non-structural appendage - oshpdsiesmic requirements

huangyhg

non-structural appendage - oshpd/siesmic requirements?
hello all,
i'm working on the design of some equipement to go into hospital applications around the country, including ca (osphd).  the equipment is going to be mounted to interior walls and cantiliver out into the room, it may be counted as essencial equipment.  the question is how do i determine the loading i need to design my bracketry, supports and such, what loads beyond the mass and performce loads i am working toward should i start my analysis at?
step 1)
i've spent a day or two digging through cbc as much as possiable (i usually do not work with civil codes, mostly well defined company internal test and performce specifications, so this is new territory), and came up with the following results:
1.  2001 california building code: section 1632 鈥?lateral force on elements of structures, nonstructural components and equipment supported by structures.  
(1632.2) design for total lateral force.
(32-1) fp = 4.0 ca ip wp 鈥?total lateral force
ca = seismic coefficient, as set forth in table 16-q
table 16-q, with soil profile - sd & seismic zone factor, z 鈥?0.4 => ca => 0.44 na.
table 16-s, with seismic source type a, ,= 2 km distance => na (worst case) = 1.5
then ca = 0.44 x 1.5 = 0.66
ip 鈥?table 16-k 鈥?1. essential facilities => ip = 1.50
wp 鈥?same as 2.1.1.3 (assumed weight of unit 135.2 lbf)
fp = 4.0 ca ip wp = 4.0 x .66 x 1.5 x 135.2 lbf = 535.4 lbf
2.  or i can use an "alternate method" as follows:
(32-2) alternative method:  
fp = (ap ca ip)/rp[1 + 3 hx/hr] wp
where: fp >= 0.7  ca ip wp <= 4.0 ca ip wp
ap - table 16-o (2.a) nonstructural components - ap = 2.5
rp 鈥?table 16-o (2.a) nonstructural components - rp = 3.0
hx 鈥?component elevation w.r.t grade (assumed 94鈥?/ 10 story building)
hr 鈥?structure roof elevation w.r.t grade (assumed 100鈥?/ 10 story building)
fp = (2.5)(.66)(1.5)/3.0[1 + 3 (94/100)] (135.2) = 426 lbf
3. (don't have faith, way lower load comes out, i think this is for signage and the like)
2001 california building standards administrative code (part 1, title 24, c.c.r.): administrative regulations for the office of statewide health planning and development (oshpd) chapter 6: seismic evaluation procedures for hospital buildings.
(2.4.6) demand on parts and portions of the building: 鈥渆quipment supported by a structure and their attachments, as identified in the building evaluation procedures, shall be evaluated to verify that they are capable of resisting the seismic forces specified below.鈥?br>total lateral seismic force fp = 0.67 ( av cc wc ).
where:
av = 0.40 assume any location therefore, maximum from figure 2.1a 鈥?effective peak acceleration coefficient (aa) and effective peak velocity coefficient (av) for california.
cc = 2.4 鈥?table 2.4.6 鈥?seismic coefficient, cc nonstructural components; exterior and interior ornamentations and appendages.
wc = 135.2 lbf weight of the element or component.
then: fp = (0.67)(.4)(2.4)(135.2) = 87 lbf
questions:
how do i used these results in my anlysis of my end of the system, ie all the structural componentry outside of the actual mounting to the wall?  is this to be assumed an additional vertical load on my joints as applied at the wall?  (asked anouther way) in my cantilever system i have a moment and shear load to design too, where do i apply this additional loading i am finding in the cbc?
i am working an access to the asce 7-02 section 9.14 as refered to from icc 2003 international build code, section 1622, but was wondering if anyone out here is familure with this code thinks it will be more or less conservative than the cbc loadings disscussed above?
once i get my loading figured out can i get pointed in a good direction to find the relationships that need to be satisfided that the structure of the building can be validated too?  my first intuition is that this unit will be required to be supported accros two "studs" (either metal or wood) and would like to find if supplying a mounting solution for oshpd installations that did not required a tear down and rebuild of the walls interior could be utilized?  in the case of cement or masonary walls is simply specify a fastening system that has a health safty factor sufficient?
it's a lot to chew on, but, i'm just a m.e. and just got tossed into a civil problem, and have no real resources internally to get some guidance.
thanks,
erik
check out our whitepaper library.
for oshpd projects, follow the sections designated with the letter "a".  for example 1632a.2.
for determining a lateral coefficient for design, the equation (32a-1) shall be taken as the maximum, 0.7caipwp from equation (32a-3) shall be taken as minimum.  in most cases, you will find that equation (32a-2) will be the governing case.  in your case, 32a-2 controls but using the result from 32a-1 will still be ok since it is slightly conservative.  note that these forces are ultimate level, not working stress level.  the forces obtained from these equations are used for design of "fasteners" to the element supporting the equipment.
the design of supporting elements shall follow the similar procedure utilizing the appropriate factors on table 16a-o, however, they need not be designed for "amplified" design forces due to footnote 14 of table 16a-o, shallow anchor conditions, etc.
as of now, the state of california has not adopted any ibc's, therefore, oshpd may not review and design based on 2003 ibc.
typically in california, the design of the equipment is performed by the structural engineer of record (provided that appropriate design fees are paid accordingly).  the detail of anchorage can either be shown on the mechanical or structural drawings.
hopefully this helps.
thanks,
still a little confused, i ran downstairs and grabed section 16a (equations the same, table values the same), exact same result?
what i am a little confused on still is... so i design (or specify) a fastening system that can hold 535.4 lbf on to the wall.  
but wait, we haven't even considered the loading situation, this item does not have it's cg right on the wall it is cantileved out from the wall.  let's say i have the cg (135 lbf) out about 30" from the wall, that's produces a momement of 3750 in-lbf.  for simplicity if i used a two fastener system to hold a couple to support this moment at 6" apart => 3750 in-lbf / 6" = 625 lbf per fastener (top in tension) alone to just support the moment.  would i then "add on" the 535.4 lbf calcuated from the code to result in a 1160 lbf total fastener load?
the end goal is to develop a mounting system used with the proper installation requirements would be oshpd approved for all ca locations.  we will be hiring licenced ca p.e. to verify the design, but, i would like to at least provide a solution with enough sufficient calculation to develop something that will not be out of the ballpark.  
phase one of that is finding some loadings that i can expect to have to test to at the mount, hence i can start working back through the rest of the mechanism and especially at areas around the mounting, and start detailed structural analaysis there.
thanks,
erik
it sounds like you are trying to obtain a pre-approval of an equipment anchorage with an oshpd opa number.  this is one way to market your system, once the design professionals are aware of your pre-approved status.
going back to your follow-up question, lets ignore the math for simplicity.  first, break down the various "types" of loading and superimpose them later.
considering a small wall mounted equipment with one screw at each corner to a backing plate.
first is the moment caused by eccentricity.  upper two fasteners will see tension force.
next, consider the seismic force on the unit outwards from the wall.  this results in tension on all four screws.
then, consider upwards acceleration on the equipment resulting in an additional vertical force (ev portion of section 1630a.1.1.) causing additional tension in the upper two screws.
combine all these for a maximum tension force in a screw.  also obtain shear per screw from each load case.  then design the screw to take the combined tension/shear.
to make things more complicated, change the seismic force direction parallel to the wall (not perpendicular) and perform the same exercise.
in your case, providing more fasteners will be of huge benefit to you and your customers at an insignificant cost increase.  the design of the wall and/or support frame is usually done by the engineer of record.
double thanks whyun.
i'm starting to see the picture now, and as i was working through some related work i started comming to the same conclusions.
i can set up a numerical model now to find the loadings in the fasteners, likely will do a tksolver model to work it out for different fastening patterns.
also, i read in the specification that no considerations are to be allowed for frictional effects on prestressed joints, so this will be done as if the fasteners were not tight but, just there, correct?
i am glad little knowledge i have was of some use to you.  i have no idea what a tksolver is.
not being an installer, i don't know whether the fasteners are tightened in the field or just "snug".  typically for wall mounted equipment connected to sheet metal, they use screws and i'm sure aisi specifications have installation requirements.