This paper summarizes the tests conducted on a 25-year-old prestressed concrete girder to evaluate the available prestress. Two methods, including a newly developed technique, were used to measure the available prestress in the girder. The focus of this paper is the application of the new nondestructive technique. The proposed method is based on the stress state around a small cylindrical hole drilled in the bottom flange of a prestressed girder. This technique overcomes some of the shortcomings associated with previously developed strain/displacement based prestress evaluation methods. Using the new method, the predicted effective prestress of the prestressing strands was compared to that obtained from destructive cracking tests. Results indicate the merit and promise of the newly developed nondestructive technique. Following application of the proposed method, the 25-year-old girder was tested to collapse. The ultimate capacity of the girder was also estimated using a theoretical analysis. The actual strength and analytical prediction were in close agreement.
