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Sunday, August 12, 2007

Petronas Twin Towers

The Malaysian tallest twin building - Petronas Twin Towers is the anchor project of Kuala lumpur City Center or KLCC. Standing at 451.9M high, it has two towers of 88-storey office building. The Towers were recorded as the world's tallest towers from 1998 to 2004. The tower’s foundationis is about 120-meter depth and were built by Bachy Soletanche with massive amounts of concrete. This is because the depth of the bedrock, the buildings were built on the world's deepest foundations.

The towers are connected at the Level 41 and Level 42 by a sky bridge, 170 metres above street level. The towers are also joined at their base to form a six-level retail and entertainment complex with a central atrium. From the atrium, two ‘streets’, lined with over 300 shops, cafés and restaurants, extend along opposite axes. In addition, the complex includes an 880-seat concert hall, an art gallery, a specialized library and an interactive science discovery centre, as well as a four-storey underground car park for 5,400 cars.

KLCC comprises of:

  1. 88 storey Petronas Twin Towers
  2. Suria KLCC - the six-level, 1.5 million sq. feet shopping centre
  3. 49 storey Menara Maxis
  4. 30 storey Menara Esso
  5. 32 storey Mandarin Oriental Kuala Lumpur Hotel
  6. 20 hectare (50 acre) Public Park
  7. Masjid As-syakirin, a mosque which can accommodate 6,000 people
  8. 2 District Cooling Centres, which use natural gas to chill water for air-conditioning

Basic Information of The Towers.

  1. Construction - April 1993–(opened on Aug,31) August 1999
  2. Project cost - RM1.8 billion
  3. Design/Architecture - Cesar Pelli & Associates (US) in Association with KLCC architects
  4. Man at work - 7,000 on the site at the peak of construction and until 1997 there were 1,000 on each tower.
  5. Site area - KLCC: 40.5 hectares - Petronas & Retail: 5.8 hectares
  6. Built area - 218,000 m2 each tower - 994,000 m2 total Petronas complex
  7. Foundation - 4.5m thick raft foundation containing 13,200 m3 of grade 60 concrete, weighing approximately 32,550 tonnes under each Tower, supported by 104 barrette piles from 60m to 115m in length.
  8. Tower 1 constructed by The Mayjaus Joint-Venture led by Japan's Hazama Corporation, consisted of JA Jones Construction Co, MMC Engineering Services Sdn Bhd, Ho Hup Construction Co Bhd and Mitsubishi Corporation
  9. Tower 2 constructed by SKJ Joint Venture led by Samsung Engineering & Construction Co and comprised Kuk Dong Engineering & Construction Co Ltd and Syarikat Jasatera Sdn Bhd.
  10. Concrete(various strength up to grade 80) - 160,000 m3 in the superstructure (5.7mil ft3)
  11. Steel - 36,910 tonnes of beam, trusses and reinforcement
  12. Number of Storeys - 88
  13. Overall Height - 451.9m from street level. Original design was 421m.
  14. Height of Superstructure (without pinnacle) - 378m
  15. Height of Pinnacle - 73.5 meters
  16. Tip of longest pile to tip of pinnacle mast - 592.4m
  17. Location of Skybridge - Levels 41 and 42
  18. Length of Skybridge - 58.4m (192ft) double-decked
  19. Height of Skybridge - 170m from street level (558ft)
  20. Weight of Skybridge - 750 tonnes
  21. Skybridge Support - Two-hinge arch with rotational pins (spherical bearings) at Level 29, rising 63 degrees
  22. Design Consultant - Ranhill Bersekutu Sdn Bhd and Thornton-Tomasetti Engineers
  23. Fabricated and assembled by Samsung Heavy Industries of South Korea.
  24. Lifting of the skybridge by VSL Heavy Lifting.
  25. Vertical Transportation - Total= 76 lifts. 29 Double-deck high speed passenger lifts in each tower. Each double-deck can carry 26 persons.
  26. Number of escalators - 10 in each tower
  27. Stainless Steel Cladding - 65,000 m2
  28. Vision Glass - 77,000 m2
  29. No of windows - 32,000 windows

Wednesday, August 8, 2007

SHOTCRETE



METHOD STATEMENT FOR SHOTCRETE


GENERAL
Shotcrete or gunite is a cement motar applied by spraying which contains no coarse aggregate. It can be sprayed over mesh, rock bolts and ribs to form part of integrated support system. The support systems maintain close contact with the rock or ground surfaces to reduce ground movements to a minimum.

MATERIALS

  1. The cement to be used shall be Type 1 Portland cement.
  2. Fine aggregate shall comply with MS 29 : 1971. The fine aggregate shall be washed.
  3. Wire mesh – BRC A4
  4. Water/cement ratio ranges from 0.35 to 0.50.

MACHINERIES AND EQUIPMENTS
  1. GENERATOR
  2. AIR COMPRESSOR
  3. CONCRETE MIXER
  4. GUNITING MACHINE
  5. WATER PUMP
  6. STAGING

APPLICATION

  1. Shotcrete or gunite is defined as concrete or mortar pneumatically applied at high velocity on to a surface.
  2. The cement for shotcrete shall conform to the requirement of BS 12. Type 1 Portland Cement will be used.
  3. Fine aggregate (sand) shall clean and free from silt.
  4. Fabric reinforcement (wire mesh) shall be hard-drawn steel wire with 7mm diameter wire (BRC A4) complying with the requirements of BS 4483:1983.
  5. Mix proportion for cement and sand shall be 1:4. Water/cement ratio ranges from 0.35 to 0.55. The concrete shall have minimum compressive strengths of 10Mpa at 7days and 20 Mpa at 28 days.
  6. Suitable air compressors shall be used to provide sufficient air volume to pump the water and the mortar to the discharge nozzle for shotcreting.
  7. Loose materials on slope surface shall be cleared before carry out shotcreting process. All rebound and loose material shall be removed by air jets or other suitable means from the surface of each layer as work proceeds.
  8. Surplus water shall be removed by air jet. If any water flowing from or across the existing surface it shall be diverted by pipes, hoses or other approved materials.
  9. The fabric reinforcement (wire mesh) shall be securely fastened with surface dowel bars at 3m centers and support with spacers to provide sufficient clearance between fabric reinforcement and the slope surface.
  10. 50mm diameter uPVC weep holes are then installed at 1.2m centers in each direction.


SHOTCRETING or GUNITING PROCESS - DRY MIX

  1. Cement and sand are thoroughly mixed by concrete mixer.
  2. Cement-sand mixture is fed into a guniting machine.
  3. The mixture is metered into the delivery hose by a feed wheel or distributor.
  4. Thus material is carried by compressed air through the delivery hose to a special nozzle. The correct pressure in a dry – mix shortcreting process is normally around 480 – 550 Kpa. Water is introduced to the nozzle with pressure and intimately mixed with the other ingredients. Water is added at the nozzle at a pressure of about 410 Kpa.
  5. The mortar is jetted from the nozzle at high velocity onto the slope surface.
  6. The spray should be perpendicular to the slope surface to minimize the rebound.
  7. No mix shall be used more than 2 hours after any water has been added. Rebound material shall not be reused.
  8. To avoid sagging and bleeding, shotcrete shall be built-up successive layers, each layer not exceeding 50mm thickness. The mortar shall cover the fabric reinforcement to a depth of at least 30mm.

Saturday, August 4, 2007

SOIL NAILING

Soil nailing is a method to stabilize and strength the existing ground or slope. The basic method is reinforcing by installing threaded steel bars (the nails) into the soil or slope as construction proceeds from top down. The bars are inserted closely spaced pattern to increase its overall shear strength.The steel bars are then grouted to create stable mass of soil. Steel bars commonly be used, with diameters ranging from 15 to 46 mm, stronger than driven nails (about 60 ksi). Grouted nails are inserted into boreholes of 10-15 cm and then cement-grouted.
The cement grouting process is by injecting the Grade 30 cement with water/cement ratio is about 0.45 to 0.5. The cement grout shall be carried out by tremie method. 0.75” to 1” diameter HDPE grout hose is inserted into the borehole and grout tremie out under a normal pressure of about 0.7 MPa or just enough to pump the grout into the borehole. The grouting process shall be continued until neat cement grout flows out from the bore holes. If temporary casings are used, the casings shall be removed by immediately after grouting work is completed. During and after removal of casing, the grout column is to be topped up when necessary.
Soil nail bars shall be locked. Stressing or locking of the soil nails shall only commence after a minimum of 5 days curing period or when the cube strength for the cement grout achieved 75% of design strength. Stressing or locking of the nail bar shall be by either a hydraulic jack or simply by a torque wrench to the required load 5kN. Soil nail head shall be constructed after stressing work finished.

Soil nail construction has many advantages:

  • Soil nail walls can be built to follow curved or zigzagged outlines.
  • The equipment used is highly portable and can fit easily into small spaces.
  • The process is flexible and makes modifications easy to carry out (e.g., nails can be moved as needed during construction).
  • Construction causes less noise and traffic obstruction on highways.
  • The process creates less impact on adjacent or nearby properties than do other construction methods.
  • It generally requires less space and manpower

Monday, July 30, 2007

C.B.R Test

C.B.R test is abbreviation of California Bearing Ratio test. The test was developed by The California State Highways Department, California USA in 1930. It is developed to evaluate the mechanical strength of road structures. The road structures are defined as subgrades, lower subbase and upper subbase. Subgrade material is referred to soils, sand for lower subbase, whilst crusher run for upper subbase.
Generally the test performed is either Laboratory Test or Insitu CBR Test
(on site). The test should be carried out in accordance with BS 1377. The good CBR value for road structrures is more than 5%. For value less than 3% is considered as poor material or Unsuitable Material (USM). During construction of road or pavement structures, samples existing subgrades shall be taken for test. If the value is less than 5%, the existing subgrade shall be removed at certain depth and replaced with suitable materials.

Thursday, July 26, 2007

Environmental Matter

Environment is normally referred to all living things and non-living things occur on Earth. In construction work, protection of environment from pollution shall be taken into account before the start of construction. Project consultant or Engineer is the key person to review the topography of the project and responsible to protect the properties and facilities adjacent to the project from environmental pollution that originates from the project.
The potential effects of construction on the local environment such as blowing dust, heavy rains causes flash flooding, silting of stream and drainage system and traffic congesting due to construction operation. During construction operation the most common environmental problem encountered is slope erosion by rainfall. There are two slope protection method, turfing or cover by plastic sheet. Turfing is the best way to protect slope and it should be carried out as quickly as possible after slope cutting. Plastic sheeting is consider as temporary prevention measure for slope protection.
Rainfall commonly cause erosion of exposed soil. Prevent soil erosion from contaminating the open water such as stream, lake or other water body is the must requirements of construction. Sedimentation basins and silt fences are the common practice to prevent surface runoff and eroded soil directly flowing to the local streams and lakes.
Blowing dust is normally could be happened during dry season and a large amount of silt-particles could be produced at construction traffic area. Wind blowing may lift large amount of particles to high enough to transport them distances. Wind dust may damage to crops and vegetations, local residents and vehicles. Spraying water on top of dust is the best way to prevent blowing dust. Water bowser lorry is commonly used at construction area.

Wednesday, July 25, 2007

Embankment Fill

Another activity related to Earthworks is Embankment Fill works. Embankment Fill work is filling of suitable material or earth at valley or low ground area up to designated level as per construction drawing.

METHOD OF CONSTRUCTION

  1. Materials for filling the embankments shall be suitable materials obtained from approved source or borrow pits.
  2. Prior to commencement of filling work, the suitable materials shall be tested for Proctor test, moisture contain test, liquid limit test, plastic limit test, atterberg limits and sieve analysis and the test result should comply to requirement and specification.
  3. Trial compaction for embankment fill shall be carried out at designated area of site project to get the rolling compaction pattern.
  4. After the rolling compaction pattern accepted by Engineer, the earth filling shall be carried out layer by layer with approximately 300mm thick. The layers shall be compacted by vibro compactor as follow the accepted rolling compaction pattern.
  5. All compacted layers shall be tested for Field density test (F.D.T) and the numbers of test point shall be accordance to specification and Engineer's advise.
  6. All tests on site or at laboratory will be witnessed by Engineer or client’s representative. They will be notified to witness the test at least a day before. All the test results should be initial by laboratory technician and approved by Engineer.
  7. Excavator will be used to loading suitable material on dump trucks at borrow pit area. A few numbers of dump truck will be used to transport the materials to embankment fill area. After the materials were unloaded motor grader will spread it on a layer with approx. 300mm thick and than compacted by vibro roller.
  8. To avoid congestion and to ensure smooth flow during transporting the materials, two lanes haul roads shall be constructed.
  9. A water bowser shall be provided at site project to control flowing dust. Flowing dust could be happened especially during dry season. Normally dust will spreading and flowing at hauls roads area. To control dust, water bowser could spraying water frequently a day.

Below are the number of machineries to be used during construction;

  1. Excavator - For slope trimming, bulk excavation and loading to dump truck.
  2. Dump trucks - For transporting the material from the cut area or borrows pits to form the embankment.
  3. Bulldozer - Ripping and loosening of rock earth. Frequently the bulldozer is used for pushing and spreading the earth in layer for compaction.
  4. Motor Grader - The motor grader can be used for spreading of sub-grades, shoulders, ditches and back slopes, maintenance of haul road.
  5. Backhoe - Excavation below existing ground in firm or hard material as in digging pipe trenches.
  6. Water bowser - For control dust on working area.
  7. Compactor/Vibrating Roller - SAKAI CA 25 Vibrating Roller and DYNAPAC CF 51 - Compacting soil

Tuesday, July 24, 2007

Rock Blasting

In earthworks activity, contractor may encounter hard material during carry out excavation works. If the material to be excavated is too hard (rock), normally geotechnical engineer and client will advise the contractor to carry out blasting work.

These are two common type of controlled blasting techniques to be used for highway rock excavation either Control Bulk Blasting or Presplit Blasting.
  1. Controlled bulk blasting is used in situation where importance is placed on accurate removal of rock. Overbreak is reduced and the resultant faces require less scaling. Smooth or trim blasting is therefore employed towards the margins of bulk blast excavations. This involves small diameter drill holes at closer centres, reduce charges detonation delays and a more careful approach to the positioning of holes relative to the design slope.
  2. Prespliting is employed to reduce further the harmful effect of blasting on the final face. This involves the drilling of closely – spaced holes along the design slope and charging these relatively lightly. The Presplit charges are detonated. Simultaneously, prior to bulk charges in the main area to be excavated. This effectively forms a fracture plane along the design slope.
Before blasting is carry out, contractor shall submit details of blasting proposal to Engineer or Client for approval not less than 24 hours. The proposal shall include the following data;
  1. Diameter of holes
  2. Spacing of holes
  3. Depth of holes
  4. Inclination of holes
  5. Type of explosive
  6. Explosive charge per hole and how it is distributed
  7. Explosive charge per delay
  8. Delay periods
  9. Blast pattern
  10. Total length of stemming in each hole
  11. Type of stemming
  12. Number of holes and total amount of charge to be fired in the blast
  13. Initiation sequence
BLASTING SAFETY CONSIDERATION
For the prevention of ground vibrations, flyrock and air blast at the blasting site, the following safety precautions should be taken.
  1. Employment of millisecond delay electrical detonators with a minimum delay of 25-millisecond delay between each shorthole.
  2. Usage of minimum charge / delay during blasting.
  3. Deck loading of explosives on boreholes to reduce the explosive charge action.
  4. Accurate positioning of boreholes so that optimum amount of explosives will be utilised.
  5. Slightly undercharging the first nows of shortholes on the free face of the trench.
  6. Usage of 76mm series drill steel for drilling purposes.
  7. Usage of earth for overburden etc, to cover the top of the free face of the rock to be blasted

Monday, July 23, 2007

Safety Regulations 1986 - Excavation Work

LAWS OF MALAYSIA
FACTORIES AND MACHINERY ACT 1967 [ACT 139]
P.U.(A) 328/86
FACTORIES AND MACHINERY (BUILDING OPERATIONS AND WORKS OF ENGINEERING CONSTRUCTION) (SAFETY) REGULATIONS 1986
PART XII - EXCAVATION WORK

Regulation 113. General requirements.
  1. No employee shall be permitted to enter any excavated area unless sheet piling, shoring or other safeguards that may be necessary for his protection are provided.
  2. The excavation site and its vicinity shall be checked by a designated person after every rainstorm or other hazard-increasing occurance and the protection against slides and cave-ins shall be increased, if necessary.
  3. Temporary sheet piling installed to permit the construction of a retaining wall shall not be removed until the wall has developed its full strength.
  4. Where banks are undercut adequate shoring shall be provided to support the ovechanging materials.
  5. Excavated materials and other superimposed load shall be placed at least 610 millimetres from the edge of open excavation and trenches , and shall be so piled or retained that no part thereof can fall into the excavation, or cause the banks to slip or cause the upheaval of the excavation bed.
  6. Banks shall be stripped of loose rocks or other materials which may slide, roll or fall upon persons below.
  7. Open sides of excavations where a person may fall more than 3 metres shall be guarded by adequate barricades and suitable warning signs shall be put up at conspicuous positions.
  8. No employee shall be permitted to work where he may be struck or endangered by an excavating machine or by material dislodged by it or falling from it

Sunday, July 22, 2007

Safety and Health at Worksite



Base on statistic accident reported by Department of Safety and Health Malaysia (DOSH) showing that the accident happened during working in industrial sector including construction site is increasing year by year. Total fatal in year 2006 was 209nos against 196nos from previous year whilst total accidents happened reported by Department Of Safety and Health Malaysia (DOSH) in 2006 were 4731 nos.

In order to prevent accident at work place, these are several basic safety rules that employers and employees should take consideration;
  1. keep working areas clean and tidily. Equipment and material should be neatly arranged.
  2. Alway keep clear of suspended or swinging loads.
  3. Ridding up on loads being handled by crane is forbidden.
  4. Use right tool for the right purpose.
  5. Be constantly on the alert for unsafe condition and report to superior.
  6. No jump between scaffolds. Use ladder or walkways.
  7. Remove foreign material such as grease, oil, wet paint, frost or ice from work area.
  8. Always wearing Personal Protective Equipment at worksite (PPE).
  9. Shaft ways and opening should be barricaded.
  10. Working at power line - qualified person must check conditions and issue specific instructions.
  11. Only qualified welders shall be allowed to do welding works.
  12. Do not stand in the bight of a line or in the angle formed by a snatch block.
  13. Safety belt and lanyard should be used for working at high position.
  14. Always check and report to foreman all tools where are burred, mushroomed, or detective in any way.
  15. Only qualified personnel should allow to conduct pressure test vessels.

Saturday, July 21, 2007

Earthworks Construction

Earthworks construction operation connected with clearing and grubbing, excavation, slope cutting, embankment filling, compaction of subgrade, benching and slope protection in preparing foundations of buildings, in constructing canals, railroads, etc. Clearing is defined as removal of trees, bushes and any materials on the ground surface. Grubbing is defined as removal of stumps and roots. Clearing, grubbing and stripping topsoil shall be carried out in all areas.
In Civil Engineering, earthworks construction is the critical activity especially when involves on ground works. A few factors that may contribute to the delay of earthworks i.e weather, land acquisition, changes of design, relocation of utility and services, treatment of existing ground and late starting of the works. But, weather is the most factor that may effect to the earthworks working hours especially at country with high volume rainfalls. Treatment of existing ground can be defined as removal of unsuitable materials and replace with imported granular fill/suitable earth and compacted to the required density/compaction. The replacement materials shall have California Bearing Ratio (CBR) value not less than 5%. Unsuitable materials can be defined as running silt, peat, logs, stump, perishable or toxic material, soft soil, slurry or mud or any materials consisting of highly organic clay and silt, containing large amount of root, grass and the vegetable matter. Soft soil is defined as material with low shear strength where the mackintosh probe (MP) ≤ 30blow/30cm.
Prior to carry out physical works, planning and calculating of mass haul diagram shall be considered especially for massive excavation works. It is important to ensure that the cut and fill volume quantity is balance. During construction, survey team shall be stationed at site to monitor and to ensure the preparation of platform level is follow as specified in approved construction drawing.
The common machineries involved in earthworks are excavators, shovel, loaders, backhoe, bulldozers, backpushers, dump trucks, motor graders, roller compactors and water bowser.

Friday, July 20, 2007

Machinery - Excavator



Excavator is the most useful machine in construction activity. Excavator is common used for site clearing work, striping top soil, excavation, demolition works, digging of holes and trenches, excavation of foundations, lifting materials and others.
Excavators come in various of sizes from mini excavator till largest model which has a maximum bucket size of 4.5m3. Excavator consisting parts i.e bucket, arm (boom), tracks or wheels and cabin mounted on a pivot or a rotating platform. The plaform can be rotated 360 degree.
Excavator is multifunctional machine. It is frequently used in many application other than excavation. Many excavators feature quick-attach mounting system for simplified attachment mounting to increase the machine's utilization on the jobsite. Instead of doing excavation it also can be used as breaker or auger.
The famous excavator manufacturer such as daewoo heavy industries and machineries, hitachi construction machinery, hyundai heavy industries, sumitomo, mitsubishi heavy industries, bobcat company, caterpillar inc and many others.
Another type of excavators are bucket-wheel excavator, compact excavator, drag-line excavator, long reach excavator, skid steer, steam showel and suction excavator.

Thursday, July 19, 2007

Commencement of construction works

The first activity in construction works is site clearing. Prior to the commencement of site clearance, survey and setting out coordinate the limit of work according to the construction drawing shall be carried out. Site clearing generally consists of the cutting and /or taking down, removal and disposal of everything above ground level, including objects overhanging the areas to be cleared such as tree branches, vegetation, structures or parts of structures. Clearing of trees, vegetation, undergrowth, bushes and minor structure is carried out by dozers and or hydraulic excavators. Major structure that cannot practically be cleared by hydraulic excavators and/or dozer, these demolition can be carried out using pneumatic tools, explosives and/or other specialized equipment depending on the size and type of structure.
All cut and demolished materials shall be removed and transport using dump trucks to the designated dumping site. Open burning is prohibited by Government Authorities.

Tuesday, July 17, 2007

I n t r o


all about construction works

Provide civil engineering information and method of construction including specialized areas of civil & structural and environmental engineering. The information on how the construction work is carry out as well as the machinery involved. Civil engineering involves the planning, designing laying out and constructing of buildings, roads, railways, expressways, bridges, tunnels.