A New Vision for Design of Steel Transmission Line Structures by Reliability Method

Transcription

1 IOS Jounal of Mchanical and Civil Engining IOS-JMCE) -ISSN: 78-68,p-ISSN: 30-33X, Volum, Issu V. II Jul- Aug. 0), PP 07-5 A Nw Vision fo sign of Stl Tansmission in Stuctus by liability Mthod Khalid A. ahab Abdalla A. Alsamad, Salih Elhadi Mohamd Ahmd Snio Stuctual Engin, puty Mang, Al-ahna Constuction Company- Sudan. Pofsso of stuctual ngining Sudan Univsity of Scincs and Tchnology,Sudan, Abstact: A liability dsign mthod fo statically dtminat and indtminat stl tansmission lins tows and pols is psntd. Th mthod is in a oad and sistanc Facto sign F) fomat. Th nominal load and sistanc valus fo dsign a obtaind fom th man valus of pobability distibution functions dscibing wind spd, adial ic thicknss and yild stss. Th load and sistanc involving th cofficint of vaiation of th abov vaiabls and a tagt liability indx. Sval cass dmonstat that us of th quations sults in stl lin having an actual liability indx naly qual to th tagt liability indx. Pobability of failu calculations by th mthods of numical intgation and th dsign point mthod a discussd. Th mathmatical lationship btwn pobability of failu and th liability indx is xplaind. Th analysis and dsign by comput pogam, using liability mthod givs mo safty and conomical sults. Kywods: Stl Tansmission Stuctu, liability, sign. I. Intoduction: On motiv fo xamining th dsign of stl utility tuss is to sd a balanc btwn initial costs and failu costs. A simplifid gaphical psntation of this concpt is shown.[] Th concpt of stuctual dsign has bn undgoing adical changs in philosophy in th last sval yas. A lag amount of sach and dvlopmnt in this aa has bn and is bing concntatd on th application of concpts of liability analysis to dsign. Majo sach ffots hav bn conductd fo sval constuction matials [,,3], and hav sultd in poposals fo altnat liability-basd oftn calld pobability- basd dsign mthodology). Th dvlopmnt of nw concpts fo dsign, involving som fom of liability assssmnt has sultd lagly bcaus of th btt contol of safty and conomy thy pomis to povid.. Th spcific sach objctiv was to dvlop an impovd dsign mthod which would sult in stuctus bing consistntly clos to th optimum liability lvl than possibl using cunt mthods,, whil taining th simplicity and low xpns of us ncssay fo a pactical dsign mthod.. Similaly in liability dsign o th distibutions of and S may b divn fowads o backwads to adjust α. Convntional dsign can lad to und dsignd failu pon) o ov dsignd xpnsiv) stuctus. Figu.). Compaison of dtministic dsign and dsignincluding vaianc..stps of Solution: Study th dsign paamts coving th dsignloads, sistanc) to concpts of liability. Study th mathmatical of stuctual analysis of stltansmission lin tows. Study mthods of calculation pobability of failu including but-up of comput pogam. tmination th pobability basd valus fo paamts coving th dsign nw poposd mthod). 7 Pag

2 A Nw Vision fo sign of Stl Tansmission in Stuctus by liability Mthod.oad and sistanc Facto sign: Th unctainty of stuctual pfomanc du to vaiabl loads and sistanc can b compnsatd fo dsigning with dcasd valus of sistanc and incasd loads. oads o load ffcts can b incasd, and sistanc can b dcasd, by applying load and sistanc factos, spctivly, to th nominal valus of loads and sistanc. A gnal dsign quation, with a summation fo multipl loads, is wittn symbolically as: ) h γ is a load facto usually gat than unity, is a sistanc facto lss than unity, is stuctual sistanc howv on chooss to quantify it, P i a gnalizd loads, and A is th analysis that convts loads to load ffcts with dimnsions comatibl to thos of. II. Poblm Study Equation) is a dsign quation xpssd in load and sistanc facto dsign F) fomat s figu and ). Th poblm of assigning valus to and γ illustats anoth majo diffnc btwn convntional and liability dsign. oad and sistanc factos fo convntional dsign hav histoically bn ignod in favo of using factos of safty basd on th judgmnt and past xpinc of mmbs of pofssional ngining socity committs. liability dsign on th oth hand, uss th logical appoach of basing th paamts of quation ), γ,, P) on th pobability distibutions of th load and sistanc vaiabls associatd with th stuctu to b dsignd. figu 3) Figu ) Figu ) b oad and sistanc facto dsign fomat 8 Pag

3 A Nw Vision fo sign of Stl Tansmission in Stuctus by liability Mthod figu 3): Th stl tansmission tow. oading conditions To maximiz stsss in tow mmbs and loadings on foundations. Th following loading combinations should b invstigatd. Intact loading cas:. Maximum tansvs, maximum vtical.. Maximum tansvs, minimum vtical. 3. Maximum tansvs conducto, minimum tansvs OHA, minimum vtical.. Maximum tansvs conducto, minimum tansvs OHA, minimum vtical. 5. Combination of vtical loads max. and min) to obtain vtical tosion spans icd and ba). 6. Bokn i o oth longitudinal) oading. Taking maximum longitudinal and vtical and minimum fo th point fom -5) abov.. Analysis of th Study Poblm dtministic dsign): nally, th pogam assums o th ngin inputs ith assumd mmb sizs o aas of mmbs into th th-dimnsional lastic analysis pogam aft th focs a distibutd basd on satisfying statics and th stiffnss matix, th mmbs a sizd. It th siz of th mmbs now slctd vay considably fom th oiginal assumd sizs, a analysis should b conductd to dtmin th xtnt to which th load distibution has changd, if at all, dtministic dsign fo tow S60 is shown blow: It would appa that a catch can and dos xist in som aas of th tow, fo inatanc, lt us assum that w hav a cossam wh th hang and main cossam mmbs can tak tnsion and compssion. t us also assum that only a longitudinal load is applid. Thus, in this study failu is assumd to occu whn ith of th vnts blow occu:. Th maximum plastic bnding stss along th tow o pol xcds th modulus of plasticity MOP) of th tow o pol.. Th maximum bnding dflction along th tow o pol an abitaily dfind allowabl limit. 3. Th ang of safty against ovtuning limit is lss than th facto of safty by scond momnt mthod. III. Comput Pogam Tow mmb sign, Analysis, and liability) is a FOTAN languag comput pogam wittn by Fols.dvlopd and nw built-up don by th authosto solv th poblm. Pogam is additionally capabl of pfoming liability analyss by ith numical intgation o th dsign point mthod. Th input quimnts fo ths computations includ th summay statistic and distibution typ fo ach andom vaiabl affcting th stuctu to b analyzd. Fo stl pols and tow mmb dsign by liability th andom vaiabls which must b dscibd a wind, ic, and yild stss. Th pogam can additionally accpt vaiabl modulus of lasticity data which a ncssay fo th analysis of tow mmb dsign by liability. 9 Pag

4 A Nw Vision fo sign of Stl Tansmission in Stuctus by liability Mthod oading cass fo tow typ on S60) fom xpinc of Sudans wok in th fild of dsign of tansmission lin tows, tabl ) No Nam in angl vtical loads ind diction. Tansvs ind-max V 'S60_90max' 60 Max 90. Tansvs ind-uplift 'S60_90min' 60 Min ind at 5.maxV 'S60_5max' 60 Max 5. ind at 5.upliftV 'S60_5min' 60 Min 5 Unbalancd load 5. vs ind-max V 'S60_70max' 30 Max vs ind-uplift V 'S60_70min' 30 Min Eathwi+ Top conducto bokn Eathwi+top conducto 'S60_ETC90max' 60 Max 90 max V lft sid) 8. Eathwi + Top conducto Eathwi+top conducto 'S60_ETC90min' 60 Min 90 bokn uplift lft sid) 9. Eathwi + Middl conducto Eathwi+middl 'S60_EMC90max' 60 Max 90 bokn max V conducto ight sid) 0. Eathwi + Middl conducto Eathwi+middl 'S60_EMC90min' 60 Min 90 bokn uplift conducto ight sid). Eathwi + Bottom conducto Eathwi+bottom 'S60_EBC90max' 60 Max 90 bokn max V conducto lift sid). Eathwi + Bottom conducto Eathwi+bottom 'S60_EBC90min' 60 Min 90 bokn uplift conducto lift sid) 3. Top conducto+ Bottom Top+ bottom conducto 'S60_TCBC90max' 60 Max 90 Conducto bokn max V lft sid). Top conducto+ Bottom Top+ bottom conducto 'S60_TCBC90min' 60 Min 90 Conducto bokn uplift lft sid) 5. Eathwi+ Top Conducto Eathwi+top conducto 'S60_ETC70max' 30 Max 70 bokn max V-v.ind lft sid) 6. Eathwi+ Top Conducto Eathwi+top conducto 'S60_ETC70min' 30 Min 70 bokn uplift-v.ind lft sid) 7. Eathwi+ Middl Conducto Eathwi+middl 'S60_EMC70max' 30 Max 70 bokn max V-v.ind conducto ight sid) 8. Eathwi+ Middl Conducto Eathwi+middl 'S60_EMC70min' 30 Min 70 bokn uplift-v.ind conducto ight sid) 9. Eathwi+ Bottom Conducto 'S60_EBC70max' 30 Max 70 Eathwi+bottom 0 Pag

5 A Nw Vision fo sign of Stl Tansmission in Stuctus by liability Mthod bokn max V-v.ind 0. Eathwi+ Bottom Conducto bokn uplift-v.ind 'S60_EBC70min' 30 Min 70 Top Conducto + Bottom. Conducto bokn max V- 'S60_TCBC70max' 30 Max 70 v.ind Top Conducto + Bottom. Conducto bokn uplift - 'S60_TCBC70min' 30 Min 70 v.ind 3. Cascad condition-max V 'S60_casc_max' 60 Max -. Cascad condition-uplift V 'S60_casc_min' 60 Min - 5. Tmpoay tminal condition 'S60_tmp' 60 Max 6. Maintnanc condition lft sid) 'S60_maint_lft' - 3 nomal 7. Maintnanc condition 'S60_maint' - 3 nomal 8. ind on tow with ovdoad facto fo tow wight) 'S60_wind_max' ind on tow without ovload facto fo tow wight) 'S60_wind_min' Eath and wi Tabl ): Most Citical loading cass numb and ) conducto lift sid) Eathwi+bottom conducto lift sid) Top+ bottom conducto lft sid) Top+ bottom conducto lft sid) Tow Typ S60 IV. Poposd analysis and dsign by liability Th dsign abov show th dtminist dsign of tow how can analyss by using many mthods, Th poposd mthod povd a lvl of contol ov dsign of fam. th contol of this dsign nabls ngins to mak th pop dcisions whn considd by th balanc btwn stuctual suvival and cost. Th ssntial lmnts of this mthod includ: ) Us of F quation. ) Pobability basd dsign valus of dad load, liv load, and wind load. Bam and column modls of sistanc MO) and modls of lasticity MOE). 3) Th spcification of tagt liability indx.. Calculation of pobability of failu: To calculat pobability of failu on nd to undstand th maning of failu Failu will occu whn th dmand xcds th capacity by fing to th pfomanc function of mathmatically as th vnt whn y < 0 thus Pag

6 A Nw Vision fo sign of Stl Tansmission in Stuctus by liability Mthod Pobability of failu) = P Y < 0).. ) Sinc y is a nomal andom vaiabl w can calculat this. imit stat Function: Tabl 3) imit stat function data fo load sistanc facto dsign) istibution Cofficint Man facto log nomal V = 3%.. nomal V = 0%.5.05 mbl I V = 5%.0.0 I V = 5%.0.0 V. liability-basd sign of Tansmission Tows Und oads and ind poposd dsign) Using qu. 3) n α n + α + α w h: n sistanc, dad load, liv load, wind load, Φ ducd facto Extm typ bml )) α = π bσ = U = μ a Thn Fl ) = xp xp α U))) f ) = α xp a u ))) xp xp a u))) π 6 v μ = 5.3 μ = 3μ /μ Substituting I 3 fo th fist itation w gt Fl = I) = Fl I) = 0.57 Thus th quivalnt paamt of, o tmin ): 3 3 g g g g E =.70 μ =.66 μ.) 0.57,. 87 sign point sign point V 5.9) o Pag

7 A Nw Vision fo sign of Stl Tansmission in Stuctus by liability Mthod 3 Pag h n V ] ln [ )) ln ))) ln ) = Standaddviation )) ) ) Man T 5) Cas ): ) ) ) 0.805) 0.805) 0.) 0.583) i Cas ): ) ) ) 0.805) 0.805) 0.) 0.583) i 5. tmin cosponding dsign point mthod: l cas cas cas I cas cas V d.3 //.97 // ).60 ) ) = d + I 6) cas cas V // )3)93.38) )

8 5.9 ducd facto: A Nw Vision fo sign of Stl Tansmission in Stuctus by liability Mthod..7) Equation 7) is th sult of wok dpnd on citical loading condition and it giv safty and conomical dsign, th facto s is uld to giv idal solution of th quation and all lations btwn loads a psnt in its citical condition to b solvd in load sistanc fomat. ight hand giv loads combinations and lft hand giv th duction facto and sistanc whil lad to final solution. sult and compaisons using quation 7) a shown in tabl ) Tabl ): sults and compaison btwn α i, β tagt and β indx and duction facto Ø) and i factos fo Equation 7) VI. iscussions: Th solution poposd by th authos has bn compad with th ASCE-F nd th koan-as and it was found that th solution was in godd agmnt with ths cods. Alngthy discussion gading that has bn givn in fnc 8). VII. Conclusions:. This study consistd of th dvlopmnt of nw vision fo dsign of stl tansmission lin stuctus tows and pols by liability taking in considiton many situation of loads ffcts and sistanc by matial of Pag

9 A Nw Vision fo sign of Stl Tansmission in Stuctus by liability Mthod pol and tows and this dvlopmnt giv th dsign gat contol ov pobability of failu of stuctu usd in tansission lin solution of poblms aising in th cous of th dvlopmnt that a convsion by tansmission lin stuctu dsigns fom cunt mthods to a pobability-basd appoach is both asonabl and bnficial.. Th cunt mthod is chaactisd by ov simplifid load modl and stuctual analysis and utilizs nominal loads and stuctual poptis and safty factos which a difficult to lat to stuctual liability. Thfo impovd load modls and stuctual analysis tchniqus w don fo calculating th pobability of failu of stuctu and factos w slctd to complt th solution of dsign in good way. 3. Th cunt mthods of slcting facto dsign F) sulting stuctal lability to incas dsign contol of liability with good way to satisfy conomy and safty. fncs [] Aifdo H-s. Mg & wilson H. Tang pobability concpts in ngining planning and dsign voluml Basic pincipls. Nw yok, ondon sydy, Toonto 975 Nw pint 000. [] Andzj S, Nowak and Kvin. Collins, liability of Stuctus, Univsity of Michigan, Intnational Edition, 000, by th Mc aw-hill companis, ibay of Congss Cotaloging in publiscation. [3] A-H-Sang and -viliavd. Stuctual ngining in natual hazads mitigation volum I hld ivin caifonia, 00. [] A-H-Sang and -Vilaud. Stuctual ngining in natual hazads mitigation. Volumll hld Ivin califonia, 00 [5] liability dsign stl tansmission pols, stuctual sach pat. [6] Egiptian Eng. Fo Tchnical constaction, Monopol Tow 30 m, Januay 007. [7] Studis of Mow am Pjct, Tansmission in oks, Ministy of Elcticity Sudan.\ [8] Abd-Alsamad, Khaid, A. ahab, sign of tansmission, M.Sc, thsis, Sudan Univsity of scinc and tchnology, July 0. 5 Pag