A practical model for moment redistribution in statically indeterminate RC beams

Abstract

Moment redistribution in the RC continuous beams occurs due to the plastic behaviour. As a result, the values of the moments at the critical sections are different from the values of moments resulting from the elastic design. This may be useful for attaining more economic-reinforced concrete sections as well as decreasing the reinforcing amount at the sections with a rush of disrupting of the reinforcement, specifically the mid-supports sections. However, in different codes of design, the values of moment’s redistribution depend only on the ratio between the neutral axes to the effective depth (c/d). Also, they vary from 30% to 20%. Therefore, in this study, 103 specimens of two-span RC beams were extracted from the previous studies and used to reveal the fundamental parameters that affect the value of the coefficient of moment’s redistribution (β). Afterward, by regression analysis of the database, a new model was established to significantly predict the values of (β) . Finally, the proposed model was compared with the different design standards. It was found that besides the proposed model is more accurate, the proposed model considers several parameters which were neglected by design codes, showing their obvious impact on defining the value of (β).

Keywords:

• Statically indeterminate RC beams
• redistribution of moments
• flexural stiffness
• design standards
• theoretical model

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the department of reinforced concrete and masonary structures of the National Research Moscow State University of Civil Engineering NRU MGSU, Moscow, Russia. Yehia A. K. Sayed is funded by a partial scholarship from the Ministry of Higher Education of the Arab Republic of Egypt.