An Analytical Field and Model Study of M-beam Bridge Decks

  • James Kirkpatrick

    Student thesis: Doctoral ThesisDoctor of Philosophy


    An analytical field and model study of M—beam bridge decks is presented. The field study involved testing four full size bridges during construction to establish the load distribution characteristics and included both tee beam and pseudo—box types of deck. After validating the grillage method of analysis using the results of these tests, simplified graphical methods of predicting the design bending moments in beams were developed analytically. These are applicable to beams at spacings varying from 1.0 m to 2.0 m with the latter being considered for economic reasons. When these design charts are combined with a series of interactive programs for the Hewlett Packard desk top computer they provide a streamlined design procedure which reduces design time to a minimum.

    The strength of the standard 160 mm M—beam deck slab under the action of the abnormal vehicle wheel load was investigated in a series of tests on a - scale model. The main variables were the percentage of steel reinforcement and the spacing of the beams. Twenty panels were tested and they all failed in a
    punching shear mode. A detailed analysis of results has shown that the ultimate capacity of bridge slabs is greatly enhanced by compressive membrane action and the failure load is virtually independent of the percentage of transverse reinforcement. A method of predicting the ultimate capacity, in which it is assumed that bridge slabs are fully restrained laterally, is presented. This is based on a modified punching shear equation with the enhancement due to compressive membrane action being accounted for by an equivalent percentage reinforcement parameter, the actual slab reinforcement being neglected. Excellent
    correlation is achieved with the model tests and with the results of relevant tests reported in the literature.

    Finally, proposals are presented for the design of M-beam deck slabs using reduced levels of reinforcement which will provide an acceptable level of serviceability and further savings in the cost of M-beam decks over and above those achieved by increased spacing of the beams.
    Date of Award1982
    Original languageEnglish
    Awarding Institution
    • Queen's University Belfast
    SupervisorLong A.E. (Supervisor)

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