Thanh Huynh

Why Modular Structures?What is a Load Path and Load Sharing?Structural ModelShear Wall CorrelationStructural DetailsWind LoadsSAP 2000 Analysis MethodSAP 2000 Output VerificationSAP2000 ResultsSAP 2000 DiscussionFuture Work

In 2004… “Prefab housing production in North America as a whole is about 300,000 units per year and valued at $11 billion USD. Consumer acceptance of such products is rising steadily and emphasis is turning towards ‘higher end’ designs.”

-Smith et.al., “High Performance Modular Wood Construction Systems”, University of New Brunswick 2007.

2011 Mcgraw Hill report shows that 25% of architects who utilize BIM (Building Information Modeling) software also incorporated modular components in their plans.

Overall lack of attention to modeling modular structures.

A load path is the path that forces are transferred between the elements of an assembly to safely travel into the foundation.

Different for• Gravity Loads• Lateral Loads

Load Sharing is the ability of individual components to work together to distribute loads that are applied.

Dependent on the stiffness of the member relative to the stiffness of surrounding elements.

“stiffness attracts load”– Dr. Thomas Miller

Simplified Model of End Wall for Calibration

• Same shear wall dimensions as analog but with no openings. • Spacing of studs changed to remain consistent with no double

studs and to create symmetry.• Calibration performed for both end wall and side walls• Different layers of sheathing analyzed separately• Pinned at the ends and out-of-plane deformations restrained• Moments released at both ends for all frame elements

South Wall

West Wall

Case A

6 ft

35.1 psf

23.3 psf

37.3 psf

26.0 psf

17.5 psf

22.8 psf

South Wall

Case B

West Wall

37.3 psf

26.0 psf

17.5 psf

22.8 psf

3 ft

35.1 psf23.3 psf

6 ft

Loading Diagram SW Corner

Load case A on the Northwest Corner. Deflected shapes are reasonable.Should expect relatively small deflections in the horizontal direction perpendicular to wind

West Wall

Case A

6 ft

North Wall

35.1 psf

23.3 psf

37.3 psf

26.0 psf

17.5 psf

22.8 psf

0.6D+0.6W NW A

Win

d D

irec

tio

n

Qualitative Check

0.15in deflection in the global y direction

• Ties and CMU elements will engage to resist overturning• Only ties resist horizontal displacements

z

y

Win

d D

irec

tio

n

Qualitative Check

Displacement in the global z direction (in)

• Largest upward deflections at center of roof.• Deflections are upward in the direction of roof uplift.• Smaller upward deflection due to steel column elements at the center.

Wind Direction

-1916.5

0.1 -1916.4 -1951.7 -1950.4

-1888.2

-119.2

-617.8

-578.7

0.1-1192.4

-189.0 -254.8 -26.80.1

-1112.2

1573.2 997.4 467.0 1321.0 227.4 477.0 1388.3 222.4 307.4 1450.7 284.4 815.9 2313.4

261.5 109.9 73.7 273.5 32.7

318.9 220.3 192.8 419.4

-200

-150

-100

-50

0

50

100

150

200

-500 -400 -300 -200 -100 0 100 200 300 400 500

y(i

n)

x (in)Location and Reactions in the z (lbs)

North

South

North

South

• Reactions in ties and CMU from 0.6D+0.6W Northwest Corner Load Case A

Wind Direction

Tension in Ties 0.6D+0.6W NW A Case

CMU

Ties

Dead Load

Wind Uplift

Lateral Wind

1.57k

1.92k

1.92k

0.618k

1.19k

Z

Y

Tie Reactions

CMU Reactions

So

uth

Wa

ll

No

rth

Wa

llWest Wall

Snapshot of reactions along the West Wall

FBD

CMU Response to overturning

Tie response to horizontal displacement

Total vertical load at foundation level is negligible.

Tie Response to overturning

Ties along north wall are not engaged. (more horizontal than vertical displacement)

0.6D+0.6W NW A Case FBD

-1916.5

0.1-617.80.1

-1192.4

1573.2

Nor

Phase 2 OptionsWall test