1.SITE INVESTIGATIION
Makna Penyiasatan Tanah-kerja penyiasatan tanah adalah satu bentuk ujian untuk menentukan kekuatan di setiap lapisan tanah di bawah permukaan mukabumi.Tanah terjadi dari berbagai -bagai jenis dan mempunyai berbagai jenis kekuatan.Ujian ini di jalan untuk menentukan jenis asas yang sesuai untuk meletakan asas bangunan di atas tanah tersebut.Tanpa ujian ini tiada siapa dapat meramalkan kekuatan tanah di bawah .
Terdapat 2 jenis ujian yang biasa di lakukan:
- Mcintosh Proba
- Bore Hole
Mckintosh Proba
- untuk projek atau bangunan yang ringan tidak melebihi 2 tingkat
- murah dan cepat
- keputusan ujian adelah 60 % tepat
- kekuatan adelah berdasarkan jumlah ketukan untun 1 kaki kedalaman
- satu jadual kekuatan yang piawai d gunakan
- untuk jumlah ketukan di bawah 15,asas jenis cerucuk di gunakan
- biasenye 3 lubang ujian di buat untuk sesuatu bangunan
Bore Hole
- untuk projek melebihi 2 tingkat
- kawasan pantai,tepi sungai,tanah gambut,tanah buangan sampah dan batu
- mengambil mase yang panjang dan harganye mahal
- keputusan yang tepat di perolehi
- jumlah ujian adelah bergantung kepada keluasan bangunan tersebut
- jenis dan kedlaman cerucuk dapat di tentukan
1A.PROCEDURE TO EVALUATE DATA FROM SI REPORT
Refering to one project did in Kajang.The procedure of soil investigation for unconfirmed sub soil condition.The first result of Bore Holes done before appointment of contractor show that the N value of SPT is 50 in the 4.5 m depth but N value along the 4.5 m depth is zero,no reading.After the appointment of contractor and kick off the project,the engineer ask to do mackin tosh at every point of column.
- JKR Mackin Tosh
- Mac kin Tosh is a test for soil to find the reading of soil bearing capasity at every 1 ft depth.A metal rod 1.2m is hammering down in the soil and every 1 ft penetration reading a hammer driven was recorded.The rod will be connect until the set when hammer driven reach 400 times.Using JKR standard graph,the driven hammer reading can give the value of soil bearing capasity at that depth.
- The characteristic of soil weather hard or soft ground cant decide by visual only,there heve to do a simple soil test like Mc kin Tosh
- Base on that above project,some point the set depth are 300mm,some 500 mm,some 3500mm and some 4500mm.Cant decide anything
- Trial Pit
- Refering to that above condition,two trial pits sizing 3000mm x 3000mm will be excavated.The depth must be at least 3000mm or more.The result is under 1 m depth,the loose boulder with various size from 1 ft to 6 fit will found.The water filled between the cavity.The excavation proceed until the boom of excavator cant reach anymore.The trial pit work will stop coz the second trial pit show the same result.
- Bore Logs
- Coz of cannot get the rock bed or the depth suitable for footing or piling,the second Bore Holes was done The Bore Holes result at the begining show the same result as the first Bore Hole done before but the engineer insist to drill a further down but the workers dont want to proceed because the diamond bit broken 3 times and replacement take a long time but at last the N value show a result.Starting from 12 up to 20 something and then reach 50 at 27 m depth.At the termination depth,the soil condition is high density sand .
- Selection of foundation
- Selection of foundation
- Pre cast pile-reject because cant penetrate until set
- To excavate and cart away all the boulders-costly and athourity would not allow coz of slope failure and dangerous and not approve
- To pump all the cavity with grouting and the boulders or loose rock act as a raft foundation-no guarantee for the structural use,if failed nothing to do but loose money
- The micro pile size 150mm without casing-try pile 1 point use drill bit ,but always stuck every 1 ft,3 ft and the drill bit block with small pieces of rock and lift out to clean the bit and the process is repeated until finish.Take 5 days to complete for 1 point and 220 point take about 1100 days equivalent more than 3 years.Impossible and costly
- The micro pile size 250 mm with the enccentric drill bits with casing and 20 T of air compressor.Grout with grade 40 concrete and T40 normal rebar the piling process takes a shorter time about 3 month to complete 225 nos of point.
2.BUILDING CONSTRUCTION
STEP 1-boundary survey work
2-site clearing work
3-Site investigation work
4-Ground levelling work
5.-Setting out and grid line
6.-Excavation of foundation work
7.Subgrade compaction work
8.Anti termite application work to foundation
9.-Laying of lean concrete to foundation base
9.-Formwork,rebar installation and concrete work to foundation
10.-Formwork to stump and concrete
11.-Backfiling to foundation
12.-Compaction to ground beam base
13.-Application of anti termite to ground beam
14.-Formwork,re bar installation and concrete to ground beam
15.-Backfilling to site of ground beam and slab base preparation
16.Laying and compaction of hardcore
17.Laying of DPC
18.Laying of lean concrete
19.-Installation of BRC
20.-Concrete to groun floor slab
21.-Erection of column re bar and form work
22.Concrete work to column
23.-Preparation strut and form work to first floor slab and beam
24.-Re bar fixing to beam and slab
25.-Installation sanitary opening and electrical conduit
STEP 26.-Concrete to 1st floor slab and beam
27.-Erection rebar to first floor column
28.-Installation formwork and concrete to first floor column
29.-If more than 2 storey repeat step 23 to 26 to roof top
30.-Preparation strut and formwork to roof beam
31.-Installation of re bar and concrete to roof beam
31.-Installation of roof truss
2.(A) SURVEY WORK
- Chain Survey
Old survey method to take distance dimension between station.To calculate the area of that palace by trigular formula and to take an offset all the feature inside the area.The chain survey introduced at 17 th century.The instrument included Chain,Tape,Compass,Ranging Rod,Arro and Cross staf.All the data are recorded and plotting are done at the office.The reader can browser internet to get further information.The author have an experience in this type of survey.
- Spot level and contour survey
Spot levelling or contour level is to survey the existing level of the ground.Using a dumpy level and staf,all the reading are recorded and a value of level are calculated.Contour survey are important for earthwork for calculated a volume of soil to cut and fill.Also important to know the existing level of the ground in order to design finished floor level for the building.A flood level for that area must consider first,the entrance level compare to existing road level are taking consideration before designing the floor level.The floor level also effect the IL for surface drain and IWK IL level to connect to the existing services.
- Theodilte
One of the survey instrument to do a boundary survey,setting out using an optical as a basic tool to survey a distance,angle and level.To set out the instrument right on the peg is not the easy way.The basic principle is left and right body rotate and the rotation of the microscope.The boundary station with the plumbob will be read and recorded and calculation of the bearing will be done at the office.Setting out of gridline for the building also use these instrument.The supervisor and IOW of the project must carefully check all the setting out point before begin any piling work.One case in Malacca,the piling point all wrong and repiling work needed.Who want to bear the cost???
- EDM/Total station
The author has a littel bit of exeperience using this type of instrument.An ultra light as a basic way to get a reading and on spot can get every data like angle,bearing and level.The reader are advise to do a browser a wen site regarding these topic.
- As Built Piling point survey
After piling works finishes,after pile head cutting,the as built survey drawing were carried out to know weather the position of the pile are on the centre of gridline.The offset at X and Y direction were survey and calculated and plot at the piling layout plan.The drawing must be signed by the license surveyor and submitte4d to the engineer before proceed any pile cap work,The allowable value for offset are not more than 75 mm at any direction.If more,the designer will calculate the capacity of offset piles and make a remedy design.
- Setting out and gridline survey
Setting out of the building is done by surveyor.The gridline must follow the architure drawing not the structural drawing.The IOW and site supervisor have to check all the value as per drawing.Any mistake or error must be reported immediately.
- TBM
TBM by meaning Temporay Bench Mark as a reference for level at that designated area.Reading are taken from BM which the reading of level for this BM is given by JUPEM.From this BM,the reading are tranfer as far as the project location.Using a Dumpy level instrument and a staf,the reading are tranfer near or in the boundary of the project.The TBM location are usually at the permanent area as apron,on the culvert,on the road or where no disturb area and sit on the hard thing like a concrete base.If none,the TBM location are peg with cemented base and guard by metal fencing.The TBM position can produced at various location,better 2 or 3 different location base on the big or small of area.The principle of taking reading are,backreading and front reading ,recorded and calculated the finished level.The site supervisor also can do this job compare to use a EDM that onle the surveyor can do this job.Taking level for building and infra inside call engineering survey.
2(B).FORMWORK
- Traditional material
Traditional material are refer to old formwork pattern.Including timber and plank and timber.Set for formwork including timber,plywood and nailing.Timber sizing 25 mm for side and top strut and plywood for mould.
- New type of form work
So many new technology and innovation in formwork.Some in material and some in a installation technology.Metal formwork are the second type of formwork.Can re used more that 50 times compare to plywood.The plywood or timber only 7 times for re used purpose.Metal at the beginning are high price but long lasting use compare to timber and plywood cheaper price to buy but not long lasting and buy a new one for every project.Aluminium formwork is the latest technology,easy to install,less weight and long lasting for re used purpose.Now days a hybrid formwork is combination from chipping from tree and metal or alum are going to replace an old material.
The installation type also a new technology for formwork,Self climbing formwork is one of the new type of technology.Now when the IBS component are introduced in construction,less form work are using at the site.All the pre cat component are built at the factory and a casted unit carry at site and a lego system to fix all the component.
- Metal strip to cover gap between playwood
Usually when a plywoos used as a mould of concrete for suspended slab.The plywood was installed and fixed not at right angle or the edge of slab not straight at connection,the gap between plywood can see from the bottom.Las time,metal strip are use to cover the gap and to find the metal strip is not easy compared now day there are use a paper strip like a selotape to cover this gap.The gap have to cover in order to avoid a water cement can flow out from this gap and reduce the strength of the concrete.
- Staging erection
Last time,staging system only use a timber.A vertical strut consist of 100mm x 50mm cmbined with 50 mm x 50 mm aa a tie and lokelike a T shape was erected below beam and slab soffit.A slab vertical strut is cmbination of 100 mm x 50 mm as strut,100mm x 50 mm also as main horizontal support spacing 1200 mm and a timber sizing 100mm x 50mm as secondary horizontal support spacing 600mm All connection are nailing and plywood a put on the top as mould of the concrete slab.
Today no more timber staging but replace with metal staging.Metal staging comes with a set,1 set of staging consists of 4 adjustable legs,4 set og 1200mm long and 900 mm high of staging and 4 set of connector and 2 set of X bracing.This system or set can buy or rent.The erection is so easy because the have a legs adjuster and top adjuster follow the high of the buiding.The primary and secondary horizontal support either from timber or metal hollow section.The metal system is more stronger than timber system and erection period are shorter but quality erection control to check before concreting work begin.
Some places or the building is rare or quite big like a aeroplane hanger,the tubeler system for staging are design by the specialist.
- Sharp edge
Sharp edge by mean at the right angle of the slab.Usually to dismantle the plywood at this are not easy.Some times a hard pressure used to dismantle and dangerous to the unmatured concrete.For the edge of concrete,should be 100 mm of plywood strip are fixed at all for edge of slab and dismantle it are so easy and not disturb the strength of concrete.
- Black oil apply to formwork
Normally last time,plywood surface are covered with black unwanted oil to easy for dismantling and for long lasting used,But now no more ,the new plywood surface are already have a thin layer of oil surface but at higher price compare to the normal plywood.
3.STEEL STRUCTURE BUILDING
There are a several step process to complete one single portal frame building
step 1-building setting out
2.piling work or footing work
3.stump work
4.fixing of HFDB bolt to stump
5.concrete to stump
6.ground floor beam work
7.ground floor slab
8.erection of one side column
9.fixing of edge beam
\10.erection of another side column
11.repeat no 9 step
12.erection of complete rafter
13.installation of turn bukling
14.fixing of roof purlin
15.installation of roofing
16.fixing of side purlin
17.installation of side bracing
18.fixing of wall cladding
4.TYPE OF MISTAKES IN CONSTRUCTION
1.Over excavation depth
2.Size of footing no enough
3.Top bar at support not enough
4.Lapping bar no enough length
5.Vertical support to formwork too far
6.Ground floor slab is always non suspended slab
7.Column verticality
8.Honeycom to harden concrete to column
9.Gap between slab plywood to big
10.Lapping to BRC not enough
11.Slab not on the top of beam but inserting to beam
12.Edge of slab BRC nor in L shape
13.Connection between slab and drop no rebar
14.No starter bar for staircase
15.No diagonal bar for opening
16.Thickness of slab not enough
17.Top of BRC at support not enough length
18.Roof truss not levelled
5.TYPE OF HOISTING MACHINE
TYPE OF MACHINE
- MONKEY HOIST
- using to lift light material up to two storey only.usually to lift concrete,cement and bricks.power by small diesel engine and with a short length of jib or boom.useful for a small project
- MOBILE CRANE
- usually mobile crane attachedwith rubber tyred or chained tyred machine and easily machine to swing.the weigth of material to lift are limited and and usually used to lift concrete and other material to the certain limit of height or below 5 storey of building.the type of this crane are depend on the tonnage of crane.40 tonne of crane is bigger capacity compare to 20 tonne of crane.
- GANTRY CRANE
- TOWER CRANE
- WORKERS LIFT
No comments:
Post a Comment