ce4221 lecture 1.pdf

8/18/2019 CE4221 Lecture 1.pdf

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Civil Engineering Practices, Quality and Legislation

Civil Engineering Practices, Quality and

Legislation

Lecture 1Taking off Quantities

Asoka Perera

Professor of Civil Engineering


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03 Credits

2 Hours/Week

2 Hours/Week

IntroductionCivil Engineering practices, quality and legislation

module aims to provide students understanding ofconstruction management, contract procedures,

related legal aspects. It also can help to develop an

understanding of bills of quantities and quality

aspects in construction.


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Learning OutcomesLO1:Communicate a basic knowledge of practices

and procedures relating to civil engineeringactivities;

LO2:Apply and use standard civil engineering

contracts with standard method of measurement and

bills of quantitiesLO3:Integrate environmental and professional

procedures and regulations, especially in terms of

social, cultural, environmental and global

implications;


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Learning OutcomesLO4:Design and evaluate solutions to problems often

encountered in civil engineering practices andprocedures; and

LO5:Exercise and reflect upon the professional and

legal responsibilities of civil engineers in the

changing workplace.


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CONTENTS OF THE MODULE Brief overview of the legal system in Australia/Sri Lanka and

comparison with other legal systems Introduction to contract

law and the formation of contracts,

Fundamentals of contract law & standard construction

contracts, general conditions of contract for Civil Engineering &

Construction Works particularly to Sri Lankan and Australian

systems; Variation and Claims procedures in construction

projects;

Environmental legislation, professional responsibility and

negligence


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CONTENTS OF THE MODULE Bill of Quantities and Standard Method of Measurement

Bidding in Construction industry

Computer aided methods for estimating and cost control

Specifications in Civil Engineering,

Methods of Pricing and Specifying in Civil Engineering and

Construction;

Quality management systems in the context of IS09000 andISO9001 requirements for civil engineering organizations, in

conjunction with the tools and techniques of continuous

improvement.


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Lecture topics1 Taking off Quantities

2 Detail Cost Estimating - Prices

3

Computer Aided Estimating

4 Construction Contract Types and Procurement

5 ICTAD SBD1 and SBD2 – Traditional Construction Contracts 1


7 ICTAD Contract for Design Work and RFPs

8

ICTAD SBD 4 –

Design and Build

9 Quality Systems 1

10 Quality Systems 1

11 Environmental Law

12

Health and Safety in Construction

13 Introduction to Industrial law




Assignments1 Taking off Quantities – Class Assignment

2 Detail Cost Estimating – Prices – Class Assignment

3

Computer Aided Estimating –

Computer Application Assignment

4 Construction Contract Types and Procurement – Group Assignment



7 ICTAD Contract for Design Work and RFPs – Group Assignment

8

ICTAD SBD 4 –

Design and Build

9 Quality Systems 1 – Site Visit and Group Assignment

10 Quality Systems 1

11 Environmental Law

12

Health and Safety in Construction

13 Introduction to Industrial law




1.1 BILL OF QUANTITIES (BOQ) AND

ITS PREPARATION.

BILL OF QUANTITYA Bill of Quantity (BOQ) is a document, which

list all the items necessary for the completion of

project. Each item consists ofa. Description

b. Quantity

c. Units.

1 BOQ -Construction Quantities Taking off





ITS PREPARATION.

The contractor’s estimator submits a rateagainst each item and price the work

multiplying the quantity by the rate. The

estimate for the contract is the summation of all

the items in the BOQ.






ITS PREPARATION.

A Typical BOQ - Sample





2.1 BILL OF QUANTITIES (BOQ)Description

•

Written description of the items of construction workis usually a description of a finished item of work

based on the type of materials incorporated into the

work. Standard phraseologies are available to derive

the description of work items.

• Ex. Standard method of measurement of building

works – SMM7 or SLS 573

• It is always better to have a standard system so that

every body understand the written description.





2.1 BILL OF QUANTITIES (BOQ)Quantity

•

Every described item within the bill is allocated aquantity of measured units. This quantity is measured

off the drawing and represents the net quantity of

material incorporated into that item of work.

• Allowances for wastage, bulk or compaction of the

materials are not included in the quantities. Those

should be accounted in the unit rate.

• There is a standard method to calculate the

quantities





2.1 BILL OF QUANTITIES (BOQ)Unit

•

Each item contains a unit of measurement. The unitmay be linear, square, cubic or just a number.

• Descriptions, which are quantified, do not contain the

unit but are described as item. Some indication of

length, width, height of the described construction

work should be given on the written description

where appropriate.

• Ex: Since plastering work measured in m2, the

description should contain thickness





1.1 BILL OF QUANTITIES (BOQ)Rate

•

The price BOQ contains a unit rate along the quantityof the described items. This rate represents the net

price the contractor will be paid for the completion of

one unit of work described in the written description.

Price (Amount)• This is the amount, which is calculated by multiplying

the qu

BOQ Reference

• The classification – guideline is given in SLS573





1.1 SLS 573 – An extract to explain


F1.2.4

Issue is not

practicing




1.2 Steps in the Preparation of BOQStep 1

•

Taking off:- Taking off is making a complete list ofitems of work involved for the proper carrying out of

the work and entering the items on the dimension

paper.

• In other words this is the measurement of the

dimensions from the drawings.


T D S Description Remarks

2/ 50

30

1:1:5 cement: lime: and 15mm thick

plaster

3000




1.2 Steps in the Preparation of BOQColumn 1: - Timing column

•

This is where multiplying figures or number of timesare entered whenever there is more than one

particular item been measured. - Ex: two walls

Column 2: - Dimension column

•

Actual dimension scale or extracted from thedrawings are entered in this column. Only one line is

entered if the unit is linear and two or three lines are

entered if the unit is square or cubic. Sequence of

entering; (1). Length, (2). Breath, (3). Height

(thickness, depth)





1.2 Steps in the Preparation of BOQColumn 3: - Squaring column

•

Multiplication of the dimensions is carried out here.Column 4: - Description column

• Work items are described here. Necessary

dimensions should be included in the dimensions.





2.2 Steps in the Preparation of BOQ

Step 2 - Squaring: - •

After the taking off the next step is to multiply thedimension and derive the quantities.

Step 3 - Abstracting:-• Collecting all the quantities, which could be grouped

under particular item, and arranging them accordingto trades or whole section after deriving the net

quantities. Arrangement of trades or work sections

depends on the method of measurement

• .





2.2 Steps in the Preparation of BOQStep 4:Writing the Bill of quantities.

Note 1 :Entering Dimensions• It is essential that ample space be left between all items under

dimension sheet so that it is possible to follow the dimension

easily to enable any item which may have been omitted when the

dimensions were first taken off be subsequently entered without

clamping the dimensions.

Note 2: Grouping of dimensions• Where there is more than one set of dimension related to the

same description the dimensions should be suitably bracketed

so that it is clear.





1.2 Steps in the Preparation of BOQStep 4:Writing the Bill of quantities.


T D S Description

6.00

5.25

12.00

10.00

Clay pipes laid and fixing with flexible

joints man-hole

1-2

2-3

3-4

4-5


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1.2 Steps in the Preparation of BOQWhere the same dimension apply to more than one

dimension the best procedure is to separate each by the

sign “&“ and bracket the description.


T D S Description

10.0

0.75

1.00

Excavation for foundation

&

Filling to earlier excavation trenchers


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1.2 Steps in the Preparation of BOQNote 3: - Dotting on -When an identical item is found

later it is dotted on to the previous dimension.


T D S Description

3/

.

1

10.0

0.75

1.00

Excavation for foundation


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1.2 Steps in the Preparation of BOQNote 4 :- Alteration of dimensions

•

Dimensions should never be erased or altered. Tocorrect dimension cross them out and write NIL in the

squaring column.


T D S Description

3/

5/

4.0

3.6

3.02

2.85

NIL 1:1:5 cement sand lime 15mm thick

plaster


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1.2 Steps in the Preparation of BOQNote 4 :- Alteration of dimensions

•

When whole item has to be omitted because of amistake then cross the full item and enter the fresh.


T D S Description

3/

5/

4.03.6

3.02

2.85

NIL 1:1:5 cement sand lime 15mm thickplaster


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1.2 Steps in the Preparation of BOQNote5:- Abbreviations

• To save the spaces and time abbreviation forms must

be used as much as possible in the description

column. Some of the common abbreviations are;

• 1. a.b -as before

•

2. a.d -as described• 3. av -average

• 4. bk.wk -brick work

• 5. Bs -British standard

• 6. w.r.t -with respect to



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1.2 Steps in the Preparation of BOQOrder of taking off

• The order of taking off follows the order of

construction. In a simple building the order of

• taking off is as follows.

• All the work unto & including DPC

•

Brick work and Block work• Floors

• Roofs & including covering & rain water installation

• Finishes of walls, ceiling and floors

• Staircases



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1.2 Steps in the Preparation of BOQOrder of taking off - Cont..

• Plumbing installations

• Drainage work

• Other services

• Other external work including roads fences etc.



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1.3 Some important considerations in taking offCenter line method


When there is a recess twice the depth of the recess should be added to the lengths of the sides


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1.3 Some important considerations in taking offCenter line method

When there is a recess twice the depth of therecess should be added to the lengths of the

sides.


5.120.6223.102 X X X elineTotalCentr

46.35elineTotalCentr

When there is a recess twice the depth of the recess should be added to the lengths of the sides.



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1.3 Some important considerations in taking offExcavation work, brickwork or similar at

corners - No adjustment is required – there is

compensation



2/2/21

xl xl nght Internalle

2/2/21

xl xl length External

21 l l lengtheffective Net



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1.3 Some important considerations in taking offExcavation work at T-junction. Therefore at a T

junction half the width of the trench should be

deducted from the centerline dimensions.



2/321 xl l l lenght lineCentre



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1.3 Some important considerations in taking offCentre line method gives accurate

measurements





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1.4 Example – 1 Excavation:Quantities are calculated based on the

dimensions of the foundation in plans from the

owner perspective.

Contractors should consider the excess of

material excavated to all for safe operations.

Prices differ based on the soil type, deep ofexcavation, ground water level, site location,

shoring system, Equipment used, etc.

Unit of measurement is cubic meter (volume)





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1.4 Example – 1 Excavation:


p g



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1.4 Example – 1 Excavation:The length of excavation = 5.4 × 2 + (4.4 – 2) × 2 = 15.6 m

Depth of excavation = 1.8 m

Width of excavation = width of plain concrete footing = 1.0mVolume = 15.6 × 1.8 × 1.0 = 18.8 m3

Consider another example (Figure 2.4). Plain concrete dimensions (1.2

× 2.0 × 0.2m), reinforced concrete footings dimensions (0.8 × 1.6 ×

0.4 m); depth of excavation 1.2 m and ground beams cross section

is (0.25 × 0.4 m). Find the Cost Estimating 30 Find the volume of theexcavated material. Distance between centerlines is 5 m.


p g



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1.4 Example – 1 Excavation:Consider another example. Plain concrete dimensions (1.2 × 2.0 ×

0.2m), reinforced concrete footings dimensions (0.8 × 1.6 × 0.4 m);

depth of excavation 1.2 m and ground beams cross section is (0.25

× 0.4 m). Find the Cost Estimating 30 Find the volume of the

excavated material. Distance between centerlines is 5 m.

Excavation for footings = 2 × 1.2 × 2.0 × 1.2 =

5.76 m3

Excavation for smell = (5 – 2 × 1) × 0.6 × 0.25 =

0.45 m3

Volume = 5.76 + 0.45 = 6.21 m3


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2.4 Example – 1 Excavation:


p g



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2.4 Example – 2 Backf i l l ing:- Unit of measurement is cubic meter (volume)

-Backfilling = Excavation – volume of all works

inside the excavated pit (footings, smells,

column necks, brickwork, etc.) + amount above

GL (or – amount below GL) as shown in Figure

2.5.




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2.4 Example – 2 Backfiling




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1.4 Example – 2 Backf i l l ing:Consider the example shown in Figure 2.4, the

volume of backfilling could be calculated as

follow:

• Volume of backfilling = excavation – concrete – brick

• Volume of concrete = 15.6 × 1 × 0.4 = 6.24 m3

•

Volume of brick = 15.6 × 0.4 × 1.4 = 8.736 m3

• Volume of backfilling = 18.8 – (6.24 + 8.736) = 3.824 m3




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1.4 Example – Site level ing :

• Measured in m2(area) if thickness less than 30 cm.

• Measured in m3(volume) if thickness more than 30 cm.

Soi l transportat ion:

• Transported soil = vol. of exc. – vol. of backfilling +

additional soil at site• Add swelling factor based on the soil type: 5% sandy

soil. 15% clayey soil and 25% for demolition material.

(owner or contractor)




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1.4 Example – 3 Concrete works Concrete works comprises of both plain

concrete (PC) and reinforced concrete (RC).

• Plain conc rete (PC):

• Measured in m2(area) if thickness < 20 cm.

• Measured in m3(volume) if thickness ≥ 20 cm.

•

Average thickness should be mentioned whenmeasurement is done by area.




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1.4 Example – 3 Concrete works Reinfo rced conc rete (RC):

• All RC elements measured by volume (m3) except

hollow block slabs measured by area (m2).

• Domes, cylindrical roofs and shells measured by area

in the horizontal projection.




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1.4 Example – 4 Br ick worksThe rules and precautions that should be

followed when measuring brick works are

(Figure 2.6):

• Measured in m2(by area) if thickness


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1.4 Example – 4Br ick works




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1.4 Example – 5 Plaster ingPlaster works are measured according to its

location of being internal or external works.

Internal plaster work measured as it is(engineering measurement).

In ternal Plaster:

•

Engineering measurement by area (m2

).• All openings are deducted.

• All openings sides are added.

• Inclined slabs are calculated based on their horizontal

projection.




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1.4 Example – 5 Plaster ingExternal plaster:

• Measured by area (m2).

• Openings with areas < 4 m2 are kept with deduction.

• Deduct half the area of the openings ≥ 4 m2.

• Openings with areas < 4 m2are kept with deduction.

•

Cantilever slabs < 1 m projection not added.• Add half the area of cantilever slabs ≥ 1 m.




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1.5 Example Application: Substructure As with most measurement exercises it is good

practice to start with a taking-off list containing

all the items that have to be included on aSubstructure – taking-off list:

Site preparation Removing trees and shrubs

•

Lifting turf• Top soil/removing/preserving




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1.5 Example Application: Substructure Excavation

• Reduce levels/disposal of excavated material

• Excavating trenches/disposal of excavated

material/filling/surface treatments

Earthwork support to sides of reduced

level/sides of trenches



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2.5 Example Application: Site levelsVirgin sites will almost certainly be covered with a layer

of vegetation that has to be removed prior to excavation

and stored separately or removed from site. Top soilcannot be used for backfilling as it would, over time,

cause damage to the substructure. The usual default

depth for topsoil is 150 mm although it could be more

than this and a test pit may be dug to accurately

determine the actual depth. Figure 2.7 shows a 5 m grid

of a survey of levels taken on a proposed site.




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2.5 Example Application: Site levelsVirgin sites will almost certainly be covered with a layer

of vegetation that has to be removed prior to excavation

and stored separately or removed from site. Top soilcannot be used for backfilling as it would, over time,

cause damage to the substructure. The usual default

depth for topsoil is 150 mm although it could be more

than this and a test pit may be dug to accurately

determine the actual depth. Figure 2.7 shows a 5 m grid

of a survey of levels taken on a proposed site.




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2.5 Example Application: Site levelsThe site is required to be reduced to a level of

35.62 and in order to calculate the volume of

excavation required the average level of the sitemust be determined. This can be quite easily

done by calculating the average level:Average site level = (35.90 × 5 + 35.86 × 3 + 35.89 × 2 + 35.92 + 35.84 × 2

+35.88 × 2 + 35.85 + 35.87 × 2) / 18 = 35.87 m

Reduced site level = 35.62 m

Average excavation depth = 0.25 m

Total excavation volume = 0.25 × 25 × 10 = 62.5 m3




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1.5 Example Application: Brick wal lsFigure 2.7 shows the ground floor plan of the

building with the external and internal walls




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2.5 Example Application: Brick wal lsFigure 2.7 shows the ground floor plan of the

building with the external and internal walls




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2.5 Example Application: Brick wal lsWorking space

• Working space is to be measured in circumstances where

workmen have to operate in situations that require them to workin trenches below ground level, for example when working with

formwork, rendering, tanking or protection. It is measurable as a

superficial item where there is less than 600 mm between the

face of the excavation and the work; all additional earthwork

support, disposal, backfilling and breaking out are deemed to beincluded with the working space item. This is another

contractor’s risk item as he must

• decide and price what space he thinks is required as illustrated

in Figure 2.9.




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2.5 Example Application: Brick wal lsWorking space

• The different quantities take-off is shown as presented below.



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