الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The increase of loads in many structures due to the increase of the dead load or due to the increase in the service load of that building or due to the increase in both dead and live load my lead to replace the Structure or try to strengthening it. One of the most effective and economic method in strengthening Structures specially steel structures is using post tensioned elements (Cables, Rods or FRPT(fiber reinforced post tensioned)), the main idea of this method is based on introducing load to the building through this post tensioned elements which act opposite to the dead and the live load of the building, usually this post tensioned elements are put at the tension zone of the structure where these element will transfer a compression force to the structure in the tension zone and a tension force in the compression zone of the structure depending on the eccentricity of these element. Most of the previous researchers studied the effect of the post tensioning on simple and continuous I-beam it also study the effect on simple trusses, some recent research study the effect of post tensioning on the corner connection of frames to decrease the lateral drift of the beam due to lateral earthquake load. This thesis studies the effects of post tensioning on different steel structures as steel frames, trusses and beams this thesis studies many variables that affect on post tensioning method behavior as the value of post tensioned force, layout of the post tensioned element, Material and geometric linearity and nonlinearity ,types of loads static or dynamic and finally the shape of the structure as an example for frames whether the frame is single bay or two, one story or more and the roof is horizontal or pitched, for trusses the thesis study single and continuous span N and warren trusses, for beams the thesis study simple and continuous span beams(I-section and Box-sections). The thesis introduces finite element models for all of the above variables by using finite element program (ANSYS) which gives good simulation for the built models, after analyzing the results that is obtained from these models it is found that post tensioning methods has great effect in strengthening steel structures, it gives the ability to increase the service load on the structure without exceeding the designed strength