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 (d) Wall Panel-to-Foundation Connection. The wall panel in
Figure 64 is attached to the foundation by means of angles welded to plates
cast in both the wall panel and the foundation. It is essential to provide
a method of attachment to the foundation that is capable of taking base
shear in any direction, and also a method of levelling ad aligning the wall
panel. Non-shrinking grout is used to fill the gap between the panel and
the foundation so as to transmit the loads to the foundation.
(e) Panel Splice. Since precast structures are of the shear
wall type, all horizontal blast loads are transferred by diaphragm action,
through wall and roof slabs to the foundations. The typical panel splice
shown in Figure 65 is used for transferring the horizontal loads between
panels.
(f) Reinforcement Around Door Openings. A standard double tee
section cannot be used around a door opening. Instead, a special panel must
be fabricated to satisfy the requirements for the door opening. The design
of the reinforcement around the door opening and the door frame is discussed
in paragraph 6.c of Section 6.
3.
GLASS.
a. Types of Glass. Glass is primarily a product of the fusion of
silica. The principal compounds added during manufacturing of window glass
are soda to improve quality and lime to improve chemical durability. There
are several types of glass, some of which are; sheet glass, polished plate
glass, and tempered, laminated, or wire glass. Usually, in blast resistant
structures, the type of glass found can be divided into two basic
categories: (1) regular glass which is that glass used in normal home
construction and (2) tempered glass which consists of regular glass whose
properties have been proportionally controlled and has been rapidly cooled
from near the softening point (annealed) to increase its mechanical and
thermal endurance.
b. Properties of Glass. The properties of glass are presented in
several literature, some of which are Response of Glass in Windows to Sonic
Booms, by McKinley, Glass Engineering Handbook, by Shand, and The Mechanical
Properties of Glass, by Preston. Glass, which is both homogeneous and
isotropic, conforms to elastic theory up to the point of fracture; i.e.,
either fracture occurs or the specimen returns to its original shape on
release of applied loads. It can be stated categorically that glass always
fails in tension. Glass strength usually depends on flaws or defects most
often found on the surface. Since glass does not yield (and is brittle),
stress concentrations at flaws are not relieved and failure is caused by the
propagation of one of the flaws. Other factors affecting strength are
moisture, temperature, duration of stress, age and induced stresses. Values
for material properties of glass can be found in the literature referenced
above.
Typical values are:
Modulus of Elasticity, E = 107 psi
Poisson's ratio, [nu] = 0.23
Unit weight, W = 0.090 lb/in3 or 155 lb/ft3
2.08-229
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