Scaled Static Testing
3 In the initial product development, UGT used scaled models to determine feasability of the product. The test compared loading relative to the surface area. The results of the scaled model would be interpolated to predict the structural performace at full size.  

 

Test Temperature

Deflection

-20 degrees F

0.045 in

Ambient ( 70 degrees F )

0.047 in

150 degrees F

0.035 in

2 See Report

    
In analyzing the free body diagram, the most loading that a frame and cover would see is 8,000 lbs. Due to the stiffness of manhole frame and cover, the   load to the adjustment course is distributed over an area of 652 in2. The resulting distributed load equates to approximately 12 p.s.i. This load is far less than what most people think. The test sample was loaded with 1750 lbs. which would equate to the 8,000 lb loading, full scale.Rousch Industries and the Detroit Testing Laboratory are accredited testing laboratories in the Detroit Metropolitan area. Rousch Industries was the main contractor.
The test was performed at 3 different temperatures, The results are listed in the table below;
The results in all three temperatures show minimal deflection and no permanent set.The last part of the test was to take the ring to a 1/4" defection or permanent set and interpolate the maximum load.

Note: These assumptions were changed to comply with the AASHTO-HS25 standard.