Author: N. Hussain
31 August 2012
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N. Hussain
The Structural Engineer, Volume 90, Issue 9, 2012, Page(s) 1
Topics of importance openly discussed...
This paper presents the results of an experimental study on the shear behaviour of reinforced concrete beams with circular pre-cast web openings. 11 simply supported reinforced concrete beams, with and without web openings located in the shear zone of the beams, were tested using a fourpoint loading procedure. Test variables included size of the web openings, horizontal location of the web openings and shear span to effective depth ratio. The test results showed an almost linear reduction of the ultimate strength of the beams with increasing size of the web openings. The most critical location for the web openings was found to be in the centre of the shear zones where the critical load path directly crosses the web openings. The shear span to effective depth ratio was also found to influence the structural performance and strength of the beams. The results of the experiments are compared with ACI code based predictions.
In this paper a procedure for the comparison of steel column design by load and resistance factor design (LRFD) method, between the Egyptian code and other codes of practice, is set out. A column design curve for slender sections was established by applying a reduction factor, Q, to the LRFD column design curve. A stability analysis was conducted to study the effect of plate local buckling on flexural column buckling. A finite element model of an axially loaded I-column was developed using shell elements. Material and geometric nonlinearities were incorporated. Geometric imperfections similar to the first buckling mode with amplitude of 1/750 of column length, L, were applied. The analysis was carried out using a general purpose finite element program ANSYS. A wide range of plate width-to-thickness ratios and column slenderness ratios was studied. Column sections were grouped into three: Group 1; sections with slender unstiffened plate elements, Group 2; sections with slender stiffened plate elements, and Group 3; sections composed of slender stiffened and unstiff ened elements. The buckling loads for 144 I-column configurations made of steel St.37, St.44 and St.52 were compared to respective values adopted by the AISC-LRFD and Eurocode 3 specifications.