Influence of Base Deformations on Stability of Frame-Rod Structural Systems

Abstract

Purpose of research. Investigation of changes in the critical parameters of stability of structural system elements, taking into account the geometric nonlinearity associated with the deformation of the “building-base” system. Methods. Under the influence of geometric nonlinearity associated with joint deformations of the “building-base” system, the longitudinal force of some racks ceases to contribute to the bifurcation of the rod [5-7, 9, 12, 13]. Therefore, at a certain value of strain ΔS, a single rack can go from active bifurcation to passive, which will cause structural and change the critical stability parameters of the entire system under consideration. This situation can lead to irreversible deformations and destruction of both the individual load-bearing element and the entire building. Results. Let’s consider a core structural system, the Central element of which is loaded with The RCR force, and the extreme elements are loaded with the RCR forces. (Fig. 1A). We find the critical parameters of the stability of the specified frame and the form of bifurcation of its compressed struts using the given equations depending on the load application coefficient α before and after stabilization of the base precipitation.

Let’s analyze the bifurcation pattern of the frame elements before and after the base deformation at the maximum precipitation of the second and third pillars at the value of the load application coefficient α=0.8 at a time when the base deformations have not stabilized, the left and right pillars lose their stability passively, the Central one-actively (Fig. 3A). Analysis of the obtained calculation results showed that when the second column precipitation is 2.4 cm or more, the character of the entire structural bifurcation system changes. Conclusion. During the theoretical research, the behavior of the elements of the frame in question during the loss of stability before and after the occurrence of an emergency situation associated with the subsidence of the base of the supports of the first and second pillars was analyzed. The dependence of the critical value of the precipitation and the difference in precipitation on the load application coefficient α for the second and third pillars of the frame was derived. Analysis of the obtained calculation results showed that when the second column precipitation is 2.4 cm or more, the character of the entire structural bifurcation system changes.