1. Dr. Ali I. Tayeh First Semester
LRFD-Steel Design
Dr.
Ali I. Tayeh
First Semester 1

2. Steel Design Dr. Ali I. Tayeh
Introduction

3. Objectives
To understand basic principles and methods for Steel Design.
To practice problem for Designing and checking Trusses, Columns , Beams (shear-Moments-Torsion…) , Beam-columns, Bolts (Geometry-Distribution..), Supports ,Welded connection.
To make congruent between the selected section and all applied force ,taking in consideration economic and availability. 3

4. Trusses and Frames 4

5. Grading
Mid Exam %
Homework and Quizzes 30%
Final Exam % 5

6. Text book
LRFD
STEEL DESIGN
Third edition
WILLIAM T. SEGUI.

7. Introduction Structural Engineering:
Design of different structures (Buildings, bridges, dams, ships, stadiums, etc.):
Satisfy needs or functions
Support its own loads
Support external loads
Steel Design:
Selection of structural form .
Determination of external loads.
Calculation of stresses and deformations.
Determination of size of individual members.

8. Introduction -Materials
Strength of a material: ability to resist Stress (tension and compression) without Fracturing
Steel
Concrete
Strength to weight Ratio: very important for design consideration
Wood
Alloys
Deformation: change in shape due to loading
Flexibility
Elasticity
Brittleness
Ductility
Stress-Strain diagram

9. Introduction
Type of steel and composition

10. Introduction Advantages of steel as a construction material
High load resisting
High ductility
Easy control for steel structure
No formed as in a concrete structure
Elastic properties

11. Introduction Disadvantages of steel as a construction material
No ability to resist the fire
No ability to resist the corrosion
High cost
Engineering properties of steel

12. Introduction -Loads
Static Loads: applied slowly that the structure remains at rest during loading
Walls
Dynamic Loads: applied rapidly to cause the structure to accelerate as a consequence of inertia forces
Cars
Earthquakes
Dead Loads: magnitude and position remains constant
Beams, columns, slabs, walls
Live Loads: magnitude and position changes
Humans
Snow
Wind

13. Introduction –Structural steel
The most interest test for steel engineering characteristics is Tensile Test
If specimen is subjected to an axial load (P)

14. Introduction –Structural steel
The applied load leads to a strain , stress
f - axial tensile stress.
P- axial load
A – cross-sectional area.
 - Axial strain.
L - length of specimen
CL-change in length of specimen.

15. Stress–Strain Diagram
Failure
Stress
Strain
Elastic
Plastic
Ultimate Strength
Yield Strength 1 2 3 4
Lower Yield Strength 4
Upper Yield Strength 3
Elastic limit 2
Proportional limit 1

16. Introduction -Steel Design
The relationship between stress and strain is linear up to the proportional limit, the material is said to follow
Hook’s law
Where:
E- Modulus of elasticity.

17. Introduction -Steel Design
Where:
e - Elongation (expressed as percent).
Lf -Length of specimen at fracture.
Lo -Original length.

18. Introduction -Steel Design
Standard cross-sectional shapes
Cross-sections of some of the more commonly used hot-rolled shapes :
W- shape OR Wide –flange Shape.
For example :(w 18×50)
W-type of shape.
18 section depth in inches .
50 section weight in pounds per foot .

19. Introduction -Steel Design
Standard cross-sectional shapes
S- shape OR American standard S
For example :(S 18×70)
S-type of shape
18 -section depth in inches .
70 section weight
in pounds per foot .

20. Introduction -Steel Design
Standard cross-sectional shapes
L- shape OR Angle shape .
For example :
(L6× L6× ¾’’)
(L6× L3× 5/8’’)
SEE FIGURE

21. Introduction -Steel Design
Standard cross-sectional shapes
C- shape .
For example :
(C18× 70)
SEE FIGURE

22. Introduction -Steel Design
Standard cross-sectional shapes
C- shape OR-American standard channel.
For example :
(C9× 20)
SEE FIGURE
C9×20

23. Introduction -Steel Design
Standard cross-sectional shapes
T- shape OR- standard Tee .
For example :
(WT18× 115)
SEE FIGURE
Note
This section produced by cutting
an I-shape member at middepth
(WT18× 115) (W36× 230)

24. Introduction -Steel Design
There are many shapes as :
Round Shafting
Honed Shafting

25. Introduction -Steel Design
There are many shapes as :
Flat Bares
Square Bares
Round Bares
Hexagon Bares
Square Tubing

26. Introduction -Steel Design
Examples :
1.5-1.
1.5-3.
Home work:
1.5-2.
1.5-4.
End