## 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

P=16,000 lb wheel load

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

M= (P/E)*S/4 (assuming the maximum loading occurs midspan)

= ((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.

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

P=16,000 lb wheel load

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

M= (P/E)*S/4 (assuming the maximum loading occurs midspan)

= ((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

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...

1. Cantilever Moment, Wheel Load.

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

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

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

## RE: FINDING DECK BENDING MOMENTS FOR WHEEL LOADS

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