Giáo trình Strength of Materials - Chapter 1: Basic Concepts

STRENGTH OF MATERIALS, 
COURSE CODE: 
INTRODUCTION: 2016 
• Lecturers: Dr. Lam Nguyen-Sy (Nguyễn Sỹ Lâm), B6, Civil Eng Building 
 Email: lamns@hcmut.edu.vn, Phone: 0916511973 
• Lectures: Monday  pm –  pm, Room 304 H2 - 205H2 Building 
 Friday pm – pm, Room 403 H2 
• Consultation: 
(1) try your peer students, 
(2) then try your tutor, 
(3) then Lecturers (room , Tuesday -pm & Wednesday -...pm) 
STRENGTH OF MATERIALS, 
COURSE CODE: 
INTRODUCTION: 2015 
MAIN BOOKS 
1. Đỗ Kiến Quốc, et al, Strength of Materials, 2007. 
2. Hibbeler RC, Mechanics of Materials, Fifth Edition, 2003. 
3. Gere JM, Mechanics of Materials, Fifth Edition, 2001. 
4. Problems on Mechanics of Materials (Vietnamese) 
AIMS 
The subject aims: 
- To equip the student with essential knowledge about external and 
internal forces occurring in simple structural elements under the action 
of various types of loadings. 
- To understand the determination of the stresses, strains and 
displacements produced by the loads. 
- To furnish an understanding of the mechanical behavior of materials, 
which is essential for the safe design of all structures in civil and 
mechanical engineering. 
LEARNING EXPECTATIONS 
What do you think the 
STRENGTH OF MATERIALS 
course should be dealing with? 
LEARNING EXPECTATIONS 
A DAM: WHAT IS THE BASIC PRINCIPLE OF ITS 
STRUCTURE? 
LEARNING EXPECTATIONS 
A DOM: WHAT IS THE BASIC PRINCIPLE OF ITS 
STRUCTURE? 
LEARNING EXPECTATIONS 
A BRIDGE: WHY DOES IT HAVE THIS SHAPE? FOR BEAUTY 
OR ANYTHING ELSE? 
LEARNING EXPECTATIONS 
ANOTHER BRIDGE: IS THERE ANY IMPLICATION IN ITS 
SHAPE EXCEPT BEAUTY? 
LEARNING EXPECTATIONS 
SOME BRIDGE MODELS: ANY GENERAL PRINCIPLES? 
LEARNING EXPECTATIONS 
HIGH-RISE BUILDING: WHY DO PEOPLE NEED THESE KINDS 
OF STRUCTURES ? 
LEARNING EXPECTATIONS 
At the end of this course, the student should be able to: 
• Knowledge 
- Draw the diagrams of internal forces: axial force, shear force, bending 
moment 
- Analysis of stresses, displacements of simple structures 
- Identify of mechanical properties of materials. 
- Analysis of stability of simple structures 
• Skills 
- Model from the real structures to analytical models 
- Extend in the professional courses 
- Explaining your works effectively in writing. 
THIS COURSE PROVIDES THE VERY FIRST BASE OF ALL 
CIVIL ENGINEERS, MECH. ENGINEERS – LIKE CHILDREN 
LEARN HOW TO SPELL. 
Assessment Components 
Notes: 
- All assignments and Exam are practice problems, no purely 
theoretical questions (i.e. No learn by heart answers). 
- No purely theory. 
Final Exam 
Lab practices 
Big Assignment (homework) 
Assignments or Mid Exam. 
(at class) 
Penalty for missing tutorials 
60 % 
20 % 
10 % 
10 % 
1 % per miss 
At end of semester 
From week 12 
At end of week 12 – Hand writing – 
must do 
During the course 
Missing 3 or more tutorials may 
result in failing the course, unless 
justified via a special consideration 
form. 
COURSE OUTLINE 
Section Content Tasks/Milestone 
1 
 Begins with a review of the fundamental concepts and assumptions and the 
importance of satisfying equilibrium 
2 Theory of internal forces is described 
3 
Analysis of normal stress in axial loaded members and discussion of some of the 
mechanical properties are given 
4 Concept of state of stress and the relations of stresses and strains are presented 
5 Application of various theories of failure are presented 
6 Geometric properties of cross sections are presented 
7 Bending problem in-plane, stress-strain relationship, ultimate stress 
8 Displacements of beams under bending moments 
9 Torsion problems Assignment 1 due 
10 Combined forces problems 
11 Stability problems 
12 Final Exam. 
Learning Strategies 
• Text books 
• Weekly lectures will be used to extend the 
practical exercise 
• Homework of each week 
• Understand the summaries, notes, conclusions 
CHAPTER 1: BASIC CONCEPTS 
1.1 BASIC CONCEPTS OF STRENGTH OF MATERIALS COURSE 
1.2 ENGINEERING SHAPES 
1.3 EXTERNAL FORCES – SUPPORTS/CONNECTION – REACTION 
FORCES 
1.4 BASIC OF FORCE – DEFORMATION STYLES 
1.5 HYPOTHESES 
1.1 BASIC CONCEPTS OF STRENGTH OF 
MATERIALS COURSE 
What is “MECHANICS OF MATERIALS” (SBVL là gì) ? 
• Mechanics of Materials is a branch of Applied Mechanics that 
deals with the behavior of DEFORMABLE solid bodies subject to 
various types of loading. 
• Other names: 
 Strength of Materials 
 Mechanics of Deformable Bodies 
 What is “MECHANICS OF MATERIALS”? 
• Mechanics of Materials is a branch of Mechanics that develops 
relationships between the external loads (ngoại lực) applied to a 
deformable body (vật thể biến dạng được) and the internal forces 
(nội lực) acting within the body. 
1.1 BASIC CONCEPTS OF STRENGTH OF 
MATERIALS COURSE 
1.1 BASIC CONCEPTS OF STRENGTH OF 
MATERIALS COURSE 
OBJECTIVES 
 STRENGTH CONDITIONS (đ/k bền) 
 no failure (không bị phá hoại) – ULTIMATE LIMIT STATE 
 RIGIDITY CONDITIONS (đ/k cứng) 
 no extra deformation (không biến dạng quá mức) – 
SERVICEABILITY LIMIT STATE 
 STABILITY CONDITION (đ/k ổn định) 
 retain the initial deformation state 
 advanced conditions 
1.2 ENGINEERING SHAPES 
(1) SOLID 
1.2 ENGINEERING SHAPES 
Pyramids and their structures 
1.2 ENGINEERING SHAPES 
Gravity dam and its structure 
1.2 ENGINEERING SHAPES 
(2) PLATE – SHELL – MEMBRANE 
PLATE 
1.2 ENGINEERING SHAPES 
SHELL 
1.2 ENGINEERING SHAPES 
MEMBRANE 
1.2 ENGINEERING SHAPES 
(3) BAR 
FRAME 
DOME 
STRAIGHT 
BAR 
1.3.1 External forces 
1.3 EXTERNAL FORCES – SUPPORTS – REACTIONS 
(1) Load – Reaction 
Load: all information are known: strength – location – time – direction 
Reaction: occur passively, depend on Load, have to calculate to know 
(2) Distribution patterns 
Point Load, concentrate load (Force): applied at a point [N, kN, MN, Ton, kGf] 
Distribution Load (Forces): 
 - applied on a line [N/m; kN/m; N/cm] 
 - applied on a surface (Area load) [N/m2; kN/m2] 
 - applied in a volume (Volume load): gravity; thermo-stress, acceleration [kN/m3] 
1.3.1 External forces 
1.3 EXTERNAL FORCES – SUPPORTS - REACTIONS 
1.3.2 Support/Connection - Reaction 
1.3 EXTERNAL FORCES – SUPPORTS - REACTIONS 
EQUILIBRIUM OF A DEFORMABLE BODY 
(CÂN BẰNG CỦA VẬT THỂ BIẾN DẠNG ĐƯỢC) 
• Support Reactions (Phản lực liên kết) 
• Equations of Equilibrium (Phương trình cân bằng) 
 F 0
M / 0 0




• If an x,y,z cordinate system is established 
• With planar problems 
x y z
x y z
F 0 F 0 F 0
M 0 M 0 M 0
  
  
  
  
x y oF 0; F 0; M 0    
• Axial forces on a two force 
member result in only normal 
stresses on a plane cut 
perpendicular to the member axis. 
Axial 
1.4 BASIC FORCES – DEFORMATION STYLES 
Axial 
1.4 BASIC FORCES – DEFORMATION STYLES 
Bending 
1.4 BASIC FORCES – DEFORMATION STYLES 
AF
A
P
ave
Single Shear 
A
F
A
P
2
ave 
Double Shear 
Shear 
1.4 BASIC FORCES – DEFORMATION STYLES 
Torsion 
1.4 BASIC FORCES – DEFORMATION STYLES 
Shear strain 
1.4 BASIC FORCES – DEFORMATION STYLES 
1.5 BASIC HYPOTHESES 
  Materials hypothesis (Giả thiết v.liệu): 
 Continuous, homogenous, isotropic, linearly 
 (liên tục, đồng nhất, đẳng hướng) 
  Analytical model or Calculating Scheme 
 (Sơ đồ tính) 
  Superpostion Principle 
 (Cộng tác dụng) 
  Small Displacements 
1.5 BASIC HYPOTHESES 
Linear Elastic 
1.5 BASIC HYPOTHESES 
Superposition principle