This is an overview of what a structural engineer does at office

1. STRUCTURAL ENGINEERING -OVERVIEW

2. OBJECTIVE
• WHAT IS A STRUCTURAL ENGINEER?
• WHAT DO THEY DO?
• WHAT DO THEY DESIGN?

3. OBJECTIVE
THE HUMAN SKELETON IS A STRUCTURE WHICH MAINTAINS THE SHAPE OF THE BODY, KEEPS THE VARIOUS
ORGANS AND MUSCLES IN THE RIGHT PLACE AND TRANSMITS LOADS DOWN TO THE GROUND

4. OBJECTIVE
THE SPIDER’S WEB IS A GOOD EXAMPLE OF A TENSION
STRUCTURE. THE WEIGHT OF THE SPIDER AND ITS PREY IS
SUPPORTED BY TENSILE STRENGTH OF THE WEB
THE TREE IS THE BEST NATURAL CANTILEVER AVAILABLE.
Structural analysis of tree trunks and branches:
tapered cantilever beams subject to large
deflections under complex loading
J. Morgan M. G. R. Cannell

5. A BUILDING SAFELY TRANSMITS ALL ITS LOADS ON TO THE EARTH BELOW
OBJECTIVE
• FLOOR
• BEAMS
• GIRDERS
• COLUMNS
• FOUNDATION
• SOIL/BEDROCK

6. THE BASIC OBJECTIVE IN STRUCTURAL ANALYSIS AND DESIGN IS TO PRODUCE A STRUCTURE CAPABLE OF
RESISTING ALL APPLIED LOADS WITHOUT FAILURE DURING ITS INTENDED LIFE. THE PRIMARY PURPOSE OF
A STRUCTURE IS TO TRANSMIT OR SUPPORT LOADS.
OBJECTIVE
THE DESIGN OF A STRUCTURE INVOLVES MANY CONSIDERATIONS, AMONG WHICH ARE 4 MAJOR OBJECTIVES
THAT MUST BE SATISFIED.
• SAFETY (THE STRUCTURE MUST CARRY LOADS SAFELY)
• ECONOMY (THE STUCTURE SHOULD BE ECONOMICAL IN MATERIAL AND OVERALL COSTS)
• UTILITY (THE STRUCTURE MUST MEET THE PERFORMANCE REQUIREMENT)
• DURABILITY (THE STUCTURE SHOULD HAVE A LONG LIFE)

7. STRUCTURAL ENGINEERING PROJECTS CAN BE DIVIDED INTO 4 STAGES.
1. PLANNING PHASE
a) MATERIAL
b) STRUCTURAL FORM
c) LOADS
2. ANALYSIS
3. DESIGN
4. CONSTRUCTION
THEREFORE, THE PURPOSE OF STRUCTURAL ANALYSIS IS TO DETERMINE THE REACTIONS, INTERNAL FORCES AND
DEFORMATIONS AT ANY POINT OF A GIVEN STRUCTURE CAUSED BY APPLIED LOADS AND FORCES.
STAGES

8. MATERIAL - TIMBER
• Advantages
• Cheap, renewable resource
• Good in Tension – ~40 MPa
• Disadvantages
• Susceptible to fire, nature
• Not very hard
• Not very strong
• Limits on shape, size

9. MATERIAL - MASONRY
• Concrete blocks, clay bricks
• Advantages
• Large compressive strength
• Cheap
• Good thermal properties – holds heat
well
• Disadvantages
• Not a cohesive material. The strength
could depend on the mortar, other
factors
• Poor tensile strength, unless reinforced
• Heavy material, requires skilled laborers
to use
• Height restriction
• Susceptible to the weather

10. MATERIAL - CONCRETE
Combination of water, cement, small aggregate, and large
aggregate.Advantages
• Very versatile – can be modified with admixtures for different
effects
• High compressive strength (4~7 ksi)
• Fire resistant
• Many diverse sizes and shapes – formwork
Disadvantages
• Long curing time
• Low tension strength (~0.4 ksi)
• Fails in shear, unless reinforced
• Fairly heavy material to work with

11. MATERIAL - STEEL
Advantages
• High tensile and compressive strength (A36 Steel ~ 60
ksi)
• Many varieties, depending on your need
• Carbon steel
• Stainless steel
• Galvanized steel
• Elastic material
• Ductile material
• Many shapes, sizes
• Disadvantages
• Expensive – limited quantities / competition
• Susceptible to fire, rust, impurities

12. MATERIAL -COMPOSITE
PUT THEM TOGETHER AND…
• Reinforced Concrete
• Concrete with steel reinforcement
• Concrete handles compression
• Steel takes the tension
• Can handle nearly 4 times the loading that concrete
alone can handle

13. MATERIAL - COMPOSITES
• Engineered compounds that have different physical or chemical
properties
• FRP – Fiber reinforced polymers
• CFRP – Carbon-fiber reinforced polymers
• Plastics
• Categories of Glass
• Categories of Wood

14. 1) TENSION AND COMPRESSION STRUCTURES (LOAD CARRYING BY AXIAL CAPACITY)
TYPES OF STRUCTURAL FORMS
1 kN
Compression
1 kN
Tension
Tensile Failure Compressive Failure

15. TYPES OF STRUCTURAL FORMS
CABLES – TENSION MEMBERS
• SIMPLE
• USES
 SUSPENSION BRIDGES
 ROOF STRUCTURES
 TRANSMISSION LINES
 GUY WIRES, ETC.
• HAVE SAME TENSION ALL ALONG
• CAN’T STAND COMPRESSION

16. ARCHES – COMPRESSION MEMBERS
TYPES OF STRUCTURAL FORMS
Arch
Arches carry the dominant permanent load case
(usually full dead load) in pure axial
compression.

17. 2) FLEXURAL BEAM AND FRAME STRUCTURES (LOAD CARRYING IS ACHIEVED BY BENDING)
TYPES OF STRUCTURAL FORMS
1 kN
Bending
Frame

18. TYPES OF STRUCTURAL FORMS
C
T
CC
T
Forces in Truss Members
Truss

19. 3) SURFACE STRUCTURES (LOAD CARRYING IS BY MEMBRANE ACTION)
TYPES OF STRUCTURAL FORMS
Shells
Chimneys
Folded Plate

20. IMPORTANT PARAMETERS FOR DESIGN
EQUILIBRIUM : PROPERTY RELATED TO STABILITY OF THE STRUCTURE. THE LOADS APPLIED ON
STRUCTURE AND THE REACTIONS OF THE SUPPORTS SHOULD BE IN EQUILIBRIUM.
STRENGTH : ABILITY TO WITHSTAND A GIVEN STRESS WITHOUT FAILURE. DEPENDS ON TYPE OF
MATERIAL AND TYPE OF FORCE (TENSION OR COMPRESSION).
STIFFNESS : PROPERTY RELATED TO DEFORMATION.
STIFFER STRUCTURAL ELEMENTS DEFORM LESS UNDER THE SAME APPLIED LOAD.
STIFFNESS DEPENDS ON TYPE OF MATERIAL (E), STRUCTURAL SHAPE, AND
STRUCTURAL CONFIGURATION.TWO MAIN TYPES; AXIAL STIFFNESS AND BENDING
STIFFNESS.

21. EQUILIBRIUM - STABILITY
ON GROUND
C.G OF OBJECT ON GROUND SHOULD BE WITHIN
MIDDLE THIRD OF ITS BASE.
UNDERGROUND
WEIGHT OF OBJECT SHOULD BE GREATER THAN
BUOYANT FORCE BY AT LEAST 20%

22. RIGID SUPPORT
BODY OR SUPPORT THAT UNDERGOES NO DEFORMATION
UNDER ANY LOAD
STIFF & FLEXIBLE SUPPORTS
SUPPORTS THAT UNDERGO CERTAIN DEFORMATION UNDER
LOAD
STIFFNESS
STIFFNESS IS A MEASURE OF HOW MUCH FORCE IT TAKES TO DEFORM A BODY BY A GIVEN
AMOUNT

23. Stiffest
StifferStiff
STIFFNESS

24. STRENGTH
ALL MATERIALS AND STRUCTURES DEFLECT, TO GREATLY VARYING
EXTENTS, WHEN THEY ARE LOADED.
THE SCIENCE OF ELASTICITY IS ABOUT THE INTERACTIONS BETWEEN
FORCES AND DEFLECTIONS. THE MATERIAL OF THE BOUGH IS
STRETCHED NEAR ITS UPPER SURFACE AND COMPRESSED OR
CONTRACTED NEAR ITS LOWER SURFACE BY THE WEIGHT OF THE
MONKEY

25. SUPPORT CONDITIONS

26. MODELLING
THE PROCESS OF DEFINING AN IDEAL STRUCTURE FROM A REAL STRUCTURE IS CALLED MODELING. TO
CARRY OUT PRACTICAL ANALYSIS IT BECOMES NECESSARY TO IDEALIZE A STRUCTURE.

27. LOADING
THE MODEL IS THEN APPLIED WITH LOADS AS UNDER:
• POINT LOADS
• DISTRIBUTED LOADS
• APPLIED MOMENTS

28. DEMONSTRATION