Hollow Triangular Cross-Section Calculating PrecastMonolithic Beams Methods with Account for Concrete Nonlinear Properties

Abstract

The article examines precast-monolithic reinforced concrete beams with a cross section in the form of a hollow triangle. The advantages of such beams are presented and say that their stiffness in torsion is ten times bigger than the similar rigidity of a T-beam with the same stiffness and bending resistance. The article introduces the method of manufacturing such beams without the use of form work which was developed by the author of the article. Earlier the authors investigated the stiffness of such beams in torsion and it is mentioned in the article. However, stiffness and bending resistance are not investigated. Resistance and stiffness of precast-monolithic beams under bending differs from the resistance and stiffness of the monolithic ones. Consequently, taking into account the nonlinear properties of materials the calculation of such beams is different. The method for calculating beams under bending is introduced and it is based on the application of the flat section hypothesis. This method is used in conventional methods of calculation. The difference from the traditional calculation is the addition of equilibrium stress to the equations which are perceived by sections of monolithic concrete with physical and mechanical characteristics that differ from those of the main part of the structure. In calculation the cross-section of the beam is reduced to the equivalent T-section.