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~~Bm~m1(t ]THE HONG KONG INSTITUTION OF ENG INEERS~m~m~~G:ft l{:)::fcttt i 1 5tft: ltSfU9~ii9 /F Isla nd B eve rle y, N o 1 G re at G eo rg e S t. C au se wa y B ay, H on g K on g~~Tel +852 2895 4446 ~~ Fax + 852 2577 [email protected] www.hkie.org.hk

The HKIE Structural Examination - Written ExaminationSection 2: Design Questions

(80% of the Written Examination)Date: 11 December 2009 (Friday)

Time: 1:15 pm- 6:15 pm

Answer ONE question only
mailto:[email protected]://www.hkie.org.hk/http://www.hkie.org.hk/mailto:[email protected]


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Question 1 Cable Equipment BuildingClient's requirementsL An equipment building is to be developed inside an existing cable station in Lantau;see Figure Q 1.2. The building line of the equipment building has to be in line with the outer edge ofthe existing retaining walL3. For aesthetic reasons, the parapet wall above the roof has to be built solid and incompliance with the local regulations.4. For equipment mobilization, the external wall along grid-line B may have to makelarge openings. The wall shall not be load-bearing. The columns, if any, along grid-

line B have to be at minimum clear spacing of2000 mm.5. The equipment building has to be built 0) with good sound-proof material; (ii) at amost economical approach, (iii) in a shortest construction duration and (iv) with aFRP of2 hours.6. Equipment cables are laid in the trench reserve area whish will be back-filled with

suitable filling material.7. In view of the tight dimensions of the building, the structural elements have to bearranged in such a way that the space utilization of the equipment building isoptimized.8. The existing cable station will remain III operation during construction of theequipment building.Imposed loads9. Roof

Ground floor lO.OkN/m 2

Site conditions10. The site is located in the suburban area of Lantau near the sea at datum level of about20.0mPD. Design wind pressure for the building has to be in accordance with thecurrent local wind code.


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l l. Ground conditions as revealed by boreholes are :-ground level (20.6mPD) - 17.3mPD compacted fi 1 1below 17.3mPD completely decomposedgravels and rock

SPT Nvvalue= 220granite with

fragments.

Ground water was encountered at 16.0mPD.Omit from consideration12. The existing retaining wall is an L-shape reinforced concrete cantilever wall with

overall dimensions shown in Fig Q 1. The r.c. details and grade of concrete of thewall are not clear. Checking of the r.c. design of the wall is not required, but stabilityof the wall, if affected by the building, must be checked.

Section Aa. Prepare a design appraisal with appropriate sketches indicating two distinct andviable schemes for the proposed structure including the foundation. Indicate clearly

the functional framing, load transfer and stability aspects of the proposed and existingstructures of each scheme. Identify the scheme you recommend, giving reasons foryour choice. (40 marks)

Section BFor the solution you recommended in (a)b. Prepare sufficient design calculations to establish the form and size of all the principalelements including the foundation. . (20 marks)c. Prepare general arrangement plans, sections and elevations to show the dimensions,layout and disposition of the structural elements and critical details for estimation

purposes. (20 marks)d. Prepare a detailed method statement for the safe construction of the structure

including foundation. (20 marks)

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~20.60 m PD

3000

R/F+2J.S5 m PO

EQUIPMENT ROOM

G/f+20.75 m PO

L+ DOmn' OOmmE TRENCHEX IST ING RETAI NI NG WALL RESERVEIEXISlINGGROUNDLEVEL-NOTES:1. ALL DIMENSIONS ARE IN mm2. DOOR OPENINGS :- 2300mm (H) x 1100mm (W)

EQUIPMENT ROOM 2P AR TIT ION W ALL ~20.75 m PO

l1100 l 58501 ,PLAN

3000

~~ISTING CA P

EXISTING eUllOING ONMINIPILEO U N D A T i O N~~I~D G~~~D TO "';".

!---H-OIISTING MINJPllES

SECTION 1-1

FIGURE Q1- 3 -


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Question 2 Aircraft HangarClient's requirements1. An aircraft hangar with an attached 2-story office building is shown in Figure Q2.

The elevations are to be clad with appropriate lightweight sheeting.

2. The aircraft requires a clear span of 45m and a clear height of ISm.

3. No internal columns are permitted.

4. The front of the hangar has to be column free so that aircrafts can be towed inand out of the hangar.

5. The roofis to be clad inmetal decking.

6. The office should have a minimum ceiling height of 3m.

7. The top of the foundations should be at least 2m below the ground surface.This is to allow the laying of utility services within the site.

8. A minimum 2-hour fire resistance is required for all the structural elements.

Imposed loads9. Hangar structure

Hangar roofLoads from lifting appliances attached to the roof structure

1.SkN/m2SkN/!"ll

Office structureRoofUpper office floorOffice ground floor

1.SkN/m25kN/m225kN/m2

Loads given above include an allowance for partitions, finishes, services andceilings.

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Site conditions10. The site is flat and is located in open country near the Hong Kong International

Airport. Design wind pressure for the structures has to be in accordance withthe current local wind code.

11. Ground conditions as revealed by boreholes are.-

ground level to 5m below ground - very loose and compressible loose fill,range of 8PT N-value ranges from 2 to 4.

5m to 8m below ground - very soft marine clay. 8PT Nwalue ranges from3 to 8.

8m to 15m below ground - alluvium, medium dense silt, 8PT N-value rangesfrom 12 to 15.

15m to 25m below ground - completely decomposed granite, dense to verydense silty sand. 8PT N-value ranges from 49to 100.

25m below ground - slightly decomposed granite, total core recovery greaterthan 85%.

Omit from consideration12. Detail design of the hangar door, the staircases and elevators within the office

building need not be given.

Section Aa. Prepare a design study with appropriate sketches indicating two distinct and

viable schemes for the proposed structure including the foundations.Candidates should indicate clearly the proposed framing schemes, the loadtransfer mechanisms and a check on the stability of the structure. Identify thesolution you recommend to the client, giving reasons for your choice.

(40 marks)

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Section BFor the solution you recommended in (a)

b. Prepare sufficient calculations to establish the size of all the principal structuralelements including the foundations. (20 marks)

c. Prepare framing plans, sections and elevations to show the dimensions; layoutand disposition of the structural elements and critical details for estimatingpurposes. (20 marks)

d. Prepare a simple method statement and programme for the safe construction ofthe structure. (20 marks)


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r50m 12-STO RY O FFICE AT THE BACK~-----t- l- --HANGAR ZONE

WITHOUT COLUMNS

2.5mLd, 112.5mJ. , k'1 " 1 '1 '

G /F P L A N(AL L D IM ENSIO NS SHOWN AR E IN M ETR ES)

ROOF TRUSS--

10m L H'1 DI G/FI '\7'---,

ANGAROOR

M IN IMUM CEIL ING HEIGHT 3m

SECTION '1 -1 '(AL L D IM ENSIO NS SHOWN AR E IN M ETR ES)

F IGURE 0 2

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Question 3 Highway BridgeClient's requirements1. It is required to construct a new bridge connecting existing road network to a housing

estate over a railway and two highway carriageways in the New Territories as shown inFigure Q 3.

2. The new bridge will carry a dual carriageway and footpath at both sides also as shown inFigure Q 3. As required by the Transport Department, the longitudinal gradient of the newbridge shall not exceed 1:15.

3. The bridge abutment walls at the eastern side of the highway envelope was built someyears ago by the housing estate authority with due allowance to take care of the worstloading combinations from the new bridge. Hence, it can be assumed that this abutmentwall can take any magnitude of horizontal and vertical loadings from the new bridge.However, concrete plinths/pedestals for supporting the bearings of the new bridge arerequired at the top of the abutment wall to suit your design. At the western side, bridgeabutment retaining wall is required.

4. No temporary nor permanent work may be placed within the railway and highwayenvelopes.

5. The railway must remain in operation at all times except from 1:OOam to 5:00am byspecial application to the relevant authorities to facilitate bridge construction. The twohighway envelopes can be closed every day from midnight to 5:00am to allow for thebridge construction. Deck or parapet construction work may only be carried out abovethe railway and highway envelopes during their closure periods.

Imposed loads

Footpath load

lOkN/m21500kN, applied parallel to the carriagewaysacross the full width of the bridge deck5kN/m2

6. Vertical traffic loadsHorizontal traffic loads

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Site conditions7. The site is in the rural area. Basic wind speed is 46mJs based on a 3 second gust: the

equivalent mean hourly wind speed is 23m/s.

8. Ground conditions as revealed by boreholes are:-

ground level to 12m below ground - decomposed rock, allowable bearing pressure450kN/m2

more than 12m below ground level- sandy rock, allowable bearing pressure 1000 kN/m2groundwater was encountered at 4m below ground level.

Omit from consideration9. Design calculations for the western abutment retaining wall are not required.

Section Aa. Prepare a design appraisal with appropriate sketches indicating two distinct and viable

schemes for the proposed structure including the foundation and the western abutmentretaining wall. The functioning framing, Ioad transfer, safety and stability aspects ofyour schemes must be clearly indicated. Identity the solution you recommend, givingreasons for your choice. (40 marks)

Section BFor the solution you recommended in (a)b. Prepare sufficient design calculations to establish the form and SIze of all mam

components including foundations. (25 marks)c. Prepare general arrangement drawings including sufficient plans, elevations, sections etc.

for the bridge structure excluding the western abutment retaining wall for quantitytaking off purposes. (20 marks)

d. (i) Prepare clearly annotated sketches to illustrate the details of the concreteplinth/pedestal for supporting the bearings of the new bridge at the eastern abutmentwall. (7 marks)(ii) Prepare an outline programme for the construction of the new bridge including thewestern abutment retaining wal1. (8 marks)

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