Mode interaction in thin-walled I-section struts with semi-rigid flange–web joints

Interactive buckling in long thin-walled rectangular hollow section struts

“…Moreover, the higher joint rigidity also leads to a smaller wavelength at the same load level. This is in accord with results in previous work on I-section struts [27] and on struts on elastic softening-hardening foundations [36].…”

“…From both the p-q s and w wc,max -q s equilibrium diagrams, it can be observed that the values of q S s for all cases are extremely close between the two models. As for the local-global mode relationship, the present model matches better with FE results, when compared to previous studies on I-section struts [27,22] using the same methodology. Apart from the fact that the cross-section functions f f , f wc , g f and g wc have assumed forms, an additional source for the stiffer response of the analytical model is derived from the underlying assumption that the neutral axis location remains unchanged.…”

“…Since previous studies [31,32,10,11,26,27] have clearly demonstrated that it is essential to include the shear strain contributions into the total potential energy formulation to model the interactive buckling behaviour, Timoshenko beam theory is assumed currently. The global mode is decomposed into two components: a pure lateral displacement W and a pure rotation of the plane sections θ, see Figure 2, known as the 'sway' and 'tilt' modes [33,31] respectively.…”

“…In previous works, it has been used successfully for mode interaction problems on stainless steel I-section columns [39], stainless steel box section columns [25], linear elastic stiffened plates [26] and linear elastic I-section columns [27]. Therefore, it is implemented currently to establish a purely numerical model for the strut with semi-rigid joints with the same structural properties as the analytical model shown in Figure 1(a) together with the properties presented in Table 1.…”

“…In order to investigate how the interaction between individual plate elements affects the nonlinear interactive buckling behaviour, the aforementioned analytical models for stiffened plates and I-section struts were extended to include rotational springs at the junctions within the cross-sections [26,27]. In both cases, a rapid erosion of the snapbacks in the equilibrium path was observed with the increase of the rotational rigidity at the junction and there was generally an increase in the residual post-buckling load carrying capacity.…”