Fire Truck lateral load 1

[Engin1]

Hello all,

I am working on a fire station job which requires to remove and rebuild elevated floor for fire engine.
Anyone knows how to determine the impact load for stop, brake, etc?
Any suggestions or code references are appreciated.

 

[KootK]

I'd be inclined to look into how AASHTO handles this for comparable sized trucks on bridges. If that winds up being too punitive maybe you can scale you load down based on the square of your anticipated vehicle speed relative to the speeds assumed in AASHTO.

 

[WestLevel]

You could look into using AASHTO or if in Canada the CHBDC.

It is probably overkill for you to use either as they use a vehicle stopping at highway speeds for their dynamic situation. I doubt your fire truck will be driving into the garage at 90kph and slamming on the brakes to stop. It is a controlled environment so they are probably rolling around at very little speed.

You could try and apply some dynamic analysis using a stopping distance and speed. But probably too much time.

Braking load is complex it depends on many factors. Which is why highway codes have done much testing to come up with a simple static load applied either at deck level or at the center of truck mass.

If you want a quick and dirty number for sanity, you could maybe take a small % of the truck GVW and apply it at either the deck surface or truck center of mass. But this is probably much smaller than your wind/seismic loading on the bldg.

 

[KootK]

You could come at it from the other side as well and use forklift braking forces scaled up for GVW.

 

[dvd]

Look at work/energy and stopping/starting distances. Skidding of tires on floor surface is the limit to how quickly the vehicle can stop.

 

[XR250]

I imagine with the truck and the platform having similar weight it will be different than a bridge.
But yeah, the frictional force limit of the tire seems like would be your worst static case.
80k x 0.7u = 56k
Hopefully it won't be a situation like kids do at parking garages and accelerate 10 cars up to speed and then slam on the brakes simultaneously to see how much they can make it sway.

 

[haynewp]

It's in AASHTO, I would use what is prescribed.

 

[Engin1]

Thank you all for the directions!

 

[XR250]

I'm no expert, but doesn't AASHTO say 5% live load for longitudinal forces? Does not seem like enough in this case.

 

[haynewp]

You missed the 25% of the axle weights of the design truck or design tandem part.

 

[XR250]

You are right - As I said, I ain't no expert.
But even 25% seems low in this case given the small space (assumed)
I would be using the coefficient of friction of the tires x the vehicle weight.

 

[WestLevel]

I dont have the canada code infront of me but I believe it is 180kN + 10% of the UDL portion of design vehicle.

180kN is around 30% of the design truck GVW.

Haynewp is correct the value is based on roughly 25% of the GVW of a vehicle.

 

[XR250]

For determining the impact load related to stopping, braking, etc., of a fire engine on an elevated floor, consulting the American Society of Civil Engineers (ASCE) guidelines, particularly ASCE 7, is a good start. It provides comprehensive details on live loads and dynamic forces to consider in your calculations. While focusing on structural integrity, don't overlook the integration of essential safety systems. For instance, installing a honeywell fire alarm control panel can ensure your fire station is equipped with reliable and efficient fire detection and alarm capabilities, crucial for a facility of such importance.

Chat GPT?

 

[dold]

Chat GPT?

No doubt. I don't understand why people are doing this? It's not like eng-tips has any sort of "reward" system other than LPS, and those don't have any value, so to speak. Nor any advertising, etc...

Sorry for the derailment, OP.

 

[jayrod12]

I'm betting it was just to get around someone flagging it as advertising. But didn't stop me.

 

[Lomarandil]

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