Strain Rate Caused by a Vehicle Moving on a Bridge

[Logan82]

Hi,

I have a road bridge with a simply supported beam. What is the equation for the strain rate of the fibre in tension in the middle of the span caused by a vehicle crossing the bridge?

An easy way to determine the strain rate would have been to use the formula developed in this thread

https://www.eng-tips.com/viewthread.cfm?qid=497472,

where the formula is: ε/t = ((V)*12*y) / (L^2), where V = velocity, y = distance betweeen neutral axis and fiber in tension, L is the length of the beam. But I am looking for a less conservative formula.

 

[GregLocock]

You have mistranscribed the equation. All you need is to work out the reaction force at each end as a function of V*t, hence calculate the bending moment at the centre of the span, and then use M/I=sigma/y, and E=sigma/strain.

Cheers

Greg Locock


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