PROBLEMS OF COMPUTER STRUCTURAL ANALYSIS AND REINFORCEMENT CALCULATION TECHNIQUES OF REINFORCED CONCRETE RIBBED SLABS

Abstract

This paper proposes an overview of computer structural analysis and reinforcement calculation techniques of reinforced concrete ribbed slabs that are used in Ukraine. It considers the fundamental hypotheses and assumptions of these techniques and analyzes the possibility of implementation of the building codes’ requirements into automated calculations. Numerical experiments confirm the existence of a relationship between the normal stress distribution pattern in the rib’s cross section and the width of the slab zone, which participates in the rib’s bending. We conclude the need to develop a generalizing methodology of FEM structural analysis for such structures, which could be implemented in modern FEM-analysis packages implementing building information modelling technology (BIM).
Design forces in the elements of monolithic ribbed floors are determined taking into account plastic deformations. This approach is based on the assumption of the formation with increasing load in statically indeterminate systems of plastic hinges, each of which leads to a decrease in the static indeterminacy of the system by one degree. The appearance of plastic hinges leads to a redistribution of bending moments, which is calculated using a static or kinematic method. In the general case, the sum of the span moment and half of the support moments for the span of a single-span beam is always equal to the span moment in a similar single-span beam. That is, the ratio of support and span moments does not affect the bearing capacity of the statically indeterminate system as a whole, but only determines the order of formation of plastic hinges.