KINETICS Pipe & Duct Seismic Application Manual

Transcription

1 KINETIC pe & Duct esmc Applcton Mnul CODE BAED EIMIC DEIGN FORCE 5.1 Introducton: The code bsed horzontl sesmc force requrements for ppe nd duct re ether clculted by the sesmc restrnt mnufcturer s prt of the selecton nd certfcton process, or vlble through convenent nd esy method provded by the mnufcturer. Knetcs Nose Control provdes onlne tools tht wll clculte the horzontl sesmc force nd mke recommendtons for the proper sesmc restrnts for the ppe or duct n queston. These tools wll be dscussed n the next secton. Ths secton s n nformtonl secton. It wll dscuss the code bsed horzontl sesmc force demnd equtons nd the vrbles tht go nto them. Ths dscusson wll provde deeper understndng for the desgner responsble for selectng the sesmc restrnts for ppe or duct nd the nture of the sesmc forces nd the fctors tht ffect them. 5.2 Code Bsed Horzontl esmc Desgn Force ACE/EI 7-05 ecton 13.3: The sesmc force s mss, or weght, bsed force, nd s such s ppled to the ppe or duct t ts center of grvty, whch s usully t the center of the cross-secton of the ppe or duct. Keep n mnd tht the erthquke ground moton moves the bse of the buldng frst. Then the moton of the buldng wll ccelerte the ppe or duct through the hngers. The horzontl sesmc force ctng on ppe or duct wll be determned n ccordnce wth Equton of ACE/EI F 0.4 = R I W z h Equton 5-1 ACE/EI 7-05 defnes nd upper nd lower bound for the horzontl force tht s to be ppled to the center of grvty of ppe or duct. The horzontl sesmc force ctng on ppe or duct s not requred to be greter thn; AGE 1 of 7 ECTION 5.0

2 KINETIC pe & Duct esmc Applcton Mnul F = 1. 6 I W Equton 5-2 And the horzontl sesmc force ctng on ppe or duct s not to be less thn; F = 0. 3 I W Equton 5-3 Where: F = the desgn horzontl sesmc force ctng on ppe or duct ctng t ts center of grvty. = the short perod desgn spectrl ccelerton. =the component mplfcton fctor. Ths fctor s mesure of how close to the nturl perod of the buldng the nturl perod of the component s expected s expected to be. Typclly ths wll vry from 1.0 to 2.5, nd s specfed by component type n ACE/EI 7-05 nd lsted n Tble 5-3. I = the component mportnce fctor whch be ether 1.0 or 1.5. W = the opertng weght of the ppe or duct tht s beng restrned. R = the response modfcton fctor whch usully wll vry from 1.0 to Ths fctor s mesure of the blty of the component nd ts ttchments to the structure to bsorb energy. It s relly mesure of how ductle or brttle the component nd ts ttchments re. The vlues re specfed by component type n ACE 7-05 nd lsted n Tble 5-3. z = the structurl ttchment mountng heght of the ppe or duct hnger n the buldng reltve to the grde lne of the buldng. h= the verge heght of the buldng roof s mesured from the grde lne of the buldng. The 0.4 fctor ws ntroduced s modfer for AGE 2 of 7 ECTION 5.0 s recognton tht the ME components nsde the buldng would rect more strongly to the long perod erthquke ground moton thn to the short perod moton. The 0.4 fctor brngs the desgn level ccelerton for the ME components more n lne wth the desgn level ccelerton tht s ppled to the buldng structure tself.

3 KINETIC pe & Duct esmc Applcton Mnul The weght of the ppe or duct beng restrned wll depend on the sesmc restrnt spcng. For the trnsverse sesmc restrnts, the weght of the ppe or duct beng restrned s; W Equton 5-4 = T w For the longtudnl sesmc restrnts, the weght of the ppe or duct beng restrned s; W Equton 5-5 = L w Where: L = the longtudnl sesmc restrnt spcng. T = the trnsverse sesmc restrnt spcng. w = the sum of the weghts of ll of the ndvdul ppes or ducts beng restrned over dstnce equl to the restrnt spcng. w = the weght per foot of n ndvdul ppe or duct over the dstnce equl to the restrnt spcng. z The term n Equton 5-1 s recognton of the fct tht ll buldngs nd structures h become more flexble s they ncrese n heght. Tht s they re much stffer t the foundton level thn the roof. nce the ground moton from n erthquke enters the buldng structure t the foundton level, the ctul ccelertons mprted to the ppe nd duct wll be greter the hgher n the buldng they re ttched. A buldng my be lkened to vertclly mounted cntlever bem tht s beng shken by the bottom. It s vbrtng system tht wll hve certn nturl perod tht s, n generl fshon, bsed on ts mss nd stffness. If the nturl perod of the buldng s t, or close too, the erthquke perod, the moton of the buldng could be extreme. Ths ws the cse n the Mexco Cty erthquke of eptember 19, AGE 3 of 7 ECTION 5.0

4 KINETIC pe & Duct esmc Applcton Mnul The ppe or duct, long wth ts hngers, wll lso form vbrtng system wth nturl perod tht depends on the mss of the ppe or duct nd the stffness of the hngers. The component mplfcton fctor ( ) s mesure of how closely the nturl perod of the ppe or duct mtches the nturl perod of the buldng. For = 1. 0 the nturl perods re not close, whle for p = 2.5 the nturl perod of the ppe or duct s very close to tht of the buldng. The component response modfcton fctor( R )s mesure of how much energy the ppe or duct long wth the hnger nd ttchments cn bsorb wthout sustnng crpplng dmge. A common term used throughout the HVAC ndustry s frglty. As the term mples, t s concerned wth how frgle component mght be. Tht s, how esly component my be dmged, nd to wht degree t mght be dmged by specfed lod nd lodng rte. The R fctor, then, s consdered to be n ndctor of how frgle ppe or duct mght be. For R = 1. 0 the component s extremely frgle. For R = 12. 0, on the other hnd, would be component tht s very robust. The vlues for nd R re ssgned by the ACE 7 commttee bsed on ccumulted experence throughout the buldng ndustry. The evoluton of these fctors my be trced through Tbles 5-1; 5-2, nd 5-3 whch represent 2000 IBC/ACE 7-98, 2003 IBC/ACE 7-02, nd 2006/2009 IBC/ACE 7-05 respectvely. The consensus of opnon ppers to be tht ppng nd ductwork, n generl, cn bsorb more energy thn hd orgnlly been thought. Indeed ppng nd ductwork tht s constructed of hghly deformble mterls wth jonts mde wth weldng or brzng cn bsorb gret del of energy wthout sustnng enough dmge to cuse loss of servce. These fcts re reflected by the lrger vlues for R whch wll led to the use of fewer nd smller sesmc restrnts on run or ppe or duct. AGE 4 of 7 ECTION 5.0

5 KINETIC pe & Duct esmc Applcton Mnul Tble 5-1; Component Amplfcton nd Response Modfcton Fctors for 2000 IBC (ACE 7-98) Component R png ystems Hgh deformblty elements nd ttchments (welded steel ppe & brzed copper ppe) Lmted deformblty elements nd ttchments (steel ppe wth screwed connectons, no hub connectons, nd Vctulc type connectons). Low deformblty elements nd ttchments (ron ppe wth screwed connectons, nd glss lned ppe) HVAC ystems Vbrton solted Non-vbrton solted Mounted-n-lne wth ductwork Other Tble 5-2; Component Amplfcton nd Response Modfcton Fctors for 2003 IBC (ACE 7-02) Component R png ystems Hgh deformblty elements nd ttchments (welded steel ppe & brzed copper ppe) Lmted deformblty elements nd ttchments (steel ppe wth screwed connectons, no hub connectons, nd Vctulc type connectons). Low deformblty elements nd ttchments (ron ppe wth screwed connectons, nd glss lned ppe) HVAC ystems Vbrton solted Non-vbrton solted Mounted-n-lne wth ductwork Other AGE 5 of 7 ECTION 5.0

6 KINETIC pe & Duct esmc Applcton Mnul Tble 5-3; Component Amplfcton nd Response Modfcton Fctors for 2006/2009 IBC (ACE 7-05) Component R Dstrbuton ystems png n ccordnce wth AME B31, ths ncludes n-lne components, wth jonts mde by weldng or brzng. png n ccordnce wth AME B31, ths ncludes n-lne components, constructed of hgh or lmted deformblty mterls wth jonts mde by thredng, bondng, compresson couplngs, or grooved couplngs. png & tubng tht s not n ccordnce wth AME B31, ths ncludes n-lne components, constructed wth hgh deformblty mterls wth jonts mde by weldng or brzng. png & tubng tht s not n ccordnce wth AME B31, ths ncludes n-lne components, constructed of hgh or lmted deformblty mterls wth jonts mde by thredng, bondng, compresson couplngs, or grooved couplngs. png & tubng of low deformblty mterls, such s cst ron, glss, or non-ductle plstcs. Ductwork, ncludng n-lne components, constructed of hgh deformblty mterls, wth jonts mde by weldng or brzng. Ductwork, ncludng n-lne components, constructed of hgh or lmted deformblty mterls, wth jonts mde by mens other thn weldng or brzng. Duct work constructed of low deformblty mterls such s cst ron, glss, or non-ductle plstcs Code Bsed Vertcl esmc Desgn Force ACE/EI 7-05 ecton 13.3: ACE/EI 7-05 requres tht vertcl sesmc lod be ppled to the ppe or duct concurrently wth the horzontl sesmc lod from Equton 5-1. The vertcl sesmc lod ctng on the ppe or duct wll be; F = ±0. 2 W Equton 5-6 V Ths force s to be ppled n the drecton tht cuses the worst cse condton. In ths nstnce t s to be ppled downwrd to the hnger(s) tht re closest to the sesmc restrnt loctons. Ths lod wll dd to the tenson lod n the hnger generted by the supported weght of the ppe of duct. A check should be performed to mke sure tht the vertcl sesmc force does not overlod the hnger(s). AGE 6 of 7 ECTION 5.0

7 KINETIC pe & Duct esmc Applcton Mnul 5.4 LRFD versus AD ACE/EI 7-05 ectons 2.3, 2.4 nd The Cvl nd tructurl Engneerng communty hs dopted the LRFD, Lod Resstnce Fctor Desgn, phlosophy. Wth ths desgn phlosophy the fctors controllng the servceblty of the structure s ssgned to the desgn lods. AD, Allowble tress Desgn, s the desgn phlosophy whch preceded LRFD. In AD, the fctors controllng the servceblty of the structure re ssgned to the yeld strength or to the ultmte strength of the mterl. Trdtonlly the fctors controllng the servceblty of the structure hve been known s the fety Fctors, or Fctors of fety. The forces clculted usng Equtons 5-1, 5-2, 5-3, nd 5-6 wll hve mgntudes tht correspond to LRFD. Mny stndrd components such concrete nchors, bolts, screws, nd etc. wll hve ther cpctes lsted s AD vlues. Components whose cpctes re lsted s AD vlues my be compred to the LRFD results from Equtons 5-1 through 5-6 by multplyng the AD vlues by ummry: Ths secton hs provded n nsght nto the wy n whch the sesmc desgn forces for ppe nd duct dstrbuton systems my be computed. It s generlly not necessry for desgner to ctully run the computtons for the sesmc desgn forces. Knetcs Nose Control provdes web bsed computer tools to help the desgner responsble for the sesmc restrnt selecton determne the sesmc forces tht wll be ctng on the ppe or duct dstrbuton system nd to mke the proper selecton for the sesmc restrnts. More bout the selecton process nd the web bsed tools wll be sd n the followng sectons. AGE 7 of 7 ECTION 5.0