Structural Concrete, Vol. 10, no. 1, March 2009
The improved n-method for the calculation of stresses in service
M. Taliano, Politecnico di Torino, Italy
This paper reports the main results of a parametric analysis which is based on the calculation of stresses on concrete and steel of r.c. rectangular sections subjected to bending under quasi-permanent and characteristic loads. Two calculation methods are used: a general method and a simplified one, namely the n-method. The main parameters that influence the calculation of stresses are then discussed and the differences that are produced by the n-method using the classical values found in the literature compared with the general method are evaluated. By varying only some of the involved parameters, appropriate new values of the modular ratio, called 'improved modular ratios', are determined and two equations for the assessment of the improved modular ratios are proposed, one for each considered load combination. In this way, applying the 'improved' n-method, it is possible to calculate the stresses on concrete and steel with good accuracy.