COMMENTS ON THE APPROXIMATE ELASTIC ANALYSIS OF CONTINUOUS NONPRESTRESSED REINFORCED CONCRETE  BEAMS AND PORTAL FRAMES

BAHMAN OMAR TAHA

doi:10.26682/sjuod.2018.21.2.8

BAHMAN OMAR TAHA Dept. of Civil Engineering, Erbil Engineering Technical College, Erbil Polytechnic University, Kurdistan Region of -Iraq

DOI: https://doi.org/10.26682/sjuod.2018.21.2.8

Keywords: Continuous beams;, Portal frame;, ACI coefficient method

Abstract

Approximate analyses methods have been remained important for professional engineers and engineering students, and also it is important in structural analysis specially during preliminary designs. The moment coefficients of two, three, four and five multi-spans continuous nonprestressed reinforced concrete beams are determined and compared with AC I- coefficient method taking different groups of span combinations into consideration. The results show that the ACI- coefficient method of elastic analysis is safe and conservative except at internal support bending moment of (wL²/10) is suggested at both side of the support and (wL²/12) (w is the total factored loads) is suggested at first and last fixed support. Negative moment appears at some midspan and positive moment appears at supports in some span combinations, which is opposite to that obtained by ACI – method. For this reason, designer engineers should take this point into mind in analyzing the continuous beams. Also, the effect of the ratio of beam to column stiffness and height of the column on the end moments and midspan moments of the beams and columns are considered for portal frame.

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