align="left">A large number of contemporary box girders have a trapezoidal cross section. Because the webs are laterally inclined, the longitudinal posttensioning profile plane is parallel to the webs. Therefore, the? post-tensioning force will produce secondary lateral and vertical component forces in the cross section. This paper considers only the lateral effects induced in the flanges as a result of longitudinal prestressing in laterally inclined planes. With the possible exception of external tendons, the stresses induced in the flanges by these secondary forces are generally small when taken alone. However,? when superimposed upon other stresses, or if other potential? cracking mechanisms are present,distress in the form of cracking may be precipitated. These lateral forces have been wholly or partially? attributed to cracking in some bridges. The proposed design procedure is illustrated with two numerical examples, one for a simple span girder and the other for a continuous girder together with the special case of? external tendons.
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