engleski

Modified non-linear method for stability analisys of R/C frames

The computation of the stability and bearing capacity of reinforced concrete frames and similar structures, whose individual elements are significantly exposed to compressive loads, i.e. respectively to centric and eccentric pressure with low and high eccentricities, always implies the influences of material and geometrical nonlinearity, since this ensures efficient usage of the considered material. Although rigorous numerical models for the analysis of these structure exist today, their everyday usage is inefficient due to the high cost of training experts to master those models. This paper presents a simple method which makes it possible to obtain the expected results relatively quickly and simply. The method is based on the linear static analysis used to determine the section forces, while the buckling length, i.e. slenderness, is determined by using a geometrically nonlinear analysis or approximate methods common in engineering practice. These results are introduced into the spectrum of the bearing capacity to determine the failure compressive force for each element. The bearing capacity spectra are non-dimensional graphs developed by numerical experiments with a material and geometrically nonlinear model. They cover the field of both the centric and eccentric pressure with low and high eccentricities as well as the field of slenderness according to the national codes. The efficiency of this method has been illustrated by an example and proved by a series of results from the relevant literature. The suggested method for determing the bearing capacity and stability yields results which are safe compared to those obtained by rigorous nonlinear numerical models ; consequently, they are acceptable from the engineering aspect.

stability; reinforced concrete; material and geometrical nonlinearity

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