Shear Wall With Boundary Element

Structural Design Calculation

SHEAR WALL BOUNDARY ELEMENT (AS PER ACI318M-11)

Published by: E.G Navarro CE- Mindanao University of Science and Technology 20-May-14

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Structural Design Calculation DESIGN OF BOUNDARY ELEMENT PARAMETERS fc' = fy = Lw = b= C= Mu = Vu = cc = d= dhoop =

32.0 MPa 460.0 MPa 3000.0 mm 300.0 mm 502.0 mm 2700.0 KN-m 450.0 KN 30 mm 16 mm 10 mm

(concrete compressive stregth) (yeild strength of reinforcement) ( length of wall) (thickness of wall) (neutral axis depth from etabs) (ultimate moment from etabs) (ultimate shear from etabs) (clear concrete cover) (size of vertical bars) (size of boundary ties/hoop)

Lw b

boundary element

boundary element

ETABS OUTPUT

vertical reinforcement provided = T16@200mm c/c shear/horz. Reinforcement required = T10@200mm c/c =

785.40 mm²

BOUNDARY ELEMENT CHECK ( DISPLACEMENT BASE)

>

750.0 mm² OK!

( ACI 21.9.6.2 )

Wall not satisfying this requirement in 21.9.6.2 shall be design by 21.9.6.3

equation 21-8

C Left top Right top Left bot Right bot

= N/C = N/C = 0.502 = 0.502

C Limit

< <

= N/C = N/C = 0.714 = 0.714

check comp. stress (21.9.6.3) check comp. stress (21.9.6.3)

BOUNDARY ELEMENT CHECK ( STRESS BASE) Stress Compression Left top Right top Left bot Right bot

= = = =

1555.56 1555.56 7765.56 7765.56

( ACI 21.9.6.3 ) Stress Limit

< < > >

= = = =

not required! not required! boundary element required! boundary element required!

6400.00 6400.00 6400.00 6400.00

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Structural Design Calculation HEIGHT OF BOUNDARY ELEMENT ( Hb)

( ACI 21.9.6.2b )

The special boundary element reinforcement must extend vertically from the critical section a distance not less than the larger of Lw or Mu/4Vu. Lw = 3000.0 mm Mu/4Vu = 2,700.0 / 4 x 450.0 = 1500.0 mm

boundary element

Hb

Hb = 3000.0 mm

LENGTH OF BOUNDARY ELEMENT ( Lb)

( ACI318-11, section 21.9.6.4a )

The special boundary element reinforcement must extend horizontally from the extreme compression fiber a distance not less than the larger C-0.1Lw or C/2. C-0.1Lw = 502.0 - 0.1 x 3,000.0 = 202.0 mm C/2 = 502.0 / 2 = 251.0 mm Lb = 251.0 mm Lbprovided = 300.0 mm

(boundary element length provided)

HOOP REINFORCEMENT (Ash)

( ACI318-11, section 21.6.6.4b )

Lbprovided Ash = 0.09.S. bc. fc'/fy S = 200.0 mm bc = 188.0 mm

(spacing of hoops) (as per figure)

b

Hoop minimum reinforcement equals to maximum of ( Ash1 or Ash2) Ash1 = 0.3.S. bc. fc'/fy ( Ag/Ach -1) = 0.3x200.0 x 188.0 x 32.0 / 460.0 (( 900,000.0 / 705,600.0- 1)) = 216.2 mm² Ag = 900000.00 mm² Ach = 705600.00 mm²

bc

(gross area of concrete section) (cross section area of concrete measured from outside of transverse reinforcement)

Ash2 = 0.09.S. bc. fc'/fy = 0.09x200.0 x 188.0 x 32.0 / 460.0 = 235.4 mm² Using Ash provided = 235.62 mm²

T10

@

200mm c/c >

3 LEGS 235.41 mm²

2

OK!

Structural Design Calculation BOUNDARY ELEMENT DETAIL 300.0 mm

300.0 mm

T10

200mm c/c @ 3 legs ties

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