4. Structure Elements
Column:
Columns carry primary Axial Loads and
therefore are designed for compression.
Additional loads from snow, wind or other
horizontal forces can cause bending in the
columns.
Columns then need to be designed for
Axial Load and Bending.
5. Structure Elements
Beam:
Beams are sized appropriately to
safely support the loads a
structure will carry.
Beams are primarily subjected to
bending and shear.
Deflection and deformation can
be calculated.
Beams are sized to provide the
maximum result with the
minimum materials. A factor of
safety is included in the design.
6. Structure Elements
Tie Rods:
A tie rod is a slender structural unit
used as a tie and (in most applications)
capable of carrying tensile loads only.
Tie rods may be connected at the ends
in various ways, but it is desirable that
the strength of the connection should
be at least equal to the strength of the
rod. The ends may be threaded and
passed through drilled holes or shackles
and retained by nuts screwed on the
ends
8. Structure: refers to a system of connected parts that can support loads while performing its primary function.
Structure can be classified according to their uses:
• Civil structures- Building,Bridges,Towers,etc. are used by civilians or
general public.
• Military strucures-Ships,Aircraft frames, Tanks etc. .Used by military etc.
• Normally all static/stationary structures used by the common public are
designed by civil engineers.
9. Type of structures
Structural system: The combination of structural elements and the
materials from which they are composed is referred to as a
structural system.
Each structural system may be composed of one or more of the
four basic types of structures.
The four basic type of structures are:
Trusses
Cables & Arches
Frames
Surface structures
11. Truss: A truss is essentially a triangulated system of straight
interconnected structural elements.
Use of trusses in buildings:
Trusses are used in a broad range of buildings, mainly where
there is a requirement for very long spans, such as in airport
terminals, aircraft hangers, sports stadia roofs, auditoriums and
other leisure buildings. Trusses are also used to carry heavy loads
and are sometimes used as transfer structures.
12. Trusses are widely used to serve two main functions:
To carry the roof load
To provide horizontal stability
13. Types of trusses
Trusses comprise assemblies of tension and compression elements. Under
gravity loads, the top and bottom chords of the truss provide the compression
and tension resistance to overall bending, and the bracing resists the shear
forces. Some of the commonly used types are shown below.
I. Pratt truss ('N' truss)
II. Warren truss
III. North light truss
IV. Saw-tooth truss
V. Fink truss
VI. Vierendeel trusses
17. Cables and Arches: Tow other type of structures used to span long distances are
the cable and the arch. They are commonly used to support bridges, and building roofs.
Cables
• Cables are usually flexible and carry their loads in tension
• The external load is usually applied vertically (not along the axis of the cable).as a
result, the cable deforms with a SAG.
• Cables have an advantage over beam and truss,especialy for spans greater than 150
ft. because they are always in tension, cable will not become unstable and suddenly
collapse, as may happen with beam or trusses.
• Cables are limited by their SAG ,weight and method of anchorage.
18. Arches:
• An arch has the reverse curvature of a cable and it
achieves its strength in compression
• The arch must be rigid in order to maintain its shape.
• It is primarily subjected to compression(but also shear
and moment).
• arches are used in bridge structures, dome roofs and
opening in masonry walls.
21. Frames: Frames are often used in building and are composed of beams and
columns that are either pin or fixed connected, like trusses, frames extend in
two or three dimensions.
Steel frames – concrete frames. Mostly commonly used buildings
There are different types of frames depending on the connection between
beams and columns:
a. Braced frames-All connection between beams and columns are pinned and
there are diagonal bracing members.
b. Moment resisting frames-connections between beams and columns are
rigid and there is no need for diagonal bracing members.
23. Surface structures: A surface structure is made from a
material having a very small thickness compared to its other
dimensions.
o The structure is subjected to in-plane(tension or
compression forces mainly).
o Surface structures may be made of rigid material such as
reinforced concrete.
o The structure may be shaped as folded plates,cylinders,etc.
o They are referred to as thin plates or shells.