Fatigue Investigation of the Steel-Free Bridge Deck Slabs


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Title: Fatigue Investigation of the Steel-Free Bridge Deck Slabs

Author(s): A. A. Mufti, A. H. Memon, B. Bakht, and N. Banthia

Publication: Special Publication

Volume: 206


Appears on pages(s): 61-70

Keywords: bridge deck slab, deck slab, fatigue resistance, steel-free deck slab, wheel loads

Date: 4/1/2002

During its lifetime, a bridge deck slab is subjected to a very large number of wheels of different magnitudes. By contrast, the laboratory investigation of the fatigue resistance of a bridge deck slab is usually conducted under wheel loads of constant magnitude. No current method seems to be available for establishing the equivalence between the actual wheel population on a bridge and fatigue test loads. The design codes are also not explicit in this respect. Taking the statistics of wheel loads from a Japanese survey, an upper-bound data-base is prepared for expected wheel population in Canada. There is close correspondence between the maximum wheel loads observed in Japan and Canada. The data-base is likely to be applicable to the USA as well. A fairly simple mathematical model has been developed to determine the number of passes of one wheel load so that the damage induced by it is equivalent to the damage caused by a given number of passes of another load of known magnitude. The model, which doesn not necessarily assume a linear relationship between accumulated damage and the number of passes, can be predetermined wheel load statistics. The method can also be used to formulate specific fatigue load requirements for bridge deck slabs. Two sets of tests on full-scale models of both cast-in-place and precast deck steel-free slabs have been described briefly. It is concluded that both these slabs have more fatigue strength than required to sustain the projected population of wheel loads.