Krishna Anish Adusumilli
Core Wall Design Calculations Athul Parayancode
(Storeys 1-7)
Design for Flexure:
Longitudinal Steel design
f'c 5000 fy 60
l_req 0.013 Determined with the P-M interaction diagram
lw_NS 18 +4 = 220 Length in the N-S direction
lw_EW 11 +8 = 140 Length in the E-W direction
b 16 Thickness of the wall
2
Ag lw_EW b 2 + lw_NS 2 b b = 7488
2
Asl_req l_req Ag = 97.34 Area of longitudinal steel required
Try #9 bars with 2 curtains:
2
Ab9 1
Asl_req
#bars ceil = 98
Ab9
Approximate spacing:
2 lw_EW + lw_NS
spacing = 10.31 Provide 9" on center
((#bars 1))
2
Since this spacing is approximate 2 curtains of #9 @ 9" on center will be used hx 8
Development length required in the foundation:
t 1.3 db9 1.128
fy t
ld9 db9 = 5.2 Provide 5.5' Development length
f'c
20
Boundary Element Checks
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Krishna Anish Adusumilli
Core Wall Design Calculations Athul Parayancode
(Storeys 1-7)
Boundary Element Checks
Positive Moment in the N-S direction:
hw 14 9 + 16 = 142
hw lw_EW
= 12.17 = 8.75 As per ACI 318-14, Table R18.10.1 the
lw_EW b governing design will be for a wall.
hw
2.0 , Check B.E. , No check required = Check B.E.
lw_EW
u
min ((0.005 , 0.010)) As per ACI 318-14 section 18.10.6.2
hw
Per ACI 318-14 ssection 18.10.6.2:
lw_EW lw_EW
a) cmax_NS cmax_NS = 15.6
u 600 ((1.5 0.010))
600 1.5
hw
From the P-M Interaction diagram cpos_NS 0.18 lw_EW = 25.2
cpos_NS cmax_NS , B.E. Required , B.E. Not Required = B.E. Required
b) Vertical length of boundary element:
Mu 15920
703
Vu = 352 since the 2 sides of the wall will take shear
2
Mu
hBE max , lw_EW = 140
4 Vu
Should extend above and below the critical section by hBE except as permitted in
18.10.6.4 (g)
As per Section 18.10.6.4 (g) of ACI the B.E. reinforcement will be extended into
the foundation at a length 5.5' of the #9 bars
As per ACI 318 14 18.10.6.4: where B.E. are required per 18.10.6.2 a) h) shall be
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Krishna Anish Adusumilli
Core Wall Design Calculations Athul Parayancode
(Storeys 1-7)
As per ACI 318-14 18.10.6.4: where B.E. are required per 18.10.6.2 a)-h) shall be
satisfied:
a) B.E. shall extend horizontally at least the maximum of:
cpos_NS
lbe max cpos_NS 0.1 lw_EW , = 12.6 Use lbe 24 for simplicity.
2
b) Not Applicable
c) Check width of the flexural compression zone:
cpos_NS
= 0.18
lw_EW
cpos_NS 3
, Check b , No check needed = No check needed
lw_EW 8
d) Not Applicable
e) Transverse reinforcements must satisfy 18.7.5.2 a)-e) & 18.7.5.3
a) Use rectilinear hoops
b) Bends of rectilinear hoops and cross ties shall engage peripheral longitudinal
reinforcing bars
c) Crossties of same or smaller bar size as the hoops shall be permitted. Consecutive
crossties shall be alternated end for end along the longitudinal reinforcement and
around the perimeter of the cross section.
In our office use 2#3 crossties.
d) 25.7.2.2 is satisfied since #3 ties are inclosing #9 longitudinal rebars
25.7.2.3 is satisfied since all longitudinal bars will be laterally supported by
ties with alternating 2#3 crossties.
2
e) hx_max min 14 , b = 10.7
3
As per 18.7.5.3 spacing of transverse reinforcement shall not exceed the smallest of
a)-c)
1
a) smax1 b = 4
4
b) smax2 6 db9 = 6.77
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Krishna Anish Adusumilli
Core Wall Design Calculations Athul Parayancode
(Storeys 1-7)
hx
14
c) s0 4 + =6
3
smax min smax1 , smax2 , s0 = 4
f) The amount of transverse reinforcement shall be in accordance with Table 18.10.6.4
cc 1
bc1 lbe cc = 23 bc2 b 2 cc = 14
2 2
Ag lbe b = 384 Ach bc1 bc2 = 322
In the direction of bc1 :
Ag f'c f'c 2
Ash1_req max 0.3 1 , 0.09 smax bc1 = 0.69
Ach fy fy
2 2
Ab3 0.11 Ab4 0.2
Use 4 legs of #3 from crossties and 2 legs of #4 from rectilinear hoop
2
Ash_prov 4 Ab3 + 2 Ab4 = 0.84
Ash_prov > Ash1_req , ok , not ok = ok
In the direction of bc2 :
Ag f'c f'c 2
Ash1_req max 0.3 1 , 0.09 smax bc2 = 0.4
Ach fy fy
2
Ab4 0.2
2
Use 2 legs of #4: Ash_prov 2 Ab4 = 0.4
ok for transverse steel reinforcements.
g) As per Section 18.10.6.4 (g) of ACI the B.E. reinforcement will be extended into the
foundation at a length 5.5' of the #9 bars
Negative Moment about the N S direction:
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Krishna Anish Adusumilli
Core Wall Design Calculations Athul Parayancode
(Storeys 1-7)
Negative Moment about the N-S direction:
Per ACI 318-14 ssection 18.10.6.2:
lw_EW lw_EW
a) cmax_NS cmax_NS = 15.6
u 600 ((1.5 0.010))
600 1.5
hw
From the P-M Interaction diagram cpos_NS 0.045 lw_EW = 6.3
cpos_NS cmax_NS , B.E. Required , B.E. Not Required = B.E. Not Required
Per section 18.10.6.5 where special boundary elements are not required a) and b) shall
be satified:
400
a) = 6.67 10 3 < l_req Therefore Cl. 18.7.5.2 (a) through (e) to be
fy
satisfied.
a) Use rectilinear hoops
b) Bends of rectilinear hoops and cross ties shall engage peripheral longitudinal
reinforcing bars
c) Crossties of same or smaller bar size as the hoops shall be permitted. Consecutive
crossties shall be alternated end for end along the longitudinal reinforcement and
around the perimeter of the cross section.
In our office use 2#3 crossties.
d) 25.7.2.2 is satisfied since #3 ties are inclosing #9 longitudinal rebars
25.7.2.3 is satisfied since all longitudinal bars will be laterally supported by
ties with alternating 2#3 crossties.
2
e) hx_max min 14 , b = 10.7
3 Provide 8" spacing
b) Provide Standard hooks.
Moment about the E-W direction
Per ACI 318-14 ssection 18.10.6.2:
lw_NS lw_NS
a) cmax_NS cmax_NS = 16.3
u 600 ((1.5 0.015))
600 1.5
hw
From the P-M Interaction diagram cpos_NS 12
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Krishna Anish Adusumilli
Core Wall Design Calculations Athul Parayancode
(Storeys 1-7)
cpos_NS cmax_NS , B.E. Required , B.E. Not Required = B.E. Not Required
Per section 18.10.6.5 where special boundary elements are not required a) and b) shall
be satified:
400
a) = 6.67 10 3 < l_req Therefore Cl. 18.7.5.2 (a) through (e) to be
fy
satisfied.
a) Use rectilinear hoops
b) Bends of rectilinear hoops and cross ties shall engage peripheral longitudinal
reinforcing bars
c) Crossties of same or smaller bar size as the hoops shall be permitted. Consecutive
crossties shall be alternated end for end along the longitudinal reinforcement and
around the perimeter of the cross section.
In our office use 2#3 crossties.
d) 25.7.2.2 is satisfied since #3 ties are inclosing #9 longitudinal rebars
25.7.2.3 is satisfied since all longitudinal bars will be laterally supported by
ties with alternating 2#3 crossties.
2
e) hx_max min 14 , b = 10.7 Provide 8" spacing
3
b) Provide Standard hooks.
Shear Design
0.6
In the E-W Direction:
Wall geometry:
lw_EW = 140 b = 16
Shear demand:
Per section 18.10.3 the design forces in accordance with the factored load combinations
were found. Since two sides of the wall will carry the shear force Vu will be divided by 2.
897.991
Vu = 449
2
2
Shear Strength Calculation: Acv_EW lw_EW b = 15.6
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Krishna Anish Adusumilli
Core Wall Design Calculations Athul Parayancode
(Storeys 1-7)
c 2.0 since hw/lw > 2 as per 18.10.4.1
1 for normal strength concrete
f'c
Vn_conc Acv_EW c = 190
Vu Vn_conc
t_demand = 0.0032 t_min 0.0025 per section 18.10.2.1
Acv_EW fy
t_req max t_demand , t_min = 0.0032
Try 2 curtains of bundled 2#4 @ spacing 12" O.C:
2
Ab4 0.20
Ab4 4
t_provided = 0.0042
b 12
f'c
Vn Acv_EW c + t_provided fy = 877 eq 18.10.4.1 ACI
318-14
f'c
Vn < 10 Acv_EW , ok , not ok = ok per 18.10.4.5
Vn > Vu , ok , not ok = ok
In the N-S Direction:
Wall geometry:
lw_NS = 220 b = 16
Shear demand:
Per section 18.10.3 the design forces in accordance with the factored load combinations
were found.
Vu 794.76
Shear Strength per ACI 318-14 Section 18.10.4:
2
Acv_NS lw_NS b = 24.4
c 2.0 since hw/lw > 2 per 18.10.4.1
1 for normal strength concrete
Non-Commercial Use Only
Krishna Anish Adusumilli
Core Wall Design Calculations Athul Parayancode
(Storeys 1-7)
f'c
Vn_conc Acv_NS c = 299
Vu Vn_conc
t_demand = 0.0039 t_min 0.0025 per section 18.10.2.1
Acv_NS fy
t_req max t_demand , t_min = 0.0039
Try 2 curtains of bundled 2#4 @ max spacing 18" O.C:
Ab4 4
t_provided = 0.0042
b 12
f'c
Vn Acv_NS c + t_provided fy = 1378 eq 18.10.4.1 ACI
318-14
f'c
Vn < 10 Acv_NS , ok , not ok = ok per 18.10.4.5
Vn > Vu , ok , not ok = ok Ab4 = 0.2 2
db4 0.5
Provide 2 curtains of 2#4 @ 12" O.C. 90 deg hooks will be provide with
develpment length if required
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