Stress Analysis And In-plane Inelastic Stability Of Tapered Members

Due to their structural economy,tapered members are more and more widely used in portal frames. However,the stress distribution and in-plane inelastic stability of tapered members are not yet fully documented. In this thesis referring to the web-tapered,cantilever members with I section,the stress and stability of tapered members are studied.Firstly,the shear and normal stresses of tapered members under the transverse load or axial load are analysed,and the stresses formulas are obtained which are different from those of the prismatic ones.Secondly,research is done on the in-plane inelastic stability of tapered members under axial loads about strong axis and weak axis. A new design method is suggested in which the tapered member is equivalent to the prismatic member with the cross-section at the larger end of the tapered member. In this part,it is also found that the equivalent prismatic column,which is obtained based on the equal elastic critical load as the non-prismatic member,is not actually equivalent to the tapered column in inelastic stability,and the latter has higher load carrying capacity.Finally,the behavior of tapered beam-column acted by combined axial load and transverse load has been investigated. A bending-thrust interaction curve is established which is similar to the ones for the design of prismatic members. This work is of some reference to the practical design.