Compressive Behavior of Concrete with Vitrified Soil Aggregate

The compressive behavior of portland cement concrete with vitrified soil coarse aggregate is the focus of this paper. A total of 10 batches of concrete were examined at four different coarse aggregate volume fractions with three different combinations of vitrified and natural coarse aggregates. For comparison purposes, the ratios of cement, water, and fine aggregates were held constant. The stress-strain curves, modulus of elasticity, compressive strength, and Poisson\u27s ratio are examined as a function of coarse aggregate content. Results show a decrease in compressive strength as the volume fraction of vitrified soil aggregate increased. Moduli of elasticity for concrete with vitrified soil aggregate are considerably higher than concrete with natural aggregate. The Hirsch-Dougill model is extended and applied to a three-phase material to predict the modulus of elasticity of concrete with natural and vitrified soil aggregates

Fatigue evaluation of highway bridges

The present work provides a comparison of current AASHTO bridge fatigue guidelines with fracture mechanics procedures. Specifically, the remaining fatigue life of several actual bridges with welded cover plate ends is estimated using the AASHTO specifications. The estimates are compared with predictions made using linear elastic fracture mechanics principles where the time required for an initial flaw to propagate to a critical depth is calculated. It is found that fatigue lives of actual steel highway bridges as determined using fracture mechanics far exceed the remaining safe fatigue life predictions made with current AASHTO guide specifications. For the case of redundant bridges, an adjustment factor is introduced which, at various probability levels, can produce closer estimates of bridge fatigue lives between the AASHTO specifications and fracture mechanics. © 1998 Elsevier Science Ltd. All rights reserved

Fatigue evaluation of bridges

The present work applies the AASHTO guide specifications to fatigue evaluation of several actual bridges. Estimates are compared with predictions made using linear elastic fracture mechanics principles where the time required for an initial flaw to propagate to a critical length is calculated. It is found that actual steel highway bridges demonstrate that fatigue predictions based solely on safe life result in excessively low fatigue lives. Mean life predictions on the other hand tend to be too long. It can be possible to calibrate the AASHTO specifications so there is a closer agreement with the fracture mechanics predictions