Design of Base Plate and Bolts Final

 

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Design of base plate for Axial Load and Moment

(RHS to Base Plate Connection)

Ultimate Bending Moment

MULS =

45.724 kNm

Utimate shear load on plate

VULS =

Utimate axial load on plate Steel column: 250x150x9 RHS W idth of 'RHS' column Depth of 'RHS' column minimum edge distance for bolts c/ c distance between bolts 'h' Length of Base plate W idth of Base Plate

NULS =

kN -0.39 kN

bf d k h hp Bp

Grade of concrete

 = = = = = =

fcu =

Permissible Bearing stress in concrete (0.6*fcu)

=

17.6

150 250 37.5 300 400 300

mm mm mm mm mm mm

32

Mpa

19.2

Mpa

With the trial plate dimensions chosen above and as per the Permissible bearing stress in concrete, the equilibriu equilibrium m eqation is:

Try x

Bp 

LHS 45724000 Compressive Force Tensile Force i)

= =

C = 0.6* Fcu*Bp*x T = C - NULS

27.72

= =

= =

mm RHS 45725873

159.6672 160.054

LHS equals RHS  OKAY 

kN kN

Bas Base e Plate Plate thick thicknes ness s for Co Compr mpress ession ion Side Side Bend Bending ing:: sw

=

sw

=

e e

= =

mc = = mc =

we weld ld si size ze for colu column mn to base base p pla late te weld weldin ing g 6 L1- 0.8*sw 70.2

mm ………….say

mm

mome moment nt pe perr mm mm w wid idth th appl applie ied d to to pla plate te st stre ress ss bloc block k 0.6* fcu * x * (e - x/2) 0.0299855 kNm

Grade of steel……….

fy =

250

Mpa Pressure below the Base plt (Comp side)

tp

=

=

21.904 mm

 

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Base Plat Plate e tthickn hickness ess for Tension Tension Side Bend Bending: ing: sw sw

= =

we weld ld si size ze for colu column mn to base base p pla late te weld weldin ing g 6 mm ………….say

m

= = =

cl clea earr di dist stan ance ce betwe etween en wl wled ed and and bolts olts L1 - k -( 0.8*s w) 32.7 mm

m

mc = = mc = tp

mome moment nt pe perr mm mm w wid idth th appl applie ied d to to pla plate te st stre ress ss bloc block k T*m 5.23

=

Provide

kNm =

22

16.707 mm

mm thick base plate.

Required base plate dimensions as per design are :

hp p= = 40 00 0 m mm m B 3 tp = 22 mm Thus, base plate size required is 400mm x300mm x300mm x22mm mini thickn ess w/o stiff ners

However providing maximum plate thickness = 16 mm, hence hence need to provide plate stiffn ers for reducing the effect of bending. STIFFNERS: Provide 8 mm thick stiffner plates, triangular in shape, around the RHS column. 2 stiffners at Long face 250 mm and 1 stiffner at short face 150 mm, each side. Weld Design : Connect 8mm thick stiff ner plate to RHS column and Base plate w/ 6mm fillet weld at each face. 6mm Fillet Weld

 

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Design of Holding down bolts Calculation of number of bolts: Diameter of bolt = 16 mm…………try Grade of bolt to be used : 8.8 Capacity of bolt in Tension = 104 kN…….threads included Capacity of bolt in Shear = 59.3 kN…….threads included (Ref from Steel Designers Handbook) Total tensile force on tension side bolts Total shear force on tension side bolts No. No. of bolt bolts s re reqd qd to re resi sist st Tens Tensio ion n Forc Force e ## No No.. of bolt bolts s re reqd qd to re resi sist st Shea Shearr Forc Force e

4

Provide

160.05 kN 17.6 kN

= = =

1.5 1.5 no's no's

=

4 no no's 's

bolts on either side of column for bending @ major axis.

 Actual tension in each bolt  Actual shear in in each bolts

40.01 kN 4.397 kN

= =

Combined check for Tension + Shear : Tactual

Vactual

Provided number of b olts are OK

+ Tpermissible

=

0.4589

<

1

Vpermissible

Calculation of Embedment length 'L' of bolts: f bu bu

=

f bu bu

=

……Permissible ……Permissi ble Ultimate bond stress of concrete 0.33*(fcu)

^0.5

T π

Thus,

Mpa

1.86676

L

* bolt dia * L

=

426.65 mm

Minimum mm embedment length in concrete is required. 430.0 However a separate Hilti design calcs run is carried out and attached below with final recommendations for  Anchor design design

 

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