Analysis of composite connections in unbraced frames subjected to wind and gravity loading

A comparison between a simplified and an advanced method of elastoplastic analysis is made for unbraced frames with composite connections. The advanced method implements a mechanical model to represent the composite node in unbraced frames, which allows considering the behavior of each component of the composite connection individually. This method includes the determination of a moment-rotation curve for loading-unloading-reloading, considering gravity and wind loading. Physical and geometrical nonlinearities are taken into account in the analysis. In the simplified method an appropriate analysis for practical purposes is implemented, on which the connections are considered semirigid for unloading and flexible for loading, after yielding by gravity loads. Second order effects are included using the P-Δ procedure. Finally, a comparison is made between the two methods attempting to transform both methods in a useful tool for composite connection design.