shear walls with openings - seaoa - home convention/2017... · course description reference codes...
TRANSCRIPT
By: R. Terry Malone, PE, SE
Senior Technical Director
Architectural & Engineering
Solutions
Presentation updated to 2015 IBC, ASCE 7-10
2015 SDPWS
Copyright McGraw-Hill, ICC
Presentation Based On:
Shear Walls With Openings
Karuna I
Holst ArchitecturePhoto: Terry Malone
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Course Description
Reference Codes
and Standards
Designers are continually getting asked to do more with less in modern
structures; shear walls are no exception to this demand. With more
openings and larger lateral forces, segmented shear wall approaches
do not always produce the most efficient structural design.
This presentation will introduce and compare rational
analysis methods for designing shear walls with
Openings and more importunately cover design
issues not commonly discussed.
Learning Objectives
• FTAO Shear Walls with a Single OpeningReview analytical methods used to solve shear walls with a single
opening.
• FTAO Shear Walls with Multiple OpeningsReview analytical methods used to solve shear walls with
multiple openings.
• Shear Walls with Multiple openings and No HeadersReview analytical methods used to solve shear walls with
cantilever pier sections (no header sections).
• Shear Walls with Small OpeningsReview how to determine when an opening size does not warrant
a detailed analysis.
Shear Walls Opening Types
Perforated Walls FTAO Shear Walls
Shear Walls with Small OpeningsCantilever Shear Walls
3’ 6’ 5.5’
14.5’
4’
3’
2’
1 2
A
B
3
C
D
4
9’
4500 lbw=200 plf
(See recent Testing-APA Form M410 and SR-105)
Tie straps full
length of wall
per SDPWS
section 4.3.5.2
Anchor bolts
or nails
(Typical boundary
Member)
Typical boundary
member
2’ min. per SDPWS
Section 4.3.5.2
(2008 requirement)
Many examples
ignore gravity loads
Example- FTAO Shear Walls
Cont. Rim joist
Strut/collector
Shear panels
or blocking
(Diekmann)-Vierendeel Truss/Frame
Method Assumptions:
• Acts like Vierendeel frame.
• Wall sections shall occur
around all edges of an
opening and shall comply
with allowable A/R.
• Point of inflection occurs mid
height of piers and mid-length
of header/sill sections.
(b) Force Transfer Around Opening
Wall
pier
Wall
pier
Wall
pier
Wall
pier Wall
pier
Wa
ll P
ier
he
igh
t
Wa
ll p
ier
he
igh
t
Wall
pier
width
Cle
ar
he
igh
t
Wa
ll p
ier
he
igh
t
Overall width
AWC SDPWS Figure 4E
Dr.
Wall
pier
width
Boundary
members
Collector (typ.)
Foundation wall
Allowable Shear Wall Aspect Ratios For FTAO Shear Walls
Note: Not
shown as
having to
comply w/
A/R
Wd.
Wd.
• The aspect ratio limitations of
Table 4.3.4 shall apply to the
overall wall and the pier sections
on each side of the openings
• Minimum pier width=2’-0”.
• A full height pier section shall be
located at each end of the wall.
• Where a horizontal offset occurs,
portions on each side of the
offset shall be considered as
separate FTAO walls.
• Collectors for shear transfer shall
be provided through the full
length of the wall.
Limitations:
ATC-7 Guidelines for the design of horizontal wood
diaphragms, 1981, page 13 – Used Diekmann Method
Most codes limit the span to width ratios of diaphragms
and also apply this limit to portions of diaphragms at
openings. A portion of a diaphragm having a ratio
exceeding the limit would be considered ineffective and
thus be ignored in analyzing distribution of forces at an
opening.
2.67’ 5.25’ 2.33’
10.25’
7’
0.5’
2’
1 2
A
B
3
CD
4
9.5’
3114 lbA/R=2.63<3.5 O.K.
Strut/collector
A/R=3<3.5 O.K.
2886 lb 2886 lb
Force Transfer Distribution –Based on stiffness
(FEA analysis)
Force distribution and location of I.P’s due
to sill section not meeting A/R requirements
Single Opening with Shallow Sill
A/R=10.5>3.5
N.G. Inflection point
A/R=2.62<3.5
O.K.
4000
C
1 2
A
3
D
4
H
I
L JK
T
F=0 lb
F=0 lbF=0 lb
F=0 lb
N.A.
5 6
T
S
R
Q
P O N M
6’6.5’6’3.5’ 3.5’
25.5’
1’
3.5’
3.5’
2.5’
F=0 lb
F=0 lbF=0 lb
F=0 lb
Not to scale
Double Opening with Shallow Headers
Force distribution and location of I.P’s due to
header section not meeting A/R requirements
Force Transfer Distribution –Based on stiffness
(FEA analysis)
4500
C
Tie strap/blocking
full width
Blocking
Point of inflection is assumed
to occur at mid-length (Typ.)
MM
V
V
V
V
M
M
1 2
A
B
3
C
D
4
C
A B
D
F
E
HG
I
L
J
K
T
V
V
M
M
MM
V
V
F=0 lb
F=0 lbF=0 lb
M
F=0
MF=0
Force Transfer Methodology (Diekmann)-Vierendeel Truss/Frame
F=0 lb
F
F
Gravity loads
to wall
1343.1 4243.1
w=200 plf
N.A.
4500 lb
4’
14.5’
208.62 lb
208.62 lb
991.38 lb
587.08 lb
F1B.5
VB.5
1 2
A
B
3
A
B
4
2’
2’
4500 lb
200 plf
200 plf
0M
0M
B.5
B.5
2691.38 lb
F4B.5
3912.92 lb
VB.5
BA
C
A
I
G
B
H
C
V2.53’
3’
Free-body of Upper Half and Upper Left Section
Point of
inflection
I
H
B.5
0 lb 0 lb
0 lb
A
C
D
B
F
587.08
VB=587.08
VB.5=587.08
(587.08)
Vc=587.08
587.08
V2
.5
15
51
.7
V2
(1343.1)
3’
3’
F2b(V)
391.39
F2C(v)
391.399
91
.38
V2
39
1.3
9
(208.62)
F2A
F2B(H)
1381
1037.1
1160.3
F2C(H)
F1B
600
F1C
182.77
E
(0)
(0)
573.23
2’
2’
2’
1 2
0M
0M0M
0M
0M
0M
Units are in lb
Corner tie
strap force
Corner tie
strap force
HG
J
I
KL
15
91
.38
(99
1.3
8)
V3
268.8
1937.1
15
51
.7
15
51
.7
236.17
3676.6
V3
(4243.1)
(2691.38)VB.5=3912.92
VB=3912.92
3912.92
(3912.92)
VC=3912.92
3912.92
(0)
5.5’
3’
2’
2’
2’
F3(V)
1422.88
F3B(V)
1422.9
F4B
1268.5
F4C
4114.3F3C(H)
F3B(H)
F3A A
B
3
C
D
4
0M
0M
0M
3’ 3’
3’ 3’
2.5
B.5B.5
2124.9
1551.7
(4500)
(4500)
F2.5A
1274.9
(xxx) Shears and forces determined
in previous step.
0M
0M 0M
200 plf 200 plf 200 plf 200 plf
F2.5C
Resultant Forces on Wall Segments
0V
0H
0V
0V
0V0V
0H
0V
0H
1551.7
1706.9931931931
(0)
Transfer diaphragm
sections
3’ 6’ 5.5’
14.5’
4’
3’
2’
1 2
A
B
3
C
D
4
T.D.2T.D.1
2.67’ 2.67’
9’
3.6
Example 2 - Blocking and Strapping Partial Width (with uniform load)
4500 lbs.
Support
Support
Support
Support
1.2w=200 plf
The Visual Shear Transfer MethodHow to visually show the distribution of shears through the diaphragm
+ -
+
Sheathing element symbol
for 1 ft x 1 ft square piece of
sheathing in static equilibrium
(typ.)
+
Describes Method of analysis
Shears acting
on edges of
sheathing
Shears
transferred into
boundary elements
and collectors
4243.1 lbs.
Pier Section Forces and Loads 2.67’
-+
A
B
3
C
D
4
T.D.2
Sign convention
1937.1
1975.8
2.83’
Support
Support
F
F
3676.6
Neg.
Pos.
Neg. 15
51
.71
59
1.4
v3.6 v4v3
Basic Shear Diagram
From Gravity Loads
Summing
w=200 plf
Transfer diaphragm shears
3.6
3676.6 lbs.
15
51
.7
4243.1 lbs.
1937.1 lbs.
Transfer Diaphragm Shears and Net Shears
2.67’
-+
1937.1
3676.6 lbs.
281.1 lbs.
2020.6 lbs.
v=281.1
2.67=- 105.3 plf
v=1656
2.67= +620.2 plf
v=2020.6
2.67= -756.8 plf
-105.3
-756.8
+620.2
+471.5+408.6
A
B
3
C
D
4
T.D.2
Sign convention
Transfer diaphragm shears
15
91
.4
vnet=349.23-105.38=+243.93 plf
vnet=349.23+620.2=+969.45 plf
vnet=349.23-756.8=-407.55 plf
1975.8 lbs.
3.6
+303.3+243.9
+1028.8+969.5
+1028.8+969.5
-348.2-407.6
-348.2-407.6 +471.5+408.6
3677.1 lbs.
(+408.57 plf)4243.1 lbs.
(+471.46 plf)
3143.1 lbs.
(+349.23 plf)
Basic Shear Diagram
Summing
vnet=408.57-105.38=+303.27 plf
vnet=408.6+620.2=+1028.8 plf
vnet=408.57-756.8=-348.21 plf
408.6
408.6
408.6
471.5
471.5
471.5
w=200 plf
4243.1 lbs.Horizontal Collector Forces
2.67’
-+
A
B
3
C
D
4
T.D.2
Sign convention
C
T
969.45
969.5
407.55
1028.81937.1
3676.6
243.9 303.3
348.2
1028.8
243.9 303.3 408.6 471.5
𝑭 = 𝟏𝟗𝟑𝟕. 𝟏 𝐥𝐛𝐬.
𝑭 = 𝟑𝟔𝟕𝟔. 𝟔 𝐥𝐛𝐬.
𝑭 = 𝟏𝟗𝟕𝟓. 𝟖 𝐥𝐛𝐬.
1975.82.83’
4243.1 lbs.Vertical Collector Forces
2.67’
-+
408.6
471.5
A
B
3
C
D
4
T.D.2
Sign convention
F=1103.5 lbs.
F=2774.4 lbs.
T
348.2
1591.4
407.61551.7
1028.8
969.5
969.5
303.3
F=0 lbs.
Summing
F=2270.3 lbs.
F=210.54 lbs.
F=0 lbs.
F=4243.1 lbs.
480.6
C
C
T
Collector
243.93
480.6
471.5
C
(See recent Testing-APA Form
M410)
Advancements in FTAO Shear Wall Analysis
Basis of APA System Report
SR-105 (in development)
SEAOC Convention
2015 Proceedings
Advancements in Force Transfer Around
Openings for Wood Framed Shear Walls
APA System Report SR-105
(Report pending)
Refine rational design methodologies
to match test results
Used test results from full-scale
wall configurations
Analytical results from a computer
model
Allows asymmetric piers and
multiple openings.
New Simpson Strong-tie FTAO Software
20’-0”
L
5’-0”
L1
4’-0”
L2
2’-6”
L36’-0”
LO1
2’-6”
LO2
4’-
8”
ho
2
8’-
0”
H
4000 lbs.
V
1’-
4”
ha
2’-
0”
hb
2
1600
1600
2’-
8”
ho
14’-
0”
hb
1
TD
Multi-story walls?
Tall shear walls?
4645
C
Tie strap/blocking
full width
Point of inflection is assumed
to occur at mid-length (Typ.)
MM
V
V
V
V
H=12’
M
1 2
A
B
3
C
D
4
CA B D FE
H
G
I
L JK
T
V
V
M
M
MM
V
V
F=0 lb
F=0 lbF=0 lb
MM=0, F=0
Force Transfer Methodology (Diekmann)-Vierendeel Truss/Frame
F=0 lb
2252.1 2252.1
N.A.
5 6
MM
V
V
MM
V
V
T
S
R
Q
P O N M
5.39’6.627’5.39’3.65’ 3.7’
2.27’
3.585’
3.585’
2.56’
F=0 lb
F=0 lbF=0 lb
F=0 lb
M
L=24.75’
A/R=1.96<3.5
O.K.
7.1
7’
A/R=1.08<3.5 O.K.
A/R=2.37<3.5 O.K.
A/R=1.94<3.5 O.K.
A/R=2.11<3.5
O.K.
Not to scale
4645
C
1 2
A
B
3 4
CA B D FE
H
G
T
F=0 lb
F=0 lbF=0 lb
Force Transfer Methodology (Diekmann)-Vierendeel Truss/Frame
1098.8
5 6
TRF=0 lb
F=0 lbF=0 lb
0 0
2.27’
3.585’
5.39’6.627’5.39’3.65’ 3.7’
L=24.75’
5.8
55
’
46451 2
A B
T
R
2.27’
3.585’
2.695’3.65’
1098.8
1098.8
0M
1190.8
1098.8
C
A
B
F
H
G
5 6
1200.1
3.7’
5.8
55
’
1098.8
0M
0V
2.695’
6.345’
5.8
55
’
6.395’1098.8
0V
0H
2254.1
0 0
0 0
A
C
D
B
F
70.79 1219.4
(10
98
.8)
0.01
1169.6
E
(0)
(0)1304.6
1 2
0M
0M
0M
0M
0M
HG
J
I
KL
1200.11304.6
10
98
.8
1211.2
62.92254.11190.8
(0)
A
B
3
C
D
4
0M
0M
0M
2.5
B.5 B.5
797(4645)
(4645)
0M
0M
Resultant Forces on Wall Segments
0H
0V
0V
0H
0V
1161.7
694.4505.8505.8685
(0)
C
D
(0)
798.8
0M
0M
B.5
B
(0)
2
0M
G
2.5
505.8505.8
L
1301.6
B1
15
3.3
0M
1243.7
F L
1214 (0)
(2252.1) (2252.1)
(0)(1098.8) (1190.8) (1098.8)
(1200.1)(2254.1)
(10
98
.8)
2.27’
3.585’
2.695’3.65’
3.585’
2.695’2.695’2.695’ 6.627’ 3.7’
2.56’
2.695’3.65’ 2.695’2.695’2.695’ 6.627’ 3.7’
2.27’
3.585’
3.585’
2.56’
3.585’
3.585’
10
98
.8
10
98
.8
10
98
.8
10
98
.8
10
98
.8
10
98
.8
10
98
.8
10
98
.8
1200.1
1200.1
1200.1
1200.1
1190.8
1190.8
1190.8
1190.8
2254.1
2254.1
2254.1
2254.1
10
98
.8
798.8
1219.4
1219.41219.41169.62268.4
23.2
11
53
.3
11
53
.3
11
53
.3
11
53
.3
11
53
.3
11
53
.3
11
53
.3
11
53
.3
11
53
.3
11
53
.3
11
53
.3
1214
1214 1214 171.1
1.72 797
1304.5
1162.8 2261.61213.8
13.71211.2 1213.8
326 plf
484 plf
340 plf
450 plf
484 plf
450 plf
324 plf
Not to scale
892.7
484 plf
42.2 plf 41.5 plf
41.5 plf 42.2 plf
463.3 plf
463.3 plf
466.3 plf
466.3 plf 103.8 plf
463.3 plf
463.3 plf
466.3 plf
466.3 plf
1620.7 1612.9 900.5285.6 plf 384.1 plf
384.1 plf 286.1 plf
286.1 plf
285.6 plf
103.8 plf
324 plf
326 plf
340 plf
450 plf450 plf
1304.6 1301.61301.61304.6
XXX Diekmann method
XXX APA Simplified method
APA Simplified FTAO Shear Wall Analysis
4645
4000
C
1 2
A
3
D
4
H
I
L JK
T
F=0 lb
F=0 lbF=0 lb
Force Transfer Methodology –Based on stiffness
F=0 lb
N.A.
5 6
T
S
R
Q
P O N M
6’6.5’6’3.5’ 3.5’
25.5’
1’
3.5’
3.5’
2.5’
F=0 lb
F=0 lbF=0 lb
F=0 lb
This slide shows force distribution
and location of I.P’s if header section
not meeting A/R requirements
Example results – double opening with shallow headers
Not to scale
V1-2
Blocking
8’
1
A
B
5
C
D
6
Tie strap/blocking
full width (Typ.)
2 3 4
V3-4 V5-6
Example 9 - Cantilever Wall Method- (Diekmann)
3’
6’
6’
4’4’3’
5’
∑ V
3’3’
23’
Fo/tFo/t
E
5’
Sections do not comply with allowable aspect ratios.
(Imagine if section is replaced by wire)
C, M, V T only, Typically, the tie
strap would be
required to extend
the full width of
the pier section
if a TD is not used
3’
T.D.2T.D.1 T.D.3
V1-2
8’
1 2
V5-6
5 6
V3-4
3 4
V4-5V2-3
V2
0M0M0M
V2
Fo/t
V5
V5
V4
V4
V3
V3
Fo/t.
0M
0M
0M
0M
F2C F3C
F3DF2D
F4C
F5D
vA-D
vD-Ev=579.7
plf
vA-C
vD-E vC-E
6’
6’4’
4’
3’
5’F5C
3’
5’
C
D
A
B
E
2’
3’
3’
Wall Section Forces
vC-D
0V0V0V
0H
0V
0H
T.D.2T.D.1 T.D.3
5 6 5 6
- +
+
-
Sign convention
A
C
E
8’
6’
3’
5’
3’
3’
VA
VE
Summing
Transfer Diaphragm TD3 Design
Po
s.
Neg
.
V5-6
Fo/t
V5
F5CF5C
V5
F5C
V5-6
T.D.3T.D.3
TD net
shear
Pier
basic
shear
+
-
+
or
When Does an Opening in a Shear Wall Require a Detailed Analysis?
(Mainly mechanical, electrical and plumbing openings)
IBC 2305.1.1
Openings in shear panels (Diaphragms or shear walls) that
materially effect their strength shall be fully detailed on the
plans and shall have their edges adequately reinforced to
transfer all shear stresses.
FPInnovations:
(Designing for openings in wood diaphragms)
Note: Recommendations should be similar
for shear walls as stated below:
It is strongly recommended that analysis for a shear wall with
an opening should be carried out except where all five of the
following items are satisfied:
a. Depth no greater than 15% of shear wall height;
b. Length no greater than 15% of shear wall length;
c. Distance from shear wall edge to the nearest
opening edge is a minimum of 3 times the opening
dimension in the given direction;
d. The shear wall portion between opening and
diaphragm edge satisfies the maximum aspect
ratio requirement. (all sides of the opening)
e. The shear does not exceed the nailing capacity of
the wall without an opening.
Most opening sizes
should be checked for
effects.
Wall-Small Opening
H
L
Suggestions:
• Use as rough guidance for MEP openings
• If opening is window, use perforated wall design
• If shear stresses are too high, use FTAO method
Criteria:
• Opening depth ≤ 0.15H
• Opening length ≤ 0.15L
• Distance from edge ≥ 3 x
the opening dimension
in the given direction;
• The shear wall portions
around opening satisfies
the maximum A/R.
• The shear does not
exceed the nailing capacity
Of the wall w/o an opening.
A
(301.6 plf)B
(362.7)
E
(362.1 plf)
G
(362.1 plf)
I
(300.8 plf)
1 2
A
3
D
4
2’6’ 6.5’
14.5’
4’
3.6
5’
1.3
5’
9’
V=4500 lbs.
C
J
(367.8)
D
(302.3)
C
(362.7)
F
(358)
K
(367.8)
H
(358)
L
(301.5)
T
Wall Potentially in Compliance with All Criteria
2’Wx1.35’H
opening
Nailing capacity of wall w/o opening
8d @ 4”/12”=380 plf ASD (seismic)
15/32” sheathing
By inspection, wall meets shear criteria
Opening:
• 0.15H= 0.15(9)=1.35’
• 0.15L= 0.15(14.5)=2.17’>2’
Edges:
• Vert.=
3(1.35)=4.05’>3.65’
• Horiz.= 3(2)=6’
Violates vertical edge
distance
Criteria:
• Opening depth ≤ 0.15H
• Opening length ≤ 0.15L
• Distance from edge ≥ 3 x
the opening dimension
in the given direction;
• The shear wall portions
around opening satisfies
the maximum A/R.
• The shear does not
exceed the nailing capacity
Of the wall w/o an opening.
A
(275.8 plf)
B
(413.8)
E
(413.8 plf)
G
(413.8 plf)
I
(284.4 plf)
1 2
A
3
D
4
2’3’ 9.5’
14.5’
3’
4’
2’ 9’
V=4500 lbs.
C
J
(387.9)
D
(299.5)
C
(413.8)
F
(343)
K
(387.9)
H
(343)
L
(302.1)
T
Wall Not in Compliance with All Criteria
Nailing capacity of wall w/o opening
8d @ 4”/12”=380 plf ASD (seismic)
15/32” sheathing
By inspection, portions of wall are 9% over-stressed in shear
Opening:
• 0.15H= 0.15(9)=1.35’ < 2’
• 0.15L= 0.15(14.5)=2.17’>2’
Violates opening height
Edges:
• Vert.= 3(2)=6’ >3’
• Horiz.= 3(2)=6’ >3’
Violates edge distance
2’Wx2’H
opening
Criteria:
• Opening depth ≤ 0.15H
• Opening length ≤ 0.15L
• Distance from edge ≥ 3 x
the opening dimension
in the given direction;
• The shear wall portions
around opening satisfies
the maximum A/R.
• The shear does not
exceed the nailing capacity
Of the wall w/o an opening.
A
(258.6 plf)B
(465.5)
E
(413.8 plf)
G
(413.8 plf)
I
(289.6 plf)
1 2
A
3
D
4
2’3’ 9.5’
14.5’
2’
5’
2’
9’
V=4500 lbs.
C
J
(372.3)
D
(294)
C
(465.5)
F
(343)
K
(372.3)
H
(343)
L
(303.7)
T
Wall Not in Compliance with All Criteria
2’Wx2’H
opening
Nailing capacity of wall w/o opening
8d @ 4”/12”=380 plf ASD (seismic)
15/32” sheathing
Opening:
• 0.15H= 0.15(9)=1.35’<2’
• 0.15L= 0.15(14.5)=2.17’>2’
Violates opening height
Edges:
• Vert.= 3(1.35)=4.05’>2
• Horiz.=
3(2)=6’>3’Violates edge
distanceBy inspection, portions of wall are 23% over-stressed in shear
In summary:
• The methods presented for analyzing openings in shear walls are
approximate methods, requiring some engineering judgement.
• Although it is acceptable practice to ignore gravity loads, their
inclusion should be considered.
• Complete load paths within the wall must be maintained.
• IBC 2305.1.1-Shear walls with openings must be fully detailed on
the drawings.
Reference Materials
http://www.woodworks.org/wp-content/uploads/Irregular-
Diaphragms_Paper1.pdf
• The Analysis of Irregular Shaped Structures: Diaphragms and
Shear Walls-Malone, Rice-Book published by McGraw-Hill, ICC
• Woodworks Presentation Slide Archives-Workshop-Advanced
Diaphragm Analysis
• NEHRP (NIST) Seismic Design Technical Brief No. 10-Seismic
Design of Wood Light-Frame Structural Diaphragm Systems: A
Guide for Practicing Engineers
• SEAOC Seismic Design Manual, Volume 2
• Woodworks-The Analysis of Irregular Shaped Diaphragms
(paper). Complete Example with narrative and calculations.
• Webinar Archive- Offset Diaphragms -Part 1
• Webinar Archive- Offset Shear Walls-Part 2
• Slide Archive-Workshop-Advanced Diaphragm Analysis
• Slide Archive-Offset Diaphragms and Shear Walls
Information on Website
Method of Analysis References
Example Offset Diaphragms and Shear WallsOffset Diaphragms
Questions?
This concludes Our Workshop Presentation
on Advanced Diaphragm Analysis
R. Terry Malone, P.E., S.E.
Senior Technical Director
WoodWorks.org
Contact Information:
928-775-9119