Prestressed Composite Girders. I: Experimental Study for Negative Moment

Limited experimental results were reported in the literature on the behavior of prestressed composite girders subjected to negative bending moment. This paper examines experimentally the behavior of prestressed composite steel‐concrete girders. The steel beams were all welded plate girders. Five composite specimens were tested to study the various aspects of prestressed composite girders, including the effects of construction stages, prestressing sequence, tendon type, and compactness of the plate girders on their structural performance. Load versus midspan deflection, strains in the concrete deck and steel girder, and the force increase in the prestressing tendons due to the applied loads were measured and studied. The test results showed that prestressing a composite girder in the negative moment region increases its stiffness by preventing the cracking of concrete under service loads; enlarges the elastic range; and increases the ultimate capacity due to the effective use of high‐strength tendons.