Question

The interaction expression for stiffeners subjected to external loads or moments is given by

(a) [(Fq-Fs)/Fqd]+(Fs/Fsd)+(Mq/Myq) < 1

(b) [(Fq-Fs)/Fqd]+(Fs/Fsd)+(Mq/Myq) > 1

(c) [(Fq-Fs)/Fqd]-(Fs/Fsd)-(Mq/Myq) < 1

(d) [(Fq+Fs)/Fqd]-(Fs/Fsd)-(Mq/Myq) > 1

I had been asked this question in quiz.

I'd like to ask this question from Stiffeners in section Gantry Girders, Design of Plate Girders & Industrial Buildings of Design of Steel Structures

Answer 1

Right option is (a) [(Fq-Fs)/Fqd]+(Fs/Fsd)+(Mq/Myq) < 1

Explanation: Stiffeners subjected to external loads and moments should meet the conditions of load carrying stiffeners. In addition, they should satisfy the following interaction equation: [(Fq-Fs)/Fqd]+(Fs/Fsd)+(Mq/Myq) < 1, where Fq is stiffener force, Fqd is design resistance of intermediate stiffeners corresponding to buckling about axis parallel to the web, Fs is external load or reaction at stiffener, Fsd is design resistance of load carrying stiffener corresponding to buckling about axis parallel to the web, Md is moment on the stiffener due to eccentrically applied load and transverse load, Myq is yield moment capacity of stiffener based on its elastic modulus about its centroidal axis parallel to the web.