Lateral force caused by gravity load
Lateral force caused by gravity load
(OP)
Is there any reference to indicate how much percentage lateral force does gravity load cause? For example, if there is a freestanding deck to be designed for gravity load, we also have to design it for lateral movement/ load caused by gravity load. How do we calculate the lateral load in this case? Wind load and seismic is not important in this case. I would appreciate your inputs.






RE: Lateral force caused by gravity load
The new Eurocodes combine both the wind load and 0.5% Equivalent Horizontal Force (EHF). This will result in higher loading on lateral stability bracing members;
For free standing platform structures and mezzanines inside a building (i.e. where wind loads are low) 2.5% of the gravity loads has been historically used as the Notional Horizontal Force; and is one I would suggest in this case.... in additional to other design load cases and local code requirements etc.
RE: Lateral force caused by gravity load
RE: Lateral force caused by gravity load
RE: Lateral force caused by gravity load
ASCE 7-10
1.4.3 Lateral Forces
Each structure shall be analyzed for the effects of static lateral forces applied independently in each of two orthogonal directions. In each direction, the static lateral forces at all levels shall be applied simultaneously. For purposes of analysis, the force at each level shall be determined using Eq. 1.4-1 as follows:
Fx = 0.01 Wx (1.4-1)
where
Fx = the design lateral force applied at story x and
Wx = the portion of the total dead load of the structure,
D, located or assigned to level x.
Structures explicitly designed for stability, including second-order effects, shall be deemed to comply with the requirements of this section.
RE: Lateral force caused by gravity load
RE: Lateral force caused by gravity load
1. For purely gravity loads, it depends on the out-of-plumbness (and out-of-straightness), which depends on the tolerance of the trade you're dealing with. For example, steel constructed according to the AISC Code of Standard Practice is held to L/500, so the maximum out-of-plumbness force is 0.2%. Note that this value is used when designing steel by the direct analysis method. Values can also be approximated for concrete and other trades.
2. For wind, most jurisdictions have adopted some form of IBC, which requires a 20psf net pressure laterally.
3. Earthquake requirements have been explained thoroughly above.
Hope that helps.
Structural Design Engineer
New York, NY
RE: Lateral force caused by gravity load
There is an absolute minimum, and I don't have the code in front of me, but I believe ASCE 7 prescribes 10 psf as an absolute minimum. Again, the minimum rarely applies.
RE: Lateral force caused by gravity load
Structural Design Engineer
New York, NY