Trouble with custom plate girder section

[reno1051]

I am trying to model a curved girder bridge with a composite concrete deck. I was able to layout the geometry and generate the plate mesh for the deck, but I do not know how to input a custom plate girder section. Can anyone help me out?

 

[SethGuthrie]

You could use a Tapered I shape (which does not have to be tapered) or a User table (see Help Contents - Technical Reference - Commands and Input Instructions - Member Property Specification and/or User Steel Table Specification for details.

 

[reno1051]

so apparently we dont have the current microsoft access so i cant edit the user steel tables. time to tell my boss we gotta spend some more money i guess!

 

[edward1]

I have modeled several curved girder bridges using Staadpro and it does not give the same stresses in the girder as that given by MDX software. It does give much the same shear, moment, and torsion forces but does not have the ability to get the same stresses. This is probably due to the change of the location of the neutral axis that occurs in the steel girder for composite dead load and composite live load + impact. For that reason I would recommend anyone designing steel curved girder bridges to use MDX software.

 

[reno1051]

We are using MDX to design the steel, we were using STAAD to model the deck in order to design the the thickness/rebar/etc. Does MDX design/check rebar in the deck?

 

[edward1]

I don't have the latest version of MDX but the one I have does not. If you can get a copy of VDOT's composite concrete deck slab design, that only requires a calculator and the charts provided to do the rebar design.

 

[edward1]

http://www.virginiadot.org/business/bridge-manuals.asp

Go to above web site and download Volume V Part 2-8. Click on Chapter 10 LRFD Concrete Deck Slab Design for Examples and Charts

 

[reno1051]

awesome thanks! ill have to check this out...does it account for any horizontal forces from live load on curved girder bridges?

 

[edward1]

No, these forces do not significantly affect the deck or girders. They are transferred to the bearings and then to the substructure (abutments and piers) which must be designed for these lateral forces. Braking Force(BR)is addressed by
AASHTO Article 3.6.4.