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3,2 Plastic Buckling Test of Wide Flange Section 
3.2.1 Introduction 
Recently "Plastic Design'' of steel structures is considered a more rational 
and economical method for design. Therefore research must be done more 
precisely on the plastic behavior of steel structures. 
The plastic design of steel structures is based on the "simple plastic theory" 
which requires the existence of the "plastic hinge". The structural members must 
be designed so as not to ruduce in strength before the structure will collapse even 
in the plastic range. Therefore the structure members used in the plastically 
designed structure are usually wide flange section. They lose stability by the local 
buckling of compressive plate elements of the sections. The compressive elements 
have sufficient geometry to prevent instability by local buckling. This geometry 
may be represented by the ratio of sufficient width to thickness of the plate. 
Theoretical and experimental research on local buckling of plates are now in 
the purpose of which is to examine 
progress. The buckling test discussed here, 
the behaviour of the flange and the web of wide-flange sections compr essed beyond 
the elastic limit, is one of the tests of the above-mentioned project. The method 
e measurement of 
of measurement by ster eo-photogrammetry is applied to th 
deformations of the flange and web. 
Use of photogrammetric methods has the benefit of being able to easily measure 
the deformation of objects three dimensionally even when the measur ement points 
on the objects move due to the change of loading conditions. These characteristics 
urement such as the dial- 
cannot be replaced by other mechanical methods of meas 
gauge instrument. Especially, in the plastic buckling test, the main problem is 
the difficulty in foreseeing the places where the buckling will occur. 
  
  
  
  
  
* . AISC-Specification *k ASCE: Commentary of Plastic Design in Steel" 
20> 
  
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