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T5 Q.1

(i) Concrete Pressure acting on formwork Density of wet concrete = 25 kN/m3

K = (36/(T+16))sq = 2.939

C1= 1.0 (Wall Form) C2= 0.5 (Mix w/retarder)

Q = 13.5 m3/hr  T = 5.0 oC (Assume lowest temperature for the max. design conc. Pressure)

H = 5.0 m L = 14.0 m W = 1.5 mR = Q/A m/hr  

= 0.643 m/hr 

Pmax=25(C1*sqrt(R) + C2*K*sqrt(H-C1*sqrt(R))) or D*h whichever is the smaller  (CIRIA Report 108)

= 87.79 kN/m3

3.51 m (= Pmax/D)

F1

Wet Concrete Height=

2.0 m 5.0 m

F2 1.49 m

1.0 m

87.79 kN/m3

(ii) Strut Design

Consider 1.0m width,F1= 1/2 x 87.8 x 3.51

= 154.13 kN/m

F2= 87.8 x 1.49

= 130.68 kN/m

Overturning moment, Mo:

Take moment about P2,

Mo = 154.13 x [1/3 ( 3.5 ) + 1.49 - 1.0 ]

+ 130.68 x [1/2 ( 1.5 ) - 1.0 ]

= 222.29 kNm/m

Resisting moment, Mr:

Take moment about P2 o

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Take moment about P2 o

Tutorial 5 Q.2

Steel Bracket Calculation

15 kN 800 mm

500 mm

(a) Two anchor boltsOverturning moment, Mo = 15 x 0.8 = 12.0 kNm

Factor of safety = 2.0sion / Compression on each bolt, F = 12.0 x 2.0 / 0.5

= 48 kN

(b) Three anchor bolts

Take moment at the lowest bolt, resisting moment, MR

= 48 x 0.5 + 48 x 0.5 / 2

= 36 kNm

Factor of safety = 36 / 12.0 = 3.00Enhancement = ( 3.00 - 2.0 ) / 2.0 = 50.0%