Erstantie 2, FIN-15540 Villähde AHK column shoes · Erstantie 2, FIN-15540 Villähde AHK column...

Erstantie 2, FIN-15540 Villähde AHK column shoesTel +358-3-872 200, Fax +358-3-872 2020 Manualwww.anstar.eu 2


CONTENTS Page

1 PRODUCT DESCRIPTION............................................................................................................................................... 4

2 SHOE STRUCTURE ........................................................................................................................................................ 4

2.1 PRODUCT RANGE ..................................................................................................................................................................... 42.2 MATERIALS ............................................................................................................................................................................. 42.3 MATERIALS ............................................................................................................................................................................. 42.4 MANUFACTURING TOLERANCES ................................................................................................................................................. 42.5 QUALITY CONTROL AND MARKING .............................................................................................................................................. 42.6 COLUMN SHOE DIMENSIONS AND THE USE OF STANDARD SHOES IN DIFFERENT CROSS SECTIONS ............................................................ 5

3 COLUMN SHOE CAPACITY ............................................................................................................................................ 7

3.1 DESIGN PRINCIPLE .................................................................................................................................................................... 73.2 SHOE CAPACITY ....................................................................................................................................................................... 73.3 STRUCTURAL DESIGN USING COLUMN SHOES ................................................................................................................................ 7

4 THE USE OF COLUMN SHOES ....................................................................................................................................... 8

4.1 RESTRICTIONS ON THE USE ........................................................................................................................................................ 84.2 PLACING OF JOINT .................................................................................................................................................................... 8

4.2.1 Design strength of concrete ....................................................................................................................................... 84.2.2 Additional reinforcement ........................................................................................................................................... 94.2.3 Design of column main reinforcement ...................................................................................................................... 94.2.4 Capacity correction ................................................................................................................................................... 10

4.3 DURABILITY AND FIRE PROTECTION ........................................................................................................................................... 10

5 ASSEMBLY ................................................................................................................................................................. 10

5.1 FIXING SHOES TO FORM WORK ................................................................................................................................................. 105.2 COLUMN ASSEMBLY ON SITE .................................................................................................................................................... 105.3 ASSEMBLY TOLERANCES .......................................................................................................................................................... 115.4 SAFETY PRECAUTIONS ............................................................................................................................................................. 11

6 ASSEMBLY CONTROL ................................................................................................................................................. 11

6.1 WORK AT THE PREFAB FACTORY ............................................................................................................................................... 116.2 COLUMN ASSEMBLY ON SITE .................................................................................................................................................... 12


1 PRODUCT DESCRIPTION

AHK column shoes are used to connect prefab concrete columns to foundations, walls or othercolumns. The bolted joint consists of a steel shoe that is cast into the concrete column and athreaded rebar placed in the foundation or in the top of a concrete wall or column. When thecolumn shoe base plate has been fixed between washers and nuts of the bolt assembly loadscan be transferred without additional support. When the grouting and nuthouse fillings havereached their compressive strength, the bolted joint can transfer the design loads.

The grouting transfers compressive forces to the structure below the column. The bendingmoment is transferred via tension bolts and compression in the grout and other bolts. Duringassembly, shear forces are transferred via the bolts, after grouting the friction between baseplate and concrete will also carry shear loads.

2 SHOE STRUCTURE

2.1 Product rangeThe standard AHK shoe can be used in either rectangular or round column cross sections or inconcrete walls. The shoe can be placed in the corner or on the side.

AHK column shoes are used together with Anstar threaded ATP and AHP rebars and are thereforesuited to bolted connections with normal force and a bending moment caused by structuraleccentricities. Column-to-foundation joints with heavy bending loads are produced with Anstar APKcolumn shoes and high strength foundation bolts.

2.2 MaterialsThe column shoes are produced with following materials- Base plate EN 10025-2 S355J2+N, S355J0+N, S355K2+N- Nut housing EN 10025-2 S355J2+N, S355J0+N, S355K2+N- Anchor bars EN 10088 B500B

2.3 MaterialsThe steel parts are manufactured according to:- standards EN 1090-1 and EN 1090-2- base plates are cut with blowpipe- anchor bars are mechanically cut- rebars are MAG welded by hand or by robot according to standard EN 17660-1

welding class C according to EN ISO 5817- surface treatment: the base plate is coated according to EN ISO 12944-5 S2.01

on request hot dip galvanizing according to EN ISO 1461.

2.4 Manufacturing tolerancesThe column shoes are produced with following tolerances:- steel plate dimensions +0-3 mm- bolt hole diameter ± 2 mm- bolt hole position ± 2 mm- anchor bar position ± 2 mm- total height ±10 mm

2.5 Quality control and markingAnstar Oy has a quality control agreement with Inspecta Certification andNordcert. The shoe production is certified according to standards EN1090-1, EN 3834-2 and EN 17660-1.The shoes are manufactured with following markings:- control mark for Inspecta Certification and Nordcert- company name ANSTAR, CE-mark, product type and week of manufacture


2.6 Column shoe dimensions and the use of standard shoes in different cross sectionsAHK shoes are typically used in rectangular column cross sections, one separate shoe part in everycorner. The concrete cover for the anchor bars are then 43-45 mm. The nut-housing roof is made ofsteel plate.

Ø

D1

A

T

B

43-45

A1

E

E

D1

H

B1

Fig 1. AHK column shoe

Table 1. AHK column shoe dimensionsType A A1 B B1 E H D1 Ø T weight colour

mm mm mm mm mm mm mm mm mm kgAHK16 80 95 80 136 50 685 2T10 25 12 1,9 yellowAHK20 86 103 95 162 50 812 2T14 30 15 3,5 blueAHK24 95 112 110 192 50 1135 2T16 35 20 6,5 l. greyAHK30 107 133 120 227 50 1430 2T20 40 25 11,5 greenAHK36 130 162 130 262 60 1615 2T25 50 30 20,0 d. greyAHK39 138 173 140 277 60 1830 2T25 54 35 24,1 orangeAHK45 160 205 140 307 60 1840 2T32 60 45 40,0 l. greenSymbols: A = width of nut housing

A1 = total width of shoeB = height of nut housingB1 = height of wall plateE = bolt hole edge distanceH = total height of shoeD1 = diameter of anchor barsf = bolt hole diameterT = thickness of base plate


AHK column shoes can also be placed in walls or on the column side, the front end of thebottom plate is then fixed to the formwork. The nut housing is filled with a separate recessformer AHK-K and the roof plate is removed. In table 2 you can find the dimensions forrectangular cross sections with six column shoes.

When using AHK standard shoes in round cross sections, the nuthouse is produced with therecess former AHK-P and the roof plate is removed. The front edge of the base plate is fixed tothe form work. The concrete cover to anchor bars in now 56-80 mm.

DE

F

E

60°

R

E

B

L C

E

60°

R

E

B

Fig 2. Column cross section with six AHK in rectangular and four in round column

Table 2. Column and recess former dimensionsRecess D F Cmin S E R Bformer type mm mm mm mm mm mm mmAHK16K, -P 200 280 230 140 50 25 80AHK20K, -P 210 320 250 150 50 30 95AHK24K, -P 230 350 280 160 50 35 110AHK30K, -P 280 400 340 190 50 45 120AHK36K, -P 330 500 400 230 60 55 130AHK39K, -P 350 540 440 240 60 60 140AHK45K, -P 410 640 540 280 60 75 140Symbols: D = minimum side dimension for a square cross section with four shoes

F = minimum side dimension for a rectangular section with six shoes per sideCmin = minimum diameter for a round column with four shoesS = minimum thickness for a concrete wall with an AHK shoeE = bolt edge distanceR = inside radius of nut housing wall plateB = height of nut housingL = c/c-distance for bolts


3 COLUMN SHOE CAPACITY

3.1 Design principleThe AHK steel shoe design is made according to:

- EN 1992-1-1 Eurocode 2: Design of concrete structures – General rules for buildings- EN 1993-1-1 Eurocode 3: Design of steel structures – General rules for buildings- EN 1993-1-8 Eurocode 3: Design of steel structures – Design of joints

Lap length in concrete C35/45 for cases with other than good bond conditionsEN 1992-1-1: 8.4 η1 = 0,7 η2 = 1,0 α3 = 0.7 α1 = α2 = α4 = α5 = 1,0 α6 = 1,5 γc / γs = 1,25

3.2 Shoe capacityThe capacity of the bolted joint is determined for normal forces and shear forces by thefoundation bolt given in table 3.

Table 3. AHK column shoe capacity [kN]Shoe type Normal force

NRd

Shear force VRd

Corresponding foundation bolt

C35/45 C35/45AHK16 62,2 3,7 ATP16, AHP16AHK20 97,0 6,9 ATP20, AHP20AHK24 139,7 10,9 ATP24, AHP24AHK30 222,1 19,1 ATP30, AHP30AHK36 323,5 30,3 AET36, AES36AHK39 386,5 36,7 ATP39, ATH39AHK45 517,2 50,8 AET45, AES45Symbols: NRd = design value for normal force

VRd = design value for shear force

3.3 Structural design using column shoesThe bolted column-to-foundation or column-to-column joint for an actual load case is designedby calculating the normal force acting in the bolt (section through the grout joint) and bychoosing bolt size to be used, then the corresponding column shoe size is determined. Theeasiest way to do this is by using the design program COLJOINT that can be down loaded fromAnstars home pages www.anstar.eu. The program is based on the assumption that the groutingis done with a non-shrinkable, expansive grout with at least the same strength as the columnconcrete. When the grouting has reached its design strength the shear forces are usuallytransferred via friction (EN 1993-1-8 chapter 6.2.2). Stirrups are placed into the column basearound the shoes and the foundation upper part to transfer shear forces.

The column is assembled on the foundation bolts with nuts and washers placed in the correctheight level. The bottom plate is fixed with upper washers and nuts to the bolt using tighteningtorque given in bolt brochure. The bolt is designed for compression load caused by dead loadand bending moment caused by wind load.

The bolts must be able to transfer the design bending load caused the shear load with lever arm(wind load).

MEd = 0,5 * VEd* (M/2 + G + T/2)

Symbols: M = bolt diameter (mm)G = grout thickness (see table 7)

T = base plate thickness (mm)


The above equation is based on the assumption that the shear force is acting in the centre ofthe base plate (CEN/TS 1992-4-1 (2009): Design of fastenings for use in concrete – General,chapter 5.2.3.4). The shear load gives the bolts a small displacement adding to the bendingload, flexural buckling must therefore be considered especially for bolts with a small crosssection (M16 and M20).

Column assembly on nuts and washers without additional support is a short term load case, thegrouting of nut housings and the joint base plate–foundation concrete should be done as soonas possible, preferably the same working day. More load must not be applied to the columnswithout this grouting, the structural engineer will decide when the grouting has reachedacceptable compression strength for further assembly.

4 THE USE OF COLUMN SHOES

4.1 Restrictions on the useThe column shoes have been designed for static loads only. For dynamic loads all projects shouldbe checked separately, if shoes can be used bigger safety factors should be chosen.

4.2 Placing of joint4.2.1 Design strength of concrete

The column shoe capacities have been determined with following assumptions:1. Column-to-column joint

The column shoes are designed for concrete C35/45, if the cross sections remain the samein the joint the grouting must have at least the same compression strength as the columnconcrete.

2. Column-to-foundation jointThe column joint is designed for column concrete C35/45 and foundation concrete C25/30.The lower compression strength is considered by using a bigger cross section and apartially loaded foundation area, see fig 3.

3. Grouting of nut houses and base plate-to-foundation concrete jointThe grouting transfers compression loads and protects against fire. The grout should benon-shrinkable and have at least the same strength as the column concrete.

In cold environments snow and ice should be melted and the grouting protected withwarming and/or mechanical protection so that the grouting can reach its design strengthwithout freezing.

C35/45

C35/45

C35/45

C35/45

C35/45

C25/30

Fig 3. Concrete strengths in different joint structures


4.2.2 Additional reinforcement

Beside standard stirrups additional stirrups Ast3 should be placed according to fig 4 to act againstsplitting forces (e.g. Eurocode 2: 8.7.4).

Ast1

Ast2

lla

ple

ngth

0

l

150

03

Ast

3

l 03 A

st3

Ast3A

st

Fig 4. AHK Column shoe additional reinforcement

Table 4. AHK Column shoe additional reinforcementShoe Ast1 Ast2 Ast3 l0

type U-links/column 1-leg link 1-leg link mmAHK16 4T6 1T8 (24 mm2) 2T8 (101 mm2) 550AHK20 4T6 1T8 (40 mm2) 3T8 (157 mm2) 690AHK24 4T6 2T8 (55 mm2) 4T8 (157 mm2) 990AHK30 4T8 2T8 (95 mm2) 5T8 (246 mm2) 1260AHK36 4T10 3T8 (120 mm2) 5T10 (402 mm2) 1435AHK39 4T10 2T10 (150 mm2) 5T10 (402 mm2) 1550AHK45 4x2T10 4T10 (255 mm2) 5T10 (402 mm2) 1770

4.2.3 Design of column main reinforcement

The lap joint has been designed for single rebars without bundling. Design bond condition withvarious coefficients have been presented in chapter 4.1.1.

In a rectangular cross section one main rebar is placed in the corner of shoes AHK16-AHK36.With shoes AHK39 and AHK45 two main rebars are used, one in the stirrup corner on the nuthouse roofing and the second between the nut houses. When rebars are bundled the lap jointlength should always be checked. In round columns either 6 or 8 rebars are placedsymmetrically in the cross section.


4.2.4 Capacity correction

Normal forceFor columns with a lower concrete strength a capacity reduction depending on the tensionstrength will be used:

n1 = fctd l/fctd C35/45 < 1where fctd l is the design tension strength of actual concrete to be used

Shear forceThe concrete strength affects on the anchoring of stirrups which can be handled withoutreducing the shoe capacity.

4.3 Durability and fire protectionThe bolted joint is protected for the same exposure class as the structural frame, the joint canalso be protected for a higher exposure class.

1. Anchor barsThe concrete cover is chosen on the basis of working life and exposure class according toEN 1992-1-1 chapter 4 and national requirements. The concrete cover 43-45 mm issufficient for a 120 minute fire. For more protection the shoe is placed inside the crosssection.

2. Steel platesUnprotected bottom plate works up to 60 minute fire. A simple way to protect the steelplates against fire and corrosion is to place the joint into the floor structure. In exposureclass XO the base plate can be visible if no fire protection is needed and if the plate canlater be repainted. In cold and damp class XC structures the shoe can be hot dipgalvanized. In exposure classes XD and XS the structural designer must check if hot dipgalvanizing can give a sufficient protection for the chosen working life with a concrete coverthat is reinforced against cracking to keep water from penetrating into the joint.

5 ASSEMBLY

5.1 Fixing shoes to form workThe separate shoe parts can be bolted to the form work or welded together to a monolithic part.The edges of the base plate are placed against the form work. The base plates should be at thesame level and perpendicular to the column axis.

Column shoes are fixed to the form work with ± 2 mm tolerance.

5.2 Column assembly on siteThe bolts lower nuts and washers are levelled to equal the column base. The column is lifted onthe washers and the bolts are provided with washers and nuts in the nut housings. The columncan be adjusted to its correct vertical position by turning the nuts. The nuts are tightenedaccording to instructions given in the bolt manual and the lifting device can be released. The nuthousings have been designed for slug wrenches according to standard DIN 7444. The groutingof base plate and nut housings is done with non-shrinking, expansive grout according to groutmanufacturer’s instructions.

The foundation bolts to be used together with AHK column shoes are placed according to table5.


GA

Table 5. Bolt height levelShoe type A G

mm mmAHK16 105 50AHK20 115 50AHK24 130 50AHK30 150 50AHK36 170 60AHK39 180 60AHK45 195 70

Symbols:A = bolt height level measured from foundation concreteG = grout thickness under base plate

5.3 Assembly tolerancesThe bolt group is placed with a tolerance ± 5 mm and the column shoes are fixed to form workwith the tolerance ± 2 mm. The bolt hole diameter is 10 mm bigger than the bolt diameter forshoes AHK16-AHK30 and 15 mm bigger than the bolt diameter for shoes AHK36-AHK45. Thistolerance has proved to be sufficient when the foundation bolts are placed on site with lasertechnology. If the bolt hole size is not big enough for the combined tolerances and this cannot beaccepted the situation can be corrected in the following manner.

Correcting proceduresThe bolt hole can be made at maximum 10 mm bigger on one side only. The standardwashers are replaced with bigger and thicker washers so that the bigger bolt hole iscompletely covered. The joint capacity must be checked for the new bolt position.

If the production schedule allows it the column can be manufactured with a bigger shoe typee.g. foundation bolt AHP24 and column shoe AHK30. It is important that the tolerances arechecked immediately after concrete casting so that suitable correction measures can betaken.

Not acceptable correction methods- foundation bolts may not be bent or heated- foundation bolts may not be cut and welded into a new position- foundation bolts may not be welded into the base plate- the bolt hole may not be widened more than said above- the shoe structure may not be altered by cutting or welding

5.4 Safety precautionsColumns must be assembled according to plan that considers working order, support andgrouting. Columns can transfer further loads when the grouting has reached its design strength.

6 ASSEMBLY CONTROL

6.1 Work at the prefab factory

Before concrete casting- check that shoes are according to plan and that steel parts are undamaged- check that shoes are positioned correctly in the formwork (edge distance, bolt hole c/c

distance).- check that shoes are tightly fixed to formwork and nut houses are protected against concrete

leaking inAfter demoulding- measure bolt hole positions and compare to given tolerances- check the concrete casting around the shoes and see that nut housings and base plates are

clean


6.2 Column assembly on siteThe bolt joint is assembled according to plan using the following check list- check that assembly order is according to plan- check the need for support before grouting- check height level and vertical position- check that nuts are tightened according to plan- check grouting material and grouting schedule- check grouting quality

Erstantie 2, FIN-15540 Villähde AHK column shoes · Erstantie 2, FIN-15540 Villähde AHK column...

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