الفهرس 
LITRA TURE REVIEWOnly 14 pages are availabe for public view
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Abstract
Many steel bridges are in need of strengthening due to fatigue. corrosion and increase in loads
due to trucks weight increase. Innovative techniques of repair, rehabilitation and
strengthening of structures are required. Fiber Reinforced Polymer (FRP) materials have been
found to be a successful technique. The structural performance of these bridges can be
improved through external bond ing of fiber reinforced polymers plates. Nowadays with the
thought of globalization and with the rapid growth in Egypt; new imported trucks with heavier
weight wi ll be used. Thus, there is a must to strengthen the existing bridges to sustain the new
live loads. This Thesis tries to determine the best method of strengthening concrete-steel
composite girders in different conditions. In this research, using a finite clement
analysis program ..ANSYS 8”; a 3-D finite element model for a concrete-steel composite beam
without any strengthening and another steel concrete composite beam strengthened by CFRP were
created and verified by experimental results. A parametric study was done on strengthening
steel bridges beam due to the increase in the live load up to failure using CFRP and using steel
plates to evaluate the two methods of strengthening and find which method is better in different
cases. The parametric study contains nine simply supported bridges with different spans and beams
spacing. For each bridge, the middle concrete-steel composite beam was modeled three times, the
first without being strengthened (as a control beam), the second is strengthened using
steel plate attached to the tension flange and the third is strengthened using CFRP layer attached
to the tension flange. A comparison between the results was done using the loading capacity and
the mid span deflections as the comparison aspects. The cost of the material is a main
comparable aspect between the two methods.