STIFFENERS - PLATE GIRDER

What is Stiffener

In  steel  building  construction when  the web  of  a  plate  girder  acting  alone  (that is  without stiffeners)  proves  inadequate,  stiffeners  may  be  provided  for  specific purpose as follows. 

To improve the buckling strength of a slender web due to shear intermediate  transverse  and  longitudinal web stiffeners;  to  prevent  local  buckling of  the web  due  to  concentrated  loading load-carrying stiffener.

• To  prevent  local crushing of the web due to concentrated loading bearing stiffener; 
• To provide torsional restraint to beams and girders at supports torsional stiffener;
• To provide local reinforcement to a web under shear and bearing diagonal stiffener.
• To transmit tensile forces applied to a web through a flange—tension stiffener are provided. 

 

Arrangement of Stiffeners

 Basically there are only two types of stiffeners, 

    Intermediate stiffeners and Bearing stiffeners. 

    The intermediate web stiffeners are used to prevent the web from buckling due to shear and,

    The bearing stiffeners to prevent crushing of web under concentrated loads.

    Any of these stiffeners may be required to perform more than one function and thus its design should comply with the requirements of all the functions for which designed. 

    For example, a bearing stiffener will be designed to check the crushing of web under concentrated load and will be checked in addition to local buckling (crippling) of the web due to the concentrated load as load bearing stiffener.

    Further, if provided at support it may also be called upon to provide end anchorage for tension field action to develop (in case tension field method of design is adopted). Such an end bearing stiffener is termed end post.

    The web of plate girder is assumed to be supported over the edges of the stiffeners. Angle sections are used if the connections are riveted/bolted,and flat sections are used if the connections are welded.