INVESTIGATION OF STRENGTH AND STABILITY OF SHALLOW FERRO-CONCRETE RIBBED SHELLS
Reinforced concrete shells of various shapes, being supported by ribs, are used as covers in large-span buildings and structures. The shells bear different loads including long-term ones. In the given article a study of shallow reinforced concrete ribbed shells functioning under the influence of continuous loads is presented. Rheological properties of reinforced concrete are described with the aid of the theory of inherited creep. Using the developed software complex PologObolochka, there was made an investigation of the stress and deformation state of shallow reinforced concrete ribbed shells. Deformation characteristics of reinforced concrete in shells are entered by the elastic modulus of concrete  and two measures of reinforced concrete creep  Distribution of the deflections and stresses about the field of shallow reinforced concrete shells of different types is obtained. Results of calculation of the deflection and stress values of shells supported by ribs are analyzed and compared to those of unstiffened shells calculation. During the creep deformation progress there takes place the growth of redistribution of stress over the field. As it is shown in the article introduction of ribs reduces the values of shell deflections significantly, and it also increases the allowable loads amount. And it is proved that while studying shallow reinforced concrete ribbed shells such factors as geometrical nonlinearity and transverse shear can be omitted.