Experimental Investigation of Reinforced Concrete Beams with Lapped Reinforcement

One of the great contributions made by President Dwight D. Eisenhower was his influence in the implementation of the National Interstate and Defense Highways Act of 1956. The National Highway System serves an important role in American citizen's ground transportation. Now more than a half of a century in age, there is a high priority to repair existing infrastructure as well as the need for expansion. Repair and expansion must be achieved efficiently by reducing construction time and improving the capacity and durability of the structure. Precast, prestressed decked bulb tees (DBTs) serve as an excellent solution to ensure quality from an on-site precast concrete fabricator and also to reduce construction time. This thesis focuses on the research involved in the interface connections of these DBTs. Eight specimens of reinforced concrete with two connection details at the center span of the beam were tested, and the results serve as a conservative estimate to the behavior of the jointed interface. Two different prospective joint designs were tested in this project. One type was a headed bar reinforcement which was tested in various spacing and lap lengths. The second type of joint was welded wire reinforcement with varying wire spacing. In order to accelerate bridge construction, it is desirable to narrow the width of the jointed zone. However, the width has to be wide enough to accommodate non-contact lapped reinforcement as well as to develop strength in the joint. According to the moment versus steel stress comparison from the strain gauge results, the 6 inch lap length specimens with headed bars behaved as a continuous reinforced specimen. Moment curvature suggests that the 6 inch lap length provides the design moment capacity and ductility. With the same 6 inch lap length, it was found that the specimen with 4 inch spacing of reinforcement provided 1.5 times the moment capacity of the 6 inch spacing of reinforcement without significantly compromising ductility.