Seismic Combination

[JStructsteel]

Got some precast cladding on a building, and calculating the Fp (Sesimic force) for them. When combining with other load combinations and calculating forces on a connection, it seems I need to combine with the DL of the panel and calculate my connection force. With the weight of the panel, this can cause a zero force on my connection in some cases (light seismic). Do you still put a nominal force to give the panel some lateral resistance in the connection?

Home I explained this right

 

[HTURKAK]

You may post your calculation together with a descriptive sketch to get better responds..

My points are ;

- The seismic force for precast cladding shall be calculated as per clause 13.3 SEISMIC DEMANDS ON NONSTRUCTURAL
COMPONENTS with Formula (13.3-1)

- Upper limit for Fp is Fp =1.6SDSIpWp

- and threshold limit is Fp =0.3SDSIpWp

- Table 13.5-1 Coefficients for Architectural Components will be used
and Body of wall panel connections: ap = 1.0, Rp = 2.5 and Fasteners of connection system: ap = 1.25, Rp = 1.0


- Regarding combination with Seismic Load pls look clause 3.6 Basic Combinations with Seismic Load Effects.


6. 1.2D + Ev + Eh + L + 0.2S ⇒ U1= (1.2 + 0.2SDS)D + 1.0E

7. 0.9D − Ev + Eh ⇒ U2= (0.9 – 0.2SDS)D + 1.0E










Tim was so learned that he could name a
horse in nine languages: so ignorant that he bought a cow to ride on.
(BENJAMIN FRANKLIN )

 

[ggcdn]

I’m confused how the weight is resisting lateral load, since they are in different directions. What does the connection look like?

-JA
try [link calcs.app]Calcs.app[/url] and let me know what you think

 

[JStructsteel]

ggcdn, for the load combinations, isnt the DL a vertical load, and the Eh a horizontal load, so DL would resist overturning?

 

[driftLimiter]

You're saying that lateral load causes overturning which is resisted by dead load? Sounds like your talking about tension/compression in the anchorage elements that are at the bottom of the non-structural component, even in the case that the tension is small or close to zero, the connection still has to resist the full seismic shear?

Really we need to see a detail or at least free body diagram to be able to understand better your question.

 

[ggcdn]

JStruct, I was thinking about shears, which obviously still need to be resisted even if the overturning can be resisted by self weight. Zero uplift can happen with heavy/squat components (you should be accounting for the worst case of Ev in the calculation).

There's also the issue of applying Omega for connection design.



-JA
try [link calcs.app]Calcs.app[/url] and let me know what you think