An improved moment distribution method for the analysis of concrete frames

Abstract

The moment distribution method is considered one of the easiest and most reliable analysis methods. However, little attention has been given to modelling the stiffness of each member separately, as currently only one factor is being used to model all structural members without taking into account the loading conditions and curvature of the member. This can significantly influence the results when modelling columns, since unlike beams, which are usually bent in a single curvature configuration, columns can be bent in either a single or double curvature configuration. This paper presents a new set of stiffness factors to model each structural member separately depending on its boundary conditions and curvature. To validate this modification, an example concrete frame was modelled and analysed using the structural analysis software ETABS, and then the results were compared with that obtained from the standard moment distribution method and the modified moment distribution method. The results have revealed a significant enhancement in the accuracy of the obtained results when using the modified moment distribution method compared with the original moment distribution method, especially the values of the columns’ bending moments.

Keywords

• Moment distribution method
• Stiffness factor
• Structural analysis
• Single curvature
• Double curvature