| In 1975, a comprehensive research effort dealing with segmental construction was initiated at The Pennsylvania State University, and an experimental post-tensioned segmental box girder bridge was constructed at the university test track. One of the items recommended for investigation was to load the bridge to failure and study its overload behavior. This work reports the results of that investigation.;A general approach for nonlinear analysis of reinforced concrete structures based on the finite element method, and using Kostovos and Newman's material model for concrete, is presented. The general approach accounts for concrete cracking with a tension stiffening effect, multiaxial behavior and strength properties of concrete under generalized stress condition, nonlinear stress-strain characteristics of the steel, and the shear stiffness in a cracked element due to aggregate interlock and dowel action. This approach is useful in enabling the nonlinear analysis to be performed using a linear finite element program (SAP IV). Also, a set of criteria for closing and reopening of cracks is considered. Three-dimensional finite elements are used to model the concrete and three-dimensional truss elements to model the steel.;Before the general procedure of analysis is applied to the bridge problem, a singly-reinforced concrete beam is analyzed to assess the applicability of the proposed method of analysis. Good agreement is obtained between experimental and finite element results. Then, girder B of the experimental segmental bridge is analyzed.;Measured center-line deflections and surface strains of girder B are found to agree reasonably well with the finite element values. Cracking, first yielding, and ultimate loads are found to be in good agreement with their respective finite element values. Experimental crack patterns, at load P = 776 kips and at failure, resemble those predicted by the finite element method.;Also, the bridge is analyzed by the standard theoretical analysis of prestressed concrete structures. Deflections and surface strains predicted by this method are found to agree closely with the observed values up to the first yielding of the steel. After first yielding, the computed ultimate load agrees well with the observed value, and the shape of the load deflection curve is similar. |
