concrete slab on grade driveway truck loading rating 2

[m1208]

This is a 4” thick concrete slab on grade residential driveway of the garage. I have large cracks in the driveway slab. I am looking for sample calculation to use to determine if the delivery truck driving into the driveway had caused the cracks in the slab. I have the weight of the truck. There are no steel rebar in the slab .

There is a soils report for the property and calls out of 1000 PSF soil bearing pressure. The 1000 PSF soil bearing pressure applies to the house and the driveway. With this information, are there any sample calculation that I can use?

 

[WARose]

ACI 360 has a variety of charts.

 

[oldestguy]

Who ever built a driveway slab should have known that delivery and other trucks are likely. I'd sue the contractor or who ever was responsible for selecting 4". You can't expect a delivery or moving van truck won't use your driveway. Was there a sign saying "No trucks"?" A 4" slab is usually reserved for walkways.

 

[JAE]

There’s no way to calculate it accurately. The difficulty is determining the in-place soil subgrade stiffness. A 4” slab can take enormous wheel loads if it rests on highly stiff material.

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[WARose]

JAE hit the nail on the head: unless you have geotechnical info.....you are not going to be able to make an argument on this (if this is indeed headed towards litigation).

 

[m1208]

There is a soils report for the property and calls out of 1000 PSF soil bearing pressure. The 1000 PSF soil bearing pressure applies to the house and the driveway.

 

[dik]

Right on JAE... I wouldn't bet the farm on winning the lawsuit. I'm surprised they didn't design the slab to accommodate 'garbage' trucks... they have some of the greatest wheel loadings of vehicles. Do you have a local code that stipulates minimum slab thicknesses?

Dik

 

[m1208]

Yes the local code calls out for 4" thick unreinforced slab, 2500 PSI

 

[m1208]

JAE:
Assuming soil subgrade is stiff, are there any sample calculation that I can follow?

 

[dik]

More difficult in court... contractor not expected to know the design ramifications... Good Luck.

I seem to recall that Alex Toma...(never could spell his last name) has a spreadsheet for SOG... search for slab on grade Ales xls... and it should pop up.

Dik

 

[BridgeSmith]

You will need more detailed information on the stiffness of the soil to assess the capacity of the slab. The 1000psf bearing capacity has to be calculated on the assumption of some amount of settlement. Unless that 1000psf is for a fraction of an inch of settlement (unlikely), an unreinforced 4" slab would likely crack under the load of large pickup, and break completely under a heavily loaded delivery van.

 

[hokie66]

Why do you think the cracks are due to truck loading? They could be restraint shrinkage cracks. How far apart are the cracks? Any photos to share?

 

[MotorCity]

It is your responsibility, not the driver's, to know any capacity restrictions of your driveway and enforce them accordingly. If you did advise the driver and he/she drove on the driveway anyway that's a different story. If you are trying to build up a legal case, i'd say it would be difficult.

If you are gathering data to run numbers for yourself, you would have to core and test the driveway to obtain the actual concrete strength and test soil samples to determine the bearing capacity and subgrade modulus.

OG - 4" thick (if you're lucky)driveways are the norm in this neck of the woods.

 

[XR250]

1000 psf is pretty darn low bearing capacity so i would not be surprised things cracked. Isn't there something in the IRC about 1500 psf minimum for soil?

 

[bridgebuster]

Attached is the spreadsheet that dik mentioned.

In NYC, residential driveways are a minimum of 7" thick. I would imagine it was intended to compensate for not having stiff soil.

 

[JoelTXCive]

Prior to being an engineer, I was a residential builder for many years. For my first few years, I worked for a large homebuilder in Texas that closed 2000+ homes a year.

The driveways were considered 'flatwork' concrete. Unless required by a specific municipality, all the driveways were 4" thick with NO reinforcement. There wasn't even any real compaction or soil prep under the driveways. The tractor guy would just scrape 2" of vegetation off and clean up the grade.

Sometimes the bottom 10ft would be reinforced where the driveway would tie into a county road, but that was it.

In our buyer walks, we would tell homeowners not to park moving trucks on the driveway.

One of the many reasons I got out of that business...

 

[dik]

Attached is the spreadsheet that dik mentioned.

Thanks, Dik

 

[JAE]

Assuming soil subgrade is stiff, are there any sample calculation that I can follow?

ACI has a publication: ACI

PCA has a slab-on-grade publication that covers this for wheel loads and rack post/column loads: PCA Concrete Floors on Ground

There is also software out there - do an online search for Concrete Slabs on Grade or Floors on Ground, etc.


Check out Eng-Tips Forum's Policies here:
faq731-376

 

[WARose]

Something else to remember is that the edge/corner condition almost always controls for this. Be sure you've checked that.