of the building:
Glulam and steel are functionally are equally capable when it comes to supporting the structure of a building. Steel is the tried and tested approach. Engineers are trained on steel, all calculations learnt are based on steel and therefore the preferred choice. Pricewise, glulam is a little costlier than steel. A Glulam beam of 360 x 140mm is priced at £35 per m whereas steel beam of 203 x 133 x 25kg would be about £20 per m. The preparation of steel leaves a huge carbon footprint which glulam does not, so glulam is a greener option. However, the bias towards steel is more pronounced as this is a huge industry and major contributor towards the economy of countries involved in its manufacture. UK usually imports steel from China, if it came to glulam imports would probably be from European countries. Glulam has a higher weight to strength ratio, about 1.5 times, and is less effective when it comes to spanning further than steel. There is a possibility of lumber deflecting a little with the passage of time. Wood expansion due to temperature changes are also an issue, although steel is susceptible as well, its chances of going out of alignment are lesser as compared to wood because it comes back to its original dimensions with the decrease of temperature. Aesthetically, glulam fares better than steel, lending that ambience of warmth which steel and concrete never can. Furthermore, steel deforms under high heat, so is glulam with special fire protective finishes perform better in cases of fire. Considering the predominantly cold and damp climate in the UK, glulam can definitely considered as an effective e alternative to steel when comes to reliability, performance aesthetics and definitely more green.
LO2 Understanding the structural behavior of construction materials
2.1 The Effects of Loading Structural materials
Roof needs to support a garden and the weight of solar water heater, also the interior needs to provide the maximum free space possible and flexibility. The internal walls cannot be structural and the beams supporting the roof can be supported only at their ends.
a). Depth of the supporting beam is the most important dimension: A beam bears or resists load perpendicular to its length mostly in flexure and shear. The strength and stiffness of a beam depends more on its height (depth) than its width (thickness). a rectangular beam with depth of 12 inches has a bending strength that is 4 times that of a beam with 6-inch depth. For a beam supporting uniform load (w) along the entire length, maximum bending moment (at midspan) is calculated as;
Moment, M = wL^2 / 8
Units for uniform load w are force per distance, such as pounds per foot (or pounds per linear foot).
Reaction force, R (acting in opposite direction to loading) occurs at each support;
Reaction, R = wL/2
Moment varies with square of span length (L), such that required moment strength increases very quickly as the span length increases. For example, increasing span length from 10 feet to 12 feet results in a 44% increase in maximum moment (for the same uniform load).
The depth or height of a beam is the most important dimension to be taken into consideration.
b). Material that would allow least beam depth: When designing a beam, at least four items must be considered:
The beam must have a bending strength sufficient to withstand the bending moments.
There must be no danger of failure due to shear forces.
The deflection of the beam, must not be too much.
There must be no risk of lateral buckling.
Give some thought to the behavior of a beam of elastic material such as timber or steel. Picture the beam to comprise of layers of longitudinal fibers with all the layers being solidly cemented together. If a load is placed on the top of the beam, which is supported at each end, the longitudinal fibers near the top of the beam will become shorter as a result of the bending and are therefore stressed in compression. The fibers near the bottom of the beam will become longer and are thus stressed in tension.
Since the fibers near the top and bottom of the beam are more highly stressed than those near the neutral axis, it is advisable to have as much material as far as possible from the neutral avis. This is why we see the shape of often used steel beam sections. Most of the steel is concentrated in the flanges where it is most effective in combating bending. The web on the other hand must have sufficient steel to withstand the shear forces. The material of the beam is obviously important. A steel beam is much stronger than a timber beam of identical dimensions.
2.2 Comparison of Timber, Steel and Reinforced Concrete Structural Members Under Load
a). Explanation of the term “slenderness ratio” with respect to the columns that support the roof: The Slenderness Ratio is the (effective) length of the column divided by its radius of gyration. The radius of gyration is the distance from an axis which, if the entire cross sectional area of the object (beam) were located at that distance, it would result in the same moment of inertia that the object (beam) possesses. Or, it may be expressed as: Radius of Gyration: rxx = (Ixx/A)1/2 (radius of gyration about xx-axis)
So, Slenderness Ratio = Le / r.
Subscript "e" indicates that, we do not use the actual length but the ‘effective length’, depending on how the column is supported.
b). Effect on slenderness ratio where the same column supports the roof and the floors:
The effect would be as shown in the diagram above of a loaded pinned-pinned column. The bending moment indicated, M and in terms of the load P, and the deflection distance y, we can write:
M = - P y.
We also can write that for columns the bending moment is proportional to the curvature of the beam, which, for small deflection can be expressed as:
(M /EI) = (d2y /dx2). Where E = Young's modulus, and I = moment of Inertia.
c). Euler’s equation for maximum axial loading on a column without buckling:
Finding Euler’s equation: Continuing from above, Then substituting from EQ. 1 to EQ. 2, we obtain:
3. (d2y /dx2) = -(P/EI)y or (d2y /dx2) + (P/EI)y = 0
This is a second order differential equation, which has a general solution form of
4. :
We next apply boundary conditions: y = 0 at x = 0, and y = 0 at x = L. That is, the deflection of the column must be zero at each end since it is pinned at each end. Applying these conditions (putting these values into the equation) gives us the following results: For y to be zero at x =0, the value of B must be zero (since cos (0) = 1). While for y to be zero at x = L, then either A must be zero (which leaves us with no equation at all, if A and B are both zero), or
. Which results in the fact that
And we can now solve for P and find:
5. , where Pcr stands for the critical load which can be applied before buckling is initiated.
6. By replacing L with the effective length, Le, which was defined above, we can generalize the formula to:
, which is applicable to Pinned-Pinned and Fixed-Fixed Also to Fixed-Pinned and Fixed-Free columns.
Thus it is a form of Euler's Equation. Another form may be obtained by solving for the critical stress:
and then remembering that the Radius of Gyration: rxx = (Ixx/A)1/2 , and substituting we can obtain:
which gives the critical stress in terms of Young's Modulus of the column material and the slenderness ratio.
Let us at this time also point out that Euler's formula applies only while the material is in the elastic/proportional region. That is, the critical stress must not exceed the proportional limit stress. If we now substitute the proportional limit stress for the critical stress, we can arrive at an equation for the minimum slenderness ratio such that Euler's equation will be valid.
Euler's Equation for columns while useful, is only reasonably accurate for long columns, or slenderness ratio's of general range: 120 < Le / r < 300, and in addition will work for axially loaded members with stress in the elastic region, but not with eccentrically loaded columns.
Most important material characteristic to avoid buckling:
Slenderness Ratio = Le / r.
Where, radius of Gyration: rxx = (Ixx/A)1/2 (radius of gyration about xx-axis) Subscript "e" indicates that, we do not use the actual length but the ‘effective length’, depending on how the column is supported.
LO3 Relation of Scientific Principles to Human Comfort Levels
3.1 Factors affecting human comfort:
a). Acceptable values in UK:
Factors for thermal comfort Acceptable value or range
Temperature 13°C to 16°C
Relative Humidity 50 – 55%
Radiant heat 7- 13 %
Relative humidity 50 - 55 %
Air velocity 0.1 to 0.2 m/s
Artificial light 30 - 150 lux
Glare Approx 6.3 SI
Sound transmission 60 db
Sound absorption 13 - 15 db
Sound insulation 2.3 db
Acoustic comfort Up to 43 db
3.2 Methods used to integrate building services into the overall building design
a). Explanation of how electric power distributed safely to all the rooms and safety precautions built in to ensure that electric wires do not overheat:
There will be alternate power sources besides the one provided by the authorities. There will be emergency supply options in the form of generators and UPS for the uninterrupted supply of electricity to prevent data loss in computer labs and offices.
For HV there will be a HV room to house HV switchgears and other equipment located near the periphery of the premises out of bounds of regular inhabitants of the building. There should be a consumer HV room for the equipment essential for the safe handling of HV supply received from the HV room. Besides there will also be a need for transformer room, UPS room and generator room, depending on scale these can be housed together in one room as well.
For LV supply same arrangement will apply and we will ensure that LV room is as close to the transformer room as possible to minimize voltage drop and expense on cable and tension of large diameter cables which are required for LV supply.
The generator room is essential to safety in case of emergencies. Fire fighters would need an alternate source to run their equipment in case of a fire because a normal cable might fail under fire. Also, keeping in mind the noise and vibration caued by these generators they should be housed separately but not too far away from the main building.
There should be sub-stations located inside the building or very near to it and near to each other and accessible to heavy maintenance vehicles, should be well ventilated
Electrical sub-main cables or service ducts to carry the cables to the upper floors or for lateral distribution are also required; they are also called riser rooms. They should be stacked as closely as possible.
For large floors, individual floor electrical room to house electrical equipment in that floor, they house the electrical panels that serve the final circuit wiring.
A sample ground floor layout of building services
A sample diagram of roof level
b). Precautions to ensure electrical wirings do not overheat:
Circuit protection devices are intended to immediately limit or shut off the flow of electricity in the occasion of a ground-fault, overload, or short circuit in the wiring system. Fuses, circuit breakers, and ground-fault circuit interrupters are three well-known examples of such devices.
Fuses and circuit breakers stop over-heating of wires. They disconnect the circuit when it becomes overloaded.
c). Room sealed central heating boiler and how it ensures safe use of gas for heating the school:
The boilers that work to the highest standard are the fan-assisted room-sealed type, it takes air from outside the building and combustion products are forced out using a fan. These are regular or conventional boilers that work on the principal of stored water and need a separate hot water cylinder. A sealed type like the one being discussed is the most efficient. They come in features that ensure safe and optimum use of gas and energy like
Room thermostat: when a set temperature is reached, an electrical contact is broken inside the thermostat to switch off the electrical
Cylinder thermostat: Fixed to the cylinder, so that when the top reaches around 60°C, it switches off the electrical supply.
TRVs: Thermostatic radiator valves on all radiators, except in rooms containing a thermostat. It automatically closes off the water supply to the radiator when the desired temperature is reached.
Dwellings should normally be divided into two space heating zones with independent temperature control (one in the living area). The heating circuit and hot water ideally be controlled separately.
Conclusion:
Here we considered a number of possible alternatives for materials and showed mathematically their effectiveness in usage. A number of scientific premises and principles were applied towards determining the right and viable options for specific work and their proper execution. Opportunities considered have been in terms of being eco-friendly, effective and cost effective. The outcome of this discussion has also kept open a number of alternative options which can be considered in similar projects.
References
1. Domestic central heating and hot water: systems with gas and oil-fired boilers– guidance for installers and specifiers, [Online], Available: http://regulations.completepicture.co.uk/pdf/Energy%20Conservation/Heating%20Systems%20-%20Boilers/Domestic%20central%20heating%20and%20hot%20water-%20systems%20with%20gas%20and%20oil-fired%20boilers%20-.pdf [29 July, 2014].
2. (2005), Construction Materials — Types and Uses, [Online], Available: http://www.g-w.com/pdf/sampchap/9781590703472_ch10.pdf
3. (2009), Rural Structures in the tropics: Design and development, [Online], Available: http://www.fao.org/docrep/015/i2433e/i2433e02.pdf
4. Adinarayana, M. (2011), Building Materials, [Online], Available: http://www.vigyanprasar.gov.in/chemistry_application_2011/briefs/Building_materials.pdf
5. (2013), alifornia Stormwater BMP Handbook, New Development And Redevelopment, [Online], Available: https://www.escondido.org/Data/Sites/1/media/pdfs/Utilities/BMPAlternativeBuildingMaterials.pdf
6. (2003), Design Guide on Use of Alternative Steel Materials to BS 5950, [Online], Available: http://www.bca.gov.sg/publications/others/design_guide_on_use_of_structural_steel.pdf
7. Milani, Brian (2005), Building Materials in a Green Economy :Community-based Strategies for Dematerialization, [Online], Available: http://www.greeneconomics.net/MilaniThesis.pdf
8. Tsoumis, G. (1991), Science and technology of wood: structure, properties, utilization, [Online], Available: http://www.fao.org/docrep/015/i2433e/i2433e02.pdf
9. Electronic Journal of Geotechnical Engineering, Vol. 13, Special Issue State of the Art in Geotechnical Engineering, December, pp. 1-38.Paterson, D.N.1971.
10. Wilson, A., & Malin, N. (1999). Structural Engineered Wood: Is it green? Environmental Building News, 8(11)
11. (2003), Zero Emissions Research Institute (ZERI)., ZERI Systems and Projects, from http://www.zeri.org/systems.htm
12. Yost, P. (2001). Getting the 'Right Stuff': A guide to green building materials retailers. Environmental Building News, 10(4)
13. Yost, P. (2000). Deconstruction: Back to the future for buildings? Environmental Building News, 9(5)
14. Wooley, T., & Fox, W. (2000). The Ethical Dimension of Environmental Assessment and Sustainable Building. Paper presented at the Sustainable Building 2000, Maastricht, The Netherlands
15. Wooley, T. (2000). Green Building: Establishing principles. In W. Fox (Ed.), Ethics and the Built Environment. London: Routledge.
16. Wojciechowska, P. (2001). Building With Earth: A guide to flexible-form earthbag construction. White River Junction, VT: Chelsea Green Publishing Company.
17. Wilson, A., & Malin, N. (1999). Structural Engineered Wood: Is it green? Environmental Building News, 8(11).
18. Whitaker, J. S. (1994). Salvaging the Land of Plenty: Garbage and the American Dream. New York: William Morrow & Co.
19. Wann, D. (1996). Deep Design: Pathways to a livable future. Washington DC: Island Press.
20. Van der Ryn, S., & Calthorpe, P. (1986). Sustainable Communities: A new design synthesis for cities, suburbs and towns. San Francisco: Sierra Club Books.
21. U.S. Environmental Protection Agency. (1998). Characterization of Building-Related Construction and Demolition Debris in the United States (No. EPA530-R-98-010): US EPA.
22. Trusty, W., & Meil, J. K. (1999, October 1999). Building Life Cycle Assessment: Residential case study. Paper presented at the Mainstreaming Green, AIA Environment Committee conference on green building and design, Chattanooga, TN
23. Trusty, W., & Horst, S. (2002). Integrating LCA Tools in Green Building Rating Systems. In Environmental Building News (Ed.), The Austin Papers: Best of the 2002 International Green Building Conference (pp. 53-57). Brattleboro VT: BuildingGreen Inc.
24. Zero Emissions Research Institute (ZERI). (2003). ZERI Systems and Projects, from http://www.zeri.org/systems.htm.
25. Rubik, F. (2001). Environmental Sound Product Innovation and Integrated Product Policy. Journal of Sustainable Product Design(1), 219-232.
26. Rodale, R. (1985). Pioneer Enterprises in Regeneration Zones: the role of small business in regional recovery. Whole Earth Review(47).
27. Reuters. (2000). Soy Adhesive Friendly to Environment, Mills, [Online], Available: http://edition.cnn.com/2000/NATURE/07/31/soy.adhesive.reut/#1
28. Rees, W. (1995). More Jobs, Less Damage: A framework for sustainability, growth and employment. Alternatives, 21(4), 24-30.
29. Robertson, J. (2000). Financial and Monetary Policies for an Enabling State: New Economics Foundation Alternative Mansion House Speech, June 15, 2000, [Online], Available: http://www.jamesrobertson.com/ne/alternativemansionhousespeech-2000.pdf
30. Mont, O. (2002a). Clarifying the Concept of Product-Service System. Journal of Cleaner Production, 10(3), 237-245.
31. Healthy Building Network. (2005b). PVC is Not a Green Building Material, [Online], Available: http://www.healthybuilding.net/usgbc/tsac.html
Table of Contents
Introduction 2
1. LO 1 Understanding the properties and uses of materials in construction: 2
1.1 The Properties of Construction Materials 5
1.2 Properties of materials: 6
1.3 Uses of materials: construction, refurbishment, maintenance, replacement,
energy efficiency:………………………………………………………………………………………………….…9
2. LO2 Understanding the structural behavior of construction materials……………………………………..10
2.1 The Effects of Loading Structural materials……………………………………………………….10
2.2 Comparison of Timber, Steel and Reinforced Concrete Structural Members under Load…….11
3. LO3 Relation of Scientific Principles to Human Comfort Levels………………………………………………..14
3.1 Factors affecting human comfort……………………………………………………………………….14
3.2 Methods used to integrate building services into the overall building design……………………..15
4. Conclusion ……………………………………………………………………………………………………………………………..18
5. References………………………………………………………………………………………………………………………………19
Introduction:
Mathematical techniques can be applied to practical engineering problems to make optimum use of resources by evaluating a number of different options which may be available in terms of material and their relative affordability and effectiveness, keeping in mind the ecology friendly features that each of these possess. This gives all concerned options to consider when looking towards executing a particular construction project.
LO 1 Understanding the properties and uses of materials in construction:
1.1 The Properties of Construction Materials
Materials Used Uses In Structures Young’s Modulus (E) Locally Available Alternative Materials
Aggregates (Gravel) (1) Clay (Soft to hard) Used as sub base support for concrete slabs for foundation, underground drainage fill and basic ingredient for concrete. 10-200 MPa Yes Glass cullet, crushed recycled concrete, granulated coal ash, blast furnace slag
(2) Sandy (loose to compact) As above 10-50 MPa Yes As above
(3) Gravel Soil (loose to compact) As above 70-170 MPa Yes As above
Clay products (1) Bricks Used for masonry work, they are the smallest unit held together by mortar 3 .00– 5..66 MPa Yes Fly ash, aerocon (autoclaved aerated concrete)
(2) Tiles
(i) Panels
Also used as a masonry unit 67-68 GPa Yes Concrete, acrylic, decra, bitumen
(ii) Porcelain Stoneware Also used as a masonry unit 50 – 80 GPa Yes As above
(3) Cement It is a binder, essential for the preparation of mortar mix for masonry and for preparing concrete. GPa Yes Geopolymer, lime mixed with pozzola (slag, fly ash, calcinated clay), sulphur, gypsum
(4) Concrete It is a composite material made from aggregate, water and cement and used for preparing the foundation and structure of the building. 17 GPa Yes Wood, cold formed steel, structural concrete insulated panel, cross laminated wood
(5) Concrete, High Strength (compression) As above 30 GPa Yes As above
Metals And Alloys (1) Iron Used mostly for reinforcement of concrete in foundation and structure of the building and for other miscellaneous items likes latches, hinges etc. 210 GPa Yes Steel, aluminium
(2) Steel, Structural ASTM-A36 As above 200 GPa Yes Reinforced concrete, cross laminated wood
(3) Copper Used in roofing, exterior cladding, electrical wiring, heating systems, plumbing etc 117 GPa Yes Brass, Crossed linked polythelene (PEX)
(4) Brass Used for making pipes, tubes, weather stripping etc 102-125 GPA Yes unplasticised PVC or HDPE products
(5) Aluminium Used for window frames, roofing, siding, door handles, window catches, air conditioning and heating systems, etc. 69 GPa Yes unplasticised PVC or HDPE products, steel
(6) Lead Used in pipes for plumbing and materials like paint, solder, coating etc. 13.79 GPa Yes R.C.C., uPVC, G.I., C.I.
Timber and timber products (1) Timber Used for wall paneling, thermal insulation, scaffolding etc 9-13 GPa Yes Fibre Reinforced Polymer Board, gypsum plaster board
(2) Plywood Used for wall paneling, thermal insulation etc 12.4 GPa Yes Use phenol bonded instead of urea bonded, Fibre Reinforced Polymer Board, Gypsum board
Plastics and other artificial materials (1) Carbon fiber reinforced Used for strengthening and increasing flexure of structure of the building, replaces steel as in structure 150 GPa Yes Steel
(2) HDPE Used for plumbing pipes and storage tanks mostly 0.8 GPa Yes R.C.C., uPVC, G.I., C.I.
(3) Gypsum plaster board Decorative and protective uses mostly on ceiling and wall linings and partitions. 2.01 GPa Yes Magnesium Oxide, Wood
(4) Ceramic tiles Used for decorative and protective purposes on floors, roofs, walls etc. 38.78 GPa Yes Hardwood, laminated tiles, marble, bamboo
(5) Glass (96% silica) Used for decorative purposes and for thermal and fire insulation and interior fittings. 46.2 GPa Yes Brick, wood, brick
1.2 Properties of materials:
a. Important characteristics of materials to be used in providing main supporting structure of the building:
1. Concrete: The effective properties of concrete would depend on the cementitious mixture of cement and water with aggregates. A lower cementitious ratio makes a stronger concrete, this ratio would also determine the density, shrinkage, resistance to abrasion and water demand. It has considerably less tensile and shear strength (5MPa) as compared to compressive strength (14-42 MPa), concrete is therefore reinforced with steel to compensate for that. Elasticity of concrete is constant 17 GPa, except under high stress levels. Its co-efficient for thermal expansion is very low and concrete subject to long term compression has a tendency to creep. Its natural advantages of high compressive strength, low elasticity, low co-efficient of thermal expansion makes it the perfect choice as a foundation material, its weaknesses compensated to a certain extent by reinforcing it.
2. Steel: Steel has a high strength to weight ratio, combined with that its comparatively high fatigue strength, ductility, ability to be prefabricated, speed and ease of erection and repair, make it the material of choice for reinforcing concrete and for making the structure of a building. The disadvantages of steel is that it has a high elasticity (200 GPa) and a tendency to buckle along with a low co-efficient of thermal expansion which is compensated by using more material and fireproofing the material.
3. Cement: It is essential for the preparation of concrete. It acts as a binder. It offers a high compressive strength which increases gradually after it sets. It has a high ability to absorb water and low elasticity both of which decreases when it sets. Combines with fly ash or other pozzolanas it binds the concrete to the aggregates.
4. Aggregates: Aggregates are gravel, either clay or sandy used to make the concrete admixture. Their water absorption capacity, elasticity, hardness depends on the kind of aggregate used.
b. Important characteristics of materials to be used for minimizing the amount of energy needed to maintain a comfortable thermal environment:
1. Aluminium: Polished aluminium has a reflectivity of 0.80 and an emissivity of 0.05 and thus makes the perfect material for maintaining a comfortable thermal environment inside the building.
2. White washing the exterior of the building is another way of maintaining the thermal environment, as it has a reflectivity of 0.70 and an emisivity of 0.90.
3. Glass: In a damp and cold external environment, large glass windows offer the option of letting the sunlight in while preventing the heat inside from escaping and are therefore a suitable material. It has a reflectivity of 0.08 and emissivity of 0.90.
If so desired, extended sunshades can be provided on windows to prevent the summer sun while allowing the winter sun to penetrate into the building through glass windows. This is particularly useful during exceptionally hot summers.
Another eco-friendly approach would be to have a roof garden which will prevent radiation at night while absorbing heat during the day.
4. Gypsum plaster boards: These are poor conductors and natural insulators, therefore they prevent heat from escaping the rooms and prevents the cold winds from entering inside and thus helps maintain the thermal environment.
c. Important characteristics of materials to be used for providing a dry and hard-wearing and smooth ground floor of the building: For a floor of these characteristics, the best materials to use are marble, Terrazzo, concrete, mosaic etc. These materials have a few characteristics in common. They are cost effective, durable and attractive in appearance, non-absorbent, resistant to staining and easily cleanable. They are smooth (except concrete floors).
d. Important characteristics of materials to be used for prevention of rising damp: Rising damps are caused by the rise of ground water through capillaries in mortar and concrete. To prevent this houses include synthetic damp proof course. Low porosity slate bricks are used for the first few courses around 15 cm above ground level through which water cannot pass
e. Important characteristics of materials to be used for producing fire doors: Fire doors are usually made of glass, gypsum, timber, steel, vermiculite or aluminum. The thermal co-efficient of these materials are very low compared to other materials. They are non-conductors.
f. Important characteristics of materials to be used for covering the play area for young children: The most common ones would be sand, pea gravel, wood chips, Bark Mulch, engineered wood fiber, shredded tires, mats or tiles, poured in place. The area should be properly fenced in for the protection of the child. Common property of the materials is they are highly elastic and porous in nature. These materials have a low density.
1.3 Uses of materials: construction, refurbishment, maintenance, replacement, energy efficiency:
Comparison between cross laminated wood materials such as Glulam with steel and concrete for the main structure of the building:
Glulam and steel are functionally are equally capable when it comes to supporting the structure of a building. Steel is the tried and tested approach. Engineers are trained on steel, all calculations learnt are based on steel and therefore the preferred choice. Pricewise, glulam is a little costlier than steel. A Glulam beam of 360 x 140mm is priced at £35 per m whereas steel beam of 203 x 133 x 25kg would be about £20 per m. The preparation of steel leaves a huge carbon footprint which glulam does not, so glulam is a greener option. However, the bias towards steel is more pronounced as this is a huge industry and major contributor towards the economy of countries involved in its manufacture. UK usually imports steel from China, if it came to glulam imports would probably be from European countries. Glulam has a higher weight to strength ratio, about 1.5 times, and is less effective when it comes to spanning further than steel. There is a possibility of lumber deflecting a little with the passage of time. Wood expansion due to temperature changes are also an issue, although steel is susceptible as well, its chances of going out of alignment are lesser as compared to wood because it comes back to its original dimensions with the decrease of temperature. Aesthetically, glulam fares better than steel, lending that ambience of warmth which steel and concrete never can. Furthermore, steel deforms under high heat, so is glulam with special fire protective finishes perform better in cases of fire. Considering the predominantly cold and damp climate in the UK, glulam can definitely considered as an effective e alternative to steel when comes to reliability, performance aesthetics and definitely more green.
LO2 Understanding the structural behavior of construction materials
2.1 The Effects of Loading Structural materials
Roof needs to support a garden and the weight of solar water heater, also the interior needs to provide the maximum free space possible and flexibility. The internal walls cannot be structural and the beams supporting the roof can be supported only at their ends.
a). Depth of the supporting beam is the most important dimension: A beam bears or resists load perpendicular to its length mostly in flexure and shear. The strength and stiffness of a beam depends more on its height (depth) than its width (thickness). a rectangular beam with depth of 12 inches has a bending strength that is 4 times that of a beam with 6-inch depth. For a beam supporting uniform load (w) along the entire length, maximum bending moment (at midspan) is calculated as;
Moment, M = wL^2 / 8
Units for uniform load w are force per distance, such as pounds per foot (or pounds per linear foot).
Reaction force, R (acting in opposite direction to loading) occurs at each support;
Reaction, R = wL/2
Moment varies with square of span length (L), such that required moment strength increases very quickly as the span length increases. For example, increasing span length from 10 feet to 12 feet results in a 44% increase in maximum moment (for the same uniform load).
The depth or height of a beam is the most important dimension to be taken into consideration.
b). Material that would allow least beam depth: When designing a beam, at least four items must be considered:
The beam must have a bending strength sufficient to withstand the bending moments.
There must be no danger of failure due to shear forces.
The deflection of the beam, must not be too much.
There must be no risk of lateral buckling.
Give some thought to the behavior of a beam of elastic material such as timber or steel. Picture the beam to comprise of layers of longitudinal fibers with all the layers being solidly cemented together. If a load is placed on the top of the beam, which is supported at each end, the longitudinal fibers near the top of the beam will become shorter as a result of the bending and are therefore stressed in compression. The fibers near the bottom of the beam will become longer and are thus stressed in tension.
Since the fibers near the top and bottom of the beam are more highly stressed than those near the neutral axis, it is advisable to have as much material as far as possible from the neutral avis. This is why we see the shape of often used steel beam sections. Most of the steel is concentrated in the flanges where it is most effective in combating bending. The web on the other hand must have sufficient steel to withstand the shear forces. The material of the beam is obviously important. A steel beam is much stronger than a timber beam of identical dimensions.
2.2 Comparison of Timber, Steel and Reinforced Concrete Structural Members Under Load
a). Explanation of the term “slenderness ratio” with respect to the columns that support the roof: The Slenderness Ratio is the (effective) length of the column divided by its radius of gyration. The radius of gyration is the distance from an axis which, if the entire cross sectional area of the object (beam) were located at that distance, it would result in the same moment of inertia that the object (beam) possesses. Or, it may be expressed as: Radius of Gyration: rxx = (Ixx/A)1/2 (radius of gyration about xx-axis)
So, Slenderness Ratio = Le / r.
Subscript "e" indicates that, we do not use the actual length but the ‘effective length’, depending on how the column is supported.
b). Effect on slenderness ratio where the same column supports the roof and the floors:
The effect would be as shown in the diagram above of a loaded pinned-pinned column. The bending moment indicated, M and in terms of the load P, and the deflection distance y, we can write:
M = - P y.
We also can write that for columns the bending moment is proportional to the curvature of the beam, which, for small deflection can be expressed as:
(M /EI) = (d2y /dx2). Where E = Young's modulus, and I = moment of Inertia.
c). Euler’s equation for maximum axial loading on a column without buckling:
Finding Euler’s equation: Continuing from above, Then substituting from EQ. 1 to EQ. 2, we obtain:
3. (d2y /dx2) = -(P/EI)y or (d2y /dx2) + (P/EI)y = 0
This is a second order differential equation, which has a general solution form of
4. :
We next apply boundary conditions: y = 0 at x = 0, and y = 0 at x = L. That is, the deflection of the column must be zero at each end since it is pinned at each end. Applying these conditions (putting these values into the equation) gives us the following results: For y to be zero at x =0, the value of B must be zero (since cos (0) = 1). While for y to be zero at x = L, then either A must be zero (which leaves us with no equation at all, if A and B are both zero), or
. Which results in the fact that
And we can now solve for P and find:
5. , where Pcr stands for the critical load which can be applied before buckling is initiated.
6. By replacing L with the effective length, Le, which was defined above, we can generalize the formula to:
, which is applicable to Pinned-Pinned and Fixed-Fixed Also to Fixed-Pinned and Fixed-Free columns.
Thus it is a form of Euler's Equation. Another form may be obtained by solving for the critical stress:
and then remembering that the Radius of Gyration: rxx = (Ixx/A)1/2 , and substituting we can obtain:
which gives the critical stress in terms of Young's Modulus of the column material and the slenderness ratio.
Let us at this time also point out that Euler's formula applies only while the material is in the elastic/proportional region. That is, the critical stress must not exceed the proportional limit stress. If we now substitute the proportional limit stress for the critical stress, we can arrive at an equation for the minimum slenderness ratio such that Euler's equation will be valid.
Euler's Equation for columns while useful, is only reasonably accurate for long columns, or slenderness ratio's of general range: 120 < Le / r < 300, and in addition will work for axially loaded members with stress in the elastic region, but not with eccentrically loaded columns.
Most important material characteristic to avoid buckling:
Slenderness Ratio = Le / r.
Where, radius of Gyration: rxx = (Ixx/A)1/2 (radius of gyration about xx-axis) Subscript "e" indicates that, we do not use the actual length but the ‘effective length’, depending on how the column is supported.
LO3 Relation of Scientific Principles to Human Comfort Levels
3.1 Factors affecting human comfort:
a). Acceptable values in UK:
Factors for thermal comfort Acceptable value or range
Temperature 13°C to 16°C
Relative Humidity 50 – 55%
Radiant heat 7- 13 %
Relative humidity 50 - 55 %
Air velocity 0.1 to 0.2 m/s
Artificial light 30 - 150 lux
Glare Approx 6.3 SI
Sound transmission 60 db
Sound absorption 13 - 15 db
Sound insulation 2.3 db
Acoustic comfort Up to 43 db
3.2 Methods used to integrate building services into the overall building design
a). Explanation of how electric power distributed safely to all the rooms and safety precautions built in to ensure that electric wires do not overheat:
There will be alternate power sources besides the one provided by the authorities. There will be emergency supply options in the form of generators and UPS for the uninterrupted supply of electricity to prevent data loss in computer labs and offices.
For HV there will be a HV room to house HV switchgears and other equipment located near the periphery of the premises out of bounds of regular inhabitants of the building. There should be a consumer HV room for the equipment essential for the safe handling of HV supply received from the HV room. Besides there will also be a need for transformer room, UPS room and generator room, depending on scale these can be housed together in one room as well.
For LV supply same arrangement will apply and we will ensure that LV room is as close to the transformer room as possible to minimize voltage drop and expense on cable and tension of large diameter cables which are required for LV supply.
The generator room is essential to safety in case of emergencies. Fire fighters would need an alternate source to run their equipment in case of a fire because a normal cable might fail under fire. Also, keeping in mind the noise and vibration caued by these generators they should be housed separately but not too far away from the main building.
There should be sub-stations located inside the building or very near to it and near to each other and accessible to heavy maintenance vehicles, should be well ventilated
Electrical sub-main cables or service ducts to carry the cables to the upper floors or for lateral distribution are also required; they are also called riser rooms. They should be stacked as closely as possible.
For large floors, individual floor electrical room to house electrical equipment in that floor, they house the electrical panels that serve the final circuit wiring.
A sample ground floor layout of building services
A sample diagram of roof level
b). Precautions to ensure electrical wirings do not overheat:
Circuit protection devices are intended to immediately limit or shut off the flow of electricity in the occasion of a ground-fault, overload, or short circuit in the wiring system. Fuses, circuit breakers, and ground-fault circuit interrupters are three well-known examples of such devices.
Fuses and circuit breakers stop over-heating of wires. They disconnect the circuit when it becomes overloaded.
c). Room sealed central heating boiler and how it ensures safe use of gas for heating the school:
The boilers that work to the highest standard are the fan-assisted room-sealed type, it takes air from outside the building and combustion products are forced out using a fan. These are regular or conventional boilers that work on the principal of stored water and need a separate hot water cylinder. A sealed type like the one being discussed is the most efficient. They come in features that ensure safe and optimum use of gas and energy like
Room thermostat: when a set temperature is reached, an electrical contact is broken inside the thermostat to switch off the electrical
Cylinder thermostat: Fixed to the cylinder, so that when the top reaches around 60°C, it switches off the electrical supply.
TRVs: Thermostatic radiator valves on all radiators, except in rooms containing a thermostat. It automatically closes off the water supply to the radiator when the desired temperature is reached.
Dwellings should normally be divided into two space heating zones with independent temperature control (one in the living area). The heating circuit and hot water ideally be controlled separately.
Conclusion:
Here we considered a number of possible alternatives for materials and showed mathematically their effectiveness in usage. A number of scientific premises and principles were applied towards determining the right and viable options for specific work and their proper execution. Opportunities considered have been in terms of being eco-friendly, effective and cost effective. The outcome of this discussion has also kept open a number of alternative options which can be considered in similar projects.
References
1. Domestic central heating and hot water: systems with gas and oil-fired boilers– guidance for installers and specifiers, [Online], Available: http://regulations.completepicture.co.uk/pdf/Energy%20Conservation/Heating%20Systems%20-%20Boilers/Domestic%20central%20heating%20and%20hot%20water-%20systems%20with%20gas%20and%20oil-fired%20boilers%20-.pdf [29 July, 2014].
2. (2005), Construction Materials — Types and Uses, [Online], Available: http://www.g-w.com/pdf/sampchap/9781590703472_ch10.pdf
3. (2009), Rural Structures in the tropics: Design and development, [Online], Available: http://www.fao.org/docrep/015/i2433e/i2433e02.pdf
4. Adinarayana, M. (2011), Building Materials, [Online], Available: http://www.vigyanprasar.gov.in/chemistry_application_2011/briefs/Building_materials.pdf
5. (2013), alifornia Stormwater BMP Handbook, New Development And Redevelopment, [Online], Available: https://www.escondido.org/Data/Sites/1/media/pdfs/Utilities/BMPAlternativeBuildingMaterials.pdf
6. (2003), Design Guide on Use of Alternative Steel Materials to BS 5950, [Online], Available: http://www.bca.gov.sg/publications/others/design_guide_on_use_of_structural_steel.pdf
7. Milani, Brian (2005), Building Materials in a Green Economy :Community-based Strategies for Dematerialization, [Online], Available: http://www.greeneconomics.net/MilaniThesis.pdf
8. Tsoumis, G. (1991), Science and technology of wood: structure, properties, utilization, [Online], Available: http://www.fao.org/docrep/015/i2433e/i2433e02.pdf
9. Electronic Journal of Geotechnical Engineering, Vol. 13, Special Issue State of the Art in Geotechnical Engineering, December, pp. 1-38.Paterson, D.N.1971.
10. Wilson, A., & Malin, N. (1999). Structural Engineered Wood: Is it green? Environmental Building News, 8(11)
11. (2003), Zero Emissions Research Institute (ZERI)., ZERI Systems and Projects, from http://www.zeri.org/systems.htm
12. Yost, P. (2001). Getting the 'Right Stuff': A guide to green building materials retailers. Environmental Building News, 10(4)
13. Yost, P. (2000). Deconstruction: Back to the future for buildings? Environmental Building News, 9(5)
14. Wooley, T., & Fox, W. (2000). The Ethical Dimension of Environmental Assessment and Sustainable Building. Paper presented at the Sustainable Building 2000, Maastricht, The Netherlands
15. Wooley, T. (2000). Green Building: Establishing principles. In W. Fox (Ed.), Ethics and the Built Environment. London: Routledge.
16. Wojciechowska, P. (2001). Building With Earth: A guide to flexible-form earthbag construction. White River Junction, VT: Chelsea Green Publishing Company.
17. Wilson, A., & Malin, N. (1999). Structural Engineered Wood: Is it green? Environmental Building News, 8(11).
18. Whitaker, J. S. (1994). Salvaging the Land of Plenty: Garbage and the American Dream. New York: William Morrow & Co.
19. Wann, D. (1996). Deep Design: Pathways to a livable future. Washington DC: Island Press.
20. Van der Ryn, S., & Calthorpe, P. (1986). Sustainable Communities: A new design synthesis for cities, suburbs and towns. San Francisco: Sierra Club Books.
21. U.S. Environmental Protection Agency. (1998). Characterization of Building-Related Construction and Demolition Debris in the United States (No. EPA530-R-98-010): US EPA.
22. Trusty, W., & Meil, J. K. (1999, October 1999). Building Life Cycle Assessment: Residential case study. Paper presented at the Mainstreaming Green, AIA Environment Committee conference on green building and design, Chattanooga, TN
23. Trusty, W., & Horst, S. (2002). Integrating LCA Tools in Green Building Rating Systems. In Environmental Building News (Ed.), The Austin Papers: Best of the 2002 International Green Building Conference (pp. 53-57). Brattleboro VT: BuildingGreen Inc.
24. Zero Emissions Research Institute (ZERI). (2003). ZERI Systems and Projects, from http://www.zeri.org/systems.htm.
25. Rubik, F. (2001). Environmental Sound Product Innovation and Integrated Product Policy. Journal of Sustainable Product Design(1), 219-232.
26. Rodale, R. (1985). Pioneer Enterprises in Regeneration Zones: the role of small business in regional recovery. Whole Earth Review(47).
27. Reuters. (2000). Soy Adhesive Friendly to Environment, Mills, [Online], Available: http://edition.cnn.com/2000/NATURE/07/31/soy.adhesive.reut/#1
28. Rees, W. (1995). More Jobs, Less Damage: A framework for sustainability, growth and employment. Alternatives, 21(4), 24-30.
29. Robertson, J. (2000). Financial and Monetary Policies for an Enabling State: New Economics Foundation Alternative Mansion House Speech, June 15, 2000, [Online], Available: http://www.jamesrobertson.com/ne/alternativemansionhousespeech-2000.pdf
30. Mont, O. (2002a). Clarifying the Concept of Product-Service System. Journal of Cleaner Production, 10(3), 237-245.
31. Healthy Building Network. (2005b). PVC is Not a Green Building Material, [Online], Available: http://www.healthybuilding.net/usgbc/tsac.html
