Theatre Design & Technology - Summer 1987 - 21

MEASURING THE DEFLECTION OF YOUR MODULAR STAGING: PREDICTED AND ACTUAL

1. Determine the actual static load-bearing ca-

pability of standard staging. This initial study
would include four variations; more variations
will be investigated in future studies.
2. Identify the existence of an algebraic mathematical model that would allow theatre technicians,
specifically technical directors, the ability to design a structure that would perform adequately
for a particular application. Specifically this investigation would determine the suitability of
simple beam analysis for this purpose.
3. Identify a design procedure which would readily
allow for informed material substitutions, given
that budget and availability concerns frequently
require investigating alternative products.
It was felt that this limited initial study would be
useful not only for the specific data it would provide, but
as a guide for determining the direction of possible future studies. Related research projects have also been
undertaken at the Yale School of Drama 2
Four platforming alternatives were designed, built,
and tested during this study. All platforms shared nearly
identical spacing and layout of framing members, column (leg) spacing, and deck attachment techniques as
shown in Figure l. To guide material selection and assembly procedure decisions, Platform C f%" plywood
deck; 2 x 4 lumber frame I was selected as the control.

Figure 1: Plan and Section Views of Four Test Platforms

Table 1: Construction Note Summary

Unit
A

Frame

Deck

l"x2"16ga 1':+"':1
Steel Tube ACX Ply

Frame
Joinery

Deck/Frame Weight
Fasteners
w/legs

Welded

I" #10
tek'" screw

PO lb.

9" O.c.
B

;,x 2"

1, ACX

,o,l/L:." X

Ply

;," Steel
C

2 x ~ SPF

ACX

Ply
D

2 x ~ SPF

aSB

flakeboard

3" #7
2" #7
Screw
screw
Welded 6" O.c.

113 lb.

16d
coated
nails

3d coated
nail

III lb.

16d
coated
nails

3d coated
nail

6" O.c.
III lb.

6" O.c.

This combination of materials is as close to a standard as
exists in theatre staging.
The four units studied were chosen to provide a variety of possible construction options. While 2 x 4 and
1 x 6 lumber are traditional framing materials for staging, l" x 2" tube steel grows increasingly popular. The
combination wood/steel frame was included as an example of an "engineered" nontraditional alternative. As
in Campbell's article, our design decisions also concentrated on the day-to-day practicality of our test units.
Principal design considerations were COSt, material
availability, weight, joining of multiple units, fabrication techniques, storage dimensions, and attachment of
legs, bracing, and facing.
The actual strength of a platform can be measured
only by means of destructive testing. Since such testing
was beyond the scope of this study, we concentrated on
determining the stiffness of each unit. Stiffness was
determined by the measurement of surface deflection
occuring from static loads. Measurements were obtained by means of multiple analog transducers

Sec.A-A
'--Lumber NOller
Ix2 Steel Tube---...J
Plotrorm A

Figure 2: Platform A with LVDTs Mounted to Underside

6'-0'

-.I -

Leg Soc e
3/4Ply"",-

..l.f

2'i'-R

-II -0+2-0-1--

." Oller:~

Lumber/Steel Frome

Sec. A-A

Plotrorm 6

- 0 - - - -.....

Frome

~) '-Leg

x4 Frome

""
" J

Leg
Sec A-t.,

Plotforms CIS. D

TD&T· SUMMER 1987

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