Contents Eurocode 2 2004 WALL 002

User Manual: Eurocode 2-2004 WALL-002

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Software Verification
PROGRAM NAME: ETABS
REVISION NO.:

4

EXAMPLE Eurocode 2-2004 Wall-002
P-M INTERACTION CHECK FOR A WALL
EXAMPLE DESCRIPTION
The Demand/Capacity ratio for a given axial load and moment are tested in this
example. A reinforced concrete wall is subjected to factored axial load Pu =
11605 kN and moments Muy = 15342 kN-m. This wall is reinforced as noted
below. The design capacity ratio is checked by hand calculations and the results
are compared with ETABS program results.
GEOMETRY, PROPERTIES AND LOADING

EXAMPLE Eurocode 2-2004 Wall-002 - 1

Software Verification
PROGRAM NAME: ETABS
REVISION NO.:

Material Properties
E=
ν=

25000 MPa
0.2

4

Design Properties

Section Properties
tb = 200 mm
H = 2500 mm
d=
2400 mm
s=
460 mm
As1= As5 = 4-35M+2-20M (4600 mm^2)
As2, As3, As4, As5 = 2-20M (600 mm^2)

f ′c = 30 MPa
fy = 460 MPa

TECHNICAL FEATURES OF ETABS TESTED
 Concrete wall flexural demand/capacity ratio
RESULTS COMPARISON
Independent results are hand calculated and compared with ETABS design
check.

Output Parameter

ETABS

Independent

Percent
Difference

Wall Demand/Capacity Ratio

1.011

1.00

1.10%

COMPUTER FILE: EUROCODE 2-2004 WALL-002
CONCLUSION
The ETABS results show an acceptable comparison with the independent results.

EXAMPLE Eurocode 2-2004 Wall-002 - 2

Software Verification
PROGRAM NAME: ETABS
REVISION NO.:

4

HAND CALCULATION
Wall Strength Determined as follows:
1) A value of e = 1322 mm was determined using e = M u / Pu where M u and Pu were
taken from the ETABS test model PMM interaction diagram for pier P1. Values for
M u and Pu were taken near the balanced condition and large enough to produce a
flexural D/C ratio very close to or equal to one. The depth to the neutral axis, c, was
determined by iteration using an excel spreadsheet so that equations 1 and 2 below
were equal.
2) From the equation of equilibrium:
Pn = Cc + Cs − T
Where

Cc =Ccw +Ccf , where Ccw and Ccf are the area of the concrete web and flange in
compression
α cc fck
0.85 • 30
Ccw=
• 200 • ( a − 200 )=
• 200 • ( a − 200 )= 3400(a − 200)
γm
1.5
α cc fck
0.85(30)
=
200 • ( 2500
=
− 1000 ) )
− 1000 ) ) 5,100, 000
Ccf
(
( 200 • ( 2500=
γm
1.5


α f 
α f
Cs =A1′  fs1 − cc ck  + A2′  fs 2 − cc ck
γm 
γm


f
f
f
T = As 4 s 4 + As 5 s 4 + As 6 s 4
γs
γs
γs

Pn1= 3400(a − 200) + 5,100, 000 +
+

As 3 
α cc fck
 fs 3 −
γs 
γm



α cc fck 
 + A3′  fs 3 −

γm 



As1 
α cc fck
 fs1 −
γs 
γm

 As 2 
α cc fck 
+
 fs 2 −

γm 
 γs 

 As 4
A
A
fs 4 − s 5 fs 5 − s 6 fs 6
−
γs
γs
 γs
(Eqn. 1)

EXAMPLE Eurocode 2-2004 Wall-002 - 3

Software Verification
PROGRAM NAME: ETABS
REVISION NO.:

4

3) Taking moments about As6:


a − tf


− tf  + Cs1 ( d - d' ) + 
1 Ccf ( d - d' ) + Ccw  d 2
Pn2 = 



e′
Cs2 ( 4s ) + Cs3 ( 3s ) − Ts4 ( 2s ) − Ts5 ( s )




=
Cs1
where
Ts 4 =

(Eqn. 2)

As1 
α cc f ck 
As 2 
As 3 
α cc f ck
α cc f ck 
=
=
 f s1 −
 ; Cs 2
 fs3 −
 fs2 −
 ; Cs 3
γs 
γm 
γs 
γm
γs 
γm 


;


As 4
( f s 4 ) and the bar strains and stresses are determined below.
γs

The plastic centroid is at the center of the section and d ′′ = 700 mm
e′ =e + d ′′ =1322 + 700 =2472 mm.
4) Using c = 1299 mm (from iteration),
a=
β1c =
0.895 •1299 =
1163 mm
5) Assuming the extreme fiber strain equals 0.0035 and c = 1299 mm, the steel stresses
and strains can be calculated. When the bar strain exceeds the yield strain, then
fs = f y :
 c − d′ 
ε s1 =

 0.0035
 c 
 c − s − d′ 
εs 2 =

 0.0035
c


 c − 2s − d ′ 
εs3 =

 0.0035
c


 d − c − 2s 
=
εs 4 
 εs6
 d −c 
 d −c−s 
=
εs5 
 εs6
 d −c 
 d −c 
εs6 =

 0.0035
 c 

= 0.00323; f s =
ε s E ≤ Fy ; f s1 = 460 MPa
= 0.00199

f s 2 = 398.2 MPa

= 0.00075

f s 3 = 150.3 MPa

= 0.00049

f s 4 = 97.5 MPa

= 0.00173

f s 5 = 345.4 MPa

= 0.00297

f s 6 = 460.00 MPa

EXAMPLE Eurocode 2-2004 Wall-002 - 4

Software Verification
PROGRAM NAME: ETABS
REVISION NO.:

4

Substituting in Eqn. 1 and 2 and iterating the value of the neutral axis depth until the
two equations are equal give
Pn1 = 11605 kN
Pn2 = 11605 kN
M=
P=
11605(1322) /1000 = 15342 kN-m
n
ne

EXAMPLE Eurocode 2-2004 Wall-002 - 5



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