Behavior of Prestressed Composite Beams

Prestressing is shown to be an effective means of increasing the yield load, the ultimate load, and the load producing the allowable steel stress, in composite beams of steel and concrete, but prestressing of these structures does not significantly reduce the deflection due to live load nor does it significantly increase the load producing the allowable concrete stress. These conclusions are based upon the analysis of the behavior of a number of prestressed and conventional composite beams for both bridges and buildings, for loads increasing up to failure of the beam. The validity of the method of analysis is shown by analyzing certain beams tested by others and comparing analytical and experimental results.