Reinforced Concrete Course Book

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University of Sulaimani

Engineering Collage

Civil Engineering Department

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

Design of Reinforced Concrete

Course Book

Mr. Kawan K. Ghafor

Sulaimani 2010

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Course Book

Course title Design of Reinforced Concrete lecturer in charge Mr. Kawan K. Ghafor Dept/ Collage Civil Eng. Dept. Engineering Collage Contact details Tel: 0770 156 2324 Email: [email protected] Course link in the University Coordinator’s name Mr. Farhad R. Kareem Contact details Tel: 0770 2248973 Email: [email protected] Course overview: mention the importance and needs of this course in two or three paragraphs. The course contain basic information of design of reinforced concrete in which it deals with teaching the students the fundamental design methods that used in designing concrete members in framed buildings like (Beams, Slabs, Columns, and ….etc). The impotency of this course can be observed in the real practice field because each building (Commercial or Educational or Residential or…..) need to be structurally designed in order to be constructed in the site. Course Objectives: identify in two or three paragraphs the important objectives of the course and show those points that students should learn at the end of the course. Course Objectives:

1. To understand different design approaches that used in concrete design and to select the proper one for each design.

2. To understand the reason of placing reinforcement in certain locations in concrete members.

3. To predict the benefits of learning (Engineering mechanics, Mechanics of Material, Concrete technologies, and Structural analysis) and to understand the relation of these courses in design of reinforced concrete members.

4. To teach the students how to design individual members (Beams, Slab, Columns ….ect) by finding the suitable dimensions and reinforcement for them.

5. To show the students about the standards that should be followed in design of concrete structures. .

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Course Reading List and References Main references:

1. Jack C. McCormac and James K. Nelson "Design of Reinforced Concrete" 7th. Edition, 2006.

2. Arthure H. Nelson, David Darwin, Charles W. Dolan "Design of Concrete Structures" 13th. Edition 2004.

3. Victor E. Saouma "Lecture notes in Mechanics and Design of Reinforced Concrete" University of Colorado, USA. Fall 2002.

4. ACI Committee "Building Code Requirements for Structural Concrete (ACI 318‐08) and commentary" Structural Building Code. January 2008.

Internet reviews: ~ Any internet sources deals with "Design of concrete structures" by using ACI code can be helpful for the course study.

Syllabus of Reinforced Concrete Design ‐3rd. Stage

Week No.

Title of the Subject Lecture’s name

1 Introduction, Syllabus and mentioning overall idea about course benefits and impotencies

Kawan K. Ghafor

2 Material Properties (Cement, Sand, Graver, Reinforcing Steel, and Concrete mix)

Kawan K. Ghafor

3 Design philosophies ( Working Stress Design and Ultimate Strength Design)

Kawan K. Ghafor

4 Design of Reinforced Concrete Beams ( Singly Reinforced)

Kawan K. Ghafor

5 Design of Reinforced Concrete Beams ( Singly Reinforced)

Kawan K. Ghafor

6 Design of Reinforced Concrete Beams ( Doubly Reinforced)

Kawan K. Ghafor

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7 Design of Reinforced Concrete Beams ( T‐ Beam Design)

Kawan K. Ghafor

8 Design of Reinforced Concrete Beams ( Shear Design)

Kawan K. Ghafor

9 Design of Reinforced Concrete Continuous Beams and One Way Slabs

Kawan K. Ghafor

10 Design of Reinforced Concrete Continuous Beams and One Way Slabs

Kawan K. Ghafor

11 Design of Reinforced Concrete Two way Slabs approximated method (Coefficient Method)

Kawan K. Ghafor

12 Design of Reinforced Concrete Two way Slabs (Direct Design Method) DDM

Kawan K. Ghafor


Kawan K. Ghafor


Kawan K. Ghafor


Kawan K. Ghafor

16 Design of Reinforced Concrete Two way Slabs (Flat Slabs and Flat Plate Slabs)

Kawan K. Ghafor


Kawan K. Ghafor


Kawan K. Ghafor

19 Design of Reinforced Concrete Columns. Short Column ( Axially Loaded Column)

Kawan K. Ghafor

20 Design of Reinforced Concrete Columns. Short Column ( Axially Loaded Column)

Kawan K. Ghafor

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21 Design of Reinforced Concrete Columns. Short Column ( uni‐axially Loaded Column)

Kawan K. Ghafor

22 Design of Reinforced Concrete Columns. Short Column ( bi‐axially Loaded Column)

Kawan K. Ghafor

23 Design of Reinforced Concrete Columns. Slender Column

Kawan K. Ghafor

24 Design of Reinforced Concrete Columns. Slender Column

Kawan K. Ghafor

25 Design of Reinforced Concrete Stair ways Kawan K. Ghafor

26 Design of Reinforced Concrete Stair ways Kawan K. Ghafor

27 Design of Reinforced Concrete Beams ( Torsion) Kawan K. Ghafor

28 Design of Reinforced Concrete Beams ( Torsion) Kawan K. Ghafor

29 Design of Reinforced Concrete Single Column Footings

Kawan K. Ghafor

30 Design of Reinforced Concrete Single Column Footings

Kawan K. Ghafor

Details of syllabus of Reinforced Concrete Design ‐3rd. Stage

Chapter 1: Introduction and Design philosophies Lecturer's name: Kawan K.

Ghafor

1.1 Introduction on the subject.

1.2 Material Properties.

1.2.1 Cement

1.2.2 Sand

1.2.3 Gravel

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1.2.4 Reinforcing Steel

1.2.5 Concrete

1.3 Concrete Properties

1.3.1 Compressive strength

1.3.2 Tensile strength

1.3.3 Shear strength

1.3.4 Shrinkage and creep

1.4 Design Philosophy

1.4.1 Working Stress Design (WSD)

1.4.2 Ultimate Strength Design (USD)

Chapter 2: Design of Reinforced Concrete Beams Lecturer's name: Kawan K.

Ghafor

2.1 Introduction

2.2 Actual Behavior of reinforced concrete rectangular beams

2.3 Equivalent behavior of reinforced concrete rectangular beams

2.4 Design of singly reinforced rectangular concrete beams

2.4.1 Solving Examples

2.5 Design of doubly reinforced rectangular concrete beams


2.6 Design of reinforced concrete beams (T‐beams)


2.7 Design of reinforced concrete beams (Shear Design)


2.8 Design of continuous beams and one way slabs

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2.8.1 Depth limitations according to ACI code

2.8.2 Moment coefficients provided by ACI code


Chapter 3: Design of Reinforced Concrete Two Way Slab

Lecturer's name: Kawan K. Ghafor

3.1 Type of reinforced concrete slabs

3.2 Design methodology

3.2.1 Approximate (Coefficient Method)

3.2.2 Detailed Method (Direct Design Method)

3.3 Analysis of Two Way reinforced concrete Slabs using Coefficient Method

3.3.1 Analysis procedure

3.3.2 Determination of slab thickness

3.3.3 Design examples

3.3.4 Arrangement of reinforcement

3.4 Analysis of Two Way reinforced concrete Slabs using Direct Design Method

3.4.1 Analysis procedure

3.4.2 Determination of slab thickness

3.4.3 Determination of moments in column and middle strips


Chapter 4: Design of Reinforced Concrete Flat Slabs


4.1 Introduction

4.2 Advantages and disadvantages of flat slabs

4.3 Checking Punching shear in flat plate and flat slabs

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4.3.1 Punching Shear in Flat plate slab

4.3.1.1 Increasing slab thickness

4.3.1.2 Increasing cylindrical concrete compressive strength (f'c)

4.3.1.3 Adding reinforcement

4.3.1.3.1 Bent bar method

4.3.1.3.2 Shear Head method

4.3.1.3.3 Design examples

4.3.2 Punching Shear in Flat Slabs

4.3.2.1 Using Drop panel

4.3.2.2 Using column Capitals

4.3.2.3 Using both drop and capitals

4.3.2.4 Design examples

4.4 Analyzing and designing flat plate slabs

4.4.1 Design Examples

4.5 Analyzing and designing flat slabs


Chapter 5: Design of Reinforced Concrete Columns


5.1 Introduction

5.2 Types and shapes of reinforced concrete Columns

5.2.1 Short Column

5.2.2 Slender (Long) Column

5.3 Analysis and design of rectangular R.C. column (Short Column)

5.3.1 Axially Loaded Column

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5.3.2 Uni‐axially loaded Column

5.3.3 Bi‐axially loaded column


5.4 Slender Column

5.4.1 Definition of slender column

5.4.2 Analysis of slender column


Chapter 6: Design of Selected topics Lecturer's name: Kawan K. Ghafor

6.1 Analysis and design of reinforced concrete beams (Torsion)

6.1.1 Introduction to torsion

6.1.2 Method of analysis

6.1.3 Combination of shear and torsion

6.1.4 Combination of flexure and torsion


6.2 Analysis and design of Stair ways

6.2.1 Introduction

6.2.2 Analysis and design of simply supported stair ways

6.2.3 Analysis and design of fixed stair ways


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Objectives and Scientific contents of chapters

Chapter 1: Introduction and Design philosophies


Chapter Objectives:

1. To have an idea about material used in reinforced concrete and their participation on preparing the most suitable mix.

2. To understand the strong and week points of concrete materials

3. To compare between design philosophies (Which one is applicable)

Scientific Content of the Chapter:

This chapter involves in giving a general idea of the physical properties of the material that participated in concrete mix, also to understand the property of fresh and hardened concrete and their effects on design strength. In this chapter the two available design philosophies (Working Stress Design and Ultimate Strength Design) that used in design of any concrete structure were presented also their advantages and disadvantages were clarified in order to choose between them.

Chapter references:

1. Arthure H. Nelson, David Darwin, Charles W. Dolan "Design of Concrete Structures" 13th. Edition 2004. 2. Internet sources.

Chapter 2: Design of Reinforced Concrete Beams


Chapter Objectives:

1. To understand the behavior of reinforced concrete beams under vertical load.

2. To teach the student how to design reinforced concrete rectangular and T‐beams for both flexure and shear and comparing the results with ACI‐Code limitations.

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3. Simplifying the design process by using several design procedures in order to identify the behavior of each beam alone.


This chapter deals with analyzing and designing reinforced concrete beams using Ultimate strength design (USD) methods also taking into account the latest ACI‐Code provisions.

Chapter references:




Chapter 3: Design of Reinforced Concrete Two way slabs


Chapter Objectives:

1. To understand the behavior of two‐way reinforced concrete slabs in framed structures.

2. To teach the student how to design reinforced concrete slabs using both approximate (coefficient method) and accurate (Direct design method) taking in to account ACI‐Code provisions.

3. To teach the student the method of arranging reinforcement in the slab.


This chapter deals with analyzing and designing reinforced concrete two‐way slabs using both approximate and accurate methods, taking in to account the effect of factored dead and live loads, also using the latest ACI‐Code provisions.

Chapter references:

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Chapter 4: Design of Reinforced Concrete Flat slabs


Chapter Objectives:

1. To identify flat slabs and flat plate slabs.

2. To teach the student check for punching shear for both flat slabs and flat plate slabs, and the methods of eliminating punching shear effect by increasing slab thickness or adding reinforcing bars for flat plate slabs and adding drop panel and capitals for flat slabs.

3. To teach the student how to design reinforced concrete flat slabs and flat plate slabs.


This chapter deals with analyzing and designing reinforced concrete flat slabs with or without drop panels by using direct design method, taking in to account the effect of factored dead and live loads, also using the latest ACI‐Code provisions.

Chapter references:




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Chapter 5: Design of Reinforced Concrete Columns


Chapter Objectives:

1. To identify types of column (Short or Long) Column.

2. To teach the student how to design short column with axially or uni‐axially or bi‐axially loaded.

3. To check the slenderness ration of long column in order to analyze it properly.


This chapter deals with analyzing and designing reinforced concrete column under several loading conditions in accordance with ACI‐Code provisions.

Chapter references:




Chapter 6: Design of Selected Topics


Chapter Objectives:

1. To design reinforced concrete beams for combination of shear and torsion also combination of flexure and torsion.

2. To teach the student how to design stair ways

3. To explain the formation of internal hinges in stair ways and it's effect on analysis procedure.


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This chapter contains two parts: the first part deals with analyzing and designing reinforced concrete beams considering tensional effects. While the second part involves in analyzing and designing of reinforced concrete stair ways of different support reactions.

Chapter references:




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Sample of Examinations and their answers

Q1/ For the continuous beam shown in figure (1). Check the safety of the beam in

order to carry the following loadings:

Service D.L. = 2000 kg/m (Including its own weight).

Service L.L. = 1500 kg/m

Material Properties:

fc' = 21 Mpa : fy = 345 Mpa : Clear Cover = 50mm.

Moment at Supports to be assumed = Wu * l2/11

Moment at Mid Span to be assumed = Wu * l2/16 (50 Marks)

Solution:

Wuli = 1.4DL + 1.7LL = 5350 kg/m

‐M = Wu * l2/11 = 21186 kg.m

+M = Wu * l2/16 = 14565.375 kg.m

At Support

As = 2φ16 + 3φ25 ‐‐‐‐‐‐‐‐ As = 1870mm2

ρ = As/bd = 1870/ 400 x 577.5

ρact. = 0.0081

ρmin. = 0.004 and ρmax. = 0.02094

Since ρmin < ρact < ρmax. So, tensile failure is guarantee

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M = φ As fy ( d‐a/2) and

a = As fy / 0.85 f'c b = 1870 x 345 / 0.85 x 21 x 400 = 90.36mm

M = 0.90 x 1870 x 345 x ( 577.5 – 90.36/2)

M = 30908 kg.m Resisting Moment at supports

At Mid Span

As = 5φ16 ‐‐‐‐‐‐‐‐ As = 1000mm2

ρ = As/bd = 1000/ 400 x 577.5

ρact. = 0.00429

ρmin. = 0.004 and ρmax. = 0.02094

Since ρmin < ρact < ρmax. So, tensile failure is guarantee

M = φ As fy ( d‐a/2) and

a = As fy / 0.85 f'c b = 1000 x 345 / 0.85 x 21 x 400 = 48.32mm

M = 0.90 x 1000 x 345 x ( 577.5 – 48.32/2)

M = 17181 kg.m Resisting Moment at supports

Check for Shear

Applied Shear = Vu = Wu x L /2 = 17655 kg

Vd = Vu – Wu xd = 14568 kg

φVc = φ x 0.17 x√f'c x b x d = 15296 kg

Since φVc > Vd Min. web reinforcement required

=60mm

S max = Least of d/2 = 289mm

3Av fy/b = 406mm

S max = 289mm < S avaible ( 200mm)

So, from the above calculation we get that the beam is O.K.

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Q2/ Design the two span Slab shown in figure (2), using the following data:

fc' = 21 Mpa. : fy = 345 Mpa. : Clear Cover = 20mm

Dead Load Placed on the Slab = 400Kg/m2

Live Load acting on the Slab = 500Kg/m2

Use (12mm bar Diameter) for reinforcement

Use ACI – Moment Coefficients…. (30 Marks)

Solution:

Determination of Slab thickness (t)

t = L/24 (One end continuous)

t = 3.85 x 100/24 = 16cm

Weight of Slab = 0.16 x 2400 = 384 kg/m2

Wult. = 1.4 DL + 1.7 LL = 1947.6 kg /m2

Using ACI moment coefficient

Exterior Support ‐M = 1/24 Wult. Ln2 = 1202.84 kg.m

Mid Span +M = 1/14 Wult. Ln2 = 2062.02 kg.m

Interior Support ‐M = 1/9 Wult. Ln2 = 3207.5 kg.m

Checking the slab thickness depending on the maximum moment

‐M max. = 3207.5 kg.m

Let ρact. = ρmax. = 0.02094

M = φ x ρ b x d2 x fy ( 1‐ 0.59 x ρ fy / f'c)

d req = 78.67mm < d available = 134mm

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The depth is O.K.

Determination of reinforcement:

Exterior Support ‐M = = 1202.84 kg.m As req. = 320 mm2

Mid Span +M = = 2062.02 kg.m As req. = 550 mm2

Interior Support ‐M = = 3207.5 kg.m As req. = 856 mm2

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

Q3/ A‐Find out the ultimate load ( Wulti. ) for the beam selected in figure (3), using

the following data:

Dead Load Placed on the Slab = 750Kg/m2 (Including its own weight.)


Ignore beam self weight…. (10 Marks)

Solution:

The System is one way slab, So

Area factor = Area / Length of the beam

= 2 x 9 / 9 = 2m

Wulti. = 1.4 x (2x750) + 1.7 x (2x400)

Wulti. = 3460 kg/m

B‐ Why, in singly reinforced concrete beams, the reinforcement ratio (ρ ) must be within the following limit?

ρmin.≤ ρact. ≤ ρ max. (10 Marks)

ρmin.≤ ρact. To prevent cracks due to temperature and shrinkage.

ρact. ≤ ρ max To prevent compression failure.

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Student’s Feedback on the Course

Course: Date: Year: lecturer: Department: College: University:

No. Evaluation Questions Level (1‐5) More Remarks – Objective ones

1 The objectives and key messages of the course were clear?

2 The contents of the subject were useful and relevant to the main goal of the department?

3 The lecturer had worked hard to prepare the course book?

4 The lecturer had worked hard to cooperate and prepare the course?

5 The lecturers in general were carefully selected and were expert in their fields?

6 The lecturer gives good attention to the students’ criticisms and claims?

7 Information on the examination process was well provided?

8 The questions of the exam were related to the contents of the course?

9 Total of the levels 10 Examples of changes for

developing the course:

Evaluation Measuring Tool 1‐2 Not Good 2‐3 Average 3‐4 Good 4‐5 Very Good

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Student’s Feedback for the Subject

Title of Subject: Course: Date: Year: lecturer: Department: College: University:

No. Evaluation Questions Level (1‐5) More Remarks – Objective ones

1 The objectives and key messages of the subject were clear?

2 The contents of the subject were useful and relevant to the main goal of the course?

3 The materials were prepared carefully as needed

4 The lecturer while lecturing tried to analyze the principles, contents and the important points of the subject simply and properly?

5 The lecturer came into the classroom on time and was committed to the duration of the lecture?

6 The lecturer’s behaved calmly and respectfully during the lecture?

7 The slides used in the lecture were clear and attractive?

8 The lecturer gave the students chance to ask questions and tried to answer them fully?

9 The reading sources are new and compatible with the subject.

10 Total of the levels

Evaluation Measuring Tool 1‐2 Not Good 2‐3 Average 3‐4 Good 4‐5 Very Good

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University of Sulaimany College of Engineering Building Construction Dept.

3rd. Year (06‐07) Concrete Design Mr. Kawan K. Ghafor

First Exam 20th. Jan. 2007 Period: 90 Minutes

Q1/ For the continuous beam shown in figure (1). Check the safety of the beam in order to carry the following loadings:

Service D.L. = 2000 kg/m2 (Including its own weight).

Service L.L. = 1500 kg/m2

Material Properties:

fc' = 21 Mpa. fy = 345 Mpa.

Moment at Supports to be assumed = Wu * l2/11

Moment at Mid Span to be assumed = Wu * l2/16

Clear Cover = 50mm. (50 Marks)

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

Q2/ Design the two span Slab shown in figure (2), using the following data:

fc' = 21 Mpa. fy = 345 Mpa.

Dead Load Placed on the Slab = 400Kg/m2


Clear Cover = 20mm

Use (12mm bar Diameter) for reinforcement

Use ACI – Moment Coefficients…. (30 Marks)

‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐‐

Q3/ A‐Find out the ultimate load ( Wulti. ) for the beam selected in figure (3), using the following data:

Dead Load Placed on the Slab = 750Kg/m2 (Including its own weight.)


Ignore beam self weight…. (10 Marks)

B‐ Why, in singly reinforced concrete beams, the reinforcement ratio (ρ ) must be within the following limit?

ρmin.≤ ρact. ≤ ρ max. (10 Marks)

Assume any missing data using reasonable values

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Reinforced Concrete Course Book