| Steel road bridges are very important structures that are used widely all over the world. Mainly, they consist of steel-RC composite sections; steel girders and RC slabs connected using shear connectors. A significant cause of deterioration of steel bridge structures is the corrosion. On the other hand, and due to the increasing traffic, the capacities of many old bridges are need to be increased. The investigation presented in this thesis focused on the behavior of steel-RC composite beams strengthened or repaired with carbon fiber-reinforced polymer (CFRP) plates attached to their tension areas side.
Carbon Fiber reinforced Polymers (CFRP) composites were proved as very effective method for strengthening, retrofitting, and rehabilitation of the RC members, especially beams. However, the research upon the strengthening of T-sections steel-RC composite beams is few. Also, the available research generally concerns the validity of using the CFRP laminates for strengthening which, in fact, was verified many times.
Adding to this, there is a great need to make theoretical models, especially using Finite Element (FE) technique, to accurately examine the behavior of the modeled systems and to get rid of all the disadvantages of the laboratory work, especially the high cost and the human mistakes and the inaccuracy of the testing procedures.
This research is to study the behavior of steel-RC composite T-section beams strengthened using CFRP plates in the positive moment (tension) zone across the spans. The beams were modeled using the Finite Element Package ANSYS and the modeling process was verified through the results of previous experimental works. The behavior is examined through the values of the stresses and strains of the concrete slab, steel reinforcement, steel beam and the CFRP plates adding to the deflection of the beams, shear stresses of the adhesive layer and the failure modes of the beams. Also, ductility and energy dissipation were calculated as ways of good expectation for the behavior of the modeled strengthened beams.
The length, width, thickness, and the location of the CFRP strengthening plates were examined relative to the behavior of the studied systems.
A criterion for calculating the optimum strengthening length and the corresponding anchorage length was proposed and verified through the research.Also, a criterion for calculating the optimum strengthening thickness was proposed and verified through the research.
The width of the CFRP strengthening laminates was studied and the effective value was determined.Finally, the optimum location to put the CFRP strengthening laminates across the bottom flange was determined.
The final aim of this study is to obtain the maximum utilization of CFRP plates when used to strengthen the steel-RC composite T-section beams.
| Abstract |