Friday, 19 October 2012

Concrete beams

One of the contributors to this blog has commented recently on research being carried out into the engineering characteristics of the concrete beams, specifically mid beam cracking. This has been evident on the busway from very early on. This picture was taken in 9 October 2011 on the section between St Ives and Fen Drayton, where the track is supported on deep piles.


1 comment:

  1. Talking with some engineering colleagues, the consensus was that the notches are "stress concentrators" and are deliberately put there to induce cracks at that location - ie on top of the mid-beam support - rather than in random other locations where they might be more damaging in the long-term.

    The Cambs busway has more cracking than others due to the long span (7.5m between supports) and we have measured the "sag" between supports to be about 0.5cm (without load). The sag will increase with the weight of a bus on top of it, but we have not measured this (yet). It is this sag which causes the vertical jolting particularly evident on the double-decker buses.

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