An experimental study with many variables was carried out to investigate the effective width of simply supported composite beams (T&L sec. beams) with & without slab opening. Three full-scale composite slab models with six different carrier simply supported composite beams (three with T-sec. & three with L-sec.) with constant slab rectangularity was tested.  Each model loaded by uniform load (in the elastic zone) then loaded by means of two-concentrated load system acting at equal distances from supports till failure. One of them without slab opening and the others with two symmetric slab openings and constant opening horizontal position. All standard tests were performed and all instructions and precautions were followed as perfect as the laboratory instruments permitted.  All experimental steps were executed in a manner such that meeting practical conditions as exactly as could. In this research, the tested model features, materials properties and measurement instrumentations are described in brief. The maximum load carrying capacity; crack patterns, generated strains and deflections at different positions were experimentally investigated. For the sake of analysis generalization and error minimization, all results were analyzed by means of dimensionless relations. The results were recorded and analyzed guided by their mechanical behavior. Interesting gained results, conclusions and recommendations are introduced.

Current research paper deals with reinforced concrete (R.C.) beams numerical modeling and suggested strengthening procedure if it is required to create an opening within their shear zones. Strengthening is assumed to be achieved during different service load application conditions. Reinforced Concrete beams with rectangular or circular opening in shear zone; as critical regions; sustain two concentrated system of loads are tested till failure before and after performing suggested opening assessing technique by means of Carbon Fibers Reinforced Polymer sheets (CFRP). The main aim of this research is simulating real practice situation where the beam is subjected to service loads, supported temporary by means of hydraulic jacks, opening is created and strengthening is performed then jacking supports are released. Results of achieved numerical nonlinear modeling are introduced and influence of strengthening achieving on improving assessed beams almost structural behavior such as initial cracking loads, load deflection curves, cracking patterns, failure loads & modes for reference (without opening), main un-strengthened control beams, and CFRP strengthened opening beams are introduced and analyzed in details. Some important conclusions & recommendations for designer and executive engineers are stated.