Sh Wall Example
-
Upload
rico-padilla -
Category
Documents
-
view
214 -
download
0
Transcript of Sh Wall Example
-
7/30/2019 Sh Wall Example
1/7
Custom Search
Search
Design of Reinforced Concrete Shear wall
Example 1: Design of reinforced concrete non-load bearing shear wall.
Example 2: Design of Reinforced Concrete load bearing shear wall
Design examples
Example 1: Design of reinforced concrete non-load bearing shear wall.
Design code: ACI 318-05
Design data:
Seismic shear force: (service load)
Roof: Vr= 100 kips
4th floor: V4
= 75 kips, ,
3rd floor: V3 = 50 kips
2nd floor: V2
= 25 kips
Floor height: H = 15 ft
Length of wall: lw = 18 ft
Page 1 of 7Sh-wall example
4/7/2013http://ce-ref.com/sh-wall_example.htm
-
7/30/2019 Sh Wall Example
2/7
Width of wall: h = 10 in
Concrete strength: fc' = 4000 psi
Yield strength of steel: fy = 60 kis
Assumption:
1.out-of-plan moment is neglectable.
2.The wall is an exterior wall.
Requirement:
Design reinforcement for shear wall
Solution:
Maximum shear occurs at load combination: 1.2D+1.4E+1.0L
Calculate maximum vertical and shear force at first floor
Maximum factored shear: Vu = 1.4 (100+75+50+25) = 350 kips
Check maximum shear strength permitted
Assume effective depth, d = 0.8 (18) = 14.4 ft
Strength reduction factor, = 0.75
Vn
= 10 fc' h d = 819 kips > 350 kips O.K.
Critical section for shear at smaller of 18 ft/2 = 9 ft , H/2 = 7.5 ft
Calculate factored overturning moment and weight of wall at critical section
Mu
= 1.4 [100 (60-7.5)+75(45-7.5)+50(30-7.5)+25 (25-7.5)] = 13130 ft-kips
Nu
= (0.15)(10/12)(18)(60-7.5) = 118.1 kips
Calculate shear strength of concrete:
Vc = 0.75 [3.3 fc' h d + Nu d/ (4 lw)] = 288.2 kips
Mu/V
u- l
w/2 = 28.5 ft
Vc
= 0.75 { 0.6 fc' + l
w( 1.25 f
c' + 0.2 [N
u/(l
w* h)]) /( M
u/V
u- l
w/2)} h d = 163.8 kips
OrVc = 0.75 (2 fc' h d) = 163.9 kips Use
Design horizontal shear reinforcement:
Vs = Vu - Vc = 186.1 kips
Use #5 bar in one layer, area of reinforcement, Av = 0.3 in2.
Spacing: S = Av
fy
d /Vs
= 12.6 in, Use 12" O.C.
Check maximum spacing: (18x12)/5 = 43 in, 3 (10) = 30 in, or 18 in O.K.
Page 2 of 7Sh-wall example
4/7/2013http://ce-ref.com/sh-wall_example.htm
-
7/30/2019 Sh Wall Example
3/7
Check minimum reinforcement: t= 0.3 in2 / (12x10) = 0.0025 O.K.
Design vertical reinforcement:
l= 0.0025 + 0.5 (2.5 - h
w/ l
w)(
t- 0.0025) = 0.0025
Use l= 0.0025
Area of reinforcement: Av
= 0.0025 (10)(12) = 0.3 in2/ft
Use #5 bars at 12" O.C
Design flexural reinforcement:
Calculate factored moment at base:
Mu
= 1.4 [(100)(60)+(75)(45)+(50)(30)+(25)(15)]=15750 ft-kip
Tension control section, = 0.9
Factor: Rn
= (15750)(12000)/[0.9(10)(14.4x12)2] = 703 psi, and m = fy/(0.85fc')=17.7
Reinforcement ratio, = (1/m)[1-(1- 2 m Rn/fy)] = 0.013
Area of reinforcement, As = 0.013 h d = 22.9 in2.
Use #10 bars, number of bars, n = 22.9/1.27 = 18
Check effective depth
Concrete cover = 2" for exterior wall. Use 3" spacing between #10 bars in two layers
Effective depth, d = (18)(12) - 2-(3)(8)/2 =202 in
Recalculate reinforcement, Factored Rn = Mu / h d2 = 514.7 psi, m = 17.
Reinforcement ratio, = 0.0094
Area of reinforcement, As = 18.9 in2.
Use #10 bars, number of bars, n = 18.9 /1.27 = 15, Use 16 # 10
Use #4 closed shape ties to enclose tension reinforcement,
Area of reinforcement for shear As = 0.4 in2.
Check clear spacing between bars, S = 10-(2)(2)-(0.5)(2)-1.27 = 3.73 in O.K.
Reinforcement detail
Page 3 of 7Sh-wall example
4/7/2013http://ce-ref.com/sh-wall_example.htm
-
7/30/2019 Sh Wall Example
4/7
Example 2: Design of Reinforced Concrete load bearing shear wall
Situation: A reinforced concrete load bearing shear wall supporting for a four story building
Design code: ACI 318-05
Design data:
Vertical load: (service load)
Dead load at each floor and roof: PD
= 40 kips
Live load at each floor and roof: PL = 25 kips
Seismic shear force: (service load)
Roof: Vr= 100 kips
4th floor: V4
= 75 kips, ,
3rd floor: V3 = 50 kips
Page 4 of 7Sh-wall example
4/7/2013http://ce-ref.com/sh-wall_example.htm
-
7/30/2019 Sh Wall Example
5/7
2nd floor: V2
= 25 kips
Floor height: H = 15 ft
Length of wall: lw
= 18 ft
Width of wall: h = 12 in
Concrete strength: fc' = 4000 psi
Yield strength of steel: fy = 60 kis
Assumptions:
1. out-of-plan moment is neglectable.
2. The wall is an exterior wall.
Requirement:
Design reinforcement for shear wall
Solution
Maximum shear occurs at load combination: 1.2D+1.4E+1.0L
Calculate maximum vertical and shear force at first floor
Maximum factored shear: Vu
= 1.4 (100+75+50+25) = 350 kips
Check maximum shear strength permitted
Assume effective depth, d = 0.8 (18) = 14.4 ft
Strength reduction factor, = 0.75
Vn
= 10 fc' h d = 819 kips > 350 kips O.K.
Critical section for shear at smaller of 18 ft/2 = 9 ft , H/2 = 7.5 ft
Calculate factored overturning moment and weight of wall at critical section
Mu
= 1.4 [100 (60-7.5)+75(45-7.5)+50(30-7.5)+25 (25-7.5)] = 13130 ft-kips
Nu = 1.2 [(0.15)(10/12)(18)(60-7.5)+4 PD ]+1.0 (4 PL ) = 462.1 kips
Calculate shear strength of concrete:
Vc
= 0.75 [3.3 fc' h d + N
ud/ (4 l
w)] = 393.9 kips
Mu/V
u- l
w/2 = 28.5 ft
Vc
= 0.75 { 0.6 fc' + l
w( 1.25 f
c' + 0.2 [N
u/(l
w* h)]) /( M
u/V
u- l
w/2)} h d = 228.2 kips (Use)
OrVc
= 0.75 (2 fc' h d) = 196.7 kips
Design horizontal shear reinforcement:
Vs
= Vu
- Vc
= 112.1 kips
Page 5 of 7Sh-wall example
4/7/2013http://ce-ref.com/sh-wall_example.htm
-
7/30/2019 Sh Wall Example
6/7
Use #4 bar in two layer, area of reinforcement, Av
= 0.4 in2. (Code requires two layers for 12" wall)
Spacing: S = Av
fy
d /Vs
= 25.7 in
Check maximum spacing: (18x12)/5 = 43 in, 3 (10) = 30 in, or 18 in Use 18"
Check minimum reinforcement: t= 0.4 in2 / (18x10) = 0.0019 < 0.0025
Use t=0.0025, spacing S = 0.4 in2 / (0.0025)(h) = 13.3 in Use 12 in
Design vertical reinforcemnt
l= 0.0025 + 0.5 (2.5 - h
w/ l
w)(
t- 0.0025) = 0.0025
Use l= 0.0025
Use #4 bars in two layers at 12" O.C
Calculate factored moment and axial load at base:
Mu = 1.4 [(100)(60)+(75)(45)+(50)(30)+(25)(15)]=15750 ft-kip
Nu
= 1.2 [(0.15)(10/12)(18)(60)+4 PD
]+1.0 (4 PL
) = 486.4 kips
Design as a column subjected to axial load and bending
Gross area, Ag
= (18)(12)(12) = 2592 in2.
Assume tension control section, = 0.9
Nu
/Ag
= 0.141 ksi
Mu/(A
glw
) = 0.253 ksi
From ACI column design chart (See column design section), Area of reinforcement, = 0.011
Area of reinforcement, As = (0.01)(18x12)(12) = 22.8 in2.
Use #10 bars, number of bar, n = 22.8/1.27 = 18
Use 10#10 bars at each end of shear wall, column ties is required since > 0.01. Use #4 ties at 12" O.C.
Page 6 of 7Sh-wall example
4/7/2013http://ce-ref.com/sh-wall_example.htm
-
7/30/2019 Sh Wall Example
7/7
Disclaimer: The content of this website was obtained and edited from various resources. The editor madereasonable effort of editing. Nevertheless, the editor does not warrant, and assume no liability for accuracy andcompleteness of its content. The viewer shall use his/her professional knowledge and judgment in use of the webcontent. Webmaster: www.ce-ref.com
Page 7 of 7Sh-wall example