Structural engineering is the backbone of safe and efficient construction, bridging the gap between innovative ideas and their tangible realization.
Definition
Building codes: These are laid down standards for any building structure.
Bending moments: These are structural reactions when a structure is subjected to moment
or applied load.
Shear force: This is the reaction imposed by a structure when loads are imposed
Determine Methods used in analyses of structural members according to building
codes
Several methods are used in the analysis of structural members. A structural system is made
up of different members and each member is analysed differently. The methods of analysis
used in beams include:
a. Energy methods
Two methods are commonly used i.e.
• Methods of virtual work
• Castigliano’s theorem
b. Displacement methods of analysis
• Slope deflection methods
• Moment distribution methods
c. Approximate methods of analysis.
• This method is used in the analysis of statically indeterminate structures.
d. Double integration method
• In this method, sign convention and boundary conditions are well defined. It
is mostly used in determining deflections.
e. Elastic beam theory
• The method relates to slope, displacement as well as the internal moments of
a beam. Its development is fully dependent on this.
f. Moment area methods
• This method is mainly used when checking for deflection. It involves
determining slope and deflection of an elastic curve.
g. Conjugate- beam method
• This method relies mainly on statics for determining deflection in beams.
h. Stiffness method of analysis
Work loadings on according to the structure
These are loadings that are subjected to a structure. Different structures are subjected to different loadings depending on the location, height as well as purpose of use.
a. Dead loads
• These are loads that are permanent in a structure. They include the self-weight
of the structure, finishes, masonry etc.
• During analysis, these loads are taken into considerations to ascertain the
safety of the structure.
b. Live loads
• These are loads that are temporary. They include people, furniture, etc.
• There are other types of live loads such as impact loads (loads imposed by
moving cars), highway bridge loads (caused by traffic), wind loads and snow
loads
Sketch structural members as per the drawings and support requirements
sketched structural members
Determine maximum moments in each section in accordance with appropriate
methods
Maximum moments in different sections of a structural member is determined using
mathematical equations.
It is also necessary to note that maximum moment occurs at zero- shear force.
The line of influence method of determining maximum moment is often used for
statically determinate structures.
The method assumes that summation of shear force area under the influence line is
the moment at any given section in the structure.
That is, Mmax= Summation of area under shear
✓ For statically indeterminate structures, the force method is used in which,
𝑀𝑚𝑎𝑥 = 𝑃𝐿
8 —– fixed support beams
𝑀𝑚𝑎𝑥 = 𝑃𝐿
8 —— Simply supported beams
Draw shear force and bending moments diagram according to structural design
requirements
Drawing shear force and bending diagrams is very essential since it creates an image of
how a structure will fail.
Before doing so, one is required to follow certain procedures as discussed below:
Shear force diagram
a. Determine Shear, V at distance x. Distance x is always the distance from
one load application to another.
b. Plot a graph of V against x
Bending moment diagram
a. Determine moment, M by find the area under shear in the SFD.
b. Plot a graph of moment M, against distance x.
The diagram attached below is an example of how to draw a bending moment diagram
(BMD) as well as the shear force diagram (SFD)
SHEAR FORCE DIAGRAM
Written Assessment
1 Which one of the following is a type of load?
a) Furniture load
b) Rail truck load
c) Live load
d) Steel load
2 Which of the following is a method is used to analyze statically indeterminate
structure?
a) Influence line analysis method
b) Superposition
c) Energy methods
d) Finite element method.
3 The following methods are used in the analysis of trussed which one is not?
a) Method of joints
b) Method of sections
c) Virial work methods
d) Influence line methods
4 Which of the following is not a displacement method of analysis?
a) Castigliano’s theory
b) Slope deflection equations
c) Moment distribution method
5 Which of the following is not a structural member?
a) Beams
b) Walls
c) Columns
d) Frames
6 Define what is a structure
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7 Explain the importance of structural analysis
8 Differentiate between Structural design and structural analysis
9 What is the difference between influence line and shear force and bending moment
diagram?
10 Differentiate between
- Column
- Beam
- Frame
- Truss
11 Discuss Displacement methods in details
12 For each of the methods outlined, discuss their shortcomings.