Método de análise de sistemas deslocáveis com ligações mistas de aço e concreto, fundamentado teórica e experimentalmente

Abstract

This thesis aims at analyzing the behavior of unbraced frames with steel concrete composite connections by means of a survey carried out on the basic components, being steel deck incorporated in the concrete slab. A method to determine the ultimate strength, the stiffness and the rotation capacity is suggested for a specific type of composite connection. This method consists of obtaining a moment-rotation curve for loading-unloading-reloading, considering wind and gravity loadings. Some specific points are also approached such as the reduction of the initial stiffness of the composite connection, the analysis of the frames with composite connections in theories of 1st and 2nd order, as well as some considerations about the use of the secant stiffness. This work is divided in two steps: - SIMPLIFIED METHOD: implementation of the composite connections in unbraced frames, providing a simplified analysis useful for designers, validated by the results of an ADVANCED ANALYSIS as well as by theoretical considerations and experimental results. ADVANCED METHOD: implementation of a finite element model where physical and geometrical nonlinearities are taken into account. The results of 16 (sixteen) tests of steel seat connections bolted to the lower beam flange are included, because its behavior is not clearly defined in the available literature. The results of 8 (eight) tests of composite joints, subjected to symmetric and asymmetric cycles of loadingunloading-reloading are also included. According to this research some analytical procedures are suggested to complement LEONs (2000) work. Finally, the parameters that influence the behavior of the composite connection in unbraced frames are critically analyzed, attempting to transform the mentioned procedures in a useful tool for composite connection research and designs.