×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

#### Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

# FINDING DECK BENDING MOMENTS FOR WHEEL LOADS

## FINDING DECK BENDING MOMENTS FOR WHEEL LOADS

(OP)
(I posted a similar question in AASHTO forum)

Reality check is requested by engineer who doesn't often stray into the AASHTO code.

I want to find the design live load bending moment in my rc deck with main reinforcing perpendicular to traffic. Following 3.24.3.1:

S=10 ft span between longitudinal members
M = ((10ft+2)/32)*16,000lb = 6,000ft-lb per unit strip of slab, and I will choose my transverse flexural reinforcing based on that force.

or, if my reinforcing is parallel to traffic, following 3.24.3.2:

S= 10ft between transverse members
P= 16000lb
E= 4+0.06*10 = 4.6ft
= ((16000/4.6)*10)/4 =8696ft-lb per unit strip and that is what i will use to choose my flexural rebar.

Am I doing this right? Many thanks in advance.

### RE: FINDING DECK BENDING MOMENTS FOR WHEEL LOADS

If you have a typical slab and girder bridge where the girders are the only support for the slab, the main reinforcing will always be perpendicular to the traffic.

You will often find that the cantilever moment controls rather than the interior (between girders) moment.  However, at a girder spacing of 10 feet it is a good idea to check the interior.

Generally, you must check...

2.  Cantilever Moment, Collision Load (impact into the barrier).
3.  Interior Negative Moment.
4.  Interior Positive Moment.

Usually, the only time you have reinforcing parallel to traffic would be the case for short spans where the slab is supported on floorbeams.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

### RE: FINDING DECK BENDING MOMENTS FOR WHEEL LOADS

(OP)
Qshake, thanks for the reply. I've read many of your's in the past and you are a great resource.

I really could use someone specifically addressing the code articles I sited, in order to be able to get through a particular problem tomorrow. Any advice out there?

### RE: FINDING DECK BENDING MOMENTS FOR WHEEL LOADS

No your not doing it right.  Span will not equal the clear span in most instances.  Also your wheel load needs to include impact (assuming service load design).

Everything else looks right, just plug and chug, it's empirical.

### RE: FINDING DECK BENDING MOMENTS FOR WHEEL LOADS

(OP)
"Everything else looks right, just plug and chug, it's empirical."

Thanks Koodi, that was the answer needed (I did not want to complicate my question with issues of determining span, load combinations, etc. Those are all clearly given in the code and not the problem. I think it's hard for engineers to assume anyone knows what they're doing until shown. I never do myself).

thanks again,

clevegar

#### Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

#### Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!