punching stress aci

7/22/2019 Punching Stress Aci

1/20

Check of Punching Shear in Flat Slabs and Rafts under N, M According to ACI 318-02 by wae

Columns (REC.or CIRCULAR)

Building: S.S.BUILDING Column: FRAME ( ) - JOINT ( )

Slab

Slab thickness = ts 300.00 mm

Concrete Cover = d` 30.00 mm

Critical thickness = d 270.00 mm

Straining Actions

Un-balanced Moment :-

Mu1 = 35.75 KN.m added t

Mu2 = 158.15 KN.m added t

Ultimate Shear force:-

Pu = 463.75 KN

Column Dimensions:

C1= 500.00 mm

C2= 450.00 mm bc=C1

D= 500.00 mm bc=D/D

as= 40.00 (20 for

d/2= 135.00 mm

Materials

Slab Concrete Grade = 43.75 Mpa

Reinforcement Steel Grade= 420.00 Mpa

Critical section in punching:- TYPE(1)

b1=C1+d 770.00 mm

b2=C2+d 720.00 mm

2980.00 mm

Flexural portion of moment (gf)=1/1+(2/3)b1/b2 0.59

Eccentric shear portion (v)=1-f 0.41

Critical section in punching:- TYPE(2)

b1=D+d 770.00 mm

b2=D+d 770.00 mm

bo= 2b = 4835.60 mm

Flexural portion of moment (gf)=1/1+(2/3)D/D 0.60


Shear/Torsion Parameters

Shear/Torsion resisting Parameters according to ACI318-02, R11.12.6.3

c=b1^2/(2b1+b2)or(c`=D+d/2)= 635.00 mm

635.00 mm

Ac= 0.65 m2

Bending MU1 0.35 m3

OTHER DIRECTION C1 0 b1= 270.00 mm

C2 0 b2= 270.00 mm

bo= 2b1 +2 b2 = 1080.00 mm

Flexural portion of moment (gf)=1/1+(2/3)b1/b2 0.60



bo= 2b1 +2 b2 =

Jcn/c=(Jcn/c')or(J/c)

c'=( b1-c) or(c=c`)=


2/20

CALCULATION OF REQUIRED SHEAR REINFORCEMENT

Shear force in reinforcement

Check if (vu) is less than (f6 sqrt(fc') ) or not

vu= 933.0028163 f6 sqrt(fc')= 2218.529919 O

fvc(for punching RFT=2SQRT(fc')= 739.51 KN/M2

Shear force to be resisted by reinforcement

Vs=bod *(vu-fvc(min))= 56.42 KN

Required Reinforcement

Total area of steel on 4 sides of column is given by

Av= Vs* S / (f*fy*d)Stirrups Spacing (s) = 75 mm

number of legs = 2

Av = 4.97553E-05 m2= 49.76 mm

2

Av/Side = 12.43882565 mm2

Then use, Vl U-bars T 3

Distribution of shear RFT

Determination of distance from column face for termination of stirrups

stirrups are not required when, Vuis less than fvc(min) bo'*d

then, bo'= 1362.582086 mm

bo'= 2C1 + 2C2 + 4 a Sqrt(2), where a is the extension of shear RFT from face of colum

a = (bo'-2C1-2C2)/4Sqrt(2)

a = -95.0029628 mm

Design Report

SLAB THICKNESS IS OK WITHOUT ANY ADDITIONAL SHEAR REINFORCEMENT

use RFT of T 3 @ 75.00 2 le

for a distance -50 mm from each side of support

s

a2

C1

bo'a


3/20

Check of Punching Shear in Flat Slabs and Rafts under N, Mx, and My According to ACI 318-02

For Edge Columns (3 sides only)

Building: AREEN Column: Edge column L16 to L24 Comb(

C3 AT AXES(6)&(C)

Slab

Slab thickness = 200 mm

Concrete Cover = 38 mm

Straining Actions

Un-balanced Moment

Mu1(perp.)= 0 KN.m added to N at inner sid

Mu2(perp.) 100.79 KN.m added to N at outer sid

Mu (parllel) 51.41 KN.m

Ultimate Shear force= 120.8 KN

Column Dimensions:

C1= 800 mm

C2= 480 mm bc= 1.66667

as= 30 (20 for corner, 30 for e

edge distance (e)= 150 mm

Materials

Slab Concrete Grade = 45 Mpa

Reinforcement Steel Grade= 460 Mpa

Critical section in punching:

b1= 1031 mm

b2= 642 mm

bo= 2b1 +b2 = 2704 mm

Flexural portion of moment (gf)= 0.5420547

Eccentric shear portion (gv)= 0.4579453



c=b1^2/(2b1+b2)= 393.10688 mm

c'= b1-c= 637.89312 mm

Ac= 0.438048 m2

Bending normal to edge: Jcn= 0.0513963 m4

Jcn=[2b1

Bending Parllel to edge: Jcp= 0.0382199 m4

Jcp=b2/2*

Edge o

N.A.

c'

c

Effective punching area


4/20

Ultimate Shear Stress

Ultimate shear force

V/A= 275.76887

Mn*c/Jcn= 0

Mn*c'/Jcn= 0 473.501 78.03702

Mp*b2/2/Jcp= 197.73185

Ultimate shear stress vu= 473.50071 Kpa Inner corner=Vu/Ac+gv

78.03702

or = 1046.3594 Kpa Outer corner=Vu/Ac+gv

Critical Ultimate shear stress = 1046.3594 KPa

Concrete Punching Strength:

f = 0.75

fvc(1)= 1650 Kpa

fvc(2)= 1424.0015 Kpafvc(3)= 1500 Kpa

fvc(min)= 1424.0015 Kpa

Is (vu)less than fvc(min) ? Yes, OK SAFE, STOP AT THIS STAGE




vu= 1046.35942 f6 sqrt(fc') 2250 OK, Slab

fvc(for punching RFT=2SQRT(fc')= 750 Kpa




Total area of steel on three sides of column is given by

Av= Vs* S / (f*fy*d)

Stirrups Spacing (s) = 100 mm

number of legs = 6

Av = 0.00023228 m2= 232.27707 mm

2

Av/Side = 77.4256889 mm2




5/20



then, bo'= 3674.01101 mm

bo'= 2C1 + C2 + 2 a Sqrt(2), where a is the extension of shear RFT from fa

a = (bo'-2C1-C2)/2Sqrt(2)

a = 563.567998 mm

Design Report


use RFT of T 5 @ 100 6 legs

for a distance 600 mm from each side of support

s

a2

C1

C2

bo'

a

a

Punching Shear Reinforcement DetailsFrom "Notes on ACI318-02, pp16-27"


6/20

1)

ge and 40 for interior col)

2*d*(b1+2b2)+d^3*(2b1+b2)]*c/6b1

(b2*d(b2+6b1)+d^3)/6

from "Notes on ACI318-02, pp 16-16"

C2

C1

slab

b2=c2+d

b1=c1+d/2+e

e

d/2


7/20

Mu1(perp)*c/Jcn+ gvMu(parallel)*(b2/2)/Jcp

Mu2(perp)*c'/Jcn+ gvMu(parallel)*(b2/2)/Jcp

thickness is adequate

@ 100


8/20

e of column


9/20




C3 AT AXES(6)&(C)

Slab



Straining Actions

Un-balanced Moment

Mu1(perp.)= 37.39 KN.m added to N at inner sid

Mu2(perp.) 0 KN.m added to N at outer sid


Ultimate Shear force= 105.6 KN

Column Dimensions:

C1= 800 mm

C2= 480 mm bc= 1.66667



Materials




b1= 1031 mm

b2= 642 mm

bo= 2b1 +b2 = 2704 mm





c=b1^2/(2b1+b2)= 393.10688 mm

c'= b1-c= 637.89312 mm

Ac= 0.438048 m2


Jcn=[2b1


Jcp=b2/2*

Edge o

N.A.

c'

c



10/20



V/A= 241.06947

Mn*c/Jcn= 130.96289

Mn*c'/Jcn= 212.51302 429.879 -29.290016

Mp*b2/2/Jcp= 57.846469


-29.29002




f = 0.75

fvc(1)= 1650 Kpa

fvc(2)= 1424.0015 Kpafvc(3)= 1500 Kpa

fvc(min)= 1424.0015 Kpa








Vs=bod *(vu-fvc(min))= -140.2284 KN





number of legs = 6

Av = -0.0002509 m2= -250.9008 mm

2

Av/Side = -83.633587 mm2

Then use, Vl U-bars T #NUM!



11/20



then, bo'= 1509.40446 mm


a = (bo'-2C1-C2)/2Sqrt(2)

a = -201.73599 mm

Design Report


use RFT of T #NUM! @ 100 6 legs

for a distance -200 mm from each side of support

s

a2

C1

C2

bo'

a

a



12/20

1)


2*d*(b1+2b2)+d^3*(2b1+b2)]*c/6b1

(b2*d(b2+6b1)+d^3)/6


C2

C1

slab

b2=c2+d

b1=c1+d/2+e

e

d/2


13/20




@ 100


14/20

e of column


15/20




C3 AT AXES(6)&(C)

Slab



Straining Actions

Un-balanced Moment

Mu1(perp.)= 26.11 KN.m added to N at inner sid

Mu2(perp.) 0 KN.m added to N at outer sid


Ultimate Shear force= 175 KN

Column Dimensions:

C1= 800 mm

C2= 480 mm bc= 1.66667



Materials




b1= 1031 mm

b2= 642 mm

bo= 2b1 +b2 = 2704 mm





c=b1^2/(2b1+b2)= 393.10688 mm

c'= b1-c= 637.89312 mm

Ac= 0.438048 m2


Jcn=[2b1


Jcp=b2/2*

Edge o

N.A.

c'

c



16/20



V/A= 399.4996

Mn*c/Jcn= 91.453361

Mn*c'/Jcn= 148.40104 976.225 -234.17332

Mp*b2/2/Jcp= 485.27187


-234.1733




f = 0.75

fvc(1)= 1650 Kpa

fvc(2)= 1424.0015 Kpafvc(3)= 1500 Kpa

fvc(min)= 1424.0015 Kpa













number of legs = 6

Av = 0.00017731 m2= 177.30781 mm

2

Av/Side = 59.1026034 mm2




17/20



then, bo'= 3427.75217 mm


a = (bo'-2C1-C2)/2Sqrt(2)

a = 476.502349 mm

Design Report


use RFT of T 4 @ 100 6 legs

for a distance 500 mm from each side of support

s

a2

C1

C2

bo'

a

a



18/20

1)


2*d*(b1+2b2)+d^3*(2b1+b2)]*c/6b1

(b2*d(b2+6b1)+d^3)/6


C2

C1

slab

b2=c2+d

b1=c1+d/2+e

e

d/2


19/20




@ 100


20/20

e of column

punching stress aci

Documents