CSE30310 Lecture .pdf thehongkongpolytechnicuniversity

CSE30310 Lecture .pdf thehongkongpolytechnicuniversity

1. Lecture 1: Introduction
CSE 30310Design of
Concrete Structures
Dr Muhammad Riaz Ahmad
[email protected]
Department of Civil and Environmental Engineering
The Hong Kong Polytechnic University
1

2. 2
Subject Information

3. Prof Yuner Huang (Subject Lecturer)
3
Work Experience
Associate Professor (2025-present), PolyU, Hong Kong
Honorary Lecturer (2025-present), University of Edinburgh, UK
Senior Lecturer (2022-2024), University of Edinburgh, UK
Lecturer (2015-2022), University of Edinburgh, UK
Education
BEng & Ph.D. in Civil Engineering (2009, 2013), University of Hong Kong
Professional Membership
Member, Institution of Civil Engineers (CEng MICE)
Member, American Society of Mechanical Engineers (MASME)
Fellow, Higher Education Academy (FHEA)
Hometown
Foshan -hometown of ceramic art, Cantonese opera, and martial arts
[email protected], ZS931

4. Dr. Riaz (Subject Lecturer)
4
Work Experience
Research Assistant Professor (2023-present), PolyU, Hong Kong
Visiting Researcher (2022-2023), University of Tokyo, Japan
Post-Doctorate Fellow (2021-2023), PolyU, Hong Kong
Education
Ph.D, Civil Engineering (2021), Shanghai Jiao Tong University,
BSc & MSc in Civil Engineering (2013, 2017), UET Lahore,
Contact Information:
Z407A, ([email protected])
More information at

5. 5
Contact information for Tutors
MrChen WU
(Tutorials in Week 7 & 9;
Assignment 2)
Dr QiuyunLI
(Tutorials in Week 11 & 13;
Assignment 2)
Miss PeilinLI
(Tutorials in Week 3 & 5;
Assignment 1)
[email protected] [email protected] [email protected]
Dr Yazan ALREFAEI
(Laboratory)
[email protected]

6. 6
1.Acquire basic knowledge on the design concepts and
detailing techniques of the slabs, beams, columns,
walls & foundations of reinforced concrete structures;
2.Understand the basic design principles of prestressed
concrete beams;
3.Carry out practical design of concrete elements
according to code requirement & communicate
logically and lucidly through construction drawings
and calculations;
Learning outcomes

7. 7
4. Appreciate the performanceof concrete structures
through design calculations and lab tests and
understand the limitations of design assumptions
through the lab tests;
5. Recognize the need for, and to engage in life-long
learning
Learning outcomes (Cont.)

8. 8
1. Course work 30% including
•Assignments (10%)
•Quiz and Mid-term test (10%)
•Lab Report (5%)
•Seminar Report (5%)
2. Examination (Final examination 70%)
Note: Student must attain at least Grade D in both course work and
examination in order to pass the course as a whole. Late
submission is not allowed.
Assessment methods

9. 9
Teaching Activities
Detailed timetable can be found in Teaching Plan
(Read carefully!
Note the Public Holiday arrangement in W11 & 13)

10. 10
Teaching Activities
Learning
Cone
Lectures
Tutorials & Lab!!

11. 11
Teaching Activities
Attending lectures, tutorials & labs are
CRUCIALfor getting good scores in this
course.
Directly impact your course enrolment in
Design Project for Civil Engineering in year 4
as part of pre-requisites, and thus your
graduation.
We will take attendance in lectures & tutorials
(submit handwritten worksheets in person
during tutorial).

12. 12
1.Introduction
2.Structural Systems
3.Loads in Structural systems
4.Properties of Reinforced Concrete
5.Types of Concrete

13. 13
1. Introduction

14. 14
Introduction
Construction Materials
Various substances or products used in the building and construction industry to create
structures and infrastructure.
Concrete is the most widely used construction material globally.
Worldwide cement production (2016)

15. 15
Introduction
Concrete Statistics

16. 16
Introduction
Plain Cement Concrete (PCC)
Mixture of cement , sand and coarse aggregate
without any reinforcement is known as PCC.
PCC is strong in compression and week in
tension. Its tensile strength is so small that it
can be neglected in design.
No Steel Reinforcement in PCC

17. 17
Introduction
Reinforced Cement Concrete (RCC)
Mixture of cement , sand and coarse aggregate
with reinforcement is known as RCC. (Tensile
strength is improved)
Steel Reinforcement in RCC

18. 18
Introduction
Supplementary Cementitious Materials (SCMs): SCMs are materials used as a partial
replacement of portland cement to improve both fresh and hardened concrete properties.
SCMs
SCMs can be from natural sources or
industrial byproducts and have lower
environmental impact than Portland
cement.
Types of SCMs
•Fly ash
•Slag
•Calcined Clay
•Silica Fume

19. 19
Introduction
Why we need Reinforcement in concrete?
Plain cement concrete is strong in compression and weak in tension. This means that while it
can withstand heavy loads pressing down on it, it is not as effective at resisting forces that try
to pull it apart or bend it.

20. 20
Introduction
Why we need Reinforced cement concrete?
Plane cement concrete is weak in tension
1.Tensile Strength
2.Crack Control
3.Ductility
4.Load Distribution
5.Durability
6.Structural Integrity
Advantages of reinforcement
Reinforced cement concrete is provide additional tensile
strength

21. 21
Introduction

22. 22
Easa, S.M.; Yan, W.Y. Performance-Based Analysis in Civil Engineering: Overview of
Applications.Infrastructures2019,4, 28.
https://doi.org/10.3390/infrastructures4020028
Introduction (Civil Engineering Infrastructures)
Buildings Bridges Dams

23. 23
Easa, S.M.; Yan, W.Y. Performance-Based Analysis in Civil Engineering: Overview of
Applications.Infrastructures2019,4, 28.
https://doi.org/10.3390/infrastructures4020028
Introduction (Civil Engineering Infrastructures)
Tunnels Roads/Pavements

24. Concretestructuresarethefoundationofmoderncivilization.Theyareextensivelyusedinbuildings,
bridges,roads,dams,floatingstructure,andtunnels.
Burj Khalifa, 828 m
Three Gorges Dam, 181 m
Hong Kong-Zhuhai-Macao Bridge US Highway 1
Floating Ports and Villas
The Lærdal Tunnel
(a) Buildings (b) Bridges (c) Road/highways
(d) Dams (e) Floating structures (f) Tunnels
24
Introduction (Civil Engineering Infrastructures)

25. 25
Introduction (Failure in RCC structures)
Collapse of a bridge
Building collapse

26. 26
Failure of Beam-Column Joints
Collapse of whole buildings
Introduction (Failure in RCC structures)
Corrosion in buildings

27. 27
Si-Chuan Earthquake (2008),
150 B USD, Casualities (88,708)
Turkey Earthquake (2023)
(34 B USD, Casualities 59,259)
Tohoku Earthquake (2023),
360 B USD, Casualities 19,759 )
Pakistan Flood (2010)
50 B USD , Casualities 2,000, 33 m people effected
Introduction (Natural Disaster)

28. 28
BuildingCollapse（Hong Kong）(29-01-2010）
Introduction

29. 29
What are the reasons
for RCC structure
failures?
Introduction

30. 30
How to achieve a safe design of RC structures?
What are the reasons for RCC structure failures?
Introduction
1.Design Errors
2.Poor Construction Practices
3.Material Deficiencies
4.Corrosion of Reinforcement
5.Overloading
6.Environmental Factors
7.Lack of Maintenance
8.Foundation Issues
9.Fatigue and Wear

31. 31
2. Overview of structural systems

32. 32
Reinforced concrete building elements
Basic structural systems
Primary functions of building systems is to support gravity loads for strength and serviceability during:
1. Normal use (service) conditions; (regular occupancy and use of the structure on day-to-day basis)
2. Maximum considered use condition; (during events such as concerts or gatherings e.g, stadiums)
3. Environmental loading of varying intensities. (wind, snow, seismic activity)

33. 33
Load Transfer mechanism
Basic structural systems
Function of structure is to transfer all the loads safely to ground.
A particular structural member transfers load to other structural member.

34. Vertical deflection (sag) Lateral deflection (sway)
Dead, imposed etc. Wind, earthquake
34
Deflections
Basic structural systems

35. 35
Beam element
Defn:Members subject to bending and shear
V
V
L
E,I,A
MM
Basic structural systems
Column element
Defn:Members subject to bending, shear, and axial
V
V
L
E,I,A
MM
F F

36. 36
Slab/plate element
Defn:Members subject to bi-directional bending & shear
Basic structural systems
One-way Slab
Two-way Slab

37. 37
Wall/diaphragm element
Defn:Members subject to shear
Basic structural systems
Shear wall subjected to lateral loads
German Cast In Situ Technology, precast technology Hyderabad -Janapriya.com

38. 38
Floor system:
Flat plate
Flat slab (w/ drop
panels and/or capitals)
One-way joist system
Two-way waffle system
Lateral load system:
•Flat plate (& slab)-column
(w and w/o drop panels and/or capitals)
frame systems
•Beam-column frame systems
•Shear wall systems
(building frame and bearing wall)
•Dual systems
(frame and shear walls)
Structural systems
Basic structural systems

39. 39
Flat Plate Floor System
Flat Plate w/Spandrel Beam Floor System
Basic structural systems
Floor systems
Beam-slab system

40. 40
One way-joist floor systemFlat slab floor system
ElevationPlan
Basic structural systems

41. 41
Waffle slab floor system
Basic structural systems
Waffle slab floor system, PolyU

42. 42
Frame:Coplanar or a non-coplanar system of beam (or slab) and column
elements dominated by flexural deformation
Gravity Load Lateral Loading
Basic structural systems

43. 43
Basic structural systems
One-way slab system
two-way slab system

44. 44
Frame lateral load systems
Basic structural systems
Flat plate systems are normally less effective in resisting the lateral load system. A
wider slab provides additional stiffness and rigidity to the system, which can
enhance its resistance to lateral load and also increase torsional resistance of
structure.

45. 45
Shear wall lateral load systems
Basic structural systems
Dual lateral load systems
In frame lateral load systems, the lateral load
resistance can be enhanced by configuring elevator
shaft or by providing shear walls within the structure.
They provide additional stiffness and strength to
resist lateral forces and can enhance the lateral
resistance of the lateral load system.

46. 46
4. Loads in structural systems

47. 47
Gravity:
1.Dead;
2.Imposed;
3.Impact;
4.Snow;
5.Ice;
6.Rain/floods.
…….
Lateral:
1.Wind;
2.Earthquake;
3.Soil lateral pressure;
4.Thermal;
5.Centrifugal.
……
Types of loads
Loads in structural systems

48. 48
Loads in structural systems
Loads

49. 49
Definition of characteristic load
Loads in structural systems
‘Characteristic load’ means that load which has a 95% probability of not being
exceeded, during the life of the structure.
Using Characteristic Load in Design
1.Determining the Characteristic Load:
2.Applying Load Factors:
3.Calculating the Design Load:
4.Structural Analysis and Design:

50. 50
5. Properties of Reinforced
Concrete

51. 51
Properties of concrete
•The first portion of curve, to about 40% of the ultimate strength f
c’, can be
considered linear
fc’ 0.85fc’
Stress
Strain
Crushing
0.0028 to 0.0045,
generally 0.0035
0.4 fc’
Stress Strain Curve of Concrete

52. 52
E
C= (1.25E
cq-19) kN/mm
2
Properties of concrete
Modulus of Elasticity
Concrete is not an elastic material therefore it does not have a fixed value of modulus
of elasticity
Strain
Tangent and Secant Moduli of Concrete
Stress
Secant or static Modulus (Ec)
Tangent Modulus
Initial tangent
Modulus (Ecq)

53. 53
Properties of concrete
Characteristic strength of concrete
Characteristic strength is defined as that level of strength below which a specified proportion
of all valid test results is expected to fail. Unless otherwise stated, this proportion is taken to
be 5%.

54. 54
Properties of concrete
Development of concrete strength

55. 55
Reinforcing steel bars
Properties of steel
Steel bars are:
Plain
Deformed (currently in use)
Deformed bars have longitudinal and transverse ribs. Ribs provide a good bond
between steel and concrete. If this bond fails steel becomes in effective.
The most important properties for reinforcing steel are:
Young's modulus, E
Yield strength, f
y
Ultimate strength, f
u
Size and diameter of bar

56. 56
Reinforcing steel characteristics
Stress-strain curves for reinforcing steel
0.002
Strain
Stress
Proof stress
Strain
Stress
Yield stress
(a) Hot rolled steel (Mild steel) (b) Cold worked steel (High-yield steel)
Properties of steel
The characteristics of steel are
1.Mildsteelbehavesasanelasticmaterial,withthestrainproportionaltothestressuptotheyield,atwhichpointthereis
asuddenincreaseinstrainwithnochangeinstress.Aftertheyieldpoint,thisbecomesaplasticmaterial,andthestrain
increasesrapidlyuptotheultimatevalue.
2.Highyieldsteelmaybehaveinasimilarmannerormay,ontheotherhand,nothavesuchadefiniteyieldpointbutmay
showamoregradualchangefromelastictoplasticbehaviourandreducedductilitydependingonthemanufacturing
process.AllmaterialshaveasimilarslopeoftheelasticregionwithelasticmodulusEs=200kN/mm2approximately.
Amount of stress that will result
in a plastic strain of 0.2%

57. 57
Short-term design stress-strain curve
for steel reinforcement (HK2013)
Properties of steel
Strain
Grade
250
Grade
500
Stre
ss
For hot rolled steel
bars

58. 58
Properties of reinforced concrete (Shrinkage)
Excessive shrinkage can be avoided by proper curing during first 28 days because half of the total
shrinkage takes place during this period.
Shrinkage is reduction in volume of concrete due to loss of water

59. 59
Properties of reinforced concrete (Shrinkage)
Calculate Shrinkage Stresses in Concrete for
(a) Restrained by reinforcement only
(b) Fully Restrained

60. 60
Reinforcement restrains shrinkage movement and generate
tension in concrete
Properties of concrete
Concrete creep and shrinkage calculator -Strusoft
Whencrackingoccurs,theuncrackedlengthsofconcretetrytocontractsothatthe
embeddedsteelbetweencracksisincompressionwhilethesteelacrossthecracks
isintension.Thisfeatureisaccompaniedbylocalisedbondbreakdown,adjacent
toeachcrack.

61. 61
Development of creep deformation with time affects deflections and crack widths
Properties of concrete
“Creep is the continuous deformation of material over considerable lengths of time at
constant stress or load”
The characteristics of creep are
1.Thefinaldeformationofthemembercanbethreetofourtimestheshort-termelasticdeformation.
2.Thedeformationisroughlyproportionaltotheloadintensityandtotheinverseofconcretestrength.
3.Iftheloadisremoved,onlytheelasticdeformationwillrecover–theplasticdeformationwillnot.
4. There is a redistribution of load between the concrete and any steel present

62. 62
6. Advantages and Disadvantages
of Reinforced Concrete

63. 63
Suitability of material for architectural and structural function
◦Concrete place in plastic condition -desired shape & texture can be obtained
with forms and finishing techniques.
◦Designer can choose shape and size.
Fire Resistance: Concrete building have 1-3 hour fire rating with no fire proofing
(steel and timber require fireproofing to obtain this rating)
Rigidity: Greater stiffness & mass reduces oscillations (wind), floor vibrations
(walking)
Low Maintenance
Availability of Materials: Sand, gravel, cement, water & concrete mixing
facilities widely available; Reinforcement -easy to transport as compared to
structural steel
Good bonding between the steel and concrete
Less chance of buckling
Advantages of Reinforced Concrete

64. 64
Low tensile strength -0.1 f
c; cracking if not properly reinforced.
Forms and Shoring (additional steps).
◦Construction of forms; Removal of forms; Prepping (or shoring) the new
concrete to support weight until strength is adequate; Labor/Materials cost not
required for other types of materials.
Strength per unit volume is relatively low.
◦f
c~ (5-10% of steel); greater volume required.
Time-dependent volume changes.
◦Concrete undergoes drying shrinkage, which may cause deflections and
cracking.
◦Creep of concrete under sustained loads causes an increase in deflection
with time.
Increased self weight
large cross-section is required only to resist self weight, making structure
costly
Disadvantages of Reinforced Concrete

65. 65
7. Types of Concrete

66. 66
•Ready-mixed concrete
•High-performance concrete
•Self-compacting concrete
•Roller-compacted concrete
•Structural lightweight concrete
•Fiber-reinforced concrete
•Engineering cementitious
composites
•Polymer concrete
•Shotcrete
•Internal curing concrete
•Self healing concrete
•Self cleaning concrete
•Recycled concrete
•Autoclaved cellular concrete
•Geopolymer
•Seawater sea-sand concrete
•3D printing concrete
Types of concrete

67. 67
✓SCC is a highly workable concrete that can flow through densely reinforced and
complex structural elements under its own weight and adequately fill all voids
without segregation, excessive bleeding, excessive air migration, and the need for
vibration or other mechanical consolidation.
✓The highly flowablenature of SCC is due to very careful mix proportioning,
usually replacing much of the coarse aggregate with fines and cement, and adding
chemical admixtures.
https://youtu.be/M38gamAlxt0
Self-compacting concrete (SCC)

68. 68
✓Fibres are added to concrete to control cracking caused by plastic shrinkage and
drying shrinkage.
✓The addition of small closely spaced and uniformly dispersed fibres will act as crack
arresters and enhance the tensile, fatigue, impact, and abrasion resistance of
concrete.They also reduce the permeability of concrete.
✓Though the flexural strength may increase marginally, fibres cannot totally replace
flexural steel reinforcement.
Fiber-reinforced concrete

69. 69
✓ECC are a special type of high-performance fiberreinforcement cementitious composites
(HPFRCC) that has been micro-structurally tailored based on micro-mechanics.
✓ECC is systematically engineered to achieve high ductility under tensile and shear
loading.
✓By employing material design based on micro-mechanics, it can achieve maximum
ductility in excess of three per cent under uniaxial tensile loading with only two per cent
fibre content by volume.
Engineered cementitious composites

70. 70
3D printing concrete
3D printing is revolutionary technology, that
allows for the faster fabrication of custom-
designed and complex concrete structures.
The process of concrete printing is completed
layer-by-layer and controlled by the blueprints
or digital models from a computer.

71. 71
End of Lecture