SECTION 4.
STRUCTURAL SUPPORTS
1.
STEEL AND CONCRETE STRUCTURAL SUPPORTS. Structural supports are those
portions of the framing system which support the various chamber components
and transfer their dead and live loads to the foundations. It is important
that the support system be rigid so as to support the chamber and its
components with as little differential movement as possible. The induced
strains resulting from the differential movements must be within the
allowable strain capacity of the chamber and its components. Although the
chamber and support systems are within themselves rigid, the interface
between them must be compliant to allow for "growth" of the chamber when
pressurized.
The design of the structural support system should be predicated on two
construction materials, namely; structural steel or reinforced concrete.
Many modern variations and combinations of design and construction methods
using these two materials are available. Various design parameters for these
two materials are discussed in the following paragraphs.
Regardless of the structural support system selected, future expansion should
be evaluated for its effect on the deflection and movement of the structural
support system for the then existing facility.
2.
DESIGN PARAMETERS COMMON TO BOTH CONSTRUCTION MATERIALS.
a.
Vertical Deflection. In either of the two framing materials
mentioned above, the differential deflections or movements from vertical
loads must be evaluated in the final design of the structural support system.
Differential movements within the structural supports produce corresponding
strains in the chamber components. The design of affected components must
include an analysis of these strains and resulting stresses.
Consideration should also be given to the possibility of settling of the
foundations requiring shimming of the chamber for realignment. A means of
monitoring (collimating) the chamber movement is also desirable.
b.
Lateral Displacement. Study the lateral displacement or side sway
of the structural support framing, and evaluate the following loading
conditions:
(1) Wind load on the entire structural frame or exposed components
of the structural support system or the chamber components themselves.
(2) Lateral forces induced by earthquake loading for facilities
located in earthquake zones.
(3) Lateral deflections or displacements resulting from unbalanced
live loading on the chamber components or on the surrounding service floor
areas.
c.
Induced Vibration. Evaluate the sensitivity of the structural
supports to vibration induced by the operation of the chamber components or
supporting auxiliary equipment, such as moving cranes and other equipment
likely to be operating on the service floor areas around the chamber, for:
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