We recently made two distinctly
different tests of the strength of the Simplex sidewalk
and skylight preformed slabs. The first by Gaut and Chase,
Engineers, was planned to approximate, as closely as
possible, real traffic conditions. The report shows that
the sidewalk slab carried a distributed load of 1753
pounds to the square foot.
To confirm these figures and to
satisfy ourselves that here was a construction that was
unbreakable under any ordinary condition we commissioned
Robert W. Hunt & Co. to make a strength test of the same
types of SIMPLEX slabs with the hydraulic press.
Gentlemen:--Report of the
"Transverse Tests" on specimens of your SIMPLEX Double
Reinforced Concrete SIDEWALK Construction made with your
glass No. 61.
Construction.
The specimens tested were 15" wide by 54", 78", and 102"
long, respectively. In the 15" width there were three rows
of the No. 61 glass.
The longitudinal reinforcement,
entirely embedded in concrete, consists of four eye beams
1½" high with a web thickness of approximately 1/8"
and a width across the flange of 3/8". These eye beams
were spaced 4¼" to 4½" c. to c. Transverse
reinforcement consisted of 5/16" twisted square bars
spaced 4¼" c. to c. and carried through the web of
longitudinal eye beams at a location 1½" to 1 9/16"
from top of slab.
Conduct of Tests.
Specimens were successively placed on supports 8', 6' and
4' c. to c. The loads were applied on the 1/3 points of
the spans and under increasing loads the deflections at
the center of the spans were measured. The observed loads
and deflections were carefully plotted.
Summary of Tests.
The following is a summary of the deflections under
calculated uniformly distributed loads.
| Slab No. |
61-6 |
61-5 |
61-4 |
|---|
| Span in Feet |
4' |
6' |
8' |
|---|
| Cal.Distr.Load, Lbs. per Square Foot |
Deflections at Center of Span, Inches |
|---|
| 0 |
.0 |
.0 |
.0 |
| 50 |
.0 |
.0 |
.03 |
| 100 |
.0 |
.02 |
.19 |
| 150 |
.01 |
.09 |
.35 |
| 200 |
.03 |
.14 |
.53 |
| 250 |
.04 |
.19 |
.69 |
| 300 |
.05 |
.25 |
.85 |
| 350 |
.07 |
.31 |
1.05 |
| 400 |
.08 |
.38 |
1.41 |
| 450 |
.09 |
.44 |
1.77 |
| 500 |
.10 |
.51 |
2.29 |
| 550 |
.12 |
.57 |
3.25 |
| 600 |
.13 |
.64 |
| 700 |
.15 |
.70 |
| 800 |
.17 |
1.02 |
| 900 |
.19 |
1.45 |
| 1000 |
.22 |
| 1200 |
.28 |
| 1400 |
.34 |
| 1600 |
.42 |
| 1800 |
.51 |
| 2000 |
.68 |
| 2200 |
.96 |
Max.Distr.Load
Sustained |
2310 | 991 | 560 |
| Deflections under Maximum Load |
1.40 | 2.20 | 3.50 |
| (Signed) ROBERT W. HUNT & CO. |
|
Load of 28,650 Pounds of Lead Billets on
5 Foot Span,
Supported at Ends Only
Gentlemen:--Simplex Slabs
tested were American 3-Way Prism Company's Standard SIMPLEX
CONSTRUCTION. Tests were all conducted under conditions
identical with those which prevail in actual service and
with uniformly distributed loads.
Readings were taken with a level
2 in. by 2 in. wood standard, two scales being read after
each load increment. One scale was graduated to thirty-second
of an inch, the other to hundredths of a foot.
Tests
Simplex Skylight Slab:
3'6"×6'6"×2 1/8"
Bearings--8" I Beams. Bearing surface,
top flange 4".
Span--5' 0" c. to c. bearings; 4' 8" clear span.
Area loaded--4' 8"×3' 6"--16.33 sq. ft.
|
| Loading |
|
Deflection |
|---|
| Increment |
Total |
Per sq. ft. |
Total |
|---|
| |
|
|
Inches |
Feet |
|---|
| 0 | 0 | 00 | 0 | 0 |
| 1910 | 1,910 | 116.9 | 1/16 | 0.0052 |
| 1910 | 3,820 | 233.8 | 1/8 | 0.0104 |
| 1910 | 5,730 | 350.7 | 7/32 | 0.0182 |
| 1910 | 7,640 | 467.6 | 9/32 | 0.0234 |
| 1910 | 9,550 | 584.5 | 5/16 | 0.0260 |
| 1910 | 11,460 | 701.4 | 13/32 | 0.0339 |
| 1910 | 13,370 | 818.3 | 17/32 | 0.0443 |
| 1910 | 15,280 | 935.2 | 21/32 | 0.0547 |
| 1910 | 17,280 | 1052.1 | 25/32 | 0.0651 |
| 1910 | 19,100 | 1169.0 | 7/8 | 0.0729 |
| 1910 | 21,010 | 1285.9 | 31/32 | 0.0807 |
| 1910 | 22,920 | 1402.8 | 1-1/16 | 0.0885 |
| 1910 | 24,830 | 1519.7 | 1-7/32 | 0.1016 |
| 1910 | 26,740 | 1636.6 | 1-3/8 | 0.1146 |
| 1910 | 28650 | 1753.5 |
After fourteenth load
was applied deflection continued until total deflection of
2 inches was reached. Load was remove and slab returned
to within ½" inch of original alignment, within ten
minutes. Concrete on top surface slightly scaled, total
area scaled about fourteen square inches. Concrete on
bottom side showed eight tension cracks through middle
third of slab.
After load was removed all cracks
closed as slab regained normal position.
|
| (Signed), GAUT AND CHASE, Engineers |
|
