3 Structural Steel Fabrication3

7/29/2019 3 Structural Steel Fabrication3

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SUBJECT: CONSTRUCTION METHODS AND TECHNOLOGY

FACULTY: PROF. K.R.RAMANA

SUBJECT CODE: MCM 115

COURSE OBJECTIVE:

Students in this subject will learn the emerging construction methodsand technologies and their applications in construction activities.

LESSON PLAN ( FOR 5 SESSIONS ):

STRUCTURAL STEEL FABRICATION, ERECTION

METHODS AND PROCEDURES, LIGHT , MEDIUM AND

HEAVY ERECTION.

SITE AND PLANT LAYOUT

MATERIAL HANDLING

METHODS STATEMENT AND METHODS IMPROVEMENT

PREFAB CONSTRUCTION AND SPACE STRUCTURES.

RECOMMENDED BOOKS FOR REFERENCE AND STUDY:

1) MANAGEMENT, MACHINES AND METHODS IN CIVIL

ENGINEERING BY CHRISTIAN A. JOHN - REFERENCE

2) METHODS IMPROVEMENT FOR CONSTRUCTION

MANAGERS HEWRY PARKER AND CLARKSONOGLESBY.

3) CONCRETE, MICROSTRUCTURE PROPERTIES AND

MATERIALS. BY PK. MEHTA AND MONTEIRO PM

PUBLISHERS : MCGRAW HILL, NEW YORK 2006

4) REINFORCED SOIL AND ITS ENGINEERING

APPLICATION BY SWAMY SARAN

PUBLISHERS I.K. INTERNATIONAL , NEW DELHI, 2005

5) SITE ENGINEERING MANUAL BY D.DORANPUBLISHERS: WHITTLES PUBLISHING SCOTLAND 2006

6) PRINCIPLES OF FOUNDATION ENGINEERING Braja

M.Das Publishers: Thompson India, 2007

Note: there will be 1 assignment and 1 class test in my portion.


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STRUCTURAL STEEL FABRICATIONERECTION METHODS AND PROCEDURES

HEAVY ERECTION

by

Prof. K.R.RamanaACM 25TH BATCH, SECTION A AND B


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STRUCTURAL STEEL FABRICATION

ERECTION METHODS AND PROCEDURES

by

K.R.Ramana, M.Tech

TOPICS BEING COVERED IN THE PRESENTATION:

METHODS OF CONSTRUCTION

RESOURCES REQUIRED FOR STEEL STRUCTURAL ERECTION

METHODS OF CONSTRUCTING STEEL STRUCTURES.

Of the various methods of construction, erection of buildings power plants, petroleum

refineries, petrochemical plants, huge hangers, ware houses are constructed out of steel

structures. These can be constructed by 3 methods.

A) In situ construction

conventional methods: In this methods engineering is carried out separately

by design team, the contractor assigned for fabricating and erecting the

structures procures the material, moves them to the site, make the preparation

at the site yard, erects the structures, places them together by a suitable

methods which may involve, riveting, fabricating or bolting, finishes them by

painting, cladding, glazing as the case may be. It is possible a single principle

contractor may be involved on the job or a number of contractors may be

involved on the job who is specialized in cladding the structural steel building

or glazing the building as the case may be.

B) Pre fabricated Construction :

In this type One agency designs the structural steel building, the second onefabricates them in the workshop or factory, the fabricated steel in different

section with raw material sections or plates are moved to the site, erection is

carried out either by the same contractor or a separate erection contractor. In

this the time required for the erection cycle on site is drastically reduced as the

preparatory works are carried out in the work shop . The quality of the steel


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structural is of superior as the fabrication is carried out in a controlled

atmosphere. The planning and execution of works is of better order.

C ) Pre-engineered Construction:

In this type the engineering and fabrication is carried out at the factory or a

huge workshop completely dedicated for the structural steel works. The

factory may be designed with a good automation as well as good facitlity for

preparing the material, fabricating the material, finishing the material. The

fabricated material is also marked well with identification numbers inline with

the engineering drawing. In this system dedicated contractors well versed in

erection of the designed steel structures are engaged so that a professional

work is carried out in the erection site. Since the entire building is pre-engineered this has advantage both from the quality and economy point of

view. The only limitation in pre-engineering construction is the design once

frozen must not be subject to change Any change after the design would

involve heavy cost as the structures are designed specific to the location and

usage.

As in all constructions the main RESOURCES in steel structure construction are:

a) MATERIAL RESOURCEb) EQUIPMENT RESOURCE AND

c) MAN POWER RESOURCE.

MATERIAL RESOURCE:a) How do you estimate the weight of structural steelb) Connections for structural steel

c) Estimating the cost of steel structures.d) Items of cost in a structural steel estimate.

EQUIPMENT RESOURCE:ii) Erection of structural steeliii) Equipment required for erecting structural steel.iv) Method of fabrication a) Bolting structural steel


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b) Welding structural steel

MANPOWER RESOURCE:

i) Labour for erecting structural steelii) Field painting of structural steel.

TYPES OF STEEL STRUCTURES:

Steel is used to erect such structures as Multistorey Buildings, Auditoriums,Gymnasiums, theatres, churches, Industrial Buildings, Roof trusses, Stadiums, Bridges,Towers etc. in addition to steel structures, steel members are frequently used for columns,beams, roof purlins, decking, joists, studs, lintels, and for others purposes.

Due to its high strength, steel is ideal for long spans and tall structures. Steel consisting ofstandard shapes or fabricated plate girders is used for many multiple span bridges.Trusses made of steel can span large arenas for entertainment or educational facilities.Galvanized steel angles are fabricated into space-truss towers to support conductors andshield wires for electrical transmission structures. Transmission towers often are 120 to200 ft ( 40 meters to 70 meters ) tall. Steel is also used to support water towers andother types of elevated storage units. Skyscrapers are typically constructed of steel.

MATERIAL RESOURCE:

MATERIALS USED IN STEEL STRUCTURES

Steel structures should be constructed with members fabricated from STANDARDSHAPES such as I Sections (W-wide flanged Beam section), C- channel section, T Tsection, L- angle section (equl or un equal angle , pipes, tubes, rods and plates.

Members made from standard rolled shapes are usually more economical than thefabricated members. However if standards shapes are not available in sufficient sizes tosupply the required strength, it is necessary to fabricate the members for several parts,such as adding plates to beam flanges or stiffners to beam webs. Large built-up plategirders can be fabricated by welding together steel in Pounds ( 1 kg = 2.205 pounds),

hundred weight (cwt) , or in tons ( 1 ton 1000 kilogram).

The Grade of structural steel denotes its yield strength, For example, a drawing may

show a STEEL BEAM as W 18 x 55 Grade 50.The W represents a wide flange I Beam section, the 18 denotes the approximate depthin inches, the 55 represents the weight in Pounds per feet length, and the Grade 50denotes 50,000 pounds ( psi)


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a) ESTIMATING THE WEIGHT OF STRUCTURAL STEEL

In estimating the weight of structural steel for a Job, the total number of linear feet foreach shape by size and weight must be determined from the drawings for a Project.

Structural steel Hand Books give the nominal weights of all sections. However,

variations in weights amounting to 2 percent above or below thenominal weights are permissible and may occur. The purchaser is charged forthe actual weight furnished, provided that the weight does not fall outside the permissiblevariation.

The weights of the details for connections should be estimated and priced separately if adetail estimate is desirable. In estimating the weight of a steel plate or irregular shape,the weight of the rectangular plate from which the shape is cut should be used. Steelweighs 490 pound per cubic foot or 7850 Kg per cubic meter.

b) CONNECTIONS FOR STRUCTURAL STEEL

In fabricating standard shapes to form the required members or in connecting themembers into the structures, two types of connections are used:

a) BOLTED CONNECTIONS

b) WELDED CONNECTIONS

There are advantages and dis-advantages in each type of connection.

c) ESTIMATING THE COST OF STEEL STRUCTURES.

In estimating the cost of structural steel for the job, a contractor will submit a set of plansand specifications for the structure to a commercial steel supplier for quotations. Thesteel supplier will make a quantity take off, including main members, detailedconnections, and miscellaneous items. Then the supplier will add the fabrication costsfor cutting, punching, drilling , welding, overhead, and profit as a basis for submitting aquotation to the general contractor.

For some jobs , the steel supplier will paint the fabricated steel before delivery to the job.When the steel fabricator paints the steel, it is called SHOP PAINT. The cost oftransporting the steel to the Project must be added to the cost of the finished products at

the fabrication shop.

General contractors who erect buildings and similar structures usually sub-contract theerection of the steel to the sub-contractors who specialize in this work. This practice isjustified because the erection of steel is a highly specialized operation, which should beperformed by a contractor with suitable equipment and a well trained erection crew.Because of these conditions, the general contractor can usually have the erection


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performed more economically by a sub-contractor than with the general contractorsequipment and employees. The charge for the erection is generally based on an agreedprice per ton of steel in place, including bolting and welding connections.

When estimating the cost of structural steel in place, a contractor will include in theestimate the cost of the steel delivered to the project, the cost of erection, and the cost of

field welding and painting as required. To these costs the contractor will add

the contractors cost for job overhead, General overhead, and Profiit.

ITEMS OF COST IN A STRUCTRUAL STEEL ESTIMATE:

The items of cost that should be considered in preparing acomprehensive detailed estimate for a steel structure include:

1) Cost of standard structural shapes delivered to the steelsupplier.(A)

2) Cost of preparing drawings for use by the shop infabricating the steel.(B)

3) Cost of fabricating the steel shapes into finishedmembers.(C )

4) Cost of transporting the steel to the Job site. (D)5) Cost of erecting the steel, including equipmentl labor,

bolts or welding(E)6) Cost of field painting the steel structure.(F)

7) Cost of Job overhead, General overhead, Insurance,Taxes and Profit. (G)

The base cost of steel is subject to change due to economicconditions. Therefore, the cost of any one or all of these itemsmay vary considerably with respect to time. Consequently, thecost of each item must be estimated for each particular Project.

COST OF STANDARDS SHAPED STRUCTURAL STEEL:

Structural steel is hot rolled into standards shapes, sizes and lengths at steel mills. Steelsuppliers purchase bulk quantities of structural steel from the Mills or from Govt ownedsteel manufacturers like vizag, salem steel in standards shapes and lengths, usually 40feet long ( 12 meter long or in multiples of 6 meters). The cost of steel delivered by themill to the steel suppliers fabrication shop depends on the shape, weight per foot ormeter, grade and total quantity ordered, Large quantities of purchased steel generally are


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priced lower than small quantities of steel. Typically, the construction contractorpurchases the steel from local steel supplier ( distributors or agents) not the steel mill.The cost of purchase steel from steel supplier before it is fabricated is commonly

called the BASE PRICE OF STEEL.

Steel supplier have shops that specializes in fabricating standard shaped steel into

members to meet the specifications required for each particular job. Before starting thefabrication process, the steel supplier prepares the shop drawings that are submitted forapproval.

COST OF PREPARING SHOP DRAWINGS

In preparing plans for a steel structure, the engineer or architectdoes not furnish drawings in sufficient detail to permit the shop tofabricate the members without additional information. The steel

supplier must prepare shop drawings before steel can be fabricated.

Reputed steel fabricators (suppliers) maintain engineering anddrafting departments, which prepare shop drawings in sufficientdetail to enable their shops to fabricate the members. Thesedrawings show the actual cut-lengths of each member, preciselocation of drilled or punched holes, details of welded assemblies,and all other dimensions necessary to fabricate the steel. Thesketch figure-1 shown below is an example of the fabrication

details for a steel Beam with bolted connections. The W 16 X 40Wide flange beam has a cut length of 18 feet 4-1/2 inch with three3/8 inch thick siffner plates and 2 drilled holes at each end. Eachmember in a structrural steel project identified with uniquedesignation, called Part number and detailed as illustrated in thefigure. After all the members are detailed in the shop drawings, aBill of Materials is prepared for the entire project. The bill ofmaterials lists each piece of steel, its size, type , length and weight.

The Bill of Material for the Beam in figure 2 is shown along withthe Beam drawing.


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Drawing showing the beam

1002100118 ft 4.5 inch

Bill of quantitites

s.no Part no Description Dimension Specification Quantity

1) 1001 stiffner 15.5X 4 IS: 2062 3 NOS

2) 2002 Beam withends

preparedfor splicingwith 1 inchhole at

both ends

18ft4.5inch

W 16 X 40 1 NO.

The shop drawings are usually prepared in A2 drawings sheet ( 24inch x 36 inch), part drawings in A4 size (12 x 8.5 inch /295x210mm) and small part in sheets of 6 inch x 4.2 inch .

The number of shop drawings required depends upon the size andcomplexity of the Job. One job may require a few as one or twosheets of structural details, while another job may require 100sheets. The costing is based on the drafting hours to produce.

Since the total cost of drawings is charged to the steel that will befurnished for a job, the cost per unit weight of steel will vary withthe total cost of the drawings and the quantity of steel.

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If only one member is fabricated, the cost per member will be high,on the contrary if many members are fabricated, the cost permember will be much lower.

After the shop drawings are prepared, they are provided to the

contractor, who submits them to the designer for approval. Thecost of preparing the shop drawings is approximately 5 to 10 % ofthe BASE PRICE OF STEEL.

COST OF FABRICATING STRUCTURAL STEEL:

Cost of fabricating structural steel varies with

Operations performed

Sizes of members Duplicability of similar members

Fabrications operationsa) Bolted connections: cutting , punching, milling ,

planning, marking each memberb) Welded connection: cutting , some punching for

temporary hole connection, milling , beveling ,planning and shop welding.

Note: It is economical, easier to perform & control welding in theshop rather than in field

Cost per ton of light weight roof trusses is higher than that oflarge size beams fabricated from rolled sections. The cost per

pound is significantly higher to fabricate angles and plates forspace truss tower compared to beams and columns of Buildings or

plate girders for bridges.1000s of members are required in space trusses , each cut to a

precise length and holes punched in each end of a member so thatit can be bolted to other members in the completed structure.

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Cost per ton or per hundred weight is based on weight of finishedmembers including details ie cutting, punching , drilling , weldingetc. The time reqd to set up fabricating eqpt is fairly constantregardless of the no. of operations performed. Hence whenidentical opn can be performed on many members , the cost per lb

will substantially lowered compared to a shop operation on only afew members.

Specification for struct steel frequently require the fabricator toapply a coat of paint after the fabrication is completed. Spray gunsare used to apply paints using which 1 to 2 T/ hr can be painted.( agallon of paint should cover about 400 sq ft of surface) .

The cost of painting structural steel is about 8 to 12 % of BASEPRICE.

Total cost of fabricating steel can range from 50 to 100% of theBase Price.

COST OF TRANSPORTING STEEL TO THE JOB SITE

Usually the steel supplier delivers the fabricated steel to the job.

However if the contractor is providing the deliver y of the steel theestimator should determine the freight or truck cost per ton or percwt for the particular project to include the correct amount in theestimate.

The cost of transporting structural steel from the fabrication shopto the job will vary with the quantity of steel, method oftransporting it, and the distamnce, from the shop to the job. A truck

can haul about 20 tonnes per load.

THE COST OF FABRICATED STRUCTURAL STEEL

DELIVERED TO A PROJECT

A complete list of material by size, shape and length must be9


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prepared to estimate the cost of fabricated steel. Example givenbelow illustrates the breakdown of costs for fabricating anddelivering steel to a project.

Example :

Structural steel, consisting of beams, columns, angles, and plates isused for framed buildings. All members are to be fabricated at ashop for high strength bolted connections. Wide flange beams will

be used for beam and column members.

A list of members and details are given in the accompanying table.The small size beams are used for short spans and larger size

beams will be used for the longer spans. The larger column sizewill be used for lower floors whereas the smaller column size isused for upper floors. Angles are used as seats and clips for beamto column connections for joining together the structural members.Steel plates are used for column base plates and splicing of columnmembers.

Based on current economic conditions, the base price of steelquoted from the supplier is 24.96 $ per cwt for beams and

columns, 28.43$ per cwt for plates and 22.17$ per cwt for anglesand clips. The steel will be delivered by 20 ton trucks from thesteel supplier a distance of 134 miles to the job at the rate of 2.75$

per mile.

An illustrative breakdown of the base, fabrication, delivery cost ofthe steel is given in the example.

For computation purposes the following percentage have beenconsidered:

a) Fabrication cost of- Main members of beams and columns: 85% of Base

Price- For plates and angle section 98% of Base price


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10

b) shop painting: 7.5% of Base pricec) Shop drawing: 10% of Base Price.

Numberofpieces

Description Lengtheach Weight in lb/linear ft. Totalweight(Lbs)

EQUIPMENT RESOURCE

The following is the list of Major equipment used forconstruction of a ware house constructed of structural steel

Value of the Project : 100 million Indian Rupees

Sl.no Equipment description Quantity

1 Hydraulic excavator 90 CK 1 no

2 Back hoe (JCB) or equivalent 2 nos

3 Dozer 1 no

4 Air compressors 2 nos

5 Mobile crane - Hydra 20 Tons 1 no

6 Pick and move crane 1 no.

5 Dumpers 12 nos6 Concrete mixer 10/7 and 14/10 6 nos

7 Vibrators As required

8 Pumps 4 nos

9 Welding sets 6 nos

10 Gas cutting set 2 nos


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11 Surveying instrument 1 set

12 Lab . equipment 1 set

13 Tool set 6 sets.

14 Fork lift truck 1, 2 Ton capacity 2 nos (Diesel opn.)

15 Lifting tools and tackles

D-shackle-0.5,1 ton capacity As requiredu-bolt As required

Bull dog clip As required

Steel wire rope slings As required

Manila ropes As required

Tie rods As required

Chain pulley block 05.1 .2.5.10 T As required

Turfer 1, 2, 5 ton capacity As required

ERECTING STRUCTURAL STEEL:

Most general contractors subcontract the erection of structural steelfor their projects . The sub contracts may be assigned to a company thatspecializes in steel erection or it may be sub contracted to the steel supplier.Many steel suppliers have the crew and equipment and are capable oferecting the steel that they fabricate and deliver to the Project.

When a structural steel building is erected, the columns are erected first onthe previously prepared concrete foundations, with anchor bolts already in

place. The ends of the anchor bolts are usually threaded to allow installationof the column base plates, which have holes drilled to match the pattern ofthe anchor bolts. Nuts are installed in each threaded anchor bolt, one aboveand one below the common base plate, to adjust and plumb the column

After the columns are erected, the beams are installed for the first tier offloors, usually two floors. The connections between the columns and beamsare temporarily bolted thro holes, by using 2 or more bolts per connection.Horizontal bracing is necessary to stabilize the structural members during

the erection process. After the tier of columns and beams is in place, it isnecessary to plumb the structures before installing the permanent bolts. Theoperation is repeated for subsequent tiers until the erection of the structure iscompleted.

EQUIPMENTS FOR ERECTING STRUCTURAL STEEL:


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The equipments used for erecting structural steel depends ona) the type of structure,b) the size of structure andc) the Height of structure.d) Its location in relation to the adjoining structures or buildings.

Roof trusses are usually delivered to the job partly or completely assembled and hoisted

directly from the delivery trucks into place by TRUCK MOUNTED CRANES.

Several types of truck mounted cranes are available. A hydraulic truck crane has aself contained boom, which enables the unit to travel on publichigh ways between projects under its own power without set up delay. A hydraulic truckcrane ideal for short duration jobs, less than several days, For taller steel structures, alattice boom truck crane is some times used. . The lattice boom is cable suspended, andthere fore acts as a compression member and not a bending member like the telescopinghydraulic boom. . However mobilisaiton and de- mobilization of the lattice boom cranerequire time. Some times a second crane is required to assemble and disassemble thelattice boom . The scanned sketch shows two truck mounded crane erecting steel roof

trusses.

Multistoreyed steel frame buildings can be erected with truckmounted cranes if theheight is not excessive, usually about 4 stories. . If a building is so tall that a truckmounted crane cannot be used , the steel members may be placed with a Tower crane.These cranes provide high lifting height with a good working radius and require limitedspaced. Several types are available. Some units have a fixed vertical tower with arotating horizontal boom truss. The climbing frame type crane is supported by the floorsof the building that it is being used to construct.

Because cranes are used to hoist and move loads , from one location to another, it is

necessary to know the lifting capacity and working range of a crane selected to perform agiven service. The lifting capacity of cranes for erecting steel structures typically variesfrom 20 T to 100T. However lifting capacity upto 500 tons are available. Individualmanufacturers of equipment furnish specifications and information that describes thelifting capabilities and tipping loads of their equipment. Steel erection contractorstypically own the lifting equipment. However , for special jobs that may require anunusually heavy or high lift, the crane may be rented. The crane can be rented per day,week or Month .

BOLTING STRUCTURAL STEEL:

When bolting structural steel, one worker will be required at each end of the member toinstall atleast enough bolts to secure the member to the supporting structure. One or twoother workers may be required on the ground level to assist in attachement of slings andrigging the next structural member to be erected. As structural members are erected,adequate lateral bracing is necessary to ensure adequate rigidity and stability of the entire

steel framing system.


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After members are erected and plumbed, two iron workers should be able to complete thepermanent bolting, including application of the proper tightening torque. For safety, fallprotection must be provided for ironworkers (fitter) when they are working at highelevation. When a tower crane is used to hoist the members and place them intoposition, it is common practice to install enough bolts in the connections to permit the

structure to be plumbed and braced as it is erected. . If this procedure is followed, the restof the permanent bolts will be installed later. Callibrated Torque wrenches, selected toproduce the desired tension in the bolts, can be used in tightening the nuts on the Bolts.

The crew size required for installing the bolts will vary with the number of bolts neededand the ease or difficulty in getting at the Bolts.

WELDING STRUCTURAL STEEL:

In general , welded connections provide more rigidity than bolted connections. Forwelded steel structures, Gasoline or kerosene operated welding machines are used.

Otherwise the general procedure and erection equipment are essentially the same as for abolted structure. Welders who are certified by laboratory tests, are used in producinghigh quality welding of steel structures. The cost of field welding can be substantiallyreduced if the structure is designed for a minimum over head welding. Various types ofstructural welds are used in structural erection

If a structure is designed for welded connections, it is possible to reduce the totalweight of steel by as much as 5 %, as compared to bolted connections. It is not necessaryto punch bolt holes in members at points of critical stress for connection purposes.Where a few holes are required for temporarily bolting members in place, the holes canbe punched at non critical points, thus permitting the use of the full strength of a member

at joints rather than a reduced net section through the member. Since the welded jointscan be made as strong as the full sections of the members, it is possible to design beamsas continuous members over several supports, thus reducing the critical bending moment stresses. As a result of these conditions, ligher beams can be used in a structure,which will reduce the total weight of steel required. Also smaller and less expensivefoundation costs should result from reduction in dead weight of the structures.

After a member of the structure is plumbed or broght to the correct position, welding ofthe connections is started. To eliminate undesirable distortion of a structure, resultingfrom unequal heating at the connections, a definite pattern for welding should beestablished and rigidly followed. If beams are to be welded to opposite flanges of a

column, the two welds should be performed simultaneously to eliminate unequlexpansion of the two sides of the column would result from welding the beam separately.

If welding girders to columns or Beams to columns and girders, the top flanges should bewelded first and allowed to cool to the atmospheric temperature prior to welding thebottom flanges. As the weld for the bottom flanges cool, the bottom flanges at the ends ofthe beams will be subjected to tension. Since the stress is opposite the stress to which thebeams will besubjected under loaded conditions, the effect of welding is to reduce the


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ultimate bending stresses in the beams. The correct procedure of welding beam tocolumn is depicted in the pictures.

MANPOWER RESOURCE

Construction laborers who erect structural steel are called Iron workers or Structural steel

workers.

The cost of labour erecting structural steel will vary with the type of structures, the typeof equipment used, size of members, climatic conditions, and the prevailing wage rates ofthe workers.

A common size of steel erection crew consists of four iron workers, a crane operator, andforeman. However, crews for erecting steel may vary from two to eight iron workers,depending upon the size of the structural members that must be handled and the height ofthe structure. For example a High rise multistoreyed building may use a crew consistingof 8 iron workers, several welders, crane operator, hoist operator and two foremen.

The data in the table gives the approximate number of crew hours per 1000 linear feet ofmembers for erecting steel for various sizes and shapes of structural steel members thathave been fabricated and delivered to the job. Wide flange beams with deeper depths canspan longer distances than shallower depth beams. However, the time to set a 25 feetlong beam is about the same as the time to set a 22 feet long beam. Therefore the crewhours per foot are less for erecting large size beams compared to smaller size beams.

If fabrication is required at the job site, the costs of fabricating and erecting the steel issubstantially higher than when using shop fabricated steel. However, some times smallermembers, such as angles, channels or junior beams, are field fabricated. Table givenbelow gives the approximate crew hours for a field fabricating and erecting small size

steel members. The crew for performing this type of work consists of only one Ironworker, one welder and one foreman.

TABLE- 1: approx crew hours per 1000 linear feet for erecting various sizes and shapesof shop fabricated steel members.

Type of work Crew hours per 1000 linear feet.1-Erecting steel beam bolted connections:

Crew 4 iron worker, 1 crane operator, 1

foreman, equipment: 1 crane.

W section 8 in deep

W section 10 in. deep




15.6-17.3 hours15.2-16.8 hours12.6-13.8 hours11.0-12.1 hours10.5-11.6 hours


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2-Erecting steel beam welded connections:

Crew 5 iron woker, 1 crane operator, 1foreman,1 welderEqpt: 1 crane, 1 welding machine.

W section 18 in deep

W section 21 in. deep W section 24 in. deep



3- Erecting steel columnsCrew 4 iron workers, 1 crane operator, 1foreman,Eqpt: 1 crane

10.3-11.4 hours

9.3-10.2 hours8.9-9.7 hours8.6-9.4 hours8.5-9.3 hours

W section 8 in deep




8.6-9.6 hours8.9-9.9 hours9.1-10 hours9.3-10.3 hours

TABLE-2: approx crew hours per 1000 linear feet for fieldfabricating and erecting of small members.

Type of work Crew hours per 1000 linear feet.Field fabricating small membersCrew: 1 iron worker, 1 welder, 1 foreman

Eqpt: 1 welding machine

Angle to 1 inch 54 to 66 hours

Angle 2 to 3 inch 104 to 127 hours

Channel 2 inch to 5 inch deep 97 to 119 hours

Channel 6 to 8 inch deep 170 to 208 hours

Junior I Beam 3 to 5 inch deep 99 to121 hours

Junior I Beam 6 to 8 inch deep 126 to 154 hours


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FIELD PAINTING STRUCTURAL STEEL

Although structural steel is usually shop painted by the fabricator,

it is some times necessary to perform limited field painting. Thecost of applying coats of paint in the field to structural steel willvary with the type of structures, size of member to be painted, andaccess to steel members. The cost of painting a ton of steel for aroof truss will be considerably higher than for a steel frame

building because of the greater area of steel per ton for the trussand also because of the difficulty of moving along the truss withthe painting equipment.

Paint is applied with a spray gun, operated by an air comprssor.One gallon of paint should cover about 400 square feet. Two fieldcoats are usually applied. Table gives the approximate rates ofapplying a field coat of paint, by using a spray gun, to structuralsteel for various types of members and structures. The costs are

based on painting 400 square feet/ gallon. A painter should be ableto field paint to 1-1/2 Ton/ Hr, depending upon the structure.

Rate of applying field coat of paint on steel structure usingspraygun.

Member / structure SQFT/ TON

Beams 200 - 250

Girders 125 - 200Columns 200 - 250Roof trusses 275 - 350Bridge structure. 200 - 250

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TUTORIALS:

Estimate the cost for erecting the following 5-storey structural steelbuilding shown in the accompanying drawing. A column scheduleis given for the Building. All beams will be W 14 X 125 with 20

feet span length.

a) Estimate the cost of erecting the beams andcolumns using average rates.

Note: The type of connections used will be Bolted for Light Beamsless than W 18 and Welded connection for Heavy Beams morethan W 18. ( All connections between columns to columns, beamto beam, beam to columns will be bolted))

DATA PROVIDED:

A ) Column schedule:

Floor-1: W 10 x 112Floor 2 : W 10 x 89Floor 3: W 10 x 72

Floor 4: W 10 x 60Floor 5: W 10 x 60

Unit Labour rates.

a) Iron worker/ Fitter: USD 20.97/ Hrb) Crane operator: USD 21.67/Hrc) Foreman: USD 28.5 /Hr.

Equipment used: A 40 ton Jib Crane is used for the erectionUnit Hourly rate of the equipment is USD 125.5/Hr.


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PLAN:

20ft

20ft

20ft

20 ft 20 ft 20 ft 20 ft 20ft

SIDE ELEVATION

60 FT

Total height 12 feet x 5floors = 60 feet.


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Solution;

Since the beam are of light schedule bolted connections will beused as connection type

No of columns= 24 in each floor ( 1 to 5)

1) 24 nos of w 10 x 112 x 20 ft = 480 Lft ---- FF2) 24 nos of w 10 x 89 x 20 ft = 480 Lft ---- SF3) 24 nos of w 10 x 72 x 20 ft = 480 Lft ---- THF4) 24 nos of w 10 x 60 x 20 ft = 480 Lft ---- FF5) 24 nos of w 10 x 60 x 20 ft = 480 Lft ---- FIFFL

Total = 2400 Lft. (x)

Beams all are of uniform length of 20 feet.

All beams are of schedule W 14 x 125

Each floor has 4 rows of W 14 x125 of 20 feet span x 5 spans

Ie. 20 ft x 5 x 4 = 400 Lft.

Each floor has 6 columns of w 14 x 125 of 20 ft span 3 spansIe . 20 ftx 3 x 6 = 360 Lft.

Total = 400 + 360 = 760 Lft.

For 5 floor Beam length = 760 x 5 = 3800 Lft. .(Y)


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Computation of weight of beams:

W 14 x 125 has 125 lbs / ft.

Total wt of beam = 125 x 3800 = 4,75,000Lbs. (a)

Computation of weight of columns:

a) 480 x 112 = 53760 Lbsb) 480 x 89 = 42720 Lbsc) 480 x 72 = 34560 Lbsd) 480 x 60 = 28800 Lbse) 480 x 60 = 28800 Lbs

Total = 188640 Lbs..(b)

Total wt of Beams and columns: (a) + (b) = 663640 LbsTotal wt in tons of Beams and columns = 663640/2000=331.82T

Assume Unit Market rate of steel as USD 1500/ Ton

Base Price of steel= 331.82 x 1500 = USD 497730/-

( From the crew charts, the crew required for Bolted connectionextracted from data base provided is

CREW: 4 Iron worker/ fitter1 crane operator1 fore man

1 40 ton jib crane (equipment resource)

(From the crew output chart for bolted connection for Beams ofW 14 Beam, 14 in ch deep output is 12 crew hours/ 1000 lftW10 Beam, 10 inch deep , output is 16 crew hours/ 1000 lft


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CREW HOURS FOR ERECTING STRUCTURAL STEEL.

Beams = 3800 x 12 / 1000 = 45.6 crew hours

Columns = 2400 x 16 /1000= 38.4 crew hours

Total crew hours for the job = 84 crew hours.

Cost of erecting beams and columns.

Iron worker: 84 x @ 20.97 USD/ HR = 1761.48 USDCrane operator: 84 x 21.67 = 1820.28 USDForeman: 84 x 28.5 = 2394 USDEqpt Jib crane 84 x 125.5 = 10542 USD

TOTAL COST IN USD = 16523.76

COST PER TON FOR THE STRUCTURAL FABRICATIONAND ERECTION JOB:

16523.76 / 331.28 = USD 49.87/ Ton

COST PER TON BASED ON BASIC STEEL PRICE ANDFABRICATON+ ERECTION:

( (331.28 X 1500) + ( 16523.76) ) / 331.28 = 1549.88 usd/ton


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QUESTION BANK:

1- What are the various methods of constructing steel structures. ?Explain them briefly? Under what conditions a pre-engineeredsteel structural erection is preferred over the Pre-fabricatedstructural erection.

2- What are the various methods of joining steel structuralmembers? List the relative advantages and dis-advantages ?

3- What are the main resources required for steel structuralerection ?

4- What are the items of cost in a steel structure estimate.?


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CONSTRUCTION METHODS AND TECHNOLOGYMCM 115ACM 23RD

1-

a) What are the various methods of constructing steel structures. ?Explain them briefly? Under what conditions a pre-engineeredsteel structural erection is preferred over the Pre-fabricatedstructural erection.

b) Estimate the cost in Rupees per Ton of steel structural workswhose break up is given below:

Weight of standard structural shapes delivered to the steelsupplier involved in fabrication , erection and commissioninga) For Beam and column section W18 ..20 Tons

b) For trusses of assorted steel sections weighing5 tonsc) Cost of preparing shop drawings7% of Base price of steeld) Cost of fabricating the steel shapes

into finished members.........15% of Base price of steel.

e) Cost of transporting the steel to the Job site. 1.5 % ofBase price of steel.

f) Cost of erecting the steel, including equipmentlabor, bolting and or welding6% of Base price of steel.

g) Cost of field painting the steel structure12% of Base priceof steel.

h) Cost of Job overhead, General overhead,including taxes and profits. 10%

( Note: 1) Assume the average cost of steel per ton is Rs 30,0002) Assume the wastage in fabrication to be 2% by weight.


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2) a)Define Plant Location, Plant Layout and Facility

Layout.? What are the factors to be considered for

plant location?b)Asian construction company adopts the Rating plan

method of locating plant for their Aggregate

production . They are seriously considering three

locations. They have identified the five important

factors for Aggregate production plant which are listed

in order of priority with respective rating points.

-----------------------------------------------------------------------------------------------------------

Factor Max.possible points Location

Site-A Site-B Site-C

1 Nearness to Raw Material 400 150 250 300

2 Nearness to Market 300 150 200 250

3 Labour supply 275 150 225 175

4 Transportation 200 125 150 140

5 Water supply 125 100 125 100

Identify the suitable plant location considering the above inputsunder the Rating plan method. Indicate the choice of location inorder of priority.

3) a) Define Material Handling ? What are the Objectives of

good Material handling ?b) Suggest suitable Material handling device for the

following:a) Transfering oil from 200 litre drum to 5 litre cansb) Dismantling engine of commercial vehicle in

workshop with out any over head cranes.


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c) Pouring concrete for casting roof slabs at 20 metersheight. ( Tall Buildings)

d) Shifting and placing building cladding materialcomprising of Aluminium and glass cladding sheets.

e) Replacing street lights on lamp posts

4) Write short notes on any 2 in about 25 to 30 lines:a) Methods statement

b) Method improvement techniques.c) Resources for structural steel constructions.d) Benefits of a good site layout

Documents

3 Structural Steel Fabrication3