Assimacopoulas, B.

Errera, S. J.

English

Lehigh University: Lehigh Preserve

Lehigh University
Lehigh Preserve
Fritz Laboratory Reports Civil and Environmental Engineering
1957
Tension overload acceptance test, October 1957
S. J. Errera
B. Assimacopoulas
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Recommended Citation
Errera, S. J. and Assimacopoulas, B., "Tension overload acceptance test, October 1957" (1957). Fritz Laboratory Reports. Paper 1589.
http://preserve.lehigh.edu/engr-civil-environmental-fritz-lab-reports/1589
TENSION OVERLOAD ACCEPTANCE TEST
by
S. J. Errera
B. Assimacopoulos
Report No. 236-30
Report No. 236·30
TENSION OVIRLOAD AeCBP"l'ANCa mST
in. tbe 5,000,000 lb luting macMne in Frlt. Laboratory on September 9, 1957.
Two earUer attempts (July 1955 and January 1956) haci reau1ted in fracture of .
the ten.ion 1'04.0£ the clevis assembly. The test was made to, accol'4ance with
paragraph 144cl of the 5,000,000 lb 'luting Mac:h1ne Contract Specifications
dated 13 May 1953.
Procedure:
A rectangu18f teet bar mea8urina 5'.3/8 11 x 12u x 28 l/sn we held
by the tension clevises of the machtna as ,bow in the pbotograph in ,lg. 1.
To obtain information on the deformation. au' tuned by ¢omponenU of the
clevis assembly durina the overload tpt, sixteen SR..4 g-aee were mounted at
different locationa on three pa.rU of the testing machine. Sight of ~he
gages were 1oc~ted on the upper tension clevis .,e8mb1y (gages numbered 1,
2,3,4,5,6,1,8), four on the upper tension rod (sase. numbered 9,10,11,
12) and four on the south main cOlumn ox the machine (gages numbered 13, 14,
15, 16). The locations of these gages ate given in fig. 2. During the Over-
load 'lest the load was applied in lncr~nts of SOO,OOO lbs up to a total
of 5,500,000 lbe. At each load increment, strain readin.g$ for all gages
were taken. Data recorcSings .bowed that two of the $&8.8 (No. 7 and No. 11)
were,lnoperative.
The ftnal tetiSion overload of, five and-one half million pouncla
. . . '
appl~ed on the test specimen wa. held unchanged fOT .. period of ten minutes.
This 10a4 wat then reduced to 3.000 ,000 pound. anel a v1$ual examination of
the clevis assembly was made. At this load, a space of about one-half inch
was found to exist between the lower retaining plate and the beulna surface
-2
of the clevis, and a sap of one inch exl$ted between the upper retaining
plate and the bearing surface of the clevis. These gaps reduced as the load
was further reduced.
Test Results:
The SI..4 gages did l\Ot show any abnormal behavior of the members dur-
ing the overload test. The strain gage data obtained from the tests is in-
cluded in the original copy of this report. A grapb of load versus strain
in the tension rod is given. in Fig. 3! Comparabl$ graphs for strains in
tbe clevis and compressive stratns in the column are given in Figs. 4 and S.
A comparison of the nominal and average measured .tresses developed in tbe
tension rod and based on 4 rod diameter of 8.654 inches and a modulus of
elasticity of 29,500,000 lbe per square inch ate given in Fig. 6.
Figs. 3 and 6 show good 4gt'eet:1e.nt between the nominal and measured
stresles in the tension rod. gOOd load di8~ribution over the rod cross-
section. and maximum rod stresses of about 93.000 Ib per sq. in. rig. 4
shows fairly good strain distribution over the clevis. and indicates max-
imum stresses of 24,000 Ib per sq. in. F1g. S indicates fairly good distri-
bution of load in the comp~e88ion column. with 1'UX1mum stresses of about
9000 lb per sq. in. It should also be noted that strains di<l not increase
while the load was held constant at S.5OO .000 lbs for ten minute. and that
all operative gage. returned to practically zero when th$ load was removed.
Upon completion of the overload te.e, tbe spec1tn$n and clevis
_sembly were removed from the machinca. The pins Were re11lQved Without dlf...
liculty $ ancIthe nuts turne4 e&$11y on thelr threads. Upon removal of the
. clevis block from the tension crosshead, chefollowing items were noted:
(1) . .Pronounced acoring had occurred on the two 2"'incn Uner plates
.adjacent to the cleVis block. It appeared that the Bcoring occurred
on upward motion of the block. The plate. a180 .uffere4 about
a 3/64-1ncb bend. ..,
(2) The bole in the clevis block was about 0.023 inehes out of
round at the upper end.
(3) The grip pock.ts ·0£ the tension cro8lhaad showed pennanel'lt·
deformation over the entite ba4l'ina area of the clevis block J .
the impression measUl'ing up to~02 inehes.
(4) The bolt cirele on the under side of the tensiOn cros,head
used· for fastening tbe tetainlnarlt18 meaaured .bout 1/8 inch
out of round. indicating po.at.ble permanent benciins deformation
of the tension erossbead. Considerable paint scaling on the
und~r side of the crossb$ad was alao noted. Howev.~, ·tb~l
tensloncrossbead keys moved £re81,1n their slots when the
ratchet W8$ applied.
(5) As11abt crack. about four incbes long was also noticed 1n
the srip pocket o~ ~he tension erOs.head•. Thie could be a .
surface defe~t in. the ea$ting.
rig'- 7 attempt~ to describe the deformations.
It.. 8~ry of the above baa Geen furnished to BaldWin fot their
review, and for ·reeommendations on further pr~c.dur~s.
s. J. 8rtera
B. Aselmaeopoulo.
SJB/BA:ml
October 24,1957

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Tension overload acceptance test, October 1957

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Tension overload acceptance test, October 1957

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