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

2

Presentation Based On:

Load Transfer Through Diaphragms

T

Based on 2012 IBC, ASCE 7-10 and 2008 SDPWS

Copyright McGraw-Hill, ICC

3

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

4

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

5

• 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.

6

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

8

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

14

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

15

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)

16


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?


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


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


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


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

21

22


Basic Information

23

Idealized as Flexible

Idealized as Rigid

ASCE7-10 Section 12.3-Diaphragm Flexibility

Or…..

24

ASCE7-10 Section 12.3- Diaphragm Flexibility

You can model it as Semi-rigid

My 3rd grade school teacher

25

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.

26

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

27

• Diaphragm stiffness/Flexibility • Boundary Elements • Complete Load Paths • Method of Analysis

Basic Information

The Visual Shear Transfer Method

28

+ -

+

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)

29

+

-

+ -

+ -

- +

Basic Shear Diagram Positive diaph. shear elements

Pos.

Neg.

Diaphragm shear transferred into boundary element (typ.)

Strut in tension

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

30

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?

31

SW

SW

Diaph. C.L.

W ( plf)

Longitudinal Collector

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


SW

Res

istin

g fo

rces

33

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



F

F

RB

RA

RC

RA

Propped Cantilever Transfer Diaphragm

a b

Simple Span and Propped Cantilever Transfer Diaphragms

Discont. Chord / strut F F

34

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…???

38

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’


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.

load transfer through diaphragms

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