Name: Md. Neshar Ahmed Limon 4th year, 2nd semester ID: 10.01.03.151 Sec: C Ahsanullah University of Science & Technology

1. Presented To
 Sabreena Nasrin
B.Sc. Engg. (Civil), BUET
Lecturer at Ahsanullah University of
Science & Technology
Presented By
 Md. Neshar Ahmed
Student ID: 10.01.03.151
4th Year, 2nd semester
&
 Munshi Galib Muktadir
B.Sc. Engg. (Civil), BUET
Lecturer at Ahsanullah University of
Science & Technology
Department of Civil Engineering
Ahsanullah University of Science &
Technology

2.  A truss is a structure composed of slender members joined
together at their end points. Planar trusses lie in a single plane.
Typically a truss is a joint framed structure which is designed to
sustain inclined, vertical or horizontal loads occurring at or
between its points of supports and has the following
characteristics:
 Straight Members
Members connected at their
intersections by means of frictionless
pins or hinges
Members so arranged that the truss is
loaded only at the joints
Typical figure of Truss & Frames

4.  Pitched Truss- Characterized by its triangular shape.
It is most often used for roof construction.
 Parallel Chord Truss- Its named from its parallel top
and bottom chords. It is often used for roof
construction.

5. Flat Truss
Queen Post Truss
King Post Truss
Lenticular Truss
Bowstring Truss
Lattice Truss

9. The analysis of trusses is usually based on the following
simplifying assumptions:
 The centroidal axis of each member coincides with the line connecting
the centers of the adjacent members and the members only carry axial
force.
All members are connected only at their ends by frictionless hinges in
plane trusses.
All loads and support reactions are applied only at the joints.

10. Method of Joints
Method of Joints: The axial forces in the members of a statically
determinate truss are determined by considering the equilibrium of its
joints.
Tensile(T) axial member force is indicated on the joint by
an arrow pulling away from the joint.
Compressive(C) axial member force is indicated by an
arrow pushing toward the joint.

17. Effect of tension vs. compression on member sizes
Potential for stress reversal
Potential buckling failure modes and approaches to preventing
Overall lateral stability (lateral- torsional buckling)
Member redundancy: Determinate vs. Indeterminate Trusses

22. Truss Determinacy Formula
n = 2j – 3 →for determinacy
„ n = Number of truss bars
„ j = Number of joints
n > 2j -3 →indeterminate
n < 2j -3 →unstable

23. Some renowned Trussed Structures
Eifel Tower

24.  Multi forced members are generally known as Frames.
 Frames are commonly used to support various external
loads.
Figure of Frames

25. Advantageous features of Framed
structure
1. Speedy construction due to simplicity in geometry –consist of only columns
and beams (or partially by the floor slab) as the main structural elements
2. Very rigid and stable –able to resist tremendous vertical (dead load) and
lateral loads (wind)
3. Reduced dead load –absent of thick shear wall etc.
4. Roofed over at an earlier stage –every floor slab being finished becomes an
cover to protect the lower floors from sun and rain
5. Offer large unobstructed floor areas –without obstacle between columns
6. Flexible utilization of space

26. Advantages features of Framed structure
(continued)
7. Adaptable to almost any shape
8. Easily altered within limits of frame –regular or non-regular grid system is
very adaptable in spatial arrangement
9. Offsite preparation possible –especially for prefabricated construction
using pre-cast concrete or structural steel elements
10. May be designed to accommodate movement
11. Acceptable distribution of natural light –window openings can be
provided easily on eternal walls
12. Easy to design structurally including computer design –again, due to
simple geometry

27. Principle factors affecting choice of frame
Structural Design consideration

Foundation consideration

Standardization of members or design

Span and floor loads

Fire resistance requirement

Maintenance consideration

Integration of architectural & structural elements

28. Features of In-situ concrete frame construction
Construction aspects
1. In-situ concrete is inconsistent in quality in performance -mixing,
delivery, placing and compacting of concrete require very tight quality
control
2. Overlapping formwork, steel fixing and concreting process make site
operations more difficult –these works are to be done almost at the
same time at the same location
3. Formwork erection is often timely, expensive, environmental
unfriendly and labour intensive
4. Increase a lot of wet-work –difficult to maintain site
in a clean and tidy environment

29.  Draw the FBD of the frame or machine and its
members as necessary.
 Then identify any two-forced members
 For a joint with more than two members or an
external force, it is advisable to draw a FBD of
the pin.

30. Some Examples Framed Structures

31. DIFFERENCE BETWEEN TRUSSES AND FRAMES
Trusses
Frames
Members are subjected
to tension/compression
only
At least one member is
subjected to bending,
shear or torsion
Composed of rods
Composed of bars
Usually more simple to
calculate, more weight
effective
Usually more simple to
manufacture, and to
place in tight layout

32. DIFFERENCE BETWEEN TRUSSES AND FRAMES
Connection by riveting,
moment-resistant

33. DIFFERENCE BETWEEN TRUSSES AND FRAMES
Connection
by welding,
momentresistant

34.  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
 A triangular truss maintains its shape, preventing shift
and sag. Thus giving stability to the structure.
 The shape of a triangle allows all of the weight applied
to the sides to be redistributed down and away from
the centre.