CE 16 –
PRINCIPLES OF
STEEL DESIGN
STRUCTURAL STEEL
What is structural steel?
Structural steel is a type of steel that is used as a construction
material.
They are designed to have good strength/weight ratio (which is
also called specific strength) and to be cost-effective in order to
be benefited as a structural component in buildings, roads,
bridges, etc.
In steel structures, structural steel is the main load carrying
material to transfer the load within them and to transfer load to
the ground
Common Steel structures
1. Roof truss in factories, cinema halls, railways etc.,
2. Crane girders, columns, beams
3. Plate girders, bridges
4. Transmission towers, water tank, chimney etc.,
Old Arch Bridge
Framed Building
Framed Building
Industrial Building
Industrial Building
Truss Bridge
Suspension Bridge
Cable Stayed Bridge
ADVANTAGES and DISADVANTAGES
Advantages
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High comp. & tensile strength per unit weight hence low construction weight, saves space
Good aesthetic view
Good quality and durability
Very high speed of construction
Reusability and scrap value – env. Friendly
Better solution to cover large span and tall structures
Disadvantages
• High cost – Initial
• Corrosion
• Low fire resistance
How are Steel made?
- First iron is extracted from iron ores like
hematite, limestone, magnetite in furnace
- Oxygen is passed through molten iron to
remove carbon and impurities to make steel.
- Manganese is added to strengthen the steel
- Adding chrome, nickel, phosphorous can impart
special properties in steel
- Semi finished products from the machine is hot
rolled to different sections like bars, plates,
angles, sections etc..,
- Adding carbon increases the tensile strength
and hardness but lowers ductility and
toughness
- In building we use structural steel which has low
carbon of upto 0.1% to have ductility and yield.
Codes and
Specifications
BUILDING CODES:
• PD 1096 – National Building Code of the Philippines
• National Structural Code of the Philippines (NSCP 2015)
• Buildings must be designed and constructed according to the provisions of a
building code, which is a legal document containing requirements related to
such things as structural safety, fire safety, plumbing and ventilation.
• A building code has the force of law and is administered by a government
• Building codes do not give design procedures but they do specify the design
requirements and constraints that must be satisfied.
DESIGN SPECIFICATIONS
• Gives specific guidance for the design of structural members and their connections.
• Design specifications represent good engineering practice based on the latest research
• They are periodically revised and updated by he issuance of supplements or completely new
editions.
• Are written in legal format by non profit organizations.
• They have no legal standing on their own but by presenting design criteria and limits in the
form of legal mandates and prohibitions, they can easily be adopted, by reference as part of a
building code.
AISC – American Institute of Steel Construction
AASHTO – American Association of State Highway and Transportation Officials
AISI – American and Iron Steel Institute
ACI – American Concrete Institute
ASTM – American Society for Testing and Materials