SYRIAN SEISMIC CODE :

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Noel Lawson
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1 SYRIAN SEISMIC CODE 2004 : Two sac mehods have bee ssued Syra buldg code 2004 o calculae he laeral sesmc forces he buldg. The Frs Sac Mehod: I s he same mehod he prevous code (995) wh few modfcaos. I s based o deermao of a desg base shear force (V), whch s he dsrbued a specfc paer over he hegh of he srucure for srucure aalyss of laeral load ressace. The oal desg base shear a gve dreco (V) s gve by: V ( ZIKCS ) * W Sesmc Zoe Facor (Z): I s represe he peak groud accelerao suded se as a perceage of gravy accelerao g (9.8 m/sec 2 ). Z facor for each zoe s show he able below: Sesmc Zoe 0 2A 2B 2C 3 Z facor Imporace facor (I): Occupacy Caegory All mpora srucures whch are requred for coued operag durg earhquakes such as: hospals, fre ad polce saos,..ec. I.50 All Srucures wh occupacy more ha 300 persos..25 All ohers srucures..00 I value o less ha 2 for aomc srucures ad all hazardous srucures. Ducly Facor (K): Buldg Type or descrpo K All buldgs o meoed hs able.00 Bearg wall sysem.30 Buldg Frame Sysem or Mxed Sysem accordg o he followg desgg case: -Frames ca bear 25% of he oal laeral loads. -Frames ca bear 50% of he oal laeral loads. Hgh aks of waer ad smlar whch carred by a group of colums o less ha four Specal Buldg such as: Chmeys, T.V owers The orgal Code s Arabc ad has bee raslaed o Eglsh by Eg. Hussam Elde Zaeh, Naoal Earhquake Ceer (NEC).

2 Dyamc Facor (C): I represes he perceage bewee equvale accelerao of he srucure o he groud accelerao ad defed from hs equao: C 2 3 0T Where: T: s he fudameal perod of he srucure (sec) a gve dreco, calculaed by: - approxmae deermao case of shear wall sysem srucures: T(sec) 0. 08N Where, N s he umber of sores. 2- approxmae deermao case of frame sysem srucures: T 0. N 3- also, T mus be esmaed by usg hs approxmae equao: Where: 3 4 T γ.( h ) h : buldg hegh from he base up o level meers. γ for seel frame. γ for RC frame. γ for oher buldgs. Noe : T s he mmum value from prevous hree equaos. Noe 2: C s equal o 0.5 for buldgs coss of oly oe or wo sores. Noe 3: oher cases C mus be less ha 0.8. Noe 4: all cases, K.C mus be less ha 0.38 ad more ha Sol Coeffce (S): T - case of : T s S.0 + T T T 0.5 s T s 2

3 T 2- case of > : T s S T s : he characersc se perod (sec). T T T 0.3 s T s 2 Toal wegh (W): s equal o all dead loads ad 25% of lve loads. Laeral Loads dsrbuo: -Regular srucures or srucural frame sysem: The oal laeral force (V) shall be dsrbued over he hegh of he srucure coformace wh formulas: V F + F F: The coceraed force a he op of he srucure shall be deermed from he formula: F T V The value of (F ) eed o exceed (0.25 V) ad may be cosdered as zero where T s 0.70 sec or less. T: he fudameal perod of he srucure (sec) he cosdered dreco. The remag poro of he base shear (V- F ) shall be dsrbued over he hegh of he srucure Accordg o he followg formula: F x ( V F ) w h Where: w x : he vercal coceraed load a level x whch equal o he wegh of hs level. w : he poro of (w) locaed a assged o level. h x : hegh above he base o level x. h : hegh above he base o level. F x : desg sesmc force appled a level x he gravy ceer of hs level. w h x x

4 2- Irregular srucures: The dyamc laeral-force procedure shall be used o aalyss hese kd of srucures. The Secod Sac Mehod: I s based o deermao of a desg base shear force (V), whch s he dsrbued a specfc paer over he hegh of he srucure for srucure aalyss of laeral load ressace. The oal desg base shear he cosdered dreco (V) s gve by: V CvI W RT The oal desg base shear eed o exceed he followg: V 2.5C R a I W The oal desg base shear shall o be less ha he followg: V 0.C I addo, for Sesmc Zoe 4, he oal base shear shall also o be less ha he followg: V 0.8ZN R a v IW I W Where C a, C v, N a ad N v from ables (3-9), (3-0), (3-) ad (3-2) respecvely. Sesmc Zoe Facor (Z): Sesmc Zoe Facor as meoed he frs mehod. Imporace facor (I): Imporace facor (I) as meoed he frs mehod. Srucure perod (T): The value of T shall be deermed from oe of he followg mehods:. Mehod A: For all buldgs, he value T may be approxmaed from he followg formula: Where: 3 4 T C ( h )

5 h : buldg hegh from he base up o level meers. C for seel mome ressg frames. C for reforced cocree mome-ressg frames ad eccercally braced frames. C for all oher buldgs. Aleravely, he value of ake as: C for srucures wh cocree or masory shear walls may be C Where Ac m 2 ad shall be deermed from he followg formula: 2 Ac Ae [0.2 + ( De / h ) ] The value of D e /h used prevous formula shall o exceed Mehod B: The fudameal perod T may be calculaed usg he srucural properes ad deformaoal characerscs of he ressg elemes a properly subsaaed aalyss. The aalyss shall be accordace wh he requremes of Seco The value of T from Mehod B shall o exceed a value 30 perce greaer ha he value of T obaed from Mehod A Sesmc Zoe 4, ad 40 perce Sesmc Zoes, 2 ad 3. The fudameal perod T may be compued by usg he followg formula: A c T 2 2π ( w δ ) ( g f δ ) The values of f represe ay laeral force dsrbued approxmaely accordace wh he prcples of Formulas (4-3), (4-4) ad (4-5) or ay oher raoal dsrbuo. The elasc deflecos, δ, shall be calculaed usg he appled laeral forces, F.

6 The elasc deflecos, δ Smplfed desg base shear: a. Geeral: Srucures coformg o he requremes of seco may be desged usg hs procedure below. b. Base shear: The oal desg base shear a gve dreco shall be deermed from he followg formula: V 3.0C R a W Where, he value of C a shall be based o Table 9-3 regardg he sol profle ype. Whe he sol properes are o kow suffce deal o deerme he sol profle ype, Type S D shall be used Sesmc Zoes 3 ad 4, ad Type S E shall be used Sesmc Zoes, 2A ad 2B. I Sesmc Zoe 4, he Near-Source Facor, N a, eed o be greaer ha.3 f oe of he followg srucural rregulares are prese: Type (, 4 or 5) of Table (3-4), or Type () or (4) of Table (3-5). c. Vercal dsrbuo: The forces a each level shall be calculaed usg he followg formula: F x 3.0C R a w Where, he value of C a shall be deermed Subseco (4-3-3-b). d. Applcably: Secos (4-2-2), (4-2-3), (4-3-), (4-3-2), (4-6), (4-0), (4-) ad 5 shall o apply whe usg he smplfed procedure.

7 EXCEPTION: For buldgs wh relavely flexble srucural sysems, he buldg offcal may requre cosderao of P- effecs ad drf accordace wh Secos (4-2-3), (4-0) ad (4- ). Whle s shall be calculaed usg desg sesmc forces from Subseco (4-3-3-b). Where used, M shall be ake equal o 0.0 mes he sory hegh of all sores. I Seco (7--8), Formula (7-2) shall read: F px 3.0C R a w px Ad eed o exceed (.C a.w px ), bu shall o be less ha (0.5.C a.w px ). R shall be ake from Table (3-6). Vercal Dsrbuo of Force: The oal force shall be dsrbued over he hegh of he srucure coformace wh Formulas (4-3), (4-4) ad (4-5) he absece of a more accurae procedure. V F + F (4 3) The coceraed force F a he op, whch s addo o F shall be deermed from he formula: F 0.07T. V (4 4) The value of T used for he purpose of calculag F shall be he perod ha correspods wh he desg base shear as compued usg Formula (4-4). F eed o exceed 0.25V ad may be cosdered as zero where T s 0.7 secod or less. The remag poro of he base shear shall be dsrbued over he hegh of he srucure, cludg Level, accordg o he followg formula: F x ( V F ) wxh w h x (4 5) A each level desgaed as x, he force F x shall be appled over he area of he buldg accordace wh he mass dsrbuo a ha level. Srucural dsplacemes (fgure 4-2) ad desg sesmc forces (fgure 4-3) shall be calculaed as he effec of forces F x ad F appled a he approprae levels above he base.

8 Fgure (4-2): Srucural dsplacemes Fgure (4-3): Desg Sesmc Forces Dyamc Aalyss Procedures:. Geeral: Dyamc aalyses procedures, whe used, shall coform o he crera esablshed hs seco. The aalyss shall be based o a approprae groud moo represeao ad shall be performed usg acceped prcples of dyamcs. Srucures ha are desged accordace wh hs seco shall comply wh all oher applcable requremes of hese provsos. 2. Groud Moo: The groud moo represeao shall, as a mmum, be oe havg a 0-perce probably of beg exceeded 50 years, shall o be reduced by he quay R ad may be oe of he followg: 2.. A elasc desg respose specrum cosruced accordace wh Fgure 5-, usg he values of C a ad C v cosse wh he specfc se. The desg accelerao ordaes shall be mulpled by he accelerao of gravy (9.85 m/sec 2 ) A se-specfc elasc desg respose specrum based o he geologc, ecoc, sesmologc ad sol characerscs assocaed wh he specfc se. The specrum shall be developed for a dampg rao of 0.05, uless a dffere value s show o be

9 cosse wh he acpaed srucural behavor a he esy of shakg esablshed for he se Groud moo me hsores developed for he specfc se shall be represeave of acual earhquake moos. Respose specra from me hsores, eher dvdually or combao, shall approxmae he se desg specrum coformg o Seco For srucures o Sol Profle Type S F, he followg requremes shall apply whe requred by Subseco (3-9-4-d): 2.4. The groud moo represeao shall be developed accordace wh Iems 2 ad Possble amplfcao of buldg respose due o he effecs of sol-srucure eraco ad legheg of buldg perod caused by elasc behavor shall be cosdered The vercal compoe of groud moo may be defed by scalg correspodg horzoal acceleraos by a facor of wo hrds. Alerave facors may be used whe subsaaed by se-specfc daa. Where he Near Source Facor, Na, s greaer ha.0, se-specfc vercal respose specra shall be used leu of he facor of wo-hrds. 3. Mahemacal Model: A mahemacal model of he physcal srucure shall represe he spaal dsrbuo of he mass ad sffess of he srucure o a exe ha s adequae for he calculao of he sgfca feaures of s dyamc respose. A hree-dmesoal model shall be used for he dyamc aalyss of srucures wh hghly rregular pla cofguraos such as hose havg a pla rregulary defed Table (3-5) ad havg a rgd or sem-rgd daphragm. The sffess properes used he aalyss ad geeral mahemacal modelg shall be accordace wh Seco Descrpo of Aalyss Procedures: 4.. Respose specrum aalyss: A elasc dyamc aalyss of a srucure ulzg he peak dyamc respose of all modes havg a sgfca corbuo o oal srucural respose. Peak modal resposes are calculaed usg he ordaes of he approprae respose specrum curve whch correspod o he modal perods. Maxmum modal corbuos are combed a sascal maer o oba a approxmae oal srucural respose.

10 4.2. Tme-hsory aalyss: A aalyss of he dyamc respose of a srucure a each creme of me whe he base s subjeced o a specfc groud moo me hsory. Fgure (5-): Desg Respose Specrum Table (4-2) shows he value of R facor for mos commo srucural sysems Syra. No. Laeral Force ressg Sysem Descrpo R Specal Mome Ressg Frame Sysems Dual Sysem Wh Specal Mome Ressg Frames whch are capable o ress a leas 50% of Prescrbed Sesmc Force Dual Sysem Wh Specal Mome Ressg Frames whch are capable o ress a leas 25% of Prescrbed Sesmc Force Dual Sysem Wh Specal Mome Ressg Frames whch are capable o ress a leas 0% of Prescrbed Sesmc Force Bearg Shear Wall Sysem whou Specal Mome Ressg Frames 4.5

11 Table (3-9), Sesmc Coeffce C a Sol Profle Sesmc Zoe Facor, Z Type Z Z 0.5 Z 0.2 Z 0.3 Z 0.4 S A N v S B N v S C N v S D N v S E N v S F See Foooe Se-specfc geoechcal vesgao ad dyamc se respose aalyss shall be performed o deerme sesmc coeffce for Sol Profle Type S F Table (3-0), Sesmc Coeffce C v Sol Profle Sesmc Zoe Facor, Z Type Z Z 0.5 Z 0.2 Z 0.3 Z 0.4 S A N v S B N v S C N v S D N v S E N v S F See Foooe Se-specfc geoechcal vesgao ad dyamc se respose aalyss shall be performed o deerme sesmc coeffce for Sol Profle Type S F Table (3-) NEAR- SOURCE FACTOR N a Sesmc Source Closes Dsace o Kow Sesmc Source 2 Type 2 km 5 km 0 km A B C The Near-Source Facor may be based o he lear erpolao of values for dsaces oher ha hose show he able. 2 The closes dsace o sesmc source shall be ake as he mmum dsace bewee he se ad he area descrbed by he vercal projeco of he source o he surface (.e, surface projeco of faul plae). The surface projeco eed o clude poros of he source a dephs of 0 km or greaer. The larges value of he Near-Source Facor cosderg all sources shall be used for desg. Table (3-2) NEAR- SOURCE FACTOR N V Sesmc Source Closes Dsace o Kow Sesmc Source 2 Type 2 km 5 km 0 km 5 km A B C The Near-Source Facor may be based o he lear erpolao of values for dsaces oher ha hose show he able 2 he closes dsace o sesmc source shall be ake as he mmum dsace bewee he se ad he area descrbed by he vercal projeco of he source o he surface (.e, surface projeco of faul plae). The

surface projeco eed o clude poros of he source a dephs of 0 km or greaer. The larges value of he Near-Source Facor cosderg all sources shall be used for desg.

12 surface projeco eed o clude poros of he source a dephs of 0 km or greaer. The larges value of he Near-Source Facor cosderg all sources shall be used for desg. Table (3-3) SEISMIC SOURCE TYPE Sesmc source Defo Sesmc source Type Sesmc source Descrpo Maxmum Mome Magude, M Fauls ha are capable of A producg large magude eves ad ha have a hgh M 7.0 SR 5 rae of sesmc acvy B C All fauls oher ha ype A ad C Fauls ha are o capable of producg large magude earhquakes ad ha have a relavely low rae of sesmc acvy M 7.0 M < 7.0 M 6.5 Slp Rae, SR (mm/year) SR < 5 SR > 2 SR < 2 M < 6.5 SR 2 PGA dsrbuo for 0% probably of exceedg 50 years (Reur Perod 475 years)

FORCED VIBRATION of MDOF SYSTEMS

FORCED VIBRATION of MDOF SYSTEMS FORCED VIBRAION of DOF SSES he respose of a N DOF sysem s govered by he marx equao of moo: ] u C] u K] u 1 h al codos u u0 ad u u 0. hs marx equao of moo represes a sysem of N smulaeous equaos u ad s me