ABSTRACT
ABSTRACT: A visually distressed vintage conventionally reinforced concrete deck girder (RCDG) bridge was identified by routine inspection. Subsequent investigation showed the distress was due to a poorly detailed splice location for the flexural steel and the ratings determined the girders to be significantly understrength. The bridge was shored to allow it to remain in service until it could be strengthened. The bridge was strengthened using near-surface mounted (NSM) titanium alloy bars. Round titanium alloy bars with a unique deformation pattern were specially developed for this application. Experimental research was conducted to evaluate the behavior of the as-built poorly detailed girder and then to evaluate the performance of the strengthening approach. Realistic full-scale girder specimens were constructed, instrumented, and tested to failure. The specimens mimicked the in situ materials, loading interactions, and geometry. The as-built strength was verified to be very low and the distress observed in the tests priot to failure and were similar to those observed in the field. Two specimens were strengthened with NSM titanium alloy bars and exhibited much higher strength and deformation capacity. The observed strengths of the specimens with NSM titanium enable the bridge to carry legal and permit loads without restriction. The member strength was shown to be well predicted using the analysis program Response 2000 and was conservatively predicted using AASHTO-LRFD design methods. The approach and materials were applied to the actual bridge, and the bridge was restored to service without the need for shoring or posting. The first ever application of titanium alloy bars to a reinforced concrete bridge was completed at a 30% cost savings compared to alternatives.
