Assessing Strength Capacity of Prestressed Concrete Girders

摘要

This report summarizes a two-phase study that was conducted to assess thestrength capacity of prestressed concrete girders. A new nondestructive technique to measure directly the available prestress in prestressed girders is developed. Experimental data indicate that this new method predicts the available prestress within a few percentages (3%) of the actual values. Experimental data also provided information to assess the available prestress in the type of girders constructed some 25 years ago. Using the effective prestress obtained with this new method, the shear capacity of two 25 year old prestressed girders were evaluated, both according to code and experimentally. Five shear tests were carried out. These tests indicated that the complex method of calculating shear strength given in AASHTO LRFD specifications is very conservative and that the simpler method given in AASHTO Standard specifications is a better approach. Guidelines for calculating ultimate strength of the prestressed girders are also provided.