Fundamental Time Period Calculation 1

[tmgczb]

When calculating Fundamental Time Period for Platform on horizontal vessel and Foundation Pedestal, Ta, using Chapter 12.8, ASCE 7-10.
Ta=Ct*Hn^x
For Platform, Hn is height from grating to grout(top of pedestal), and seismic force acts at platform beam level.
For Pedestal, Hn is height from grout to grade, seismic force acts at half Hn.
Is it correct or not?

 

[HTURKAK]

The horizontal tank can be assumed rigid non building structure on short rigid piers .

You may calculate the base shear for the tank and anchorage with formula V=0.33*SDS*I*W assuming R=3.0 and for supporting structure (for piers ) 0.3*SDS*I*Wt

Use the formula (13.3-1) for the platform.

 

[tmgczb]

The horizontal tank can be assumed rigid non building structure on short rigid piers .

You may calculate the base shear for the tank and anchorage with formula V=0.33*SDS*I*W assuming R=3.0 and for supporting structure (for piers ) 0.3*SDS*I*Wt

Use the formula (13.3-1) for the platform.

Kindly please guide
for vessel, platform, pier
how to determine, R value and recommend a formula to calculate seismic force.

 

[HTURKAK]

-In your case , Clause 15.4.2 Rigid Nonbuilding Structures applicable to calculate seismic effects for vessel and piers ,
-The relevant formula (15.4-5) is for horizontal vessel base shear and anchorage would be calculated,
V =0.30*SDS*WIe
- You would use the same formula to get pier base shear but with using the total wt ( piers+ vessel operating wt+ platform )
- For platform connection design etc you would use expression (13.3-1)

 

[tmgczb]

-In your case , Clause 15.4.2 Rigid Nonbuilding Structures applicable to calculate seismic effects for vessel and piers ,
-The relevant formula (15.4-5) is for horizontal vessel base shear and anchorage would be calculated,
V =0.30*SDS*WIe
- You would use the same formula to get pier base shear but with using the total wt ( piers+ vessel operating wt+ platform )
- For platform connection design etc you would use expression (13.3-1)

View attachment 2742

Now vessel load is given, that is, seismic load due to vessel weight is given by vendor.
If we simply calculate base shear due to weight of platform and pier, how should we consider?
Value of R, height hn, acting point of base shear.