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Article 1: Behavior of Epoxy Injected Diagonally Cracked Full-Scale CRC Deck-Girders.
Many cast-in place reinforced concrete deck-girder bridges (RCDG) remain in the national inventory and exhibit diagonal cracking. Epoxy injection has been in use for several decades as a method for sealing diagonal cracks, but the effects on girder behavior have not been validated. Much of the existing data regarding performance of members injected with epoxy have been gathered through testing of reduced-scale specimens. This investigation reports structural responses of five full-scale RCDG specimens constructed to reflect mid-twentieth century proportions and details. Specimens were loaded to produce diagonal cracks, injected with epoxy under varying degrees of axial tension and service loading, and tested to failure. The experimental results indicate that epoxy injection produced minimal capacity increase, increased crack re-initiation loads, and reduced stirrup serviceability stresses compared to original performance and the control specimen. The addition of cyclic live loading during injection and curing of epoxy produced variable pressures within the crack volume and also produced small bubbles within the epoxy matrix. These bubbles did not reduce performance for the loading considered.
Article 2: Investigation of the Effects of Imposed Axial Tension on Diagonally Cracked Full-Scale CRC Deck-Girders.
Many cast-in place reinforced concrete deck-girder bridges (RCDG) remain in the national inventory and are exhibiting significant diagonal cracking. Current codes for rating and evaluation of bridges permit analysts to neglect temperature and shrinkage effects when calculating load ratings for bridge components with well distributed reinforcement. The proportions and details of 1950's vintage bridges are unlikely to be considered well detailed, and existing research regarding the performance of members subjected to axial tension is insufficient. Seven full-scale reinforced concrete specimens were constructed and tested to reflect mid-twentieth century proportions and detailing, including light shear reinforcement and straight flexural cutoff details. Specimens were loaded under combined axial tension and transverse forces. Results indicate that axial tension and flexural cutoffs reduce member capacity and stiffness and methods for predicting capacity were compared. |
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