Figure 18. Column tilt trends

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diagrams (Walsh 1992), despite the use of fric-

ances were not of the order witnessed in previ-

tion-reducing bearing pads and the attempts to

ous years. These lower figures increased the

reduce opposing loads. In addition to the fric-

probability of accuracy for the 1988 readings,

tional load from the weight of the truss on the

which were used by the CRREL engineers in for-

truss support bearing, the frictional forces due to

loaded sway bolts 90 from the sway bolt being

mulating their opinion of the structural safety for

building occupancy and projections of structural

measured must also be considered. For a side

stresses at DYE-2 for the Air Force.

load of 44.5 kN (10 kips), the resulting breakout

Analysis of the data collected for all aspects of

force is 34.7 kN (7.8 kips) and the sliding force

the system indicate an inexorable tilt of the struc-

would be 25.3 kN (5.7 kips). The presence of one

ture along with related structural stress increases.

highly loaded bolt on a collar can thus greatly

The direction of tilt is towards the "warm"

affect the readings derived from bolts with

southwest corner of the building. The highest

smaller loads on the same collar level. From a

Figure 19. Example of load (pressure)displacement measurement.