Métodos simplificados, basados en el Código Modelo 90, para el cálculo de flechas instantáneas en elementos de hormigón sometidos a esfuerzos combinados de flexión y compresión

Model Code 90 based methode for instantaneous deflections of concrete elements under combined bending and compression

Model Code 90 establishes, for deflections, general bases for the behaviour of cracked concrete in the field of elements under combined bending and compression. Neverthless, this formulation arrived at needs considerable calculation. A more simplified method proposed by CEB Manual on Cracking and Deformations is refered in the Model Code 90. This bilinear method leads to differences, in relation to the general method, up to 50% of the deflection. In this paper a simplified expression for the mean curvature for computing deflection is proposed. This expression depends on the simple bending values of the characteristics of the section, hence, of easy evaluation. Moreover, anew bilinear method based on the interpolation between deflections in the cracked and the uncracked hypotesis, with axial compression, is described.