The document outlines the principles of structural steel design, detailing advantages and disadvantages of using steel, as well as the design process which includes load determination, structural analysis, and compliance with building codes. It emphasizes the importance of safety, serviceability, and economy in design responsibilities while discussing various types of loads that structures may encounter. Additionally, it covers material properties, classifications of structural steel, standard cross-sectional shapes, and references for further reading.

2. Paktia
university
Engineering faculty
Civil engineering
department
Prepared by fazalrahman
rang

3. Steel
design

4. Chapter 1: Introduction
 Why Structural Steel
 Structural Design
 Loads
 Building Codes
 Design Specifications
 Structural Steel
 Standard Cross Sectional Shapes

5. Advantage and disadvantage
of steel structure
 Advantage of steel :
 High Strength to weight ratio
 Uniformity (or predictable properties)
 Highly Ductile
 Good Fracture toughness
 Easily Constructed and Modified structures
 Easily recycled
 Steel is weldable.

6. Disadvantages
 Requires Maintenance and Corrosion
Protection
 Requires Fireproofing
 Often Results in Slender members that are
susceptible to buckling
 Fatigue
 Brittle Fracture

7. The Design Process
 It is both creative and technical and requires a fundamental
knowledge of material properties and laws of mechanics
which govern material response.
 It is a cycle.
 It requires the determination of the overall proportions and
dimensions of the supporting framework.
 Determination of the external loads that can be expected to
act on the structure.
 Calculation of deformations and internal forces (stresses and
strains) produced in all the members of the structure produced
by external loads.
 Selection of the size and cross-section of individual members
of the structure to support and resist the applied external load
to satisfy both the strength and serviceability limit states (i.e.
Safety and to make sure that the existing action and
deformations are acceptable).

8. Elements of Design Process
 Selection of the type of structural form to be used and
the material out of which the structure is to be made.
 Determination of the external loads that can be
expected to act on the structure.
 Calculation of the internal forces (actions) and
deformations that are produced in individual
members of the structure by the external loads.
 Determination of the size of the individual members so
that the existing actions and deformations are
acceptable (i.e. satisfy the strength and serviceability
limit states).

9. Steps of the Design Process
 Identify the Constraints.
 Select form and material.
 Create geometric model of structure.
 Determine loads and load paths.
 Conduct structural analysis.
 Select member size based on limit state
(strength, serviceability, fatigue, etc. )
 Check compliance with code
 If needed, repeat or iterate to solution.

10. Design Responsibilities
 Safety
– Adequate strength during and after construction
– Resistance to progressive collapse
– Perceived as safe by users
Serviceability
– Deflection control
– Vibration control
 Practicality
– Can it be built as designed
– Reasonable tolerances must be allowed
– Is the construction unreasonably complex or dangerous

11. Design Responsibilities
 Economy
– Use readily available sections and materials - talk
to suppliers!
– Consider the total cost of the structure:
material and fabrication.
– Use only as many elements as needed – it cost
money to handle each element.
– Use the simplest details that are appropriate and
take advantage of repetition

12. Loads
Loads: Loads are forces that act on a
structure.
 Loads must be determined before
designing a structure.
 Applied loads can either be :
 Static (gravity type loads)
 Dynamic (earthquake type loads, due to
inertia of the mass of structure).

13. Loads
 Common Types of loads:
 Dead Loads - stationary loads of constant
magnitude (caused by the weight of the
structure).
 Live Loads - moving loads or loads that vary in
magnitude (people, furniture, vehicles, etc.).
 Wind Loads
 Snow Loads
 Earthquake Loads

14. Loads
 Other Types of loads:
 Hydrostatic
 Soil Pressure
 Blast
 Temperature Changes
 Differential Settlement of the Foundations
 Moving loads (moving trucks on highway
bridges)

15. Building Codes
 Are legislative documents that make the model
specifications “legal” requirements, regulating
building construction.
 Establish the minimum acceptable requirements
for preserving the public safety and welfare in a
built environment.
 Adopted by Government Legislative Authorities
for Buildings Within Their Jurisdiction.
 Applies to New Construction, rehab or alteration.

16. Model Building Codes
 Uniform Building Code (UBC-1997): by the
International Conference of Building Officials, ICBO.
 National Building Code (NBC-1999): by the Building
Officials and Code Administrators, BOCA.
 Standard Building Code (SBC-1999): by the Southern
Building Code Congress International, SBCCI.
 International Building Code (IBC-2012): by the
International Code Council
 ASCE 7-10 load provisions.

17. Design Specifications
 Give more specific guidance for the design of
structural members and their connections.
 Are recommendations of good practice
based on the accepted body of knowledge.
1. American Institute of Steel Construction (AISC):
2. American Association of State Highway and
Transportation Officials (AASHTO):
3. American Railway Engineering and
Maintenance-of-Way Association (AREMA):
4. American Iron and Steel Institute (AISI):

18. Structural Steel
 Mechanical Properties:
 If a test specimen is subjected to an axial load P, the
stress and strain can be computed as follows:
 where
• f = axial tensile stress
• A = cross-sectional area
• e = axial strain
• L = length of specimen
• L = change in length
Ϫ

19. Structural Steel
 Material Properties:
 Steel is an alloy made by combining molten iron with other
elements to obtain specific properties.
 Carbon is the main strengthening element in steel. However,
increased carbon content can reduce ductility, toughness
and weldability.
 Chromium and copper both increase resistance to
atmospheric corrosion, and are used in weathering steels.
Weathering steels form a protective oxide film on the
surface early on, which will help protect the remainder of
the steel.
 Sulfur has an undesirable effect on surface quality, ductility,
toughness and weldability. However, sulfur improves
machinability.
 Manganese can control the harmful effects of sulfur. It also
increases hardness and strength (but not as much as
carbon).

20. Classification of Structural Steel
 Plain Carbon Steel (ASTM A36 - Grade 36)
 low cost
 works easily
 No longer “preferred” specially for WF
sections
 Low-alloy steel (ASTM A572 - Grade 50)
 High-alloy or Specialty Steel (ASTM A992)
 High Strength
 Increased Corrosion Resistance

21. Classification of Structural Steel

22. Other Structural Steel
 A529 - Structural carbon steel
 Higher strength
 Still have the same good characteristics of
A36
 Atmospheric Corrosion Resistant High-
Strength Low Alloy
 the “Weathering steels”
 reduced maintenance in some
environments

23. Standard Cross-sectional
Shapes
 Hot-Rolled:
 W- Wide flange
 S - American Standard
 L – Angles may have equal or unequal
length legs
 C – Channel sections
 T – Tees are cut from Wor S sections
 Z – Zee sections
 Others (HP, M, WT, ST, MC, HSS, etc.)

26. Common Built-Up Sections

27. Standard Cross-sectional
Shapes
 Cold-Formed:

28. Main References
 Steel Design, Segui, W. T., 5th Ed. (2013),
Cengage Learning, USA.
 Manual of Steel Construction, 13th Ed.
(2005), American Institute of Steel
Construction (AISC).
 Structural Steel Design: Lecture Notes
(2013), Dr. Mohammad AlHamaydeh
Amarican University of sharjehUAE.