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, 145
210

 

STRUCTURAL [THIGH 0T AN MW MNSPGRT
THESIS FOR DEGREE UT 8. S.

O. A. ALASPA
1938

 

.E \
\
I»

 

T'T TI. nqc. 4

{'1

utructural Design Of &n auto Transport

A Ehesis Submitted to

The Faculty of

1.. «2.37“ -'."Y‘ a“? .-, 'w' '1’ an
quiLAUAR ¢.=n:.;> vUbu.nt.a

of

, n13; Nv‘wv wn‘v‘j "f4. . 9:01 y f' 1; I “‘ 5* r3 ‘9 7 '3 .1... :-
(sadly 2, .141. min". «nun at): L 1-4) Jv¢uuuu

by

O. A. ﬁlﬁapa

Candidates for the Degree of

Bachelor of Science

June 1939

Structural Design of an Auto ﬁransport

The aim of this thesis is to check the design or the
Auto Transport which is shown in the accompanying crowinga.
In checking this design. I have made use of the following
facts:
1. The weight of each car is 3300?.
2. The center of gravity lies midway between the front
and rear wheels and 2' above the ground.
3. Wheel-base is 120".
4. Gage distance of wheels is 4' - 9”.
5. The distance between beads on the rim is 4 1/2 ".
6. The radius of the wheels when inflated is 14".
7. All Joints are welded and I have considered the weld-
ed Joint to be as safe as the metal welded.
8.Foroc due to Impact will be used as 100%.
9. Allowable stress due to banning . 20.00% lbs laq. in;2£2
éO, 000 AA: 5f. 2/7, (bx/7P.
10. Allowable strong due to shear . 13,000 lbs./cq. in.
I have tried to pick the worst conditions that may arise
and this is very evident from the fact that the force of inp-
act is taken as 100%. Of course this is not true in all inst-

ances and these cases will be pointed out as they arise.

118393 Ihi~

 

 

 

 

 

3ztai

g¥5ﬂo*'

Fig. 1.

The runway 58 is shown
in its true position during
the process of loading the

upper deck.

 

 

"g

—-——~‘

‘ ’11-“
4 -3. I

 

Chock Stresses In Eenbcr AB.

(a) Moment of inertia of cross-section a-a.

The one-half inch aquarc bars are omitted in this comp-
utation because they do not take up any of the bending in

the direction of the runway.

 

 

 

 

 

 

4‘
3 W
'X '— } ‘ -3ZII _ X Tu“?
/y ““- 7 ' ‘ "'{Ef ‘A
14 / 1/ (7/4/7/76/
Fig. 2

 

1.19 x 1.5 - 1.31 5.66 .. .353 no .37" .
x " 1.31:7 Ll? "' y

I 8 '1“ 12 - [1.6+l.199 1.13 )j . [1.2. 1.2-1t1.03)2

1.6 ‘1' 1.53 + 1.2 ‘f' 1.39
4

1 = 5.72 v .
3+(03? -025) z 3.13"

O
I!

(b) Stress due to bending n:nent.
The maximum moment occurs when the rear wheel reaches

the ccntor of the span as shown in Fig. 1.

cd = 6 xoin 1;." = 1.04:
c = arcsin ﬁ-Q‘L 3 5" 53'
32:50 a O

0'

‘33éfi;'537 3600 - 10 3 cos 5° 53 s o

m 9 093 A” f
a ' 1 cos 09—55. - 15~0

 

.z = 6 nos 10" x 910 a 539.3 “3‘

. - .10.. : .5899 X 13 X 353 a 29,700 lbs. / eq. in. Ten.

5.72

8 8 5390 X 12 X 3412 l 507?. I 35.300 1'09. I sq. in. C0731).

The cars are in this pnsition only when they are being
loaied. and they are maved up so slowly that the force of
impact would be very small that it way be neglected.

(0) Stress due to shear.

There is such a slight airfarenee in the Inaae. which
are transmitted by the wzeels due to the airfarence in elev-

ation. that they may be considered equal for check purposes

orlly o

 

 

 

 

 

 

 

3400*
r - Gaff
35M
554%“
XrZ/ \
v4
[3’
Fig. 3
. _, ~ 2.1 n, p, z.‘
VA 8 1.330 4' IT" 1300 a 2103

Q s 1.31 )(1.03 + 1 3/8 X 1/4 1.24 *‘.12 3/16 1.66
O 1035 7‘ .08 + .0013 I 1.43

a . %%.. £$§27;;%;%;Is . 23?? lbs. I 84. in.

The shearing stress is so low that I was safe in assume-
w/ree/
ing that e chloerriea the same load.

(4)

 

 

id) Stresses due to the bending masont and the sheer
in.the 1/2" square bore.

In checking the ateeees on the her. i have consiiered
the tire to be flat, which is the worst possible case thct

may exist.

ﬂ&

3 L3
#_ Is-‘gg .Jﬁi§§l.

I 2 1/192“4

 

§\\

3g
max
35k
ék§
\\\

o 2 ,. 0
133 fnie'bii

1 1
: 13/153 ( ebg + a'b'?‘ )

- 900 a [1 15/16 (6 7/15)?

“5 .574},
5 7/16 (1 15/12'J2]

‘ I‘
l...
II
M
II

 

 

 

 

kg.
(4,
<\
3
e
‘2
§

 

 

 

 

 

 

 

 

 

 

u §
Money/J14 mm “‘2 . 1340”

-/!40”#

Fig. 4
e381 . 900 ;:1.933 - 1&40 . 405"“

Is 31:2- 405‘ owe/(53
a : 19.400 lbs. / sq. in. Ten. o Comp. 0.x.

3? - A'9~ .
B O BISH- - W . 5400 lbﬁ. I 8Q. in. Oak.

(5)

Cheek :treeeea 1n ﬁember 33.

V {a} ﬁement of inertia of section b-b.

AZ' .1

 

 

 

 

 

 

 

II [n
.11.—

/

 

3%. 2!."
.10 '
4

F13. 5.

»3 .3 ‘3
1 :W+g[i£§§ﬂ.+szé (1£)2+L_’i_é32_+
axwwﬁ 4.1%): 7. } 1%1122 2]

: .o1s.+ 2 [f.8551‘ 8.310 + .001 1.3.545 4—.209 +'1.419;7
: 0016 7" 2 K 7.24 ’

1 . 14.495 Bay 14.50 "‘

(b) Cheek the stresses.

 

1900* .
u . 3.1 1'900 t 2793';
3/' 3/’

‘ a 12' ' _ 110 2790 x a x3.375
ng | T900”. ‘1' ' 1
l l
l

m

I Tﬁ\kiJ\LJ\Ll\

| I “*2 ”0" i
' I
l

I l

Slear Did-Vim” I B O 7.775 lbs. I 8Q. 1110

 

 

 

Ten. & Co . .K.
-%m* mp 0

 

 

 

 

 

 

 

 

 

 

F‘s. 6 . Mame/77‘9"”? rah?

(6)

 

Vmux I 1300 j

4‘ 0 3.: xi x13 +1135”); +.
I 1.431 f .813 r.515

Q I 3.75

a . 1370 lbs. / sq. 1n. 1 0.x.

Cheek Stresses in Bottom Runway.

(a) noment of inertia of Fig. 7.

 

 

 

 

 

 

 

 

 

 

 

W,"
N___ __ ______ __z; 1: A
L {13.75.
X - /sz‘ _ I
Fig. 7.
x : 1‘4 X 13‘ X 1/8 f' [5
3 .575 + 1.531 f .5?3 k .75 = 3.239
4.3125 2W“. ‘._
x 8 .75.!
3 :5 3 I... 1. 3 .5. 3
I . 12 Xlg") + 3 (5/3) + LTx—a'il-XSS {-.875 (1)2 + 3: ”(312 +

{1)3 2

.188 xi: 5/8)2+—§I;—__. f .35 3(33)
1 - .016 + 1.17:: “393; +4175 +.;-01 1‘ “3:9 r491 #1.015
1 a 3.67"4

(7)

(b) Stetieel mement of inertia of Fig. 7.
‘1 '3 X5/3+21%x5/8.l.875+.070

(o) Stresses due to bending moment and shear.

Xaxieum Bending assent will occur with the wheel on the

incline to the rear of the trailer as shown in Fig. 8.

 

y
A37' i
.1

 

 

 

 

 

 

Fig. 8.

£331: .-. 2.13.5 x 1300 . 3,3110%”E

 

 

 

 

 

 

 

 

 

 

 

., g
Vmax : 1300
" 1“: 9 e 5 .
, . 3F. - ‘13-°%{5;° " a 94:20 lbs. I sq. in. can 0.x.
.. z.- .7 -.
8 ‘ “340’(§2’¥2 5 8 39,5‘0 lbs. / sq. in. Camp. 0.x.
- V7 1%00 X l.“4§ - ,. . . V
s . TS . 3.37/(3 "" 3.9».0 lbs. I 311. in, Ueh.‘
Stresses In The 5 Inch Channel 0n The Rotten Deck.
(5) Eoment of inertia of Fig. 9. nL, :" ;g
7st“ 1 .
4 W ‘T 1_ "-‘R44,4
12_2 a .23" (from hendbeok) {:L L ¢3{.
(b) Statiesl moment of inertia :- ﬁfi‘
Fig. 9.

01' £118 0 9 o
(8)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

. sees "

”25’ ,4— 9”
600” ' l /500“‘
' : I |
l

I l l I

| I I l

I ' I +4366“f

| I

I I

i l Mame» 7" Wtajfa’" I

' If £900.; I E s 1800 1: 1.32.5
l
|
l

 

 

Jﬁenr EJaymm

 

 

V;

 

-/600#

 

Fig. 100

21-. a [1/12 x {- x(.935)2]+ .935/4 1: .935/8]
4. - e [.019 4- .109] . .254

' . §1 '3 2385 I 12 x .935 . 3.410 lbs. I am. in. T0110

0

. . §§ . 180° 11.3“ g 4,570 lbs. I ﬁg. 1110 00K.

. 3 2335 x 12 .4e . e. 330 1113. I sq. in. Comp. 0:; x.

(9)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

N h ‘ k
m p I k I
V V ~ M V
§ I §ﬁr" N \
\ N "N
‘I r V
WW.
“i
=J:__:I
\N \m
§ QQ.
‘ II
$
4% LI
\I: .
‘\
“Q
m
“5
E :3
‘8” t ‘° 2
Q
~ 0.
8.9
I. / 1*
i 3
3%
g:
t "
EUL__E§ EQJL+ K_ 4
5‘9 ‘Q N
Flg. 11.

 

 

 

 

(10)

Qﬂfé” 0/ 90”}47

This drawing shows
the pdﬁiﬁion of tho oars
than they are loaded

for transportation.

 

Find The ﬁhoel Leads

(a) Find wheel 10353 A and B.

 

 

 

‘ﬂ_____,._JL___ﬂ_—__ﬂ_ﬂﬂ
YB X. Cofé.’ )2
J’ 1'
f?‘ 9 giﬁr" [2,
/o‘ (A
$13. 12.

9 a arcain 1.3/10 3 6 53'

£533.: 0
3600 X 5.13 ~ 9.93VA a 0

VA

‘zfri . 0

v3 . 3500 - 1.330 g 17:20"

(h) Fina wheel loads C and D.

 

F180 13.

9 : arcsin .7/10 3 4 1'

(11)

Q

Fig. 128.

a C 9.92 1.3

.0
O.

0-. a,

(#6?

1.2 ' ,
x'm'9'95 am?” 14
‘Ws.

_§.14 x 9.98 '
X1 3 10 . 5.13

525930
5.13 I 3600 - 9.98 V9 : 0

70 ' *9.93 ' 18”0

IF, 3,0

76.: 3600 - 1850 : 1750”
(0) Find wheel loads E and F.

VF x, -CJG.

 

 

ca/G:

 

 

 

 

4

(F180 14. 1?ng 141.3.

9 : arcain 1.7/10 3 9 47'

X : 15% . 9.83.

x1 ‘ 4.85 x 9.83 a 4.57,
3F ; 0

4.57 x 3600 - 9.83 V3 3 0
932, 1670 #
{3'30

y

9
VP 3 3600 - 1570 3 1930
(d) Find wheel loads G and H.

(12)

 

'SK
*

 

$3
3%
5:

 

 

 

 

915. 151'

9 : aroeln 1.8/10 : 10 22'

1'3 . 9.89'

I. an 1..

g 5.8? x 9.82 - , n '
x1 *10 ’ 5"?”

z' -
EH _ 0

5.275 x 3000 - 9.82 vu : °
VG . 1935?
szy : 0

Va : 1655*

a‘}\ 16'
/a ’ LC’

50%?
1'
0

F18. 1530

2 z a s 9.82 z 1.8

(a) Calculations for reactions 31 and Re.

2 2519.2 = 0

- 1.4 x 1670 ‘ 1.12 x 1380 + 8.8 x 1720 + 8.43 x 1930 +
15.1(1935 + 1750) + 85.08 x 1850 + 24.92 x 1635-

23.? 31/2 3 -2340 - 3110'+ 15,150 + 16,280 0 55,700 r
45,400 . 40,150 = 159,030
5
£11 : 7,160
- é
R1 " 14.320
QEF' 3 0
y 9
a = 4 x 72.00 - 14,320 = 14.480

(10)

’wﬁec/ 4a.! 0

/5 :{0

ﬁt [05’ [7 [6’ 1/

Zéé'

F16. 1650

2:95 8 0

2.6 B 3 3.68 x 1850
B 3 2620?

21' s. O

” - a :
7.162119%”;er A - 2630 - 18-0 770;

 

[as/463:2

 

 

 

 

 

 

 

 

 

 

 

 

1:5?310‘ b!

315. 16.

P13. 17.
The etreeoee. cue to bending. 1n.the here 0: F13. 17

‘I111 be considered safe because the size of the plate an

the trunk. upon which it route. 10 ant known.
The aeximun shear on the here 0: F13. 17 are cue fourth
01' the reaetion 1-11 which 1. equal to 14.32010 . 3.5903.

8 . abeoxx 1'3 I 3.880 1b../’Qe 1:10 O'K‘

a = 2 (1 3/332 x a + (1 0/3)“3 x 3/15 11% = 1.3
(1‘)

 

 

Check stress in bar 0 0! F13. 16.

Take moments about 0 or the portion to the left of sec-

tian a-a of Fig. 16.

£530 3 O
1.6 x 770 x 2 1 14530 x 3.9 - 4.3 x 2620 x 2 - 5.1 x 1665 x2 -

2.5 P I O
1.25 P 3 1.6 x 770 1 7160 x 3.9 ~ 4.2 x 3630
P a 985 . 22350 - 8800
y = 14,5351
A 3 2 (1.95) + 4 x 1.19 = 8.66 sq. in.

a-.§.. 2%.; . 1,6801ba./sq. in. 6611- 0-K-
D

The tenlls dtrsas just found 13 resisted by 4 - 3n_ 4.1.

channels and 2 - 5“ - 6.7; channels.

Check the stresses in bar 0 of Fig.16f
In order to get the nax1mum shear and band1ng moment.
wheel load H of F13. 1t W111 be 7' from the front of the
trailer. In mov1n5 the wheels loads G and H hack 5.1 feet.

tha reaction R1 will be reduced but for check purposes 1t

 

will be sonsldsred to be the same 1n both cases. This

assumption 15 on the safe side.

See F15. 18 on the next page.
‘E'gn : 0

6.85 VB - 3590(2.25 + 3.55) I 20,750
v3 - 30305
VA 8 7160 - 3030 - 4,130:‘2

(15)

 

 

 

 

 

 

 

 

 

 

 

1—[ [ Ska!” (7’49’7‘7’77

 

 

 

 

 

 

 

 

 

 

 

 

 

 

I
I l
7 Movie/’7' fray/am , f I

- W

//
~2500’ L~1LVLL

#
-/o,ooo’

 

 

 

 

 

 

 

 

 

 

 

F13. 180

u..x a 3030 x 3.3 . - 10.000'f

s " w II 4:690 1bs./sq. 1n. Ten and Comp. 0.1:.

v ..x a 4.130;

 

s - 1130*: '3 - 4.490 lbs./sq. 1n. 0.x.

who portion to the loft or section b-b of I15. 16 tons
a cantilever and. 1t 1s tho nut scabs: to ho shocked. Bond-
1ng scours about b-b and about tho cantor 11ns C.-L. I on

 

only comer-nod. with the one that 11111 prodnos the maximum

mun: .0th.
(16 1

 

 

 

 

 

 

 

400‘“
.\f"—‘
N
4wv*
___$_
33.3, i 2.1 x 4130
3:3 ' - C . 3670"
#-
4%E11, gh-b = 2.8 x 4130
.‘\ f!
N a. s .. "
4/30# \ “max - 11b-b - 12,000.
A ,
. i
.# vmsx I 4,130
4am
T 2”“ IAVAV
It

F13. 19.

a . 12000 x 2.5 .

4.050 lbs./sq. 1n. Ten and Camp,

8 -'#l%9.§3%1§' 5,070 1bo./sq. 1n. 0.x.
0 I

Cheek 13 x 12 x11” angles for tenslle stress.
Th: max1nnn stress W111 occur when the front wheels or

the car are Just above the 5” channel at polnt 0 of F15. 11.

 

. afc
Y - I680”! C' 1;? .- ”10d
1.} '
5
0 $400”
F13. 20.

The loads of F13. 20 are so close to the loads of Fig.
(17)

12 that 1 have aeeumed then to be the eene. Theretor the
#

maximum lead :111 be 1880 an the channel. This load is

to be split up between the two an51ee ee followe:

g.- ”60”! xaaf‘

VA; 720‘
T '3' 1 /. 3' I

Z.”

313. 21.

V- 3 1.3 x 1580/2.1 ’ 1160

v- = 1330 - 1160 - 720‘1

i

3 -._EL 3 ¢£%§g..c 2.030 lbe./eq. 1n. 02x.

 

Cheek etreeeee 1n 3% x 3% x 3“ angle IcJ of F15. 11.
The naxlmun bending moment will occur in panel 2 0: F15.

The wheel leads will 1
be the same as in Fig. 14.

 

 

3.5 v3 = 1.7 x 1930

 

 

 

 

 

 

VB . 938i
8 1930 - 938 = 992*

 

Y ,

A

 

 

 

 

 

 

 

 

no u 1.7 x 992 a 1.685'#

 

 

 

 

. g 1635 x 13 x 1‘1 3 12,450 lbs./sq. 1n. Ten.

.. 1685 x 12 x 2.3% ,
W

26,800 1bI./sq. 1n. Comp. 0.x.

 

The maximum shear s111 oeeur when the ear 13 1n the
sens poe1t10n 0e 1n.F1¢. 20. Theretor the maximum she r
.111 be 1150 i (315. 21). I ‘

 

 

 

 

 

2 a”
0 - (2.39) x & xi = .710 IN 2 _ 14
/«//"
217—“
F18e 23s
. . 1150 i -'715 a 1.350 1be./sq. 111. 0.1:.

Check stresses 1n heater 3 of P15. 11.
The reeet1en R2 is split up 1nto two components
as shown 1n F15. 24.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

+5300”
f
Jitar ,71‘49 ram
.. I
- N40“ |
l l I
| | I
l .
I Momcn/ Pia/Ore”) I F16. 34.
' l
I ..
I |
I . |
i .W" I
' 4! I '
[/60 I l)?
6' '
T ﬂ, ‘14. 1 t6 .R
71 g 7240 We. -
E7 j{1240”

(19)

 

Z ML " O

 

 

6 Va = 4.4 x 7240
VR = 5300? Max.
VL : 14,480 - 5500 = 9,180#
mmax = 5300 x 1.6 8,480'#
. %
= 84:02x 1“ ' 3,980 lbs./sq. in.
= 5300 X 1.3 = r‘ r
s 3.2 x 3/3 ..,740 lbs./sq.
Check bar 4 of Fig. 11 for
s - _§l : .%%%g = 6,375 lbs./sg.

Check for the

'ﬁ ‘7!-
U .15. .

Ten and Comp.

in. O.K.

compression.

stresses in the 2% x 2%" columns.

Failure will occur by buckling or lateral bending rather

than by direct compression.

I shall check the column at the

rear of the trailer which is the most stressed member.

Moment of

 

4 4
d - d
I1-1 ' ““I§‘l‘
1-1 12

(2%)4 - (2)4

 

12
l . 9&1l4

inertia of cross-section of column.

 

 

 

 

(20)

 

 

 

 

 

 

 

 

 

 

2150?

"U
N

e 8 .5' or 1.2"
6 8 e ( see V?/EI ‘1 - l)
= 1.2( see ’Véliéoii5"5"”£"'i05'"36 '1‘2'233 x 7.1 x 12 - 1)

3 1.3 ( 800 .52 - 1) .J'C
3 1.2 ( sec 29 - 43' - 1) _T
' r' -—|r‘

6 = 103 X 1031 3 10212”

H = 21m ( 1.21 + 1.2) = 5190"? 7

a :W . 3,3501be./sq. in. 0.x.

zsz’

Z/'

This concludes the check of the design.
The results or my computations show that the
trailer is safe, and has a fairly high factor of tety
in most oases. The size of certain members

may be made smaller upon further investiga-

 

 

 

 

tion. but will not be considered here due { t

 

to the leek or time. ‘d
Fig. 26.

(21)

DO’E

‘ ‘t...’ I." .-

- '1',
‘Itlﬁfl fl s
{if ' I S

I" 'Illnlll' I’i!:.

li-'l II

 

 

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522