الفهرس 
Transmission TowersOnly 14 pages are availabe for public view
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Abstract
The fundamental property of the elastic critical load is that at
critical load the frame, with its members remain elastic, offers no
resistance to a small disturbing force or moment, for then the stiffness of
the structure is equal to zero.
In the static buckling analysis, the assumption is made that the
stress remain within the elastic region and the material follows Hook’s
Law.
In general, to study the buckling strength of transmission towers,
the joints are assumed rigid and the towers are treated as space frames.
The transmission towers members are apparently slender and cannot
resist safely the bending moments induced by rigid-joints. Thus, the
analysis is not realistic. Also the computer capacity and the time
consumed for the analysis are almost four times that of the space truss
having pin-joints. Little attention has been paid to the actual stress-strain
relationship above the proportional limit. The transmission towers are considered herein space trusses pinjointed.
The members are of uniform cross sections and the loads are
concentrated at joints.
Beyond the yield stress, the relation between the change in stress
and the change in the strain depends on the magnitude of the initial stress
and is given by the slope of the compression test curve.
An actual stress-strain curve of structural steel material is used for
members stressed beyond the proportional limit to find formulas that
relate the stress-strain and modulus of elasticity.
Applications are performed for transmission towers made of
structural steel in order to find their buckling strength. The towers were
treated as rigid-joints space frames with its material follows Hook’s Law
and as space trusses of pin-joints using an actual stress-strain curve. The
results show that the buckling strength of the space frames are almost
double that of the space trusses.
It may be concluded that the buckling loads of the transmission
towers being treated as space rigid-joints are not realistic. The analysis of post buckling behavior, introduced in this thesis,
IS capable of predicting precisely the behavior and buckling strength of
transmission towers. It offers significant aid for the design of structures.