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Integral Abutment-Pile Cap Moment and Shear Diagram

Lin Engineer — Tue, 16 Mar 2021 19:34:12 GMT

I was modeling a prestressed girder bridge with integral abutment. Analysis option I was using Integral Abutment.

For abutment pile cap, one HP pile was put right under each girder location. However, when I plot moment and shear diagram of the cap under DC1 (which is applied right at the pile location), they didn't look right.

Attached are the model pictures and moment diagrams.

Could someone explain why the moment and shear diagram under DC1 look like these?

How to model a tapered bridge in a curved portion in Leap Steel?

Lin Engineer — Mon, 22 Feb 2021 14:13:33 GMT

The PGL of the bridge is a straight line followed by a horizontal curve. The curve portion starts at the middle of a span. Bridge deck is tapered for the straight line portion and constant for the curve portion.

I tried the three different ways (Independent, concentric to align., custom beam path) in Member Group of Leap Steel to model the girder layout, but couldn't find a way to model it exactly as the plan shows.

Could you let me know how to solve this problem?

Thank you.

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Tue, 28 Jul 2020 03:04:15 GMT

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Shear and Torsion Design for RC Pier

Lin Engineer — Tue, 28 Jul 2020 13:02:41 GMT

Hello,

I have a question regarding shear and torsion design in RC Pier.

In RC Pier, under Analysis---AD Parameters---Shear and Torsion Calculation, there is option which says "Shear force is equally distributed among stirrups".

I read the Help Document, and find it hard to understand. It says "Option of Shear force is equally distributed among stirrups, and the default is unchecked. However, when this option is checked, it assumes the equal distribution of shear force among all legs at failure, where the demand of transverse reinforcement is based on the controlling case of exterior legs." Can someone help me explain what it means?

I did an example to see what this option does, see the screen shots. Basically one is check shear force is equally distributed among stirrups and the other is not.

I compared the shear design result at a specific location between the two method, see below.

According to the comparison I noticed that when you check the shear force is equally distributed among stirrups , Av/s is calculated as the sum of Avs/s and quantity of Ats/s times the number of legs. When unchecked, Av/s is calculated as the sum of Avs/s and quantity of Ats/s times two.

But I also noticed phi*Vn is different, because Vs is different. I can't understand why. Can someone explain this for me?

Thanks.