A force method for calculating time varying stresses in concrete structures

A method for the linear time varying stresses of concrete structures at elevated temperature is presented. The method described is of a one-step direct formulation technique based on the principle of variational calculus.The analytical procedure of the variational principle is briefly described and the equations for the uniaxial state of stress are developed.The application of the method is described and the solution is carried out by a finite element stiffness analysis for two different types of stress distribution and a set of self equilibrating stress distribution. Predicted stresses by the proposed method are compared with other analytical methods based on a step-by-step analysis.