Reference no: EM132571539
Unit 3 Science and Materials - Higher National Certificate in Construction & the Built Environment
Material Performance and Human Comfort
Learning Outcome 1: Justify material choice for a given building using performance properties, experimental data, sustainability and environmental consideration.
Learning Outcome 2: Evaluate the performance of a given building in respect of its human comfort requirements.
Scenario:
Tensile testing of metals is very important in the construction and manufacturing sectors for high-quality materials, and avoiding the major legal responsibility associated with the provision of noncompliant metals. It also ensures operational workability, personnel and project safety (reducing field failures) at both fracture and service conditions.
A Client organization (which include Kent County Council)believes that one of their sub-contractors (a local steel and metal fabricator) has imported some large amount of cheap and substandard steel alloy; from a non-renowned international steel manufacturing companyin Bangladesh (in the Indian Sub-continent). Metal alloys are explicitly designed or tailored to specific applications and use in classified projects; such as the one that is currently being provided and undertaken by the Client organization for the UK Government.
The recent fatalities from a building/factory collapse in Bangladesh where over 1100 workers lost their lives partly due to sub-standard steel materials and loading under service conditions; and the recent Grenfell Tower disaster in London, has imposed greater scrutiny on all contractors and construction practitioners work in the UK.Therefore, there is a necessity under statutory and contemporary expectations to undertake the relevant checks of such materials before use; especially their tensile and ductility performance testing checks.
One of the tensile test results obtained for the alleged "cheap steel" under ASTM E8 (an international standard for determining the tensile strength of metals); using "eXpert 2600 Series Dual Column Universal Testing Machine with wedge grips and extensometers is summarized in
Sample 1: 100mm length of 10mm diameter steel bar; and Sample 2: 100mm length of 8mm diameter steel bar.
The client organization above has also obtained an outline planning permission for the development of the Civil Engineering and Construction Laboratory Building project with an area size of 5000 X 25000mm for the University Centre Maidstone (UCM) and for the conversion of an old Victorian Farmhouse (situated on site) into a modern office space for the local Surgery/Health Centre. A speculated 3D model of the laboratory project is shown in Figure 1 below. The budget for this development is approximately £7million. The model in Figure 1 is not to scale.The assumption for the laboratory project portal frame could either be steel, timber, prestressed timber or reinforced concrete (precast, insitu, prestressed).
The old Victorian Farmhousecomprises traditional load-bearing walling at ground floor level and load-bearing stud partition at first floor. Stakeholders are very keen on achieving a comfortable working environment as much as possible for the Health Centre staff and patients.
Table 1 Tensile Strength Results (Specimen 1)
|
Load(kN)
|
Extension(mm)
|
|
0
|
0
|
|
1.88
|
0.01
|
|
5.65
|
0.03
|
|
9.42
|
0.05
|
|
11.3
|
0.06
|
|
18.84
|
0.1
|
|
22.61
|
0.12
|
|
26.38
|
0.14
|
|
28.26
|
0.15
|
|
29.4
|
0.2
|
|
30.6
|
0.3
|
|
31.1
|
0.365
|
|
31.8
|
0.5
|
|
34.2
|
1.15
|
|
37.8
|
1.925
|
|
Table 2 Tensile Strength Results (Specimen 2)
|
|
Load(kN)
|
Extension(mm)
|
|
0
|
0
|
|
3
|
0.02
|
|
8.2
|
0.07
|
|
13
|
0.09
|
|
16
|
0.1
|
|
22
|
0.14
|
|
27
|
0.18
|
|
31
|
0.2
|
|
33
|
0.21
|
|
34
|
0.22
|
|
35
|
0.3
|
|
35.3
|
0.365
|
|
37
|
0.5
|
|
38
|
1
|
|
42
|
1.9
|
|
Figure 1 3D Model (Use of Portal Frame)
As an Assistant Civil Engineer at Berrystone and Sandymount Associates (a civil and structural engineering consultancy and construction firm).The firm that undertook the laboratory tests and commissioned to undertake the project by the client organization, you have been tasked with the following responsibilities by your line manager:
Task 1
Using data in Table 1 and 2 above, you are to calculate the following:
a. Produce a conventional plot of both data on the same graph sheet to ascertain material behaviour under the given loading conditions and calculate the following:
I. Young's modulus.
II. 0.2% proof stress.
III. Estimated yield stress.
IV. Ultimate stress.
b. Explain which of these measurements is used for specification of steel (in line with the regulatory requirements) and why it is used.
Task 2
To develop a report which ascertain and assess the effectiveness, suitabilityand use of each of thedifferent structural materials mentioned above for the project portal frame atUCM.
This report is intended for the relevant stakeholders meeting taking place at Midkent College in four weeks' time. You are strongly advised to provide in your report all the relevant illustrations for every elements/form explained
Task 3
To use simple analogies (i.e.using comparative examples like commercial or domestic buildings) to explain/demonstrate how forces act on structures (load chasing) to both the property developer, the client and other stakeholders of the project. This has become necessary sincethese stakeholders have no knowledge of structural Mechanics.
Alongside you are expected to explainclearly (with the aid of simple diagrams)the behavior of structural member subjected to the following loading conditions:
I. Uniformly distributed load
II. Compressive stress
III. Tensile stress
IV. Shear stress
V. Bending/flexural stress
VI. A 200 cm long rod having a diameter of 2 cm is subjected to an axial pull of 25 KN. Determine the stress, strain and the elongation of the rod if the modulus of elasticity of the material (rod) is 2 x 105 N /mm2.
Task 4
As part of the reconversion of the Old Victorian building, your line manager (Senior Structural Engineer)at Berrystone and Sandymount Associates has identified two structural members (a beam and roof truss system; see Figures 2 and 3 below) he intends to design for the project. However,he has assigned you to undertake some very basic structural analysis of these members for the preliminary assessment of their loading impact on the supporting walls and building foundationand to identify which of the roof truss system member is undergoing tension and compression stress conditions.
She (your line manager) has instructedthe following:
i. using the applied loadings conditions on the simply supported beam and roof truss system shown below (Figure 2 and 3), determine their support reactions.
ii. Using Graphical method or method of Joints, you are to determine the value and type of force in each element of the pin-jointed truss system in Figure 3 below.
Task 5
Your firm has been approached by the client organization to provide a report that can be used to educate the stakeholders on how to achieve a comfortable working environment within the Victorian Building Conversion project in line with the following:
a) Describe using at least four factors that influence an individual's overall perception of comfort in the internal environment. These should include factors from the thermal, acoustic and visual environment.
b) Using the correct units describe the basic methods used to measure each of the factors described in item "a" above. No calculations are required at this stage.
c) Using the correct units, state acceptable values or range of values for each of the factors identified above
d) You are expected to produce clear calculations and accurate answers for the following sets of calculations.
I. Calculate the amount of heat energy required to heat 200 kg of water from 10 Celsius to 60 degree Celsius. Note the specific heat of water is 4200 J / kg Celsius.
II. Calculate the amount of heat energy produced by the complete combustion of 80 kg of timber having a calorific value of 16 MJ / Kg.
III. Calculate the rate of heat loss through 6 m2 of concrete when the temperature inside is 12 degree Celsius higher than outside. The concrete has a thickness of 150 mm and thermal conductivity of 1.5 W / m Celsius.
IV. An external cavity wall has a U-value of 0.80 W / m2 Celsius. Calculate the rate of heat loss through 4 m2 of external cavity wall when the temperature difference of 20 Celsius exists between the inside and outside temperature.
V. The sound level is 90 dB at 2 m from a source. Calculate the sound level at 6 m.
VI. Calculate the illuminance produced by a 65 candelas lamp on a surface 2 m away
VII. The daylight factor for a kitchen is 2.22 % and the illuminance outside is 5000 Lux. Calculate the expected illuminance inside the kitchen due to daylight.
e) You are to identify and explain the basic factors with relevant examples that affect human welfare for a balanced indoor environment; these must include the following:
I. How the thermoregulatory system is affected by air temperature, mean radiant temperature, relative humidity, airspeed, activity and how clothing level creates the perception of thermal comfort.
II. How specific values for factors that affect the visual environment interact with the vision system that enables us to perform our task.
III. How specific values for factors that affect the aural environment interact with the hearing system that enables us to concentrate and make the space fit for purpose.
Attachment:- Science and Materials.rar