Civil Engineering ( Frames & Truss)

1. UNIVERSITY OF INFORMATION TECHNOLOGY
& SCIENCES

2. CE 302
 Structural Analysis & Design Lab 1

3. Civil Engineering
An outlook on

4. PREPARED BY
MD. IMRAN HOSSAIN (ID:12310177)

6. DEFINITION OF FRAME
 A-Frame is a basic structure designed to bear a load in a
light weight economical manner.
 A frame is a structural system that supports other
components of a physical construction.
 Multi forced members are generally known as Frames.
 Frames are commonly used to support various external
loads.

7. FRAME

8. FRAME

9. ANALYSIS OF FRAME
 A free body diagram of the complete
frame is used to determine the
external forces acting on the frame.
 Internal forces are determined by
dismembering the frame and
creating free-body diagrams for each
component.

11. WHAT IS TRUSS ?
A truss is a structure comprising one or more triangular units constructed
with straight members whose ends are connected at joints or nodes.
If all the bars lie in a plane, the structure is a planar truss.
The main parts of a planar truss.
TRUSS ANALYSIS
 In other words, Trusses are designed to form a stable
structure.

12. TRUSS ANALYSIS
Following characteristics of Truss
* The members of the truss should be in a plane.
* Members are connected at their intersections by means of
frictionless pins or hinge.
* Loads and reactions are applied only at joint.
* The centroid of the members must coincide with centroid of
the joints.

13. Truss Members
 The members which from the outline or perimeter of a truss are
generally called the chord members.
There are two chord members -
01. Top Chord: Top members
02. Bottom Chord: Bottom members
 Web Members – The interior members connecting the joints of the
chords are called the web members.
There are two members-
01. Diagonal members
02. Vertical members
TRUSS ANALYSIS

14. TRUSS ANALYSIS
Why are trusses strong?
Trusses derive their strength from the triangle.
The simplest of plane polygons, a triangle is unique in
that it is defined by the length of its sides. That is, one
and only one triangle can be drawn if the length of all
three sides is given.

15. TRUSS ANALYSIS
Why are triangles used in trusses?
 Rectangles and squares are not very strong because the
middle of each side would tend to bend or buckle easily.
And these are not used in truss.
 A truss is a structure made up of triangles. Because
triangles are strong because when you define the length of
the three sides the relationship between the nodes is fixed.
Similarly when you identify any two angles an a side or two
sides and a common angle all other properties are fixed. In
any other shape there are more degrees of rigidity required
to create a fixed structure.
Triangles have sides that reinforce each
other. They divide up the load.

16. TRUSS ANALYSIS
Application of trusses-
 Roof of factory shade.
 Ware house
 Railway platform
 Garage shed
 transmission towers
 Crane truss
 Bridge Truss
 Sport Stadium Truss

17. TRUSS ANALYSIS

18. TRUSS ANALYSIS

19. TRUSS ANALYSIS

20. TRUSS ANALYSIS

21. TRUSS ANALYSIS

22. TRUSS ANALYSIS
 Joint Method
 Determine the Support
Reaction.
 Apply Fx = 0 and Fy = 0 to
every node and determine
member force
 Dismember the truss and create
a free-body diagram for each
member and pin.
METHOD OF TRUSS ANALYSIS

23. TRUSS ANALYSIS
 SECTI ON METHOD
 Determine the Support Reaction.
 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.
 With only three members cut by
the section, the equations for static
equilibrium may be applied to
determine the unknown member
forces, including FBD.
METHOD OF TRUSS ANALYSIS

24. TRUSS ANALYSIS
Comparison of Trusses and Frames
Trusses Frames
 Members are subjected to
tension/compression only
 At least one member is subjected
to bending, shear or torsion
 Forces are applied at the joints
only.
 Forces may act anywhere on the
member.
 Member does not bend.  Members may bend/may not
bend.
 Composed of rods.  Composed of bars.
 Used for large loads.  Used for small and medium
loads.

25. TRUSS ANALYSIS
Advantages of Truss & Frame
 Cost Effective.
 Can be installed quickly even without heavy equipment to lift it into
place
 Unique properties of a triangular object allow trusses to span
across longer distances

26. TRUSS ANALYSIS
Common Types of Trusses-
 King post & Queen post Truss.
 Warren Truss.
 Howe Truss.
 Pratt Truss.
 English Truss.
 K- Truss.
 Baltimore Truss.
 Continuous Truss.
 Bowstring Truss.

27. TRUSS ANALYSIS
 Also known as Crescent Truss
 Is a truss consisting of curved
top chord meeting bottom
chord at each end.
 Has diagonal load-bearing
members.
 Often confused with tied arch
bridges
Bowstring Truss-

28. TRUSS ANALYSIS
 King post
 It is used for simple short-span
bridges.
 Fewest number off truss
members.- two diagonal
members, kingpost braces, that
meet at the apex of the
truss, one horizontal beam and
the king post which connect the
apex to the horizontal beam
below.
King post & Queen Post Truss-

29. TRUSS ANALYSIS
 Queen post
 It has two vertical post.
 Very strong and stable.
 It s more stable and can support
a wider span than a kingpost.
King post & Queen Post Truss-

30. TRUSS ANALYSIS
 It uses equilateral triangles to
spread out the loads on the
bridges. The equilateral
triangles minimize the forces to
only compression and tension.
 This bridges are often used
with verticals to reduce the
panel size.
Warren Truss-

31. TRUSS ANALYSIS
 It became very popular and was
considered one of the best
designs for railroad bridges back
in the day.
 Wooden beams for the diagonal
members, which were in
compression. It used iron (and
later steel) for the vertical
members, which were in tension.
Howe Truss-

32. TRUSS ANALYSIS

33. TRUSS ANALYSIS
 Very common type but has many
variations
(Baltimore, Pennsylvania, and the
Parker)
 The basic identifying features are
the diagonal web members which
form a V-shape. (Howe truss bridge
has a A-shape).
 Commonly used for supporting
railways.
 The Pratt truss’s verticals
functioned as compression members
and diagonals functioned as tension
members.
 The Pratt truss required more iron
than a Howe truss,
Pratt Truss-

34. TRUSS ANALYSIS

35. TRUSS ANALYSIS
 The length of members
undergoing compression is
reduced. This reduction in length
enables components of bridges to
endure the compressional force.
 The design is complicated and it
is considered to be one of the
hardest bridges to build.
K- Truss-

36. TRUSS ANALYSIS

37. TRUSS ANALYSIS
Roof Truss-
 Roof trusses, which are
structural components of houses
or commercial
buildings, support the weight of
roof timbers and coverings.
 Usually, they are constructed
from pieces of timber or steel
which are nailed, bolted, or
pegged together to form a
mutually supporting and strong
base for a roof.

38. TRUSS ANALYSIS

39. TRUSS ANALYSIS
Design of industrial roof truss:
 Steps of work
1. Selection of truss type.
2. Estimation of loads.
3. Analysis & design of purlin.
4. Analysis & design of sag rod.
5. Dead load(DL) and Wind load(WL) analysis
of truss member.
6. Combination of DL and WL to determine
the design bar forces.
7.Design of member according to the bar forces.
8.Design of bracing system.
9.Design of connection.
10.Detailing.

40. TRUSS ANALYSIS
We will design a Industrial roof truss

41. TRUSS ANALYSIS
 Design of Purlin
 Then calculating of purlin number and Purlin spacing.
 Then load analysis-
01. Dead load analysis.
02.live load analysis.
 Then we find out member force by grasp software.
 Bracing design-
01. Top chord bracing.
02. Bottom chord bracing.
03. Vertical bracing.

42. TRUSS ANALYSIS
Types of Truss Connection-
01. Pinned Connection.

43. TRUSS ANALYSIS
Types of Truss Connection-
02. Gusset plate Connection.