XBRate shear capacity and LR factors

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hz36
XBRate shear capacity and LR factors

Hi Rick,

This is Hao Zhuang from Jacobs. I have 2 questions about a model I'm building in XBRate for a load rating task. It's an intermediate pier with two columns and 5 girder lines. I'm using XBRate Version 4.1.4 x64.

1.
I was verifying shear capacity calculations and saw different values for d_e 's along the crossbeam as M_u varies. I was guessing that XBRate does a strain compatibility analysis using the flexural demand, in which it takes account of capacity provided by concrete located in tensile zone, and then it calculates the distance from compression side to centroid of resultant tensile force. Can you confirm that?

2.
I noticed that the LR factors in the report for Inventory Truck Shear are slightly off compared to the results I got by plugging in the values to the equation shown above the table. For the controlling case, the report shows RF = 1.13 compared to RF = 1.04 I got. Not sure what caused the difference. I assumed that the variable V_SH in the table is the same as V_SR in the table.

My model is attached. Because the website doesn't allow me to upload XBRate file, I changed its extension to .txt. You may want to change it back to .xbl to open in the program.

Thanks for your time put into this!

Hao Zhuang

Rick Brice
XBRate shear capacity and LR factors

You are basically correct regarding de. Moment capacity is computed using the equivalent rectangular stress block method. However, all longitudinal reinforcement is used in the calculation. The depth "c" is iterated until equilibrium is achieved. The strain in the longitudinal may or may not be beyond yield. This is taken into account in the analysis. de is the distance from the extreme compression force to the resultant tension force.

Regarding the shear rating factor. This is a bug. The software is computing the numerator of the rating equation as Vr - DC + DW. It should be Vr - DC - DW. We are putting together a new release of the BridgeLink suite this week. I'll get this problem corrected and in the release. Thanks for bringing this to our attention.

Rick Brice
XBRate shear capacity and LR factors

BridgeLink 4.1.5 has been posted. It fixes this issue.

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