Holding Down Bolts

Project

Job Ref.

Section

Sheet no./rev.

1 Calc. by

Date

A

Chk'd by

Date

App'd by

Date

09-Jan-12

L_proj (Clear projection of bolt above nut)

t_was (Washer thickness)

t_p (Base plate thickness t hickness))

t_gr (Thickness of bedding)

Concrete

L_bolt (Overall length of bolts)

PULL-OUT CAPACITY OF HOLDING DOWN BOLTS These calculations calculations assume that there is no coexistent shear in the holding-down bolts. Tension capacity of bolts ;

Maximum tension force per bolt; bolt ;

;

Try M24 (Grade 8.8); 8.8) ; bolts; bolts;

Ft = 29.0 kN Pt = 158.9 kN ;

dnut = 19 mm Check F t t  ≤ ; Pass Pass - Bolt tension capacity ;  ;  ≤    P t  t  ; 

Pull-out resistance of concrete ;;

Overall length of bolts; bolts;

Lbolt = 1000 mm

;

Clear projection of bolt above nut; nut;

Lproj = 25 mm

;;;

Thickness of washer, baseplate & grout; grout ; Depth of embedment; embedment ;

twas = 2 mm ;

tp = 25 mm ;

de = Lbolt - Lproj - dnut - t was - t p - t gr = 879 mm

From BCSA HDBolts document, effective conical surface area ; for two bolts; bolts;

;

tgr = 50 mm

Depth of embedment selected; selected ;

de = 879 mm

Design spacing of bolts (c/c); (c/c) ;

Xccs = 75 mm

Shear strength of concrete; concrete;

vc = 0.34 N/mm2

Design pull-out resistance, per bolt; bolt ;

Ptc = Aec × vc / 2 = 627.0 kN

Aec = 36885.0 cm 2

Check F t t  ≤ ; Pass Pass - Concrete pull-out resistance  ≤    P tc  tc  ;  Bolts require adequate anchorage by suitably sized washer plates or equivalent under the bolt heads. BS 5950: Part 1: 2000: Sections 4.13 & 6.6 'Holding down systems for steel stanchions' BCSA / Constrado 1980

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