# Simplified LRFD Bridge Design 6th Ed. By Kim VS FHWA Bridge Examples



## zas07001 (Jun 28, 2018)

I'm trying to prepare for the SE Bridge exam and started working through the 'Simplified LRFD Bridge Design' book for example problems. In the first design example the author finds all the interior and exterior girders and determines the longitudinal moments. For dead load moments equal shares of the total are applied to each girder. 

Then he considers the dead load transversely as a continuous beam across the girders to recalculate maximum moments on interior and exterior girders.  

The exterior beam under consideration in the transverse slab-continuous-beam analysis has the maximum moment which he carries against distribution factors for final design.

I'm wondering if its typical to do the second transverse analysis, and if it wouldn't be a torsional force. 
In the FHWA bridge load calculation examples I don't see that transverse second continuous beam analysis for maximum moments.


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## ChrisRoth (Oct 4, 2020)

That's a really good question, the answer of which I'd be very glad to hear, too.


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## ChrisRoth (Oct 7, 2020)

ChrisRoth said:


> That's a really good question, the answer of which I'd be very glad to hear, too. Continuous structures such as beams, rods, cables, and plates can be modeled by discrete mass and stiffness parameters and analyzed as multi-degree of freedom systems, but such a model is not sufficiently accurate for most purposes. Furthermore, mass and elasticity cannot always be separated in models of real systems. Thus mass and elasticity have to be considered as distributed or continuous parameters. For the analysis of structures with distributed mass and elasticity it is  necessary to assume a homogeneous, isotropic material that follows Hooke’s law, similar to the material from which is made the custom splashback for you and your kitchen when you want to customize your kitchen.


That's pretty much it.


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