Investigação numérica da robustez estrutural de edifícios metálicos

Abstract

The evolution of constructive methods, high-performance materials and more refined methods of structural analysis have led to the development of increasingly slender structures that have design loads closer to structural capacity. This advance brought a great rationalization of the materials used in the construction and as a consequence a significant decrease of the works' cost. On the other hand, slender structures offer a lower redundancy level when the same type of structural solution is analyzed. In the last decades, the media has more frequently reported a series of events related to the buildings collapse caused by fires, earthquakes, accidental or intentional explosions (terrorism). These events have generated concern of the society about the structures collapse risks when submitted to exceptional loads and has motivated countless researches around the world. Structural engineers are currently concerned with procedures that increase the structures robustness and decrease the likelihood of a progressive or disproportionate collapse due to low probability actions. In this study is analyzed the structural robustness of steel braced frames and frame moment resisting frames. The ability of steel moment frames to withstand progressive collapse in the scenario of abrupt removal of a column using numerical models of the frames through the finite element method is determined by nonlinear static analysis and nonlinear dynamic analysis. The results showed that the final displacement values obtained by the static analysis are more conservative than those obtained by the dynamic analysis. The analyzes showed that Brace elements improve the structure performance against progressive collapse. In relation to the redundancy degree it was possible to observe that the structural elements number located above the removed column shown to be an interesting factor for the increase in structural robustness. The use of trusses at the top of buildings was studied in order to increase sturdiness levels and improve the buildings behavior against progressive collapse. In fact, trusses provided better performance to buildings in order to avoid progressive collapse in all column removal scenarios.