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CORK INSTITUTE OF TECHNOLOGY
INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ
Semester 2 Examinations 2010/
Module Title: Construction Technology
Module Code: BULD
School: Mechanical and Process Engineering
Programme Title: Bachelor of Engineering (Honours) in Sustainable Energy – Year 1
Bachelor of Engineering in Building Services Engineering – Year 2
Programme Code: EBSEN _7_Y
ESENT_8_Y
External Examiner(s):. Prof. E. Coyle, Mr. R. Linger
Internal Examiner(s): Dr. Ger Kelly
Instructions: Answer THREE Questions
All Questions carry equal marks.
Duration: 2 Hours
Sitting: Summer 2011
Requirements for this examination:
Note to Candidates: Please check the Programme Title and the Module Title to ensure that you have received the correct examination paper. If in doubt please contact an Invigilator.
Q
a) Explain the difference between a horizontal line and a level line. (4 marks) b) Outline how you would check the level of the bottom of a trench. ( 4 marks) c) Figure Q1 shows a site layout plan of the Glasgow College of Building (GCB) outdoor centre. It is proposed to lay a sewer pipe along the line F1-F4 at a gradient of 1 in 40. A manhole exists at F1 with an existing invert level of 2.950m AOD and 3 further manholes are to be built along this line at points F2 – F4. Prior to excavation of the trench for the sewer pipe the levels of the road along this line were taken. The levelling commenced by taking a BS reading onto a temporary bench mark at point B
(7.780m AOD) and levels were taken at the centreline the existing roadway along this line from F1- F4 at 8m distance intervals. The final level reading taken was onto another temporary benchmark at point D whose reduced level was 5.555m AOD. Table Q1 shows the readings obtained during the levelling along the line of the proposed foul sewer FI-F
i. Calculate the reduced levels of the ground at the various points indicated. (8 marks) ii. Check the error in the levelling measurement at D. (5 marks) iii. Draw a longitudinal section along the line F1 -F4, showing clearly: the ground surface the proposed sewer, rising from the existing invert level (2.950 m AOD) of manhole F1 at a gradient of 1 in 40. (6 marks) iv. Calculate the invert levels of the proposed manholes F2 – F4. (6 marks)
Note You may assume for simplicity that the invert level coincides with the bottom of the trench excavation
BS IS FS Reduced Level
Distance (m)
Remarks
0.320 7.780 Point B (7.78m AOD) 1.440 0.000 Manhole F1 (Existing) 1.310 8.000 C/L of proposed Sewer 1.150 16.000 C/L of proposed Sewer 1.250 1.490 24.000 Proposed Manhole F 1.390 32.000 C/L of proposed Sewer 1.460 40.000 C/L of proposed Sewer 1.790 48.000 Proposed Manhole F 1.860 56.000 C/L of proposed Sewer 1.150 1.640 64.000 Proposed Manhole F 1.622 TBM at D (5.555m AOD)
Table Q1 Readings taken along proposed sewer line F1-F
Q2.
(a) Describe both the advantages and disadvantages of steel as a construction material. (6 marks) (b) Outline the mechanism of fire spread in the stardust fire. ( 6 marks)
(c) Elements of structure will only act as effective firebreaks if they have the necessary degree of fire resistance. Briefly describe the three criteria necessary for fire resistance. ( 6 marks)
(d) What is a section factor and explain how it is used in fire resistance calculations. (6 marks)
(e) Compute the section factor for a Structural Tee Beam 305x457x127 kg/m which is to be protected on 3 sides. Hence or otherwise determine the required thickness of Cafcote 280, a sprayed Cementitious mineral fibre material to give a fire resistance of 2.5 hours. ( 6 marks)
(f) If it was decided to us a box protection for this T section described in part (e) above, rather than profile protection, what would its section factor be for 3 sided protection? ( 3 marks)
Note partial Cafcote 280 data sheet is provided as Table Q2.
Q3.
(a) For a given aggregate content describe the factors upon which the compressive strength of concrete depends. How is the strength of concrete determined. What is meant by characteristic strength of concrete. (5 marks)
(b) Describe and sketch common shear reinforcement in RC beams. Outline where and why is it used, and how it differs from longitudinal reinforcement. (8 marks)
(c) Discuss considerations for accommodating services within the depth of a concrete beam in the vicinity of the supports and in the middle of the span of the beam. (8 marks)
(d) The figure below (Figure Q3) shows an elevation detailing the reinforcement of a concrete beam of rectangular cross section 300 wide by 400mm deep. Draw cross sections through the beams at points 1, 2, and 3 showing the details and marking of the reinforcement. Assume a standard cover to the bars (12 marks)
Figure Q3 Reinforced concrete beam
4 R 1004-100 8 R 1004-
2400
9 R 1004-
2600
2 R 1203 & 2R 1205
02 02 2 R 1601 & 2 R 1202
1
1
2
2
500
05
2000
3
3
4 R 1004-100 8 R 1004-
2400
9 R 1004-
2600
2 R 1203 & 2R 1205
02 02 2 R 1601 & 2 R 1202
1
1
2
2
500
05
2000
3
3
Q4.
(a) Describe the following natural ventilation strategies and identify the form and building layout for which they are best suited. (i) Single sided ventilation (3 marks) (ii) Cross ventilation (3 marks) (iii) Stack ventilation (3 marks )
(b) Describe the relationship between air inlet size and height in a building. What implications has this on the ventilation strategies likely to be employed on the upper floors of a building. (8 marks)
(c) A shopping centre is to be cooled using natural (stack) ventilation. The shopping centre has vents at a low level and in the roof. The proposed free area of the lower vents is 5m^2 , the proposed free area of the top vents is 10m^2 and the proposed height difference between the vents is 30m. If the desired volumetric flow rate in the stack is 14.0 m^3 /s, and the mean internal air temperature is 32°C, estimate the upper limit of external air temperature at which this design will function. Assume the Coefficient of discharge of the openings is 0.61. (16 marks)
Useful Formulae
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av
o t d n
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V C A
2 2 2
An Ain A out
