the next section). Leuder lines, distortions in the
In 1987, the column footings were shimmed in
surface of a structural member indicative of
an attempt to decrease the amount of column tilt.
localized yielding, were first observed in the
A secondary purpose of this task was to lower
supporting structure at the base of the columns
the stresses experienced at the sway bolt loca-
below the footing support blocks in early 1988.
tions at the collar levels and in the building. As
These Leuder lines were thought to be evidence
the rate of tilt was not decreasing, a similar
that high horizontal stresses, and therefore high
"mini-life-extension" was scheduled for the
moments, were being experienced by the col-
summer of 1988 to maintain noncritical loads at
umns. An example of Leuder lines is shown in
all column locations. This work was not carried
Figure 11, which shows evidence of yielding be-
out, and structural stress projections derived
low the support block of column A3.
from the analysis of data obtained using the
measurement techniques and considerations de-
scribed in following sections resulted in the U.S.
Air Force's decision to abandon DYE-2 in late
August of 1988. Table 1 contains a chronology of
major work performed at DYE-2 since its con-
struction in 1959.
Table 1. DYE-2 milestones.
Year
Event
1959
Original construction on Greenland ice cap
1962
Building raised 1.8 m
Truss enclosure extended up
a. February 1988.
1965
Building raised 2.7 m
Truss enclosure extended up
1967
Building raised 3.2 m
Truss enclosure extended up
1970
Building raised 7.6 m
Subsurface truss added
Truss enclosure extended up
1976
Building raised 8.2 m
Subsurface truss extended up
Truss enclosure and column A1 modified
1982
Building moved to new footings
Above-snow trusses constructed
1983
Building raised 8.2 m
b. June 1988.
Column enclosures constructed
1987
Building leveled
Column bases jacked and leveled
Footings strengthened
1988
Site closed
MEASUREMENT CONSIDERATIONS
The stress analysis of the DYE-2 structural sys-
tem consists of two components. The first com-
ponent to be considered is the axial load on the
supporting columns from the building, the trusses,
and the columns themselves. The second compo-
nent is the horizontal load, derived from the
sway bolt measurements taken at the building
c. August 1988.
and collars. The sum of the stresses created by
Figure 11. Leuder lines: column A base.
these forces results in the combined stresses,
6
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