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STRUCTURAL STEEL EDUCATIONAL COUNCIL

TECHNICAL NFORMATION& PRODUCTSERVICE

JULY 1999

P r a c t i c a l D e s i g n a n d D e t a i l i n go f S t e e l C o l u m n B a s e P l a t e s

byW i l l i a m C . H o n e c k

D e r e k W e s t p h a lF o r e l l E l s e s s e r E n g i n e e r s , Inc .

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Acknowl edgmen t sT h e a u t h o r s w i s h t o t h a n k t h e f o ll o w in g p e r s o n s f o r t h e i r i np u t , r e v i e w a n d c o m m e n t s o n t h e c o n t e n t o f th i sSteel Tips pub l i ca t i on :

M e m b e r s o f t h e S t r u c t u r a l S t e e l E d u c a t i o n a l C o u n c i lR o g e r F e r c h , H e r r i c k C o r p o r a t i o nB e r n i e L o r i m o r , R o c k y M o u n t a i n S t e e lS t e v e R i c h ar d s on , W & W S te el C o m p a n yR i c k W i lk e n s e n , G a y l e M a n u f a c t u r in gD a v e M c E u e n , C a l i fo r n ia E r e c t o r sJ i m M a l le y , D e g e n k o l b E n g i n e e r sJ im P u t k e yM a s o n W a i t e r s , F o r e l l / E l s e s s e r E n g i n e e r s .P r o f e s s o r S u b h a s h G o e l , U n i v e rs i ty o f M i c h i ga n

DisclaimerT h e i n fo r m a t io n p r e s e n t e d i n t h i s p u b l i c a ti o n h a s b e e n p r e p a r e d i n a c c o r d a n c e w i t h r e c o g n i z e d e n g i n e e r i n gp r inc ip le s a nd cons t ruc t i on p rac t ices and i s fo r gen e ra l i n fo rm a t ion on ly . W hi l e i t i s be l i eved to be ac cu ra t e ,t h i s i n fo rma t ion shou ld no t be u sed o r re li ed upon fo r any spec if ic app l i ca ti on w i thou t com pe te n t p ro fess ion a lexam ina t ion and ve r i fi ca ti on o f i ts accu ra cy , su i tab i li ty , an d app l i cab i li t y by a l icensed p ro fess iona l eng ine e ro r a rch it ec t. The pub l i ca t ion o f t he ma te ri al con t a ined he re in i s no t i n t ende d a s a rep re sen t a t i on o r wa r ra n tyo n t h e p a r t o f t h e S t r u c t u r a l S t e e l E d u c a t i o n a l C o u n c i l, o r o f a n y o t h e r p e r s o n n a m e d h e r e i n , th a t t h isi n f or m a t i o n i s s ui ta bl e f o r a n y g e n e r a l o r p a r t i c u l a r u s e o r o f f r e e d o m i n f r in g e m e n t o f a n y p a t e n t o r p a t e n t s .A n y o n e u s i n g t h i s i n f o r m a t i o n a s s u m e s a l l li a bi li ty a r i si n g f r o m s u c h u s e .

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No,

PRACTICALDESIGNAND DETAILINGOF STEEL COLUMNBASE PLATESTable of Contents

Description Page No.

1.0

2 .0

3 .0

4 .0

5.06 .0

I N T R O D U C T I O N 21.1 Pre fac e 21 .2 P u rp o se 21 .3 Org aniza t ion 2D E S I G N G U I D E L I N E S F O R M A T E R I A L S A N D F A B R I C A T I O N2.1 Mater ia ls

2 .1 .1 A n c h o r B o l t s a n d N u t s2 .1 .2 P la tes

2 . 2 B a se P l a t e D e s ig n fo r F a b r i c a t io n2 .2 .1 M ater ia l versus Lab or2 . 2 . 2 We ld in g2 .2 .3 B a se P l a t e D im e n s io n s

D E S I G N G U I D E L IN E S R E L A T E D T O E R E C T IO N3 .1 A n c h o r B o l t s

3 .1 .1 A n c h o r B o l t P o s i t i o n M is lo c a t io n3 . 1 .2 R o ta t e d A n c h o r B o l t P a t t e rn s3 .1 .3 A n c h o r B o l t s S e t T o o L o w o r T o o H i g h3 . 1. 4 C o l u m n s N e x t t o W a l l s

3 . 2 W a s h e r s3 .3 B a se P l a t e L e v e l in gE N G I N E E R I N G G U I D E L I N E S F O R D E S IG N O F B A S E P L A T E S4.14 .24 .34 .44 .54 .64 .7

D e s i g n f o r T e m p o r a r y C o n s t r u c ti o n L o a d sD e s i g n f o r G r a v it y an d O t h e r D o w n w a r d L o a d sD e s ig n fo r G ra v i ty L o a d s in C o m b in a t io n w i th U p l i f t L o a d sD e s ig n fo r G ra v i ty L o a d s in C o m b in a t io n w i th S h e a r F o rc e sD e s ig n fo r G ra v i ty L o a d s in C o m b in a t io n w i th S h e a r F o rc e s a n d Mo m e n t sD e s ig n fo r Mo m e n t s d u e to S e i sm ic F o rc e sA rc h i t e c tu ra l I s su e s

C O N C L U S I O N SR E F E R E N C E S

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889

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PRAC TICA L DESIGN AND DETAILING OF STEEL COL UMN BASE PLATES

1.0 INTRODUCTION

1 . 1 P r e f a c eSt e e l c o l umn ba s e p l a t e s a re on e o f t he mos t~ nda me n t a l pa r t s o f a s t e e l s t r uc t u r e , ye t t hede s i gn o f ba s e p l a t e s is c omm on l y no t g i ve n t hea t ten tion tha t it should by engineers . This resu l t sin base plate detai ls that are expensive , diff icul t tof a b r i c a t e a nd ma y e ve n c on t r i bu t e t o t he ha z a r dso f t he s t ee l e r e c t ion p r oc e s s by no t p r ov i d i ngs tab i li ty for e rec t ion load s appl ied to the co lumn.Base p la tes se rve tw o bas ic fianct ions :1 . They t ransfe r co lumn loads to the suppo r t ingmem ber or founda t ion . These loads inc lude ax ia ldue t o g r a v i t y , mome n t s , s he a r s a nd s ome t i me saxial due to upl if t ;2 . T he y a l l ow t he c o l umn t o s ta nd a s atem porary vert ical cant i lever af ter the l i f t ing l ine isr e l ea s e d w i t hou t ha v i ng t o guy o f f t he c o l umn .T he c o l umn a nd ba s e p l a t e mus t w i t h s t a ndtemporary wind and e rec t ion loads sa fe ly .S teel fabr ica tors and e rec tors w ho a re m embers oft he S t r uc t u ra l S t e e l E duc a t i ona l Counc i l ( SSE C )ha ve c omm e n t e d t ha t t he r e a r e a va r i e ty o f ba s epla te des igns and de ta i ls f rom engineers . Som efabr ica tors a re c r i t i ca l o f many of these des ignsbeca use they a re d i f f icu l t to fabr icate , o r spec i fyma t e r i a l s t ha t a r e ha r d t o ob t a i n o r t ha t do no tex is t in the s izes spec i fied . The des igns of tenresu l t in co lumns tha t a re hard to e rec t o r a reuns ta b le w i t hou t guy i ng t he c o l umn . W he n a nc ho rbol t s a re no t p roper ly se t , expens ive cor rec t ivewo rk i s required before the co lumn can be e rec ted ,resu l t ing in de lays in the s tee l e rec t ion process .This publ ica t ion of S teel Tips a t tempts to addressthese issues.I n o r de r t o u nde r s t a nd be t t e r a nd re s pond t o t hefabricat ion and erect ion issues, a qu est ionna ire wasdis t r ibu ted to severa l SSEC member f i rmsr e que s t i ng t he i r c omme n t s a bou t p r ob l e ms

expe r ienced in the i r shops dur ing fabr ica t ion andin the f ie ld durin g steel erect io n. Specif ic issuesi nc l uded o ve r l y e xpe ns ive de s i gns a nd p r ob l e mswith obtaining the materials specif ied. S ugg est ion son how t he s e de s i gns c ou l d ha ve be e n mor ee c onom i c a l we r e s o li c it e d . T he que s t ionna i r easked about ~ tee l e rec t ion problems exper ienceda nd r e que s t e d s ugge s t i ons t o m i t iga t e t hos ep r ob l e ms . T he r e s pons e s r e c e ive d we r e ve r yi n f o r ma t i ve a nd ma ny o f t he s ugge s t i ons i n t her e s pons e s ha ve be e n i nc o r po r a t e d i n t o t h i spubl ica t ion .1 . 2 P u r p o s eT he p u r pos e o f t h is is s ue o f Steel Tips is toprovide prac t ica l gu ide l ines for engineers ,f a b r i c a to r s and c on t r a c t o r s r e ga r d i ng t he de s ignand de ta i l ing of s tee l co lumn base p la tes .Gu i da nc e i s p r ov i de d t owa r d r e s o l v i ng c ommondes ign , fabr ica t ion and e rec t ion problems. M anyof t he t op i c s d i s c us se d a r e s i mp l e t o i mp l e me n t ,ye t a r e o f t e n ove r l ooke d .Unf o r t una t e l y t he be ha v i o r o f ba s e p l a t e s i nmome n t f r a me s a nd b r a c e d f l a me s s ub j e c t e d t oear thq uake forces i s no t f ia lly unde rs tood .Re s e a r c h a nd c ode gu i da nc e a r e l im i t ed . T hee ng i ne e r i s f o r c e d t o u s e j udge me n t i n o r de r t oachieve a des i red leve l o f per formance and i t i shope d , tha t th i s pu bl ica t ion wi l l in i t i a te morer e s e a r c h a nd de ve l opme n t in t he a r e a s o f ba s epla te behavior and des ign guide l ines for base p la tea s s e mb l i e s t ha t a r e s ub j e c t e d t o h i gh mome n t swh e r e s ome s o r t o f y i e l d ing i s ne c e s s a r y t oachieve the des i red per forman ce .1 . 3 O r g a n i z a t i o nT he f oc us o f t h i s i s sue o f Steel Tips is directedt ow a r d t he p r a c ti c a l a spe c t s o f t he de s i gn a ndde ta i l in g of base p la tes par t icu la r ly as they re la teto economica l fabr ica t ion and s tee l e rec t ion .Sec t ion 2 .0 d i scusses fabr ica t ion issues. Sec t ion3 . 0 d i s cus s e s e r e c t ion a nd a nc ho r bo l t p l a c e me n t

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issues. Section 4.0 discusses the "issues" involvedin the design of base plates, rather than providing"how to" design methods or guidelines, and liststhe names of other authoritative publicationswhere the reader can find design formulas anddefinitive procedures for design of base plates.Section 4.0 also discusses fixed and partially fixedcolumn bases, for instance, moment frames whichresist wind or earthquake forces.

2 .0 D E SI G N G U I D E L I N E S FO RMATERIAL S AND FABRI CATION

Engineers have numerous types of steel to choosefrom when designing anchor bolts and base plateassemblies. However, materials are often specifiedthat are not readily available or are not suitable forspecific applications. Base pla te details often arehard to fabricate, overly complicated, call forexpensive welds and/or specify impossible welds.The following sections provide design guidelinesfor specifying suitable materials and suggestionsfor details to make fabrication easier and moreeconomical.2 . 1 M a t e r i a l s

A c c o rd in g to t h e A IS C S p e c i f i c a t io n fo rStructural Steel Buildings Allowable Stress Designand P las t ic Des ign (ASD Spec i f ica t ions) , there a re1 6 A S T M d e s ig n a t io n s sp e c i f i e d fo r s t ru c tu ra lappl ica t ions . Fo r spec i f ic mater ia l p roper t ies ,su i tab le appl ica t ions and comple te d imens iona lin format ion , the reader should re fe r to the ASTMSpeci f ica t ions .2 .1 .1 A n c h o r B o l ts a n d N u t s

T h e m o s t c o m m o n a n d r e a d i ly a v a i la b l e a n c h o rbol t mater ials a re AS TM A36 and A307. Smal le rbo l t s ge0era l ly a re suppl ied in A307 and la rgerdiameter in A36. Th e material prop ert ies fo r thes ere la t ive ly " low s t reng th" bo l t s a re very s imilar .T h e se tw o g ra d e s a r e w e ld a b le a n d sh o u ld b espec i f ied wh en poss ib le .

Wh e n h ig h - s t r e n g th b o l t s a r e r e q u i r e d , t h emater ia ls typ ica l ly ava i lab le a re A449, A354 andA 1 9 3 ty p e B 7 (o f t e n r e f e r re d to a s " B 7 " ) . B 7b o l t s a r e th e s a m e m a te ri a l a s A IS I 4 1 4 0 a n d c a nb e su b s t i t u te d fo r A 4 4 9 b e c a u se A 4 4 9 a n d B 7bol ts bo th have mater ial p rop er t ies th a t a re a lmostid e n ti c a l. A 3 2 5 b o lt s o n ly c o m e in " h e a d e d "form, a re limi ted to 1 1 /2 inch d iame ter max imumand are limi ted in the leng ths ava ilab le. Thepropert ies and chemistry for A325 bo lts are s im ilarto A449 and B7. Genera l ly , it i s be t te r to spec i fyA 4 4 9 , A 3 5 4 o r B 7 b o l t s w h e n h ig h - s t r e n g th b o lt sa r e n e c es sa ry . H ig h - s t r e n g th b o l ts c o m e a s p la inb a r s to c k a n d th r e a d s m u s t b e c u t i n to b o th e n d s.H e a d e d b o l t s f a b r i c a t e d f ro m A 3 2 5 , A 4 9 0 o rA588 should no t be spec i f ied s ince these a re no tread i ly ava i lab le . A l l o f these h igh s t rengthmater ia ls a re hea t t rea ted a l loy s tee ls and a retherefore no t su i tab le fo r weld ing . Beforespecifying a bolt material , c on tact local fabric atorsfor in format ion reg ard ing mater ia l av a i lab i li ty andre v ie w th e A S T M s t a n d a rd s fo r t h e g ra d e s b e in gcons idered to d e te rmine the i r su i tab i li ty .I t i s im p o r t a n t t o sp e c ify t h e c o r r e c t g r a d e o f n utth a t c o r r e sp o n d s to t h e sp e c i f i e d a n c h o r b o l tm a te r i a l. A S T M A 5 6 3 sp e c if i e s t h e v a r io u s n u tgra des tha t a re typ ica l ly used in bu i ld ingc o n s t ru c t io n a n d n u t s su i t a b l e fo r u se w i th t h ev a r io u s g ra d e s o f b o l t s ( s e e R e fe re n c e 4 ). T h e" H e a v y H e x " n u t s ty l e sh o u ld b e sp e c i f i e dregard les s o f the nu t g rade tha t i s se lec ted .F o o tn o te A b e lo w t a b l e X 1 . 1 m a k e s r e f e r e n ce toA S T M A 1 9 4 g ra d e 2 H a s a su b s t i t u t e fo r A 5 6 3w h e n c e r t a in s i z e s c o n fo rm in g to A 5 6 3 a r e n o tava i lab le . A19 4 is a spec i f ica t ion for p ressurevesse l and non-bui ld ing uses , bu t the gradesre f e r e n c e d in fo o tn o te A a re su it a b le fo r u se fo ranch or bo l t s in bu i ld ings .2 . 1 . 2 P l a t e s

T h e m o s t c o m m o n b a se p l a t e m a te r i a l s a r e A 3 6 ,A 5 7 2 a n d A 5 8 8 . F a b r i c a to r s r e sp o n d in g to t h eq u e s t io n n a i re r e c o m m e n d e d th a t A 3 6 m a te r ia l b espec i fied i f poss ib le becau se i t is the mo st read i lyavailable material. Th e table on the follow ing pa ge

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contains material availabilityguidelines based onplate thickness.

T a b l e 1 - A v a i l a b i l i t y o f P l a t e M a t e r i a lT hi c kne s s ( t )

,, ,

t _< 4 "

4" < t _< 6"

Pla te Avai lab i l ityA 3 6

A572 G r 42 o r 50A588 G r 42 o r 50

A 36A 5 7 2 G r 4 2A588 G r 42

t > 6" A362 . 2 B a s e P l a t e D e s i g n f o r F a b r i c a t i o nTypica lly , except for very la rge co lum ns w i th veryheavy base p la tes , such as for h igh r ise bu i ld ings ,base p lates a re shop welded to the co lumn. Unlessthe weld i s a co mp le te pene t ra t ion , weld , thebo t t om e nd o f the c o l um n ne e ds to be c u t s qua r eso tha t there wil l be fu ll bear ing w here the co lum nis in contac t wi th the base p la te . Som e years ago ,th i s was accompl i shed us ing mi l l ing machines int he s hop . T od a y t he c o l d s a wi ng e qu ipme n t u s e din mos t shops provides a co lu mn f in i shed end w i tha ma x i mum A NS I r oughne s s he i gh t va l ue o f 500wh i c h i s s a t i s f a c t o r y f o r c on t a c t be a r i ngc ompr e s s i on j o i n t s.For very la rge co lumns , the base p la te i s e rec tedf i r s t , us ing three leve l ing bol t s a round theper im eter of the base p la te to leve l i t, then thec o l umn i s e r e c t e d on t o t he ba s e p l a t e a ndc onne c t e d u s i ng a ng l e s o r o t he r c onne c t i onme t hods . T he ba s e p la t e i s g r ou t e d be f o r e t hecolumn i s e rec ted . Th e ma t ing sur faces should bep r e pa r e d by mi l li ng o r o t he r me a ns s o t ha t t hecolum n i s in fu ll con tac t wi th the base p la te . Useo f t h i c k ba s e p l a t e s c a n i n t r oduc e we l d i ngp r ob l e m s . due t o d i ff i cu l ty o f m e e t ing p r e he a trequi rements .2 . 2 . 1 M a t e r i a l v e r s u s L a b o rA c om mo n s ugge s t i on f r om s te e l fa b r i c a to r s fo rengineers to remember i s tha t "mater ia l i s cheap

re la t ive to labor ." I f spec i fy ing th icke r base p la teswi l l resu l t in no t hav ing to add s t i ffener p la tes tothe base plate , this wil l resul t in less labor tofabr ica te and wi l l resu l t in a more economicdes ign . Add ing s ti f feners and o the r p la tes to abase p la te assembly i s l abo r in tens ive co mp ared tous ing a th icker base p la te tha t cou ld e l imina te theneed for these addi t iona l s t i ffener p la tes .

2 . 2 . 2 W e l d i n gT he e ng i ne e r s hou ld a t t e m p t t o a t l e a s t ma t c h t heth ickness of the base p la te wi th the co lum n f langet h i c kne s s i n o r de r t o p r e ve n t wa r p i ng du r i ngweld ing , par t icu la r ly i f heavy weld ing , such aspar t ia l o r com ple te pene t ra t ion welds , i s requi redt o c onnec t t he c o l umn t o t he ba se p la t e. T h i c ke rbase p la tes wi thout s t i f feners a re of ten moree c onom i c a l tha n u s i ng a t h i nne r ba s e p l a t e w i t hst i ffeners . St i ffeners , i f used, w il l hav e an imp acton co lum n f in i sh d imens ions . See Sec t ion 4 .7"A rchi tec tura l I ssues" for fur ther d i scuss ion .Ano ther comm on sugges t ion f rom fabr ica tors i s toreduce we ld s izes as much as possible (but acc ou ntf o r m i n i mum AW S we l d s iz e s ba s e d on m a t e ri a lth icknesses ) and spec i fy f i l l e t welds in l i eu ofc om pl e t e pe ne t r a t i on we l ds w he r e pos si b le .Compl e t e pe ne t r a t i on we l ds r e qu i r e mor e l a bo rdue to the need to beve l the end o f the co lum n andfi t up, and require extens ive inspect ion . I t is m oreeco nom ica l to de ta i l l a rger f i ll e t welds , even i fmore w eld meta l i s requi red for the f i ll e t welds , asa subs t i tu te for par t ia l pene t ra t ion welds .Fabr ica tors have a lso po in ted out tha t "a l l a round " "welds should be avoided . F i l l e t welds tha t wrapa r ound t he f l a nge t oe s ( e nds o f c o l umn f l a nge s )a nd t he c o l umn we b- t o - f l a nge f i l l e t s ( t he "k"reg ion) can cause c racks due to h igh res idua ls t resses in the welds . Such welds of ten requi reweld ing repa i r . S top f i ll e t welds 1 /2 inch f romthese loca t ions . See F igure 1 for c la ri f ica tion .W elds should be de ta i led to a ccoun t for c learancesa nd a c c e s s o f we l d i ng e qu i pme n t . Obv i ous l y t hee ng i ne e r s hou l d no t s how we l ds t ha t a r e

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impossible to access. For example, a commonmistake is to specify "all around" welds at platewashers that are backed up against the columnflange or web.High strength bolts fabricated from high strength,heat treated steel (such as A354, A449 or B7)cannot be welded - not even tack welded - withoutadversely affecting the properties of these steels.2 . 2 . 3 B a s e P l a t e D i m e n s i o n s

Wh e re p o s s ib l e , t h e p l a t e d im e n s io n s a n d b o l tpa t te rn of base p la tes should be symm etr ica l aboutb o th a x e s. T h i s w i l l p r e c lu d e w e ld in g th e b a sep la t e ro t a t e d 9 0 d e g re e s f ro m th e c o r r e c to r i e n ta t i o n . H a v in g a d o u b ly sy m m e t r i ca l b o l tpa t te rn wi l l a l so he lp avoid po ten t ia l f ie ldproblems (See Sec t ion 3 .1 .2) .T h e e n g in e e r sh o u ld t ry t o sp e c i fy t h e s a m e b o l th o le d i a m e te r w h e n e v e r p o s s ib l e to e l im in a t e t h eneed fo r mul t ip le d r il l b i t s izes . This a lso appl iesto any ven t ho les requi red to v en t ou t a i r fromu n d e r t h e l a rg e r b a se p l a t e s d u r in g th e g ro u t in gopera t ion .O b v io u s ly t h e b a se p l a t e d im e n s io n s sh o u ld b esuff ic ien t to accommodate the co lumn d imens ionsp lus anchor bo l t ho les wi th suf f ic ien t d imens ionsto t h e c o lu m n f l a n g e s a n d to t h e e d g e o f t h e b a sep la te . A lso acco unt fo r any square p la te wash ers ,i f used . Severa l fabr ica tors have s ta ted tha te n g in e e r s so m e t im e s e r ro n e o u s ly a s su m e th e i r" typical" base plate detai l wil l cove r al l condit io ns.C o lu m n s th a t a r e i n d i ff e r e n t s iz e g ro u p s r e q u i red i f fe ren t base p la te s izes . I t is genera l ly moreeconomica l to des ign a " typ ica l" la rger base p la teto c o v e r m o re th a n o n e c o lu m n s i z e i n a c o lu m ng ro u p ( su c h a s Wl0 , W1 2 , W1 4 g ro u p in g s ) , t h a nto design specific base plates for each colum n size.T h e f e w e r v a r i a t i o n s o f b a se p l a t e s r e q u ir e d w i l lg e n e ra l ly r e su lt i n e c o n o m y in fa b r i c at io n e v e n i fmore mater ia l i s requ i red . This is t rue because ofthe labor sav ings in shop draw ing prep ara t ion andthe d i f fe ren t shop se tups requi red for eachvar ia t ion in base p la te conf igura t ion . I t i s a l sot ru e th a t h a v in g f e w e r " d i f f e r e n t " a n c h o r b o l t

pa t te rns wi l l lead to less conf iasion dur ing anchorbol t p lacemen t . See F igu re 1 on the fo l lowingpage for sugges ted de ta i l s .

3 .0 D E S I G N G U I D E L I N E S R E L A T E D T OE R E C T I O N

A n c h o r b o l t s a n d b a se p l a t e s sh o u ld b e d e s ig n e dand de ta i led to a ccom mo date s tee l e rec t ion loads .Som e simple, yet effecctive, at ten tion to detai ls a ndd im e n s io n s c a n g o a l o n g w a y in h e lp in g top re v e n t so m e c o m m o n p ro b le m s e n c o u n te re ddur ing s tee l co lum n erec t ion . A prev ious ed i t iono f Steel Tips (Reference 7) con ta ins usef ia ls t ra teg ies fo r dea l ing wi th common f ie ld e rec t ionerrors .3 .1 A n c h o r B o l ts

Anch or bo l t p lacement i s obvio us ly a d i f f icu l t taskbut too of ten e r rors resu l t due to poor qua l i tycont ro l and qua l i ty assurance or lack ofprepa redne ss in the des ign . The re a re severa lways to mis loca te anchor bo l ts and typ ica l ly one ofthe fo l lowing wi l l occur.3 . 1 . 1 A n c h o r B o l t P o s i t i o n M i s l o c a t io n

P o s i t i o n m is lo c a t io n i s u n fo r tu n a t e ly a c o m m o np ro b le m . T h e h o r i z o n ta l l o c a t io n o f t h e a n c h o rbol ts i s o f ten incorrec t by as much as 1 to 2 inches .In some cases one o f the anch or bo l t s i s no t in thecorrec t loca t ion wi th respec t to the rem ain ing bo l t sand in o ther cases the en t i re layou t i s in the w ron gloca t ion . There a re severa l wa ys to avoid th isp ro b le m d u r in g th e d e s ig n p h a se .1. T h e b e s t m e th o d fo r p r e v e n t in g a n c h o r b o l tm i s lo c a t io n i s f o r t h e c o n t r a c to r t o p ro p e r ly s e ta n d h o ld a n c h o r b o l t s i n t h e c o r r e c t p o s i t io n fo rp lan loca t ion and e leva t ion . I t i s the cont rac torsrespons ib i l i ty to se t anc hor bo l t s cor re c t ly wi th inth e to l e ra n c e g iv e n in t h e A IS C C o d e o f S t a n d a rdP ra c t i c e (R e fe r t o R e fe re n c e 3 ). A c h e c k b y a nin d e p e n d e n t su rv e y o r w i ll h e lp l o c a t e m i sp l ac e dbolts before steel is erected so tha t co rrect ions canb e m a d e b y th e c o n t r a c to r b e fo re s t e e l e r e c tio n

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