IstructE Questions

Describe master sequence of a typical project.

1. Building design (with preliem showing layout, floor area and usage) 2. Statutory submission such as lease modification, utility diversion, landscape planning. 3. Gi works and hoarding plan design and submission 4. GBP preparation and submission 5. Foundation Preparation and submission 6. Foundation Tender (3 months) 7. Superstructure submission 8. Hydraulic submission 9. Superstructure tender (6 months) 10. E&M design tender 11. Construction (2 years) 12. Occupancy permit (1 month)

How do you determine water table with limited GI information?

1. By standpipe piezometer. 2. If less permeable layer such as clay, colluvium and alluvium presents below ground, piezometer is preferred to measure perched water table and response zone should located at top and bottom of these layer, otherwise standpipe is used.

What is shear lag?

1. Cause by non-uniform stress distribution 2. Mostly occur at connection where not all the flange elements are connected in a bolted/welded connection, hence one flange has high tensile stress.

How you completed any cost estimation? How?

1. Concrete = $700 /m3 for 40 MPa 2. Steel Rebar = $4500/T 3. Steel H-pile = $1050/m for 305x305x223 UC 4. (Large Diameter Bored Pile) LDBP per meter run: $4200/m for 2% Steel Estimate quantity, then multiply rate.

Can you compare the use of concrete and structural steel?

1. Concrete is good at compression, but weak in tension 2. Concrete can be formed into irregular shape 3. Steel have greater capacity and less selfweight to support the same loading 4. But it has poor corrosion resistance, causing high maintenance cost 5. Steel has poor fire resistance

State any safety legislation

1. Construction site safety - green card 2. Hong Kong Occupational Safety and Health Ordinance and its regulations (1st aid, drinking water, fence around openings) 3. Hong Kong Factories and Industrial Undertakings Ordiance and its Regulations (occupational diseases, noise at work)

What are composed in a Contract and Tender Document?

Contract Document: 1. Contact Scope of Works (quantities, schedule of rates, cost break down, programme) 2. Payment terms 3. Terms and Conditions Tender Documents: 1. Conditioning of Tender (criteria set out) 2. Form of Tender (LD, completion date) 3. Specifications (material, acceptable standard) 4. Special conditions (responsibilities) 5. General preliminaries (works 6. General Preambles 7. Bill of Quantities 8. Scope of Works 9. Appendixces

Please draw a sketch of the record of final set and what does Cp and Cq mean?

Cp is the elasric shortening of the pile. Cq means the recoverable movement of the ground

How to prevent shrinkage crack?

Design: Place steel reinforcement closer to concrete surface and make sure minimum reinforcement are provided to design code Construction: During curing spray water to prevent cracking

What is EIA?

Environmental Impact Assessment completed to implement preventions/mitigations to protect the environment of the designated project.

State typical floor construction sequence.

FRP. 5 days cycle for area of 300m2. Formwork can be strip with props 4 days for slab, 7 days for beam and 1 days for wall/column. Fully stripped without props 10days for slab, 14 days for beam and 28 days for transfer beam.

If the contractor do not carry out works on site what would yo do?

Find out why, then issue verbal instruction and finally followed by site memo sending to Project Architect and client.

If pile verticality is slightly beyond the requirement, what would you do as an RE for LDBP and Steel H Pile?

For LDBP: Increase the steel % to take the additional force induced. For steel H pile: check actual pile capcity, additional pile can be added and pile cap design to be revised.

What shall you look for in a concrete test report?

For detail you have to look at Regulation 59, in general, the average of 4 consective test results shall exceed the specified grade strength by 5 MPa for 20D, and individual test should not be less than specified grade sterngth by 3 MPa.

How do you verify design pile length for end bearing, LDBP and RSHP (reinforced Solider H Pile)?

For end bearing/rock socket pile, GI will be carried out before foundation works to justfy rock head. Before installation 5m deep predrilling should be carried out below rock head. For LDBP all piles should be carried out predrilling. For RSHP, predrill boreholes should be located in area where all piles were within 5m extent of predrilling boreholes, after installation post drilling may be carried out for 2 in 100 piles.

What are functions and your rules in design tie beams?

Function is to tie pile caps together to resist overturning moment due to 75mm offset. For cap with single piles, they should be tie in 2 directions and 1 direction for caps with 2 piles.

How many grade of soil/rock as per geoguide, how to descrbe the 1st and, 2nd last and last grade of soil/rock?

Grade 1 = fresh rock Grade 5 = completely decomposed Grade 6 = Residual Soil

What is the concrete grade of pile cap and why do you choose this grade?

Grade 40 MPa. Pile cap within water level and in contact with soil, hence exposure condition is morderate.

What do you know about the HKIE?

HKIE is a organisation found in 1947 which promotes interests and technical standards in Hong Kong. It's coporate members are recognised by HK government for civil service. It has many disciplines and it a measure of benchmark for enigneers.

What is the design approach for high and low rise buildings?

High Rise: Subject to wind load, so flexural stiffness to resist lateral load is important. Low Rise: Mainly gravaity load.

If subcontractors work are found to be unsafe or below substandard, will you instruct subcontractor to rectify directly?

I should contact the Authorized Signatory (AS) T2/T3 in the capcity of RSE/RGE's T3.

What is the quality system in your site / office?

ISO9001:2000. A Plan-Do-Check-Act (PDCA) 1. Plan to customer requirements 2. Do to implement the process 3. Check and monitor the process 4. Act to improve the process

How to assess EOT?

If activities are on critical path and reason of EOT. Inclement weather is usually fine.

What is the vibration limit for the driving of H-pile works and which PNAP should be referenced?

In absence of engineering analysis, PNAP 289 empirical guidlines should be referenced. To avoid damage to MTR = look at PNAP 77 and 279 To avoid damage to water retaining structure = 7.5 mm/sec To avoid damage buildings = 15 mm/sec

What are the safety measures on site and which government department look after this?

In terms of gernal safety, the Labor Department set guidlines with reference to the ordiance; 1. Must have green card and wear PPE 2. Eraction of Site Hoarding 3. Use of safety belt / fall arrester when working from height For job specific, further qulification and training are required, such as electrician or working in confinement area.

What is the full name of I Struct E?

Institution of Structural Engineers.

Do you think we should adopt "pay for environmental protection"?

It is in accordance to the law stipulated in WBTC "Works Bureau Technical Circular" to ensure construction and demolition materials are properly covered or disposed. Also control air, dust, noise and wastewater pollution.

What is negative skin friction piles?

It is the drag down forces on piles due to soil consolidation.

Is there any requirement for minimum pile spacing for LDBP or Driven H-pile?

LDBP = 500mm between bellout Driven H pile = perimeter of pile or 1m, for boundaru = 0.5m of perimeter of pile of 0.5 whichever is greater

Can you explain the characteristics of LDBP.

LDBP has less settlement, noise and vibration. It is more flexible as capacity of pile can be increased by changing size of shaft/bell out and steel ratio. However it is expensive,

What are the criteria for differential settlement for pile cap?

Less than 25mm or 1/500

State some forms of contract in Hong Kong.

Main types of contracts are Design and Construct and Construct only. They can have many forms; 1. Lump sum with drawings and specification 2. Lump sum with firm BoQ 3. Cost reimbursement contract (Final price to be determined near end of project, contractor can stop working when all funds are spent) 4. Remeasurement contract containing B0Q

How do you set the vibration limit if emprical guidelines are not to be used?

Make reference to BS7385 Part 1:1990 for detailed assessment.

Who is the president of I Struct E?

Mr Don McQuillan. James Lau for HK.

What is preliminary, contingency and provisional item? How much does it take up the percentage of total contract sum?

Preliminary: Initial set-up of site, eg storage, site offices, 20% Contingency: Money to pay for unexpected cost; 10% Provisional: Works not foreseeable

What is the difference between ISO9001:2000 (a quality management system) and its previous edition?

Prevous edition is ISO9001:1994, the main difference is "continual improvement of the prevention of non-conformity (NC)". If NC was found during audit, it will be recorded in the non-conformance report.

What is the advantages if using Pulverised-fuel ash (PFA) in concrete?

Product derived from waste produced by a coal-fired power plant. It reduces the water demand but produce same workability in concrete. Hence it avoid segregation and bleeding in fresh concrete. I treplaces part of cement and results in cost saving. It also improve strength and long term durability by max 25%.

Can you explain the characteristics of rock socket steel H pile.

Rocket socket steel H pile is wasy to install, less settlement, noise and vibration.

Which sujects labout department pay attention to?

Safety: 1. Working height 2.ppe 3. scaffold safety 4. certificate for tower crane operator

Please state 4 floor systems and how to choose a suitable one.

Selection depends on client's requirement" Beam slab is the most common form and simple to design. Waffle, ribbed slab and flat slab provide more headheight. But waffle and ribbed slab are difficult to form. While flat slab required drop panels at column which affects its outlook. .

What is SSSP stand for?

Site Safety Supervision Plan.

What is the typiccal value of properties of soil and rock?

Soil density to be 19 kN/m3, friction angle = 30 degs, c=0 Rock allowable bearing capacity = 5000 kPa for grade 3, 85% total core recovery and UCS not less than 25 MPa.

When to use steel H pile and LDBP?

Steel H-pile for Building < 3 floors LDBP for building 3 - 25 floors

What will you consider when choosing driven H pile in the schedule area?

The driven H pile should be drillling into rock for 20m and design pile capcity should be 0.6 times of original pile capacity.

What is the definition of critical path?

The longest sequence of task that must be completed in order to complete the project.

What is the final set table?

The measured permanent displacement of steel H-pile to the ground by 10 blows.

How to check programme submitted by subcontractor?

We can check if any missing items and if duration of each item is reasonable. Typically we do not check, we instruct the subcontractor the programme and agree a programme mutually.

How do you deal with the contractor? Any liaison meeting held?

Yes, for Kennedy town meeting, they mainly concern about the constructability of the 2m bored pile wall as the soil platfrom may not be able to sustain the load of the bored pile machine. There were two solutions, 1. Provide Haul Road with slope stability or 2. A steel platfrom for machine to sit on.

What is the name of the Istruct E Journel, how often is it published?

"The Structural Engineer", each month.

What is tensile strain limit of concrete??

0.0025

What is the qualification of AP?

1. A registered Archietct, RPE or registered professional surveyor. 2. Need to be recommended by the respective registration committie 3. Should have a continous period of 1 year practical experience gained in Hong Kong, wiithin 3 years preceding to date of application

Please tell me the code of conduct for MIStructE and HKIE (Ape Human)?

1. Act with integrity and fairness 2. Have regard to public interest and to the interest of those affected by their professional activities 3. Uphold reputation of the profession. 4. Maintain and broaden their competence, and assist others to do so 5. Perform tasks for which they are competent 6. Exercise appropriate skill and judgement 7. Not recklessly injure or attempt to injure the reputation of another person 8. Avoid conflict of interest

What are the major quality control procedure of LDBP?

1. After drilling completed, Koden test could be done to check bell out diameter. 2. Tremie concrete to be poured continously to prevent first batch setting. Setting time could be prolonged by adding admixture. 3. 100mm Dia. tube should be inserted for sonic test to check verticality of pile. 4. Full core to check pile toe and bedrock interface, concrete quality (density and concrete strength) for 2 in 100 piles or 1% for more than 100 piles.

What is the yield stress/ and grade of aluminimum, stainless steel?

1. Aluminimum BS8118:1991, 6063-T5, 1/3 steel yield = 110 N/mm2 2. Stainless steel BS1449:1983, Grade 316, yield = 205 N/mm2

Please state four structural forms

1. Beam Column 2. Beam Column with Core Wall 3. Beam Column with plane shear wall

State the laws, statutory legislations related to construction industry.

1. Building Code Regulation 2. Building Planning Regulation 3. Building Admininstration Regulation 4. BD Guidelines 5. PNAP 6. Code of practices

What procedure has to do if the Contractor wants to work after 7pm ?

Apply for construction noise permit.

How to discharge waste water?

As per Licence for Discharge which requires permit.

How do you inspect the driving of H-pile?

As per the final set table.

How do plan for environmental protection?

As the designer; design temporary works with bolts and nuts and steel sections which can be recycled in the project. Design to 85 to 90% of member capacity. As developer; plan for solar panels. For excavation projects; pay attention to delievery of disposal material to locations designated by CEDD.

In private sector, which organisation is repsonsible for ensuring quality?

BD. They inspect sites regularly to ensure works are constructed to approval plans and building ordinances.

Which regulation govern Building Construction?

CAP 123B

Which regulation govern Air Pollution?

CAP 311

Which Regulation govern Waste Disposal?

CAP354

Which Regulation govern Water Pollution?

CAP358

Which Regulation govern noise control ordinance?

CAP400.

What is thermal cracking

Cause by change in temperature which exceeds tensile strain of concrete. It can be prevented by installation of movement or expansion joint in a structure.

How to assess eligible contractors?

Check BD list of acceptable contractors. Vet for budget, programme, reputation and safety training.

Case study, if contractor claims EOT for the construction of extra manhole, what would you do?

Check if that extra manhole is within their Contract, then check critical path. Also check the criteria of EOT in Contract.

What is the most common type of rock located in Hong Kong Island and Kowloon?

Coarse Grained Granite.

What is the most common soil in hilly terrrain in Hong Kong and what is its maximum thickness?

Colluvium of 10m thick.

How can management be efficient?

Construct programme based on scope, time and cost. Have subcontractor, seniors review and commit to the programme. Mitigations stagegies must be implented if delay occurs.

Describe the quality control procedure for final set driven pile.

1. Each pile should be driven continously until final set is reached 2. Final set of each pile shall be recorded as penetration in mm per 10 blow. 3. The final set is established by Hiley Formula and depends on pile length and temporary compression (Cp+Cq). During measuring the final set, the pencil should be set on stable frame in fixed position. 4. PDA (pile dynamic analysis) test tested on any bending of pile, measure force and acceleration of pile during driving and find out the static pile capacity. 5. CAPWAP (case pile wave analysis programe) find out the toe bearing of pile, soil resistance distribution, skin friction and soil stiffness.

Why do you choose concrete as construction material in your design?

1. Easy for fabrication 2. Good fire rating 3. Raw material (water, cement, aggregate) readily avalible

What insurance should be bought by the contractor?

1. Employee's compensation insurances (accidents to labour) 2. 3rd Party insurance (for subcon injuries on site) 3. Risk insurance (Fire, typhoon, flood etc)

Please explain your understanding of IStructE?

1. Form in 1908 2. The leading professional body in providing sources of opinion about structural engineering and safety issues in built environment. 3. It has many branches in all over the world. In Asia, there is HK, China, 4. It qualifies its members by examination and interview.Singapore and Malaysia.

What are the most common 2 types of rock in Hong Kong?

1. Granite 2. Volcanic

What are the 6 factors affect foundation choice?

1. Ground condition (eg, rock head, soil stratum and water level) 2. Effects on surrounding structures (eg, blds, tunnel, MTR) 3. Site constraints (eg, utilities or site boundary) 4. Cost and programme

Please describe the monitoring devices at your site.

1. Ground settlement point 2. Building settlement point 3. Vibration Monitoring point 4. Tilting plate 5. Utility Monitoring point 6. Standpipe pizometer

What are the major quality control procedure of socket steel H-pile?

1. Odex method should be used. The drilling hammer will be drilled down into soil together with the steel casing to prevvent soil collapse. 2. 5m verticality should be checked during installing. 3. For grouting, bleeding and flow cone test should be carried out to ensure the quality of grouting. 4. Finally pile load test for 1 at 100 piles, load a[pplied at 2 times of the pile capacity, check the settlement less than 0.05mm in 10 mins increment. Maintain 72 hrs, release and check for rate recovery again. Unsatisfactoy if the followings occur; a) Total settlemenet > 2WL/AE+D/120+4mm b) Rate of recovery < 0.1mm/hr in 15mins, residual > D/120+4mm or 25% pile head settlement in test

Can you compare pre cast and cast insitu concrete?

1. Precast concrete are completed in factory, formwork can be reduced and construction can be speeded up. 2. But the down side is high cost for small scale project 3. Doesn't allow changes in rebar arrangment 4. hence cast insitu concrete is more flexible.

What are the differences between rigid and flexible cap approach, provide examples?

1. Rigid Cap: Assume stiffness is high and will not bend & deflect. (For steel H-pile where spacing is small, load transfer in the form of truss and transfer to element above at 45 degs directly. 2. Flexible Cap: Stiffness is low, will bend. For LDBP, the pile capacity is large and required piles are less, the pile cap will be deflected under the column/wall load above.

What is the definition of soil and rock?

1. Rock can be broken down by hand into its constituent grains 2. Rock cannot be broken down, or can only be broken down by hand

What are the major site correspondence?

1. Site memo 2. RFI 3. Material submission 4. Shop drawings submission 5. Method Statement

What are the design considerations when construction on slopes?

1. Slope stability should be checked under construction load case first and in design load case. If ok, design foundation. 2. If pile foundation is adopted, it should be found on rock to avoid differential settlement. 3. In wind analysis, topography factor should be considered.

What are the common test on concrete?

1. Slump Test 2. Concrete cube Test 3. Coring test

What test to be completed to check compliance of concrete?

1. Slump test 2. Concrete cube Test 3. Flow Cone test 4. Flow table

How does spalling of concrete occur and how to prevent it?

1. Spalling occur when rapid rates of heating, large compressive stresses or high moistures contents 2. I can be prevented by using lightweight aggregate instead of high portion of silica or to provide additional reinforcement such as welded steel fabric within the cover at 20mm of concrete face.

What is the most effective measure to ensure safety on site?

1. TCP Technical Competent Person 2. Precautionary measure 3. Risk assessment report

What are the common tests for steel reinforcement?

1. Tensile test 2. Bend and rebend test 3. Elongation

Besides EIA; what other legistrations are related to environmental protections?

1. Waste disposal 2. Air Pollutions Control Ordinance 3. Noise Pollution Ordiance

What is the common bearing pressure of rock?

3 to 7.5 MPa.

How much is liquidated damages in the project?

5-10% of surety bond.

Do you know how many CPD days are require after chartership for MIStructE?

90 hours over 3 years

What is alkaline aggregate reaction (AAR) and how to prevent?

AAR is a chemical process cause by alkalis combining with some mineral in aggregate when moisture is present and produces a gel to absorb water and expand to cause cracking. To control it, need to ensure sodium oxide is less than 3 kg/m3 as per PNAP 180.

What are the differences between AP, RSE and RGE?

AP: Qualified to perform functions of the co-ordinator of building works or streets works RSE: Qualified to perform functions of structural engineers for more advanced structural design of building works and street works RGE: Qualified to perform functions of geotechnical design related to building works or street works