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  • 1.  Pipe Support Seismic Design Loads for Pipes Immersed in Water-Filled Tanks

    Posted 09-01-2023 11:12 AM

    I am looking for some clarification regarding the seismic load calculation for a pipe support anchorage design.  The scenario is a pipe submerged in a water-filled concrete basin which is located in a high seismic region and experiences sloshing.  In such a scenario, I understand that the pipe and its supports should be acted upon by the following 3 seismic loads:

    1. The 1st seismic load acting on the pipe and its supports is the seismic response of the pipe itself.  This load is calculated per Chapter 13 of ASCE 7-16, Table 13.6-1 of which provides R and Ω0 factors for different piping systems. 
    2. The 2nd seismic load acting on the pipe is the impulsive load of water sloshing.  The impulsive load is calculated based on Chapter 15 of ASCE 7-16, Table 15.4-2 of which provides R and Ω0 factors for different tanks.
    3. The 3rd seismic load acting on the pipe is the convective load of water sloshing.  The convective load is calculated based on Chapter 15 of ASCE 7-16 with an R=1.5 (which is implicitly included in Eqn. 15.7-6).  I have not found an Ω0 factor in ASCE 7-16 for the convective loads (if there is one and I have missed it, I would appreciate it if you could point me to it for my information).

    Specifically for the design of the pipe support anchorage: the seismic load from the seismic response of the pipe itself (Seismic Load #1 listed above) needs to be multiplied by the Ω0 factor provided by Table 13.6-1;  do the impulsive and convective loads on the pipe need to be multiplied by an Ω0 factor too?  If yes, which Ω0 factor would be appropriate in that case?

    Thanks,

    Kostis Oikonomou


    #ASCE7-16
    #Seismic
    #LoadCombinations

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    Konstantinos Oikonomou Ph.D., P.E., M.ASCE
    Senior Engineer I
    Mesa AZ
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  • 2.  RE: Pipe Support Seismic Design Loads for Pipes Immersed in Water-Filled Tanks

    Posted 09-05-2023 10:19 AM

    The only load that need be considered for a pipe submerged within a basin i the inertial seismic load on teh pipe (and its contents) alone.  Convective and impulsive loads, important to design of tank shells are not applicable to pipes within the basin.  This is becasue the pipe is surrounded by fluid and will see equal pressure on all sides and no unbalanced force.  Tank walls see these forces because they restrain the contained fluid.

    There is no Omega-0 factor associated with convecctive loads.  This is because Omega-0 is a function of the structure and its ductiltiy and ovestrength.  Convective loads are not subject to these phenomena.



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    Ronald Hamburger, SE
    Consulting Principal
    Simpson Gumpertz & Heger
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    Original Message


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