Basic Civil Engineering first year Notes- Chapter 4 Building.pptx
The perfect power point presentation slides for Truss
1. Course Name: Engineering Materials and Mechanics
COURSE CODE : CV1001
CREDITS : 04
MODE OF DELIVERY : OFFLINE
FACULTY : DR. GAURAV SANCHETI
EMAIL-ID : gaurav.sancheti@jaipur.manipal.edu
MODULE : 4
DATE OF DELIVERY : 2023
B.TECH. FIRST YEAR
ACADEMIC YEAR: 2023-2024
1
2. Topics to be covered
Relevant Course Outcome
2
• Analysis of truss by method of Joints
• Analysis of Truss by method of Sections
• Degree of freedom of a structure
The students will be able to:
• Students will be able to analyze the truss and calculate the forces in
the truss members
• Calculate the degree of freedom of a 2D structure
3. ▪ A truss is an assembly of
structural members connected
at joints. No member is
continuous through a joint.
▪ Forces acting at the member
ends, reduce to a single force
and no couple. Only two force
members are considered.
▪ Most structures are made of
several trusses joined
together to form a space
framework
TRUSS
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4. ▪ Each truss carries those loads
which act in its plane and
may be treated as a two-
dimensional structure.
▪ When forces tend to pull the
member apart, it is in tension.
When the forces tend to
compress the member, it is in
compression
4
TRUSS
13. • We assumed that all the forces in the members were tensile.
But we got some of them negative.
So, the negative sign indicates that the forces in the members are
compressive
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FAB=8.84kN (T)
FBC=10.62kN (C)
FAC=2.13kN (C)
14. 14
PROBLEMS ON METHOD OF JOINTS
Q.2- Determine the force in each member of the roof truss shown in the fig.
State whether the members are in tension or compression. The reactions at the
supports are given
15. 1
5
PROBLEMS
Q.2. SOLUTION
Only the forces in half the members have to be determined as the truss
is symmetric with respect to both loading & geometry
21. 21
Analysis of Trusses by the Method of
Sections
• When the force in one or a very few members
are desired, the method of sections works well.
• To determine the force in member BD, pass a
section through the truss as shown and create a
free body diagram for the left side (or right
side).
• With only three members cut by the section,
the equations for static equilibrium may be
applied to determine the unknown member
forces, including FBD.
22. 22
PROBLEMS ON METHOD OF SECTIONS
Q.1 Determine the force in members CF and GC of the roof truss. State
whether the members are in tension or compression. The reactions at the
supports have been calculated.
25. Q 2 Determine the force in member GF and GD of the truss. State
whether the members are in tension or compression. The reactions at the
supports have been calculated
PROBLEMS OF METHOD OF SECTION
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26. Q.2 SOLUTION
PROBLEMS
26
The distance EO can be determined by proportional triangles or realizing that
member GF drops vertically 4.5 – 3 = 1.5m in 3m.
Hence, to drop 4.5m from G the distance from C to O must be 9m
30. Degrees of Freedom
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• Each structure transfers the forces of it from top to bottom into the
foundations.
• The foundations are idealized as supports in structural engineering.
• They are to be understood as degrees of freedom, and thus form the
boundary conditions for a structure.
• That is to say, they prevent the displacement or rotation in a certain
direction, so that no deformation can occur.
• Depending on the definition, supports can restrict certain degrees of
freedom.
31. Degrees of Freedom in 2D system
31
• A planar structure (2D) has three possibilities of movement
(degrees of freedom).
➢ Displacements in the horizontal X-direction
➢ Displacements in the vertical Z-direction
➢ As well as one rotation about the global Y-axis.
32. 32
Degree of Freedom
• Provide resistance to vertical forces only.
• Degree of Freedom = 2 (Non-resistive to horizontal force and rotation)
• Provide resistance to vertical and horizontal forces.
• Degree of Freedom = 1 (Non-resistive to rotation)
• Provide resistance to vertical and horizontal forces and rotation.
• Degree of Freedom = 0
