Impact of Field Exposure Conditions on High Strength Concrete Produced for Prestressed Bridge Girders;Research rept. Jan 00-May 03

摘要

This is the fourth in series of four reports that document the findings of a Texas Department of Transportation sponsored project to evaluate the allowable stresses and resistance factors for high strength concrete (HSC) prestressed bridge girders. The third phase of this research study, which is documented in this report, focused on determining the impact of different exposure conditions on the compressive and flexural strength of HSC mixtures used for prestressed girders in Texas. The allowable tensile stress at service for HSC prestressed bridge girders was evaluated based on the results from the experimental program. This phase of the project involved several key tasks: (1) an experimental study to assess the effect of several field exposure conditions on the compressive and flexural strength of HSC and development of a modified tensile stress limit based on material testing from this project; (2) a parametric study to evaluate the impact of the modified tensile stress limit derived from the material testing in this study when applied to the design of HSC U54 prestressed girders, and (3) a reliability study to determine the probability that the tensile stress would exceed the modulus of rupture to determine the safety against flexural cracking for designs based on both the current and modified tensile stress limits when applied to HSC U54 prestressed girders.