Load Transfer Through Diaphragms
Transcript of Load Transfer Through Diaphragms
By R. Terry Malone, P.E., S.E.
SE University, January, 2015 www.LearnWithSEU.com
Load Transfer Through Diaphragms
Senior Technical Director Architectural & Engineering Solutions [email protected]
Copyright Woodworks
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Presentation Based On:
Load Transfer Through Diaphragms
T
Based on 2012 IBC, ASCE 7-10 and 2008 SDPWS
Copyright McGraw-Hill, ICC
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Complete Example with narrative and calculations
http://www.woodworks.org/publications-media/solution-papers/
Download Process: • WoodWorks.org website • Publications-Media tab • Wood Solutions Papers
http://www.woodworks.org/wp-content/uploads/Irregular-Diaphragms_Paper1.pdf
Course Description
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This presentation will provide a review of a method of analysis that can be used to address irregularities that commonly occur in todays structures. Topics will include code requirements, how to recognize diaphragm irregularities and discontinuities, how shears are distributed through complex diaphragms, how to solve the transfer of discontinuous forces across areas of discontinuity, and the analysis of flexible wood sheathed or untopped steel decking diaphragms with horizontal offsets.
Learning Objectives
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• Basic Information Discuss boundary elements, complete lateral load paths, diaphragm flexibility and review an analytical method used for solving complex diaphragms and shear walls (Diekmann Method) using “Transfer Diaphragms” and the “Visual Shear Transfer Method.”
• Diaphragm Flexibility Requirements Discuss the diaphragm flexibility requirements of ASCE 7-10.
• Diaphragms With Horizontal Offsets Learn how to analyze a diaphragm with a horizontal offset and how to transfer forces across areas of discontinuity.
• Diaphragms Segmentation Learn how to break down complex diaphragms into manageable segments that will help simplify the analysis.
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Presentation Assumptions
Assumptions:
• Loads to diaphragms and shear walls • Strength level or allowable stress design • Wind or seismic forces.
• The loads are already factored for the appropriate load combinations.
Code and Standards:
• ASCE 7-10 “Minimum Design Loads for Buildings and Other Structures” • 2012 IBC • 2008 SDPWS-”Special Design Provisions for Wind and Seismic”
Analysis and Design references:
• The Analysis of Irregular Shaped Structures: Diaphragms and Shear Walls-Malone, Rice
• Woodworks-The Analysis of Irregular Shaped Diaphragms • Design of Wood Structures- Breyer, Fridley, Pollock, Cobeen • SEAOC Seismic Design Manual, Volume 2 • Wood Engineering and Construction Handbook-Faherty, Williamson • Guide to the Design of Diaphragms, Chords and Collectors-NCSEA
Poll Question
Do you typically account for offsets and other diaphragm irregularities in your designs? Yes. Spot check some of them No, they aren’t important.
7
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Evolution to Complex Buildings
• Simple structures Complex structures
• The method of analysis is: Required for all construction types. Straight forward and simple to use. “Based on simple statics!”
• Today’s presentation focuses on: • Continuous load paths across areas of discontinuities. • Flexible wood sheathed or un-topped steel deck diaphragms.
Wood diaphragms are well suited for these shapes as they can be easily adapted to the building shape and are cost effective.
9 Marselle Condominiums 5 stories of wood over 6 stories concrete Structural Engineer engineer: Yu & Trochalakis, PLLC (podium) 2 above grade Photographer: Matt Todd Photographer
Mid-rise Multi-family
10
Dis
cont
inuo
us c
hord
s Tr
ansv
erse
Cant.
Mid-rise Multi-family
SW SW SW SW
SW SW SW SW SW
SW
Lds. Discontinuous struts Longitudinal
Lds.
No exterior Shear walls
Flexible, semi-rigid, or rigid???
11 Harrington Recovery Center Structural engineer: Pujara Wirth Torke, Inc. Photographer: Curtis Walz
Offsets in the diaphragm and walls
Vertically offset Diaphragms?
Openings in diaphragm
12
• Boundary Elements • Complete Load Paths • Diaphragm Flexibility • Method of Analysis
Basic Information
13
SW
Struts, Collectors, and Chords- (my) Terminology
W ( plf)
Chord
Chord
Chord
Stru
t
Diaphragm support
Col
lect
or
SW
Collector Chord
Cho
rd/C
olle
ctor
Chord
Stru
t
TD1
Chord
Cho
rd/C
olle
ctor
SW
Discontinuous diaphragm chord
SW
Strut- receives shears from one side only*. Collector- receives shears from both sides. Chord-perpendicular to the applied load and receives axial tension and compression forces. *[ Drag struts and collectors are synonymous in ASCE7]
SW
Diaphragm support
T
C Chord
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Diaphragm 1 Diaphragm 2
Diaphragm 2 Boundary (typical)
Chord
Chord
Col
lect
or
Stru
t St
rut
Chord
Stru
t
Fundamental Principles: A shear wall is a location where diaphragm forces are resisted (supported), and therefore defines a diaphragm boundary location.
Note: Interior shear walls without a collector or a complete alternate load path are NOT ALLOWED!
Diaphragm Boundary Elements
SW1
SW2
SW3
Note: All edges of a diaphragm shall be supported by a boundary element.
Diaphragm 1 Boundary (typical)
• Diaphragm Boundary Elements:
• Chords, drag struts, collectors, Shear walls, frames
• Boundary member locations: • Diaphragm and shear wall perimeters • Interior openings • Areas of discontinuities • Re-entrant corners.
• Diaphragm and shear wall sheathing shall not be used to splice boundary elements. • Collector elements shall be provided that are capable of
transferring forces originating in other portions of the structure to the element providing resistance to those forces.
Required for Seismic and wind
1 2
B
3
C
A
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Loads
Col
lect
or
Collector
Diaphragm 1 Diaphragm 2 St
rut
Chord Chord
Stru
t St
rut
Diaphragm 2 Boundary
Diaphragm 1 boundary
Re-entrant corner Tearing will occur if collectors are not installed at re-entrant corner.
1 2
A
B
3
C
Deflection if no tie
Deflected curve if proper tie Deflected curve if no tie
SW1
SW2 SW3
SW4
Chord
Chord
Boundary Elements “L” Shaped Buildings-Transverse Loading
Deflection if tie
Diaph. Boundary (Longitudinal loading)
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• Boundary Elements • Complete Load Paths • Diaphragm Flexibility • Method of Analysis
Basic Information
Complete Continuous Lateral Load Paths 17
Strut/chord
Open
3
4
5
2 1
F
E
D
C
B
6 9 10 7 8
Strut/chord
Stru
t
Stru
t (ty
p.)
Strut chord
Strut chord
Strut /chord
Stru
t
Strut/chord
Strut/chord
SW1
SW5
SW2 SW3
SW6
SW4
Stru
t
MR
F1
Multiple offset diaphragm
Offset strut
Support Support
Col
lect
or
Collector
Collector (typ.)
Collector (typ.)
Collector (typ.)
Col
lect
or (t
yp.)
A
Analysis: ASCE7-10 Sections: • 1.3.1.3.1-Design shall be based on a rational analysis • 12.10.1-At diaphragm discontinuities such as openings and re-entrant corners, the design shall assure that the dissipation or transfer of edge (chord) forces combined with other forces in the diaphragm is within shear and tension capacity of the diaphragm.
What does this mean?
Complete Continuous Lateral Load Paths 18
Strut/chord
Open
3
4
5
2 1
F
E
D
C
B
6 9 10 7 8
Strut/chord
Stru
t
Stru
t (ty
p.)
Strut chord
Strut chord
Strut /chord
Stru
t
Strut/chord
Strut/chord
SW1
SW5
SW2 SW3
SW6
SW4
Stru
t
MR
F1
Support Support
Col
lect
or
Collector
Collector (typ.)
Collector (typ.)
Collector (typ.)
Discontinuous diaphragm chord/strut
Discontinuous diaphragm chord
Discont. diaph. chord
Discont. diaphragm chord
Discont. diaphragm chord
Col
lect
or (t
yp.)
A
ASCE7-10 Section 1.4-Complete load paths are required including members and their splice connections
Complete Continuous Lateral Load Paths 19
Strut/chord
Open
3
4
5
2 1
F
E
D
C
B
6 9 10 7 8
Strut/chord
Stru
t
Stru
t (ty
p.)
Strut chord
Strut chord
Strut /chord
Stru
t
Strut/chord
Strut/chord
SW1
SW5
SW2 SW3
SW6
SW4
Stru
t
MR
F1
Offset shear walls and struts
Support Support
Col
lect
or
Collector
Collector (typ.)
Collector (typ.)
Collector (typ.)
Offset shear walls
Col
lect
or (t
yp.)
A
ASCE7-10 Section 1.4-Complete load paths are required including member and their splice connections
Complete Continuous Lateral Load Paths 20
Strut/chord
Open
3
4
5
2 1
F
E
D
C
B
6 9 10 7 8
Strut/chord
Stru
t
Stru
t (ty
p.)
Strut chord
Strut chord
Strut /chord
Stru
t
Strut/chord
Strut/chord
SW1
SW5
SW2 SW3
SW6
SW4
Stru
t
MR
F1
Opening in diaph.
Support Support
Col
lect
or
Collector
Collector (typ.)
Collector (typ.)
Collector (typ.)
Col
lect
or (t
yp.)
Vertical offset in diaphragm
A
Design: • IBC 2305.1.1-Openings in shear panels that materially effect their strength shall be fully
detailed on the plans and shall have their edges adequately reinforced to transfer all shear stresses.
Poll Question
Do you routinely consider the stiffness between the diaphragm and vertical resisting elements? Yes Occasionally No
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• Boundary Elements • Complete Load Paths • Diaphragm Flexibility • Method of Analysis
Basic Information
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Idealized as Flexible
Idealized as Rigid
ASCE7-10 Section 12.3-Diaphragm Flexibility
Or…..
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ASCE7-10 Section 12.3- Diaphragm Flexibility
You can model it as Semi-rigid
My 3rd grade school teacher
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Average drift of walls
Is maximum diaphragm deflection (MDD) >2x average story drift of vertical elements, using the Equivalent Force Procedure of Section 12.8
Maximum diaphragm deflection
Semi-rigid (Envelope Method)
Is diaphragm untopped steel decking or wood structural panels
Idealize as
flexible
Is span to depth ratio ≤ 3 and having no horizontal irregularities ?
Is diaphragm concrete slab or concrete filled steel deck ?
Structural analysis must explicitly include consideration of the stiffness of the diaphragm (i.e. semi-rigid modeling).
Is any of the following true? 1 & 2 family Vertical elements one Light framed construction Dwelling of the following : where all of the following are met: 1. Steel braced frames 1. Topping of concrete or 2. Composite steel and similar material is not concrete braced frames placed over wood structural 3. Concrete, masonry, steel SW panel diaphragms except or composite concrete and for non-structural topping steel shear walls. not greater than 1 ½” thick. 2. Each line of vertical elements of the seismic force-resisting system complies with the allowable story drift of Table 12.12-1.
Idealize as rigid
Idealize as flexible
Yes
Yes Yes
No
No
No
No No
Star
t ASCE7-10 Section 12.3 Diaphragm Flexibility Seismic
Yes
Yes
Section 12.3.1- The structural analysis shall consider the relative stiffnesses of diaphragms and the vertical elements of the lateral force resisting system.
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Is diaphragm untopped steel decking , concrete filled steel decks or concrete slabs, each having a span-to-depth ratio of two or less?
Yes
Yes
No
Diaphragm can be idealized as flexible
Is diaphragm of wood structural Panels ?
Diaphragm can be idealized as rigid
No
Is diaphragm untopped steel decking , concrete filled steel decks or concrete slabs, each having a span-to-depth ratio greater than two ?
Yes Calculate as flexible or semi-rigid
ASCE7-10, Section 26.2 Diaphragm Flexibility Wind
Start
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• Diaphragm stiffness/Flexibility • Boundary Elements • Complete Load Paths • Method of Analysis
Basic Information
The Visual Shear Transfer Method
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+ -
+
Positive Direction
+ -
Transverse Direction (shown)
Lds.
Shears Applied to Sheathing Elements
FY
FX
+M
Symbol for 1 ft x 1 ft square piece of sheathing in static equilibrium (typ.)
+
+ -
Shears Transferred Into Boundary Elements
Unit shear transferred from the sheathing element into the boundary element (plf)
Unit shear acting on sheathing element (plf)
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+
-
+ -
+ -
- +
Basic Shear Diagram Positive diaph. shear elements
Pos.
Neg.
Diaphragm shear transferred into boundary element (typ.)
Strut in tension
Resisting wall shears
Resisting wall shears
Resisting wall shears
Strut in Compr.
Strut in comp.
Strut in tension
SW 2
SW 1
SW 3
Diaphragm C.L.
Strut Forces Strut Forces T
C
T
T
C
C
1 2
A
B
Negative diaph. shear elements
(-)
(+)
(+)
(+)
(-)
(-)
(-)
+ -
Positive sign convention
Maximum moment
1 ft. x 1 ft. square sheathing element symbol at any location in the diaphragm.
Shear Distribution Into a Simple Diaphragm The Visual Shear Transfer Method
Support Support
SW
SW
All edges of a diaphragm shall be supported by a boundary element (chord, strut, collector) or other vertical lateral force resisting element (shear wall, frame).
w=uniform load
Introduction to Transfer Diaphragms and Transfer Areas
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Col
lect
or
T Collector
(support)
(support)
Chord
Chord
TD1 TD Ratio=4:1
Maximum Col
lect
or
T
Framing members, blocking, and connections shall extend into the diaphragm a sufficient distance to develop the force transferred into the diaphragm.
Transfer Diaphragm
• sub-diaphragm • Transfers local forces out to primary
chords/struts of the main diaphragm.
What does this mean?
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SW
SW
Diaph. C.L.
W ( plf)
Longitudinal Collector
Diaphragm chord
Discontinuous diaphragm chord
1 2
A
B
3
C Diaphragm chord
Dra
g st
rut
Diaphragm support
Diaphragm support
Transfer Diaphragm Members and Elements
4
Transfer Area
Diaphragm chord
• The length of the collector is often determined by dividing the collector force by the diaphragm nailing capacity. (Wrong!) • The collector is often checked for tension only. (Wrong!) Compression is rarely checked.
Typical callout CMST14 tie strap x 10’-0” with (xx) 10d nails over 2x flat blocking. Lap 2-8” onto wall.
32 Transfer Mechanism
1 2
B
3
C
T C
Main chord
Main chord
B
C
A
2 3
Disrupted chord
Res
istin
g fo
rces
Transfer area without transverse collectors
Transfer using beam concept
Transfer Diaphragm
( Beam)
Transfer area
Disrupted chord
Support
Support
Collector
Rotation of section
This force must be transferred out to the main chords. A complete load path is required.
Collector must extend the full depth of the transfer diaphragm
NOTE:
SW
Collector Full depth Chord
Cho
rd/C
olle
ctor
St
rut
TD1
Cho
rd/C
olle
ctor
SW
Discontinuous diaphragm chord
SW
Res
istin
g fo
rces
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TD1
Support
Support
Discont. Chord / strut F
a b
A
C
B
2 1 Transfer Diaph. depth
Tran
sfer
Dia
ph. l
engt
h
LaFRA
)(=
L
LbFRC
)(=
Transfer Diaphragm
Analogous to a simple span beam with a concentrated load
TD1
Support
Support
Discont. Chord / strut F
A
C
B
2 1 Transfer Diaph. depth
Tran
sfer
Dia
ph. l
engt
h
bLFRB
)(=
L
baFRA
)(=
Transfer Diaphragm
Analogous to a propped cantilever beam with a concentrated load
Simple Span Transfer Diaphragm
Collector Chord, strut or shear wall
Chord, strut or shear wall
Chord, strut or shear wall
Chord, strut or shear wall
F
F
RB
RA
RC
RA
Propped Cantilever Transfer Diaphragm
a b
Simple Span and Propped Cantilever Transfer Diaphragms
Discont. Chord / strut F F
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SW
Col
lect
or
T T
+
-
Analogous to a beam with a concentrated Load.
Chord force at discontinuity
Subtract from basic shears
Add to basic diaphragm shears
1
A
B
2
C
Collector
(TD support)
(TD support)
Chord
TD1
Basic Shear Diagram at transfer diaphragm
-75 plf
+250 plf
+300 plf +225 +225
plf plf
vnet=+300+(250)= +550 plf
vnet =+225–(75)= +150 plf
3
TD depth
Tran
sfer
dia
phra
gm le
ngth
+
, Shear = VC
DTD DTD
, Shear = VA DTD
vnet=+300-(75)= +225 plf
vnet =+225 +(250) = +475 plf
Transfer Diaphragm Shears
a b
VA=
VC=
LTD
T(b) LTD
T(a) LTD
LTD
Method of Analysis-Method by Edward F. Diekmann
+500 plf
Main chord
Main chord
Disrupted chord
The transfer diaph. aspect Ratio should be similar to the main diaphragm.
No outside force is changing the basic diaphragm shear in this area
No outside force is changing the basic diaphragm shear in this area
T
C
Col
lect
or
35
+ +
+ +
+225 plf +150 plf
+550 plf +475 plf
Resulting net shear diagram on collector
325 plf 325 plf
Net direction of shears acting on collector
Shear Distribution Into The Collector
Direction of shear transferred into collector
Collector
• Collector force=area of shear diagram
Shear left=+550-225= +325 plf
2
• Place the net diaphragm shear on each side of the collector
• Sum shears on collector (based upon direction of shears transferred onto collector).
Fcollector=(325+325)(Lcollector) Dir. of force on collector
B
2 3
Net shear
Note: The net shears will not always be equal.
Lcollector
• Place the transfer shears on each side of the collector
Shear right=+475-150=+325 plf
36
Diaphragms with Horizontal Offsets
Poll Question
Do you currently know how to design diaphragms with horizontal offsets? Yes No Have you ever seen examples on how to design offset diaphragms? Yes No
37
SW1
SW2
Diaph. C.L.
Diaph. chord Collector C
olle
ctor
Diaph. chord
1 2
A
B
3
C
Col
lect
or
Support
Support
TD1
4
Diaph. chord
Connection design with 25% incr.
Support
Irregularity Requirements for Diaphragms with Horizontal End Offsets-Seismic
Support
ASCE 7-10 Section 12.3.3.4 -Requires 25% increase in diaphragm design forces (Fpx) for horizontal irregularity Type 2 (SDC D-F) for the following elements:
• Connections of diaphragm to vertical elements and collectors (diaphragm supporting elements-TD) • Collectors and their connections to vertical elements
Design diaphragm connections to SW and struts using 25% increase per ASCE 7-10 Section 12.3.3.4. (Grid lines 1 and 4) St
rut
Design transfer diaphragm connections to boundary elements (chords) at Transfer Diaphragm using 25% increase per ASCE 7-10 Section 12.3.3.4. (Grid line C and A??)
Stru
t St
rut
Design transfer diaphragm connection to collector using 25% increase per ASCE 7-10 Section 12.3.3.4.
Exception: Forces using the seismic load effects including the over-strength factor of Section 12.4.3 need not be increased.
Design collector and connections to SW using 25% increase per ASCE 7-10 Section 12.3.3.4. (Grid lines 1 and 4)
Not…???
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39
SW 1 SW 2
Diaph. C.L.
25’ 20’
15’
w=200 plf
Diaph. chord Collector
Col
lect
or
TD c
hord
s
Diaph. chord
80’
35’ 50’
Discontinuous diaphragm chord
1 2
A
B
3
C
Col
lect
or
TD c
hord
s
Support
Support
TD1
+ -
Sign Convention
4
Diaph. chord
F2B
RL lb
200 plf
25’
F2A
Free body for F2B
1 2
A
B
∑M=0 35’
M2B ft.-lb F2B lb
Support RL lb
RR lb
Example 1-Diaphragm with Horizontal End Offset-Transverse Loading
V2 lb
V3 lb
A/R=2.5:1
Support
40
SW 1
SW 2
Diaph. C.L.
25’ 20’
15’
80’
V=Basic shear - TD shear plf
F2B
v= DTD VC plf
VA lb
VC lb v= Net shear> 3x Basic shear
v2R plf v2L plf
v1 plf
v3 plf
1 2
A
B
3
C
Basic shear diagram
Net TD shears (basic shear +/- transfer diaph. shears)
No net change Net change occurs in TD
No net change
35’
Transfer Diaphragm and Net Diaphragm Shear
+ -
Sign Convention
4
15’
35’
RL lb
RR lb
(Net shear)
Pos.
N
eg.
v4 plf
TD s
hear
dia
gram
F2B
v= DTD
VA plf
41
SW 1 SW 2
Diaph. C.L.
25’ 20’
15’
F3C
FCL
C
T F2B
T
F2A
1 2
A
B
3
C
F2B
+v2
-v3 x1’
x2’ +F lb -F lb
Longitudinal Chord Force Diagrams
0 plf
+ -
Sign Convention
4
17.5’
v1 v2L
Support
Support
0 plf
FCL
F2B
F3A
42
SW 1
25’ 20’
15’
F=6000 lb
F=6000 lb (this is not an insignificant force.)
F3B
F3B
T C
1 2
A
B
3
C
Transverse Collector Force Diagrams
+ -
Sign Convention
Net shear Net shear
43
Diaph. C.L.
w1
A B
1
2
3
Deflection of rectangular diaphragm Deflection of
offset diaph.
C
w2
Diaphragm Deflection Equations Equation variables for offset diaphragms • Varying uniform loads • Concentrated loads from discontinuous shear walls • Varying moments of inertia
ATC7 • Modify the bending and shear portion of the
standard rectangular deflection equation to fit the model:
Bending deflection Shear
deflection
Nail slip Adjusted for non-uniform nailing (ATC-7/APA)
Chord slip
NOTE: Multiply deflection x 2.5 for unblocked diaphragm Multiply nail slip by 1.2 if not Structural I plywood
P
Shear Deflection -USDA Research Note FPL-0210 • Simplification of the conventional energy method • The integrations of the equations can be reduced to multiplying the total area of the shear diagram due to the general loading by the ordinate of the shear diagram due to a dummy load applied at the desired point of shear deflection.
I1 I2
SDPWS combines
Standard deflection equation for simple span, rectangular blocked diaphragm (at C.L.)
Cannot use
b b’
L
44 Diaphragm Nailing Callouts
10d
@ 4
/6/1
2 B
1
2 3 Transfer area Boundary (High shear area)
Transfer diaphragm Boundary (Typ.)
Boundary locations
Diaphragm boundary
357.
2 pl
f 32
0 pl
f
285
plf
214.
3 pl
f 42
.9 p
lf
37.1
plf
70
plf
214.3 plf 357.1 plf
70 plf Basic shear diagram 150 plf
10d
@ 6
/6/1
2 B
10d
@ 6
/12
UB
C
ase
I
10d @ 4/6/12 B
10d
@ 6
/12
UB
C
ase
I
10d
@ 6
/12
UB
C
ase
I
Check the shear capacity of the nailing along the collector
Callout all nailing on drawings: • Standard diaphragm nailing • Boundary nailing • Collector nailing
x4 x3 x1 x2 Special nailing along collectors Sum of shears to collector or highest boundary nailing-greater of
45
NOTE: v max=1864 plf
F=7626 lb
v=304 plf
F=25230 lb
F=6991 lb F=7454 lb F=7512 lb
v max=1748 plf
F=25278 lb @ c.l. diaphragm (calc’d=22500 lb)
F=24905 lb
v=328 plf v=244 plf v=504 plf
v=997 plf v=588 plf v=390 plf v=997 plf
(designed)
• Diaphragm designed as a simple rectangular diaphragm, no offset, using only a spreadsheet. • Checked only diaphragm shear and chord force (maximum depth, not offset depth). • No collectors, connection designs or details at re-entrant corners. • Forces on trusses at collectors were not called out on drawing.
Example-Actual Project
Steel decking
Diaphragm Shears
Critical connections
Transfer diaphragms and collectors are required
4 ft. offset
45 ft.
95 ft.
Open
3 4
2
1
D
C
B
A
5
6 7
L1 L3
A Quick Note on Segmentation
w7 w8
w6 w4
L2
Www
L5
W
WLw
w1
w5
L4
L7 L6
W
W
W
W
d1
d2
d3
OM
RF
SW
SW
SW
TD1 TD2
Ww
w
WLw
w2 w3
Chord Collector Collector
Col
lect
or
Chord
Col
lect
or
Col
lect
or
Diaphragm 1 Cantilever
Dia
phra
gm 2
Offs
et
she
ar
wal
ls
w9
Collector Collector
Collector
Support
Support
46
TD1
TD2
Cant. Diaph.
Www=123 plf
WLw=77 plf
W=200 plf (wind) W=200 plf W=200 plf (wind)
W=200 plf (wind)
Support
Support
Collector
Col
lect
or
Collector
Col
lect
or
Collector
Col
lect
or
Stru
t C
olle
ctor
Collector Collector
Chord
Chord
Chord
Chord
Chord Chord Chord
Col
lect
or
Rig
id fr
ame
Chord
Chord
Collector
Chord Chord
Stru
t
3 4 1
D
C
B
A
5 6 7 2
Segmentation of the Diaphragm for Transverse Loading
Chords force transferred to TD2
Designed as diaph. with opening
Sub-Chord
Sub-Chord
47
TD1
Diaph.1
Diaph.2
Diaph.3 Diaph.4
Diaph.5
Ww
w=1
23 p
lf
W=2
00 p
lf W
=200
plf
C
3 4 1
D
B
A
5 6 7 2
TD2
Support
Support
Collector
Col
lect
or
Collector
Col
lect
or
Collector
Col
lect
or
Cho
rd
Col
lect
or Collector
Collector
SW
Strut
Strut
Strut
Strut Strut
Strut Strut
Cho
rd
Collector
Cho
rd
Cho
rd
SW
SW
SW SW
Rig
id fr
ame
Cho
rd
Segmentation of the Diaphragm for Longitudinal Loading
WLw
=77
plf
Strut force transferred to TD2
48
By R. Terry Malone, P.E., S.E.
49 SE University, January, 2015 www.LearnWithSEU.com
This Concludes Our Presentation on: Load Transfer Through Diaphragms
Senior Technical Director Architectural & Engineering Solutions [email protected]
Copyright Woodworks
CHALLENGE QUESTION:
Which item related to Load Transfer Through Diaphragms is the answer to this session’s Challenge Question?
A. Boundary Elements B. Complete Load Paths C. Diaphragm Flexibility D. Method of Analysis
Please circle the answer that is announced so that you can use the information to complete your quiz (NY) or form (FL) for PDH.