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Cork Institute of Technology
Bachelor of Engineering (Honours) in Structural Engineering- Stage 3
(CSTRU_8_Y3)
Summer 2008
Engineering Practice
(Time: 3.5 Hours)
Instructions Answer ALL questions In Section A. Answer ONE question from Section B, and TWO questions from Section C.
Use separate answer books for each section
Examiners: Mr. A. M. Conway Mr. F. Delaney Mr. A. Mac Ilwraith Mr. P. Anthony Prof. P. O’Donoghue
Section A – Answer all questions
QA1 .(a) The attached drawing shows the cross section and plan of concrete retaining wall.
You are required to measure quantities using the civil engineering standard method of measurement (CESSM3) for: (i) Provision and placing of concrete. (ii) Formwork to sides of concrete foundations (bottom) (iii) Reinforcement to concrete foundations (bottom). 25 mm high yield steel is used; the bars are straight with a concrete cover of 30 mm. (25 marks)
QA2. (a) Discuss what is meant by the following terms used in the I.E.I. conditions of contract.
(i) Interim certificates (2 marks) (ii) Completion certificates (2 marks) (iii) Maintenance certificates (2 marks) (iv) Final certificates (2 marks) In your answer refer to when the certificates are issued.
(b) Discuss the conditions that might entitle: (i) the employer (ii) the contractor to terminate a contract. (7 marks)
Section B: FIRE
ANSWER 1 QUESTION FROM THIS SECTION (20 MARKS)
QB1.
(a) A new rapeseed oil production plant is proposed to be constructed using a 2 bay steel portal frame structure, as set out in Diagram B1 below. The confined site boundaries and nearby location of neighbouring buildings require that the boundary walls are fire-resisting. The steel boundary columns will be protected with intumescent paint, and will be required to remain in place in the event of a fire. Calculate the overturning moment, horizontal and vertical forces at foundation baseplate level, due to a boundary column in a fire scenario? (10 marks) (b) Examine the adequacy of 4 M24 holding down bolts, placed centrally on the column’s footprint, with a longitudinal spacing of 300 mm in the direction of bending. (10 marks) Additional information: a. The roof sheeting & purlins have a combined mass of 24 kg/m^2 , and 75% of this mass remains in the fire situation. b. The Haunch can be assumed to have an average mass of 35 kg/m c. The Boundary wall consists of Solid heavyweight cavity plastered blockwork weighing 7.6 kN/m^2. Assume wall loading taken fully by the foundation, and column to wall ties detailed accordingly d. The Portal Frames are at 5.4m Centres e. 1No. M24 holding down bolt has a maximum tensile load of 84.7 kN & a maximum shear load of 56.5 kN f. Both rafter and column are 533 x 210 x 82 kg/m UB, with an Ultimate Moment Capacity of 566 kNm & an overall depth of 533.2 mm
Section C
QC1 (a) With respect to chimneys and flues, what factors affect the final centreline height of the plume emitted from the flue or chimney? (2 marks)
(b) The flues for three boilers exit through a building and are mounted on a common support structure with each boiler at 2m centres relative to each other. Roof level is at 15m above ground level. The relative positions of the flues with respect to each other are shown in fig QC1.1. Flue A is from a 5 MW boiler, Flue B from a 5 MW boiler and Flue C from a 10 MW boiler. Using the attached tables and charts calculate the final heights of the flues in the multiple flue arrangement. (8 Marks)
Q2C (a) With respect to the Energy Performance of Buildings Directive state what is explicitly required under Article 3, 4, 5, 6, 7, 8, 9, 10 and 15. (7 marks)
(b) Explain what provisions the Irish government has put in place to implement Articles 3, and 7. (2 marks)
2m
2m
Flue A Flue B
Flue C
Roof Plan
Fig. QC1.
2m
(c) Detail the timeframe for the implementation of Articles 5, 6 and 7. ( marks)
QC3 (a) A fan coil unit air conditioning system serves a 3 storey office block with the air handling unit located in a roof top plantroom. The occupancy levels are as indicated in table QC3. and the ventilation rate is 10 litres per second per person. Using the attached sizing charts and tables, determine suitable supply and extract ductwork sizes for the main risers and branches off the riser. Assume the ductwork is to be rectangular cross section and the available ceiling void space limits the depth of ductwork branches off the riser to 400mm maximum. Estimate the space requirements for the installation of the riser. (9 marks)
(b) Explain why substantially larger ductwork would be required in the riser shafts if a variable air volume air conditioning system was to be installed. (1 mark)
QC4 The roof structure in diagram QC4.1 can be considered as thermally bridged. Calculate the U- value for the structure. Assume the resistance of the attic air space, rafters, felt, battons and tiles is 0.2 m^2 K/W. The thermal conductivity of the insulation, timber joist and plasterboard are 0.04, 0.13 and 0.25 W/mK respectively. Surface resistances are given in Table QC4. The percentage area of timber joists and insulation in the thermally bridged section is 8% and 92% respectively. (10 marks)
Occupancy Ground Floor 50 1 st^ Floor 80 2 nd^ Floor 60
Table QC3.
