Encyclopedia of Environmental Science and Engineering, Volume I and II

288 ELECTROSTATIC PRECIPITATION

movement over one quarter of the building length rather than

over one half, at least in the north–south direction.

Design Phase

To accomplish the above design changes, four major obsta-

cles had to be overcome:

1) The centerline support girders for each precipita-

tor unit had to be fixed, or at least stiffened, so that

they could come as close to being a zero expansion

line (N–S) as possible.

2) Expansion points had to be designed for the 36

Line girder connections.

3) Column Line 36 had to be braced in order to

stabilize the building after the connections were

cut free.

4) Provisions had to be made for the outward move-

ment of the peripheral columns around the building.

For the normal operating temperature of the units (670°F),

it was decided to assume the support steel temperature would

rise to an average of 500°F during operation, and provide for

the large movements involved. This temperature rise would

be applied to all steel directly below the plan dimensions of

each unit with the framing beyond these dimensions only

assumed to rise to 200° F. Under this assumed combination

of temperature rises, the maximum differential movement

expected was approximately 2½ in the north–south direc-

tion as well as in the easterly direction. The heavily braced

LL Column Line in the boiler house would act as the zero

movement line in the east–west direction.

The center support girders for the lower units were restrained

by shifting adjacent vertical diagonal bracing to fix the PP320,

PP390, M320, and MM390 columns at the + 42−8 elevation.

The G5 girders on the upper units were stiffened with horizon-

tal members and bracing as indicated in Figure 10.

The expansion joint design for the 36 Line connections

utilized ball bearing assemblies except for the G4 connections

ROCKER

BEARING PLATE

SUPPORT BRACKET

HANGER ROD

640"

G4 GIRDER

DETAIL " A"

DETAIL "B"

3 " CLEAR

3" CLEAR

SECTION "4–4"

SECTION "1–1"

FACE OF COLUMN

G4 GIRDER

BEARING PLATE

SUPPORTINGBRACKET FACE OF COLUMN

STOP

SOLE

ROCKER

ROCKER BEAM

(^44)
COLUMN
0036
SHELL PLATE
"HOT POCKET"
HOPPER
INSULATION
HOPPER PLATE
HOPPER STIFFENER
SUPPORT GIRDER
EL + 105'-6"
EL + 125'-2"
EL + 126'-2"
EL + 133'-2"
EL + 42'-4"
EL + 38'-11"
EL + 25'-2"
EL + 15'-0"
EL + 114'-6"
TRUSS
TRUSS
GRADE
ROOF
430 36
2 12 " EXPANSION
SECTION "3–3" SECTION "2–2"
3 " CLEAN
BALL BEARING
ASSEMBLY
BEARING
4 41 " HANGER ROD
9'-1^12 "
FIGURE 11
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