Live Load Deflection

[jike]

Should I calculate the deflection based upon the full live load or the reduced live load when comparing it to L/360?

In this particular case, my reduced live load is 64% of the full specified live load. It is a hotel beam supporting the precast at the corridor.

 

[CESSNA1]

JIKE: What is the reduced live load? Building and City codes usually specify the design/stress/deflection criteria to be used. In a public structure, I would say be conservative.

Regards
Dave

 

[MotorCity]

jike,

Be consistent with your design approach in sizing the beam. If you used the reduced live load to design the beam, use the reduced live load for serviceablity. The purpose of the reduction is to account for the fact that the structure may never actually see the full live load. In other words, compare apples to apples.

If you are comfortable from a design standpoint that the beam will not fail using the reduced live load, the same should apply for the deflection.

Good luck.

 

[JAE]

Reduced live load is the one to use..this is the true live load applied to the member taking into account the statistical nature of the live load on large areas.

 

[Lutfi]

I must agree with JAE.

Lutfi

http://www.cdeco.com

 

[wyanko]

I really try not to use live load reduction on any flatwork members (beams, slabs) mainly due to future lawsuit implications (wall cracking and window damage). I agree with the statistical reasoning for using reduced live load, but just can't bring myself to use them for flatwork knowing that we (structural engineers) are the first to get sued by a condo association or building occupant when cracks form.

 

[J1D]

Jike
I support the viewpoint to be consistent. You size members with both strength and serviceability considerations. If the tributary loading area of the beam is larger than, say, 80 sq.m, the reduction factor should be used. The 1/360 limit was setup for damages like cracks, etc.

 

[haynewp]

I don't understand why you would design for full live load for deflection but a reduced live load for strength. If the beam could fail under full live what would it matter what the deflection is? So I also think you should be consistent with whichever you choose.