Browsing by Subject "Grouts"

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    Field Instrumentation of Steel Highway Bridges
    (1993-02) Leon, Roberto T.; Galambos, Theodore; Schmit, Jeffrey J.; Teng, Ai-Lien
    Two projects dealing with field instrumentation of bridges are described in this report. In the first project, a portable, rugged and multi-purpose bridge instrumentation system was developed. This was accomplished by using fourteen removable instruments and a portable data acquisition. The instrumentation included eight reusable strain sensors and six inclinometers, which allowed load distributions, stresses, and displacements to be measured in steel girder bridges. In the second part of the project the portable data acquisition system was used to measure strains near fatigue critical details in steel bridges to determine stress ranges under both controlled and random traffic. For this part of the project conventional strain gauges were also used. Overall this acquisition and modelling system worked quite well for determining strains and deflections of simply supported bridges under static loadings. A new measurement technique for finding deflections, based on slope sensors, was developed and verified. This technique can now be readily used in bridge evaluation. The system should be extended now to various types of bridges including continuous span, concrete girder, and timber bridges.
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    Retrofit of Wood Bridges
    (1993-02) Leon, Roberto T.; Beltaos, Demetrios O.; Seavey, Robert
    A retrofit scheme to widen and strengthen nail-laminated timber bridges was evaluated in this project. The scheme consists basically of laying a second, transverse layer of timbers above the existing deck, and casting a grout layer between the two wood ones to insure good force transfer. An old wood bridge was evaluated before and after it was retrofitted in order to investigate the effectiveness of the retrofit technique. In addition, three laboratory specimens, representing portions of the retrofitted bridge deck (ungrouted and grouted), were tested to investigate the strength and the effects of fatigue on the retrofitted bridge deck, and to evaluate the transverse load distribution of the original and retrofitted bridge deck. An analytical model of the retrofitted bridge deck was also developed utilizing the finite element method, the deflection and transverse distribution results from the model studies were compared favorably with the laboratory results.