الفهرس 
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Abstract
In some steel structures, it is essential to allow the utility cables and pipes to pass through beam webs in order to ovoid the excessive building height. In the ordinary steel structures, the beam webs are not highly stressed and the application of castellated beams is of a great advantage. In the other cases, opening should be made through the beam webs. Provisions for beams with web opening and its specification for the design were not potentially covered in most of the design codes.
This research aims at study the effect of the geometry, location and dimensions of the opening on the structural behaviour and design of thin walled steel beams. Analytical model was developed to predict the failure mode and the load carrying capacity of the beams.The finite element non-linear ealsto-plastic analysis was used to validate the developed mathematical models.
The developed model accounts for local buckling in solving the problem of thin-walled simply supported steel beams with a rectangular web opening of any dimensions and at any location along the beam axis and subjected to a uniformaly distributed load. Finite element analysis was applied for the beam using COSMOS 2.6 finite element program to verify the analytical model results. lateral torsional buckling was prevented in all analysis performed in this research.
The developed model and the finite element analysis were applied to cold-formed beams with rectangular opening. The mode of failure, the load carring capacity and the normal stress distribution around the opening were investigated. The effect of many factors such as the effect of opening location through the beam axis, the opening dimensions on the ultimate resistance of the beam and the failure modes were also investigated
To quantify the degrading effect of web opening, a study has been conducted including the loading conditions of bending, shear, and conbined bending and shear, and compared to different experimental data. Based on the finding of this study, the interaction equation employed by the american iron and steel institute AISI soecification is evaluated and modified to account for the influence of the web opening in cold-formed beams.
Enhancement of the web behaviour with web opening by providing stiffeners around the opening was also investigated.Parametric studies were performed to investigate the effect of horizontal and vertical stiffeners in improving the structural behaviour of web of web with opening.
In the light of the results of the developed model and the performed finite element non-linear elasto-plastic analysis, design aids were introduced to help the designer engineer to consider the existence of opening into his account.
Finally, recommendations to the specifications for the design of thin walled beams with web openings were given.