FINITE ELEMENT MODELLING OF STRUCTURES SUBJECTED TO THERMAL LOADING

Abstract

Thermal analysis of RC structures under the effect of uniform temperature change poses a special kind of problem, where the high axial stiffness of horizontal beam elements used in finite element analysis produces correspondingly high lateral forces, and straining actions in the supporting columns, especially the ground floor columns. This effect is most pronounced for the external columns. In this study, a novel proposal is made for developing an analytical approach for assessment of the effect of bending cracks along the beam length on its axial stiffness. The proposed approach is utilized for the development of a software package for the computation of the effective axial stiffness of beams, taking into consideration the resulting cracked-section strains at the top and bottom fibers of the beam sections along its length. Effect of applying varying axial force levels to the beam is studied in detail, and curves are developed showing the variation of the beam’s axial stiffness with the applied axial loads. Effect of different parameters including steel reinforcement level, and span length are also taken into account. The developed relationship curves are utilized using a newly developed analytical algorithm for the iterative analysis of RC multi-storey frames u