1. Structural Elements

2. Type of Materials Used Concrete Steel / Metals Wood
Brick / Stone/ Masonry
Plastics and Polymers

3. Types of Steel Mild Steed Plain Carbon Steel Most Common form of Steel
Low Prices – Acceptable Strength
Major properties are Toughness, high tensile strength and ductility.
Normally used in manufacturing of girders, plates, nuts and bolts and other general purposes.

4. Types of Steel Medium Carbon Steel
contains less Carbon contents, 0.30% to 0.70%.
It is stronger and harder than mild steels, less ductile, tough and malleable
It is used in making metal ropes, wire, garden tools, springs etc.

5. Types of Steel High Carbon Steed Contains 0.70% to 1.40% carbon.
The major characteristic is its hardness.
It is the hardest of the carbon steels, but is less ductile, tough and malleable.
It is used in making Chisels, hammers, drills, files, lathe tools, taps and dies.

6. Types of Steel High Speed Steel
Contains medium carbon, tungsten, chromium and vanadium.
Its special characteristic is that it retains hardness at high temperatures

7. Advantages of Steel Structures
High Strength to Weight Ratio (strength/unit weight)
Excellent Ductility and Seismic Resistance
Elasticity
Predictability

8. Disadvantages of using Steel
Corrosion
Maintenance
Loss of Strength at High Temperatures
Needs Fireproofing
Fatigue and Brittle Fractures

10. Beams
Carries a load that is applied transverse (perpendicular) to its length.
Usually a horizontal member that carries a vertical applied load.
The top fibers of a beam are in compression; the bottom fibers are in tension.
Beams are sized to provide the maximum result with the minimum materials.

11. Columns
A vertical structural element that carries an axial force in compression
Additional loads from snow, wind or other horizontal forces can cause bending in the columns.

12. Girders Attached column-to- column Take the load from the beams
Transfer it to the columns
Generally shaped as an I- Beam

13. Structural Engineering
Civil Engineering and Architecture Course
Unit 6 – Lesson 6.1 – Intro to Structural Engineering
Girder
Beam
Isometric View of the proposed structure.
The
Column
Footing
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Copyright 2005

14. Introduction to Structural Design
Civil Engineering and Architecture
Unit 3 – Lesson 3.2– Structures
Truss
A structural element that is composed of smaller structural members typically configured in triangular arrangements
Some truss members carry a tension force; others carry a compression force
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Copyright 2010

15. Forces
Influence on an object that causes a change in a physical quantity
Types:
Compression – shortens or crushes
Tension – stretches or pulls apart
Shear – pushes parts in opposite directions
Torsion – twists

17. Compressive strength measures the largest compression force the material can withstand before it loses its shape or fails.
Tensile strength measures the largest tension force the material can withstand before failing.
Shear forces bend or tear a material by pressing different parts in opposite directions at the same time. Shear strength measures the largest shear force the material can withstand before it rips apart.
Torsion forces twist a material by turning the ends in opposite directions. Torsion strength measures the largest torsion force the material can withstand and still spring back into its original shape.

18. Forces
Stress -the internal distribution of forces within a body that balance and react to the loads applied to it.
Compression
Force / Area
Strain-is the response of a system to an applied stress. 
Tensile
Deformation / Length

20. What is “Load”
The External Force acting on an object, eg: weight, pressure from wind/water
Static Load – changes slowly or not at all, eg: bricks in a building, twigs in nest
Dynamic Load – move or change, eg: car crossing bridge, oil in pipeline

21. Examples of Static or Dead Loads
Structural Engineering
Civil Engineering and Architecture Course
Unit 6 – Lesson 6.1 – Intro to Structural Engineering
Examples of Static or Dead Loads
Weight of the structure
(steel, concrete, timber)
Partitions/ Walls
Ductwork
Piping
Electrical fixtures
Floor coverings
Roof coverings
Ceiling
Dead Load is a gravity load, since it acts downward and is always present.
The weight of the structure is considered Dead Load as is ductwork, lighting fixtures, plumbing, floor covering Dead Loads are usually known but not until the design is finalized.
Dead Loads are determined by using the density of the material and converting it to a uniform loading condition. dead load carried by pounds per lineal foot of beam
A Uniform Dead Load everywhere should be used as the loading as it is a n approximation of actual conditions
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Copyright 2005

22. Load Paths in Structures
Load Path is the term used to describe the path by which loads are transmitted to the foundations
Different structures have different load paths

23. Specific Strength Known as Strength to Weight Ration
Material’s Strength
Force per Unit Area at failure
Density
The Degree of Compactness of a Substance
M.S. ÷ Density = Specific Strength

24. How do we judge the materials?
Strength – Tensile/Compressive
Density
Hardness
Ductility / Brittleness
Elasticity
Toughness

25. Strength Ability of a material to withstand loading
Tensile strength – ability of a material to withstand a pulling force
Steel is good at this, but concrete performs very poorly.
Compressive strength – ability of a material to withstand a pushing force
Wood, concrete, steel, and masonry perform well

26. Density Mass per unit volume of a material Units – mass/volume
Typically, materials with a high density are very strong and offer great protection.
However, a high density means that they are heavy and difficult to work with

27. Hardness
Ability of a material to resist permanent deformation under a sharp load
Relates to the elasticity of a material
Diamond is a very hard substance. If we built a wall out of diamond, we could be sure that very few things would scratch it.

28. Ductility / Brittleness
Ability of a material to deform without fracture
We want materials with high ductility, because they will indicate structural failure without a sudden collapse.

29. Elasticity
Ability of a material to deform and return to it’s original shape.
Ratio of stress to strain
Stress = Force / Area
Strain = Deformation / Length
Generates a stress-strain graph

30. Toughness
Ability of a material to resist fracture when stressed (amount of energy absorbed per unit volume)
Units – J/m3 or Lb-f/ft3
Area under the stress-strain curve, evaluated from 0 to the desired strain.