Note: Descriptions are shown in the official language in which they were submitted.
I
1~2
Docket 2589
SH:EET METAL BEAM
Background of the Invention
In the construction of a metal building, it is common to
use a frame ~hhich supports paralleL 3paced 3teel bearns or purlins to
which corrugatecl 3heet metal roof panels are attached. The purlins
have a Z-shaped cross-sectional configuration, for example, as il-
lustrated in IT. S Patents No. 2, 871, 997, No. 3, 290, 8a~5, No.
3, 982, 373 ancl No. 3, 513, 614. Similar Z-shaped beams are attached
to the silles of the frames and are commonly referred to as vvall girts
for 3upporting the roll-formed sheet metal side walL panels. The
most cornmollly used purlins are roll-formed from a.relatively heavy
gauge steel strip, such as fourteen gauge (. 074"), and have a height
of appro.~imately eight inches. Thus the flange portions of a purlin
are integrally connected by the flat web portion, and all of the port-
ions have a common uniform thickness which results in a weight of
approximately 3j 67 pounds eer linear foot for an eight inch purlin.
While eight inch purlins are mo~;t commonly used be-
cause of its strength/weight ratio, purlins having a greater height,
such ais twelve inches, are also used in view of the fact that the
3trength of the purlin increa3es as the square of ~he height. However,
as the flat web portion of a conventionaL purlin increases to provide
the purlin with a greater height, the adclitional thicknes.s of steel
needed in the web pOrtion adds little to the increased strength but sub-
stantially increases the weight of the purlin.
It has also been found desirable for the flange portions(
of a purlin to have a 3ubstantially flat outer surfaces to provide pro- .
per attachme:nt of the purlins to the rnetal frame and of the roof pan-
els to the purlins by 3uitable fasl:eni rs. While il one-piece conven-
I ' , `~.. '
~ Zl~
¦ Do~ket 2589
¦ tional Z-shaped purLin rr-ay be cfficlently manufaclured by roll-form- ing il does not provide maximLIm utiLization of the strength of the
¦ steel and thus does not obtain the maximurrl strength/weight ratio.
l While there have been many othér types of sheet metaL beams either
5 ¦ proposed or rnacle none of these boams have been found satisiactory
for replacing the above clescribed purlin3 commonly used in the con-
struction ;>f a metal buiLding
Summary of the Invention
I Ihe present inventio~ is directecl to an improved sheet
10 ¦ metal beam which obtains maximum utilization of tho strength ol the
¦ sheet metal in order to minimize the thickness or gauge of the sheet
metal and to obtain a maximum strength/weight ratio. While the
¦ beam of the mvention is ideally suited for use as a purlin in the con
¦ struction of a metal building the beam of the invention may also be
15 ¦ used in the construction of other building structures and may aLso be
u3ed as a verticaL column
A beam constructed in accordanc~e with the invention is
also adapted to be efficiently manufactured at a significantly lower
cost than the cost of manufacturing conventional metal beal-ns or pur-
lins and further provides a significantly Lower ~eight per linear foot
of beam 30 that the cost of handling and transporting the beam is sig-
nificantly reduced. While a number of desirable features and advant-
ages of a beam constructed in accordance with the invention are ap-
parent from the drawing3 other features and advantages of the in-
vention will be apparent from the following description and claims in .
reference to the drawings.
. '
¦ D ~< k ( I 2589 lZZ1~18
E3rief Description of the Drawin~s
I . _
¦ FIC. 1 is a perspective view of an end portion of a Z-
¦ shaped purlin or beam constructed in acc:ordance with the invention;
l FIG. 2 is an end view of the beam shown in FIG. I;
¦ FIG, 3is a fragmentary section taken generally on the
¦ line 3-3 of FIG, 2;
FIG, 4 is a perspective view similar to E`IG. 1 and show-
I ing another embodiment of a beam constructed in accordance with the
¦ in v en tiOII;
10 ¦ FIG, 5is an end view of the beam shown in FIG, 4;
¦ FIG, 6 is a fragmentary section taken generally on the
¦ line 6 6 of FIG, 5;
¦ FIG, 7 is another perspective view similar to FIGS. I
¦ and 4 and showing another embodiment of a beam constructed in .
15 ¦ accordance with the invention;
¦ FIG. 8 is an end view of the beam shov~n in FIG, 7;
¦ E`IG 9 is a fragmentary section taken generally on the
¦ line 9-9 of FIG, 8; .
I FIG, lOis an end view of a beam constructed in accord-
201 ance with a further embodiment of the invention;
; FIG, llis a fragmentary sectioll taken generally on the .
line 11-11 of FIG. 10;
- FIG, 12 is an end view, simiLar to FIG. 10, of a beam .
constructed in accGrdance with still another elllbodiment of lhe in-
vention;
E`LG, 13 is a fragn-entary section taken generally on the
line 13-13 of FIG, 12;
Z~L23~
Docket 258g
FIG. 14 is an end view of a sheet metal "I" beam constructed
in accordance with a further embodiment of the invention;
FIG. 15 is a fragmentary section taken generally on the
line 15-15 of FIG. 14;
FIG. 16 is an end view of another beam constructed in
accordance with the invention and showing the assembly of conforming
strut members;
FIG. 17 is a fragmentary section taken yenerally on the
line 17-17 of FIG. 16;
FIG. 18 is a perspective view of a strut member used in
the embodiment shown in FIGS. 16 and 17;
FIG. 19 i5 an end view of another beam embodiment forming
a modifi:cation oF the beam shown in FIGS. 16-18,
FIG. 20 is an end view of a modified beam constructed in
accordance wi.th another embodiment of the invention;
FIG. 21 is an end view of another embodimént of a purlin- :
type beam constructed in accordance with the invention;
FIG. 22 is a fragmentary section taken generally along
the line 22-22 of FIG. 21; and
FIG. 23 is an end view oF another modiFied purlin-type
beam similar to the beam shown in F.IG. 21 and also constructed in
acctrdance wlth the invention.
.
,
-4a-
. . ~ . .
! ` l;~Z~ ..
Docl<-~t 2589
De3cr etion of the Preferred Ernbodiments
. ~
The sheet metal bearll or purlin illustrated in FIC. 1-3
i3 constructc:d of a relatively thin gauge sheet metal such as Z4 gauge steel
which is 024 inch in thiclcness. The beam 15 includes an upperflange
16 and a lower flange 18 which are integrally connected by a v~eb por-
. tion 20. The flanges 16 and 18 project in opposite directions from the
web portion Z0 to provide the beam with a Z-shape cross-sectional
configuration so that a number of the beams may be stacked in a close-
fitted nested relation for shipping and storage purposes. The web
portion 20 is rol~formed with a corrugated cross-sectional configura-
tion to form a pLurality of longitudinally exLending ribs 22 which pro-
ject from flat coplaner base wall portions 24 Each of the ribs 22 has
a trapezoid cross-sectional configuration, ancl the outer flat walL
portions 26 of the ribs 22 are subslantially the same 3iYe as the base
wall portions 24. Sets of parallelogram shaped holes 27 (F'IG. 3) are
formed within the ribs 2Z at longitudinally spaced intervals along the
beam 15, and a formed sheet metal strot 29 e~-tends throu~sh each set
o alignecl holes 27 Each strut 29 corresponds in length to the
height of the web portion 20 and has a Z-shaped configuration so that
2 the flanges of the strut 29 rnay be conveniently spot-welded or other-
wise fastened to both the outer flat'walls 26 of the ribs 22 and the flat
base wall portions 24, as illustrated in FI~G. 2.
Each of the flanges 16 and 18 of the beam 15 are t'ormed
of integral sections of the sheet metal panel and include a first or
inner flange portion 32 having a rib 33 of trapeY.oid cross-sectional
configuration. The panel section is fol(li.~d back upOn ilsclf to form a
second or outer flange portion 36 which has a pair of longitudinally '
extending 'V-shaped ribs 37 for recc~iving the l~ib 33 on Ihe innor wall
11 ~_ I
~ z~
¦ Dock(~ 2589
portion 3Z Preferably, the inner flange portion 32 and outer flange
porLion 36 ar e secllred together by Longitudinally ,pacecl spot-wclds
located at the top of the rib 33 'I`he flange portions 32 and 36 are
thus integrally connected by an outer edge wall portion 39 which co-
operates to provide the flange with a tubular or hollow outer'edge por-
tion The outer flange portion 36 of cac h flange extends to form a
right angle lip portion 41 ~;vhich projects inwardly and is secured by
spot-weld3 to the adjacent flange of each strut 2'3
The strut3 29 may be inserted into the corrèsponding sets
of openings or holes 2 7 within the rib3 22 while the dheet rnetal panèl
is being roll-formed and before one of the outer flange portions 36 i9
folded back into engagement with its adjacent inner flange portion 32
After the 3truts 29 are inserted, the spot welding of the flat wall
portions and lip portions 41 to the 6truts is progressively performed
as another operation
The construction of the beam 15 provides a substantially
high strength/weight ratio as a result of the configuration of the flanges
16 and 18 and the integration of the struts 29 with the stiffening ribs 22
The ribs 33 within each of the flange portions 32 of the beam also
cooperate with the lip portions ~LI to form a rigid and braced connection
of each flange to the web portion The integration of the ribs 2Z and
struts 29 also minimizes the overall thickness of the web portion 20
thereby providing for clo3er nestihg of the beams when arranged in
stacked relation The beam 15 may also be conveniently constructecl
entirely of light gauge 6heet metal ~hich has a galvanized or other
protective coating to provlde an outer 3urface rnore durable ihan paint
lZ'I'lZ
I ~ ~3
¦ Docke~ 2589
¦ l-~ eforring ~o E`IC;S. 4-6 which illustl atcs another embo(li-
ment of a bealn constructed in accordance with thc invention a beam 45
is roll-formed from a light gauge sheet metal such as Z4 gauge steel,
l and includes upper and lower flangès 46 and 48 which are integrally
5 ¦ connected by a web portion ~0 in a manncr aimilar to the beam cle~cribed
above in reference to FIGS. L-3. ~n the embodiment of FIGS. 4-6, the
web porlion 50 has two Longitudinally extending ribs 52 which project
¦ from coplanar flat base wall portions 54 and a series of longitudinalLy
l spaced sheet metal struts 58 are positioned adjacent lhe base wall
10 ¦ portions ~4. I'he struts 58 are secured Lo lhe bclse wall portions 54 by
fasteners or spot welds 59.
¦ The upper flange 46 of thc beam 45 is const:ructed sub3tan-
¦ tially the same as Lhe upper flange of ~he beam 15 and thus is identified
l with the same reference numbers. The flange has a corresponding lip
15 1 portion 63 whic:h projects downwardly or inwardly and is spot-welded
~to lhe struts 58. The lower flange 48 is also constructed similar1y to
the Lower flange 18 except that the inner or second flange portion 66 has
a lip portion 68 which is copIanar with the lip portion 63 and is also se-
cured by spot welds to the struts ~8. As 3hown in FIG. (~ in some
20 beams it may be desirable for ~he strut member 58 locatad at the encls
of the beam to l~e of a heavier sheet metal const.ruction than the inter-
mediate strut members ~8 in order LO carry the higher shear Loads
at the end portions of the beam. While the strength/weight atio of the -
beam illustrated in FIGS. 4-6 is approximately that of the beam shown
25 in FIGS. 1--3 the use of slrutY out3ide the web sub3tantially lesscns
the nesting effectivenes3. On thc othcr hand the bearll 45 re(l-lire s a
somewhat Les3er inve~tmcnt in Looling for man-lfacturing the beam. .
lZZlZl~ . ~
L)ock~ 2589
F[C. 7-') illustrat< s ilnother ernbocliment of a purlin or
bearn 75 constructed in accordance with Ihe invcntion ancl which i9 also
adapted lo be I oll-formecl from a light ga-lge ~heet metal such as 24
gauge 3teel. The bearn 75 includes an upper flang~ 76 and a Lower
5 flange 78 which are integrally connected by a web portion 80. rhe flanges
76 and 78 are roll formed Lo a contiguration 3imilar Lo Ihe lower flange
48 of the beam 45 diYcussed above in connection with FLGS. 4-6, and thus
required no rurther detail description. liIowever, the web portion 80 of
tlle beam 75 is impressed or forrned with a ~eries of longitudinally
10 spaced and vertically extending ribs 82 each of which has a trape~oid
cross-sectional configuxation and projects from adjacent flat coplanar
wall portions 84. The longitudinal spacing of the ribs 82 is preferably
selected 30 that the web portion 80 of the bea~n 75 has uniform corruga-
tions each formed by flat wall 3ections.
The inwardly projecting lip portions 86 of the flanges 7~
and 78 are 3ecured by 3pot welds to the outer flat wall 3ections of the
ribs 82 and the flat wall sections 84 to proYide the beam 75 with sub-
stantial rigidity and a high strength/weight ratio While the beam 75
provides the desirable advantage of close nesting of adjacent beams in
20 a stack, 3imilar to the beam 15 disclosed above in FIGS. L-3, the beam
75 requires separate progressive die tooling for forming the transverse
ribs 82 which are formed in the 3heèt metal panel while it is generally .
flat and before roll-forming to produce the flanges 76 and 78.
Referring to FIGS. 10 and 11, another sheet rnetal purlin
25 or beam 95 is constructed in accordance with the invention and is
roll-formed frorn a light gauge 3heet rnetal panel to form flange pol~ions
lZ21Z113
Do c ket 2589
98 int~g~ralLy connec:t~d by a wel~ portion 1()0. rt`he panel has a series of
lon~ituclin.llly extc:ncling rib3 102 with three of the ribs projcctirlg from
one si.de of the sheet metal panel and a fourth rib projecting from the .
opposite 3ide of che panel. The roll-formecl panel is then bent along two
5 parallel longitudinal lines to form the flange portions 98 and the integral-
ly connecting web portion 100. Thus each of Lhe flange po:rtions 98
is provided with one of lhe ribs L02 and the web portion 100 is provided
with two of the ribs 102 each of which has a trapezoid cross-sectional
configur ation .
A series of ~ongitudinally spaccd and t.ransversely ext( nd-
. ing struts 105 (FIG. Il) are spot-welded or riveted to the c oplanar Llat
wall 3ections Lo6 of the web portion 100 ancl a formed sheet metal
second flange portion or cap member 108 is attached by 3pot welds or
¦ other fasteners to each of the first flange portions 98 of the beam 95 to
15 ¦ reinforce and stiffen the l'lange portion. As illustrated each of the cap
¦ members 108 may be formed of a heavier gauge sheet rnetal and
¦ includes an inwardly projecting lip portion 110. The Lip portion 110 of'
the upper cap member 108 is attached by pot welcls to the outer flat
wall sections of the struts 105 and the lip portion 110 of the lower cap
2 member 108 is attached by spot welds to the lower flat wall section 106
of the' weh portion 100
The purlin or beam 95 illustrated in FIGS. 10 and 11 is
adapted to be rnanufactured with a lower toolingr investment and a higher
labor cost than required for producing the beams described above in
reference to FIGS. 1-9. Thus the beam 95 is ideall.y sllited for maller
..,
.
-~ ~
Do~ ket 2589 3lZZ~
volume production. Ln addition, the web portion l00 of the bean7 95
may be rnore easily changed so that the beam may be produced accord-
ing to the specific use of the beam,
Another Z-shaped purlin or beam L15 constructed in accor-
dance with the invention, is illustrated in FIGS. L2 and L3. In this .
embodiment, the beam 115 is formed of a thin gauge slleet metal panel
in the same manner as the ~eam 75 to provide an upper flange portion
116 and a lower flange portion ,118 integrally connected by a web portion
120. The flange portions 116 and L18 are roll-formed in a mannor aimi-
lar to the corresponding flange portions of the beam 95, and each flange
portion inclucles a longitudinally extending 3tiffening rib 121 ancl an
inclined edge portion 12Z. The web portion 120 of the beam 115 LS
formed in the, same manner as the web portion 80 of the beam 75, that
is, with longitudinally spaced and transversely or vertically extending
ribs lZ5 each defined by flat wall sections forming a trape~.oid cross-
sectional configuration. Each of the flange portions 116 and Ll8 of tbe
beam 115 is further reinforced by a second Llange portion or'cap rmember
128 which is preferably formed of a heavier gauge sheet metal and
is attached by 3pot welds or rivets to the corresponding first or inner
2 flange portion. Each of the cap members LZ8 also includes an inward-
ly projecting lip portion 129 which is spot welded or otherwise fastened
to the web portion 120 to form a rigid second connection between the
flange portions and the web portion 120.
',
~2~Z1~115
Docket 2589
Referring to FIG. 14 which illustrates an I-beam 135
constructed in a manner similar to the Z-shaped beam described above
in reference to FIGS. 1-3, a sheet metal panel is roll-formed to pro-
duce a web portion 136 which has longitudinally extending and vertically
5 spaced ribs 138 forming a corrugated vertical cross-sectional config-
uration. The sheet metal panel extends to form upper and lower first
or inner flange portions 141 which are connected to the web portion
by inclined or angled brace portions 142. The inner flange portions
141 are integrally connected to corresponding upper and lower outer
flange portions 144 each of which has a longitudinally extending and
inwardly projecting rib 146. From the upper and lower outer flange
portions 144, the sheet metal panel returns inwardly to form upper
and lower inner flange portions 148 which connect with the web portion
136 to provide each flange of the beam 135 with a hollow configuration.
15 Each flange portion 148 may also bç a separate strip.
As shown in FIG. 15, the rihs 138 have longitudinally spaced
sets of vertically aligned holes or openings 152. The sets of openings
are spaced at longitudinal intervals, for example, at intervals of
two to three feet, and each set of vertically aligned openings receives
a formed sheet metal strut member 155 having a Z-shaped cross-sectional
configuration. Each strut member 155 is secured by spot welds or
rivots or other fasteners to the web portion 136 so that the strut
members positively maintain the corrugated cross-sectional configuration
of the web portion.
A separate flange strip 158 extends longitudinally of the
beam within each of the upper and lower hollow flanges and seats on
the adjacent ends of the struts 155. As shown in FIG. 14, each flange
strip 158 is preferably formed of sheet steel having a substantially
greater thickness than the thickness of the sheet metal panel forming
-10-
~zz~
Docket 2589
the web portion 136 and flange portions 141 and 144 of the beam. A
series of longitudinally spaced screws or fasteners 161 and 162 secure
the flange portions 141, 144 and 148 to the corresponding adjacent
flange strip 158 and cooperate to provide the beam 135 with a signifi-
5 cantly higher strength/weight ratio, for example, in comparison toa conventional serpentine bar joist which may be replaced by the beam
135 with a significant cost savings. It is also within the scope
of the invention to use heavier gauge sheet metal for forming the
struts 155 in the areas of greatest stress and/or to use a heavier
sheet metal web portion and/or closer spacing of the strut members.
Another form of I-beam construction is illustrated in FIGS.
16-18. In this embodiment, an elongated beam 175 includes a web portion
176 which is roll-formed from a sheet metal panel and includes longit-
15 udinally extend,ing ribs 177. The panel also forms inner flange portions
178 each having a V-shaped rib. The beam 175 also includes outer
flange portions or flange members 181 which are roll-formed from a
heavier gauge sheet metal. Each of the outer flange members 181
includes longitudinally extending and inwardly projecting parallel
edge sections or portions 182 and an intermediate rib 183 which is
secured to the adjacent inner flange portion 178 by a series of
longitudinally spaced spot welds or fasteners 184.
The beam 175 also includes a series of sheet metal strut
members 190 (FIG. 18) which are arranged at longitudinally spaced
intervals along each side of the web portion 176 and extend vertically
~between the upper and lower outer flange portions or members 181.
Each of the strut members l90 has a main portion with a Z-shaped cross-
sectional configuration and a set of vertically spaced ear portions
192 which are trapezoid in configuration and project into and between
the ribs 177 of the web portion 176 in conforming relation. The ear
~2~
Docket 2589
portions 192 have right angle tabs 194 which are secured by spot welds
or fasteners 196 and 197 (FIG. 17) to the web portion 176 and to the
strut members 190 on the opposite side of the web portion. Fasteners
198 secure the strut members 190 the edge sections or portions 182
5 of the flange members 181.
The use of the double strut members 190 on opposite sides
of the web portion 176 enables the beam 175 to be produced with relatively
wide upper and lower outer flange members 181, and it is apparent
that the strut membçrs maintain the corrugated vertical cross-sectional
configuration of the web portion 176 in addition to carrying the vertical
loads between the upper and lower outer flange portions. The construction
of the beam 175 also provides for flexibility in that the vertical
height of the beam may be changed without requiring substantial changes
Tn the tooling for roll-forming the sheet metal panel forming the
web portion 176 and before the inner flange portions 178 are formed.
FIG. 19 illustrates another I-beam 205 which is constructed
in a manner similar to the beam 175 described above in reference to
FIGS. 16-18. The beam 205 includes upper and lower outer flange portions
or members 181 which are identical to the outer flange portions or
members 181 shown in FIG. 16. A substantially thinner sheet metal
panel is roll-formed to form a web portion 208 having longitudinally
extending ribs -Forming a vertical corrugated cross-sectional configuration.
The sheet metal panel extends to form upper and lower inner flange
portions 210 each of which has two V-shaped ribs forrning a trapezoid
cross-sectional configuration. The inner flange portions 210 are
connected by longitudinally spaced fasteners 212 to the ribs 183 within
the outer flange portions 181.
In the embodiment shown in FIG. 19, the beam 205 includes
-12-
~z21~8
Docket 2589
longitudinally spaced sheet metal strut members 215 each of which
has a main portion with a Z-shaped cross-sectional configuration.
The outer flange of each strut member 215 is secured by spot welds
or fasteners 198 to the edges 182 of the outer flange portions 181,
and the inner flange of each strut member 215 is secured by fasteners
217 to a web conforming member 222 having a vertical cross-sectional
configuration mating with the corrugated cross-sectional configuration -~
of the web portion 208. As shown in FIG. 19, preferably each of the
web conforming strut members 222 is molded from metal as a die casting
or from an injected plastics material so that the web conforming member
222 may be economically produced in high volume. Identicai strut
members 222 are used on opposite sides of the corrugated web portion
208, and fasteners 224 secure the upper and lower flange portions
210 to the inner flanges of the sheet metai strut members 215. The
15 construction of the beam 2~5 also provides for producing beams of ~ -
different heights without requiring substantial additional tooling
for producing each component of the beam. For example, the length
or height of the Z-shaped sheet metal strut members 215 may be easily
changed for changing the height of the beam 205, the outer flange
portions 181 remain the same, and the heignt of the web portion 208
may be changed by adding or deleting another rib before the upper
and lower flange portions 210 are formed, for example, on a press
brake.
FIG. 20 shows a beam 235 which is constructed similar to
the beam 175 described above in connection with FIG. 16. The beam
235 includes a sheet metal panel which forms a web portion 236 having
longitudinally extending and vertically spaced ribs 238 forming a
vertical corrugated cross-sectional configuration. The sheet metal
panel extends to form upper and lower inner flange portions 241, and
LZ18
Docket 2589
upper and lower outer flange portions of members 181 are connected
to the inner flange portions 241 by spot welds or fasteners 184 which
extend through the ribs 183 of the flange members 181.
In place of the sheet metal strut member 190, the beam 235
includes a series of longitudinally spaced strut members 246 which
are molded frorn a metal or plastics material. As used herein,'molding
includes die casting of a metal as well as injection molding of a
plastics material. Each of the strut members 246 extends vertically
between the outer flange portions or members 181 and includes portions
lG 248 which project into the ribs 238 of the corrugated web portion
236. Each strut member 246 is also provided with holes for receiving
self-threading fasteners 25) which secure the strut member to the
web portion 236 and to the flange portions 181. While the beam 235
is illustrated with a series of strut members 246 on only one side
of the web portion 236 "nolded strut members may be used on both sides
of the web portion 236 in longitudinally offset or alternating relation
so that there is always convenient access for insert7ng the fasteners
251 which secure the strut members to the web portion 236.
Another Z-shaped purlin or beam 255 is shown in FIG. 21
and includes a thin sheet metal panel which forms a web portion 256
' and upper and lower inner flange portions 258. The web portion 256
is corrugated to form vertically spaced and lo~gitudinally extending .
ribs 261 each having a trapezoid cross-sectional configuration. Each
of the inner flange portions 258 also has V-shaped ribs forming a
trapezoid cross-sectional configuration. The beam 255 also includes
upper and lower outer flange portions or members 264 which have a
thickness substantially greater than the thickness of the web portion
256. For example, the web portion 256 may be formed of 24-gauge sheet
steel, and the flange portions 264 may be formed from 17-gauge sheet
steel.
:lZ~
Docket 258~
The opposite edge portions 266 of each flange member 264 are
formed or bent inwardly to provide the flange member with two V-shaped
ribs forming a trapezoid cross-sectional configuration conforming
to the shape of the adjacent inner flange portion 258. A series of
longitudinally spaced bolts or fasteners 267 secure the correseonding
upper and lower adjacent flange portions 258 and 264. Each fastener
267 may be provided with a countersunk flat head, or the flange portions
may be attached by longitudinally spaced spot welds.
The purlin or beam 255 also includes longitudinally spaced
pairs of strut members 272 each of which is molded of a metal or plastics
material and has portions 274 which project into or between the ribs
261 of the web portion 256. Each pair of strut members 272 are secured
together by self threading screws or fasteners 276 (FIG. 22) and clamp
the web portion 256 between the strut members for positively maintaining
the corrugated cross-sectional configuration of the web portion. Another
series of longitudinally spaced fasteners 276 also secure the strut
members 272 to the over-lapping edge portions 266 of the outer flange
members 264. While the fasteners 276 are shown with projecting head
portions, the fasteners may have countersunk flat heads so that they
do not project from the outer surfaces of the strut members 272. The
! strut members 272 may then serve as bumpers when a plurality of beams
255 are stacked in nestiQg relation.
FIG. 23 illustrates another Z-shaped purlin or beam 285
which is constructed in a manner similar to the beam 255. The beam
285 includes a sheet metal panel which Forms a web portion 286 having
longitudinally extending and vertically spaced ribs 288 each having
a V-shaped cross-sectional configuration and thus provide the web
portion 286 with another form of generally vertical corrugated cross-
sectional configuration. The sheet metal panel also extends to form
-15-
~ ~"
18
Docket 2589
upper and lower Inner flange portions 291 which are secured to outer
flange portions or members 264 by longitud7nally spaced fasteners
292 in the form of rivets or bolts or spot welds.
in reference to the beam 255 shown in FIG. 21, the upper
outer flange portion or member 264 overlaps the lower outer flange
portion or member 264, whereas in the beam member 285 shown in FIG.
23, both of the upper flange portions 291 and 264 overlap both of
the lower flange portions. In a manner similar to the beam 255, the
beam 285 includes a series of longitudinally spaced pairs of strut
members 294 which are also molded of a metal or plastics material
and include portions which project laterally into and between the
ribs 288. Each pair of strut members 294 are clamped together by
fasteners (not shown) which extend through aligned holes within the
strut members and the web portion 286 so that the strut members 294
positively maintain the corrugated cross-sectional configuration of
the web portion. Longitudinally spaced fasteners 297 also secure
each pair of strut members 294 to both of the inner and outer flange
portions 291 and 264.
From the drawings and the above description, it is apparent
that a sheet metal beam constructed in accordance with the present
invention provides desirable features and advantages. For example,
each of the beain constructions is initially formed of a relativeiy
light gauge sheet metal panel having a thickness less than .040 inch
and preferably about .024 inch. The sheet metal panel is formed in
a manner which provides for utilizing the inherent strength of the
sheet metal and to obtain a maximum strength/weight ratio. As a result,
a beam constructed in accordance with the invention significantly
reduces the cost for constructing a beam having a predetermined strength
and thus makes more efficient use of the metal. The substantially
-16-
~Z~
Docket 2589
higher strength/weight ratio of the beam also results in significantly
reducing the weight of each linear foot of the beam from the weight
of a conventional beam so that the beam of the invention may be more
easily handled and more economically shipped than a conventional beam.
A beam constructed in accordance with the invention also
provides for flexibility in design in that the height of the web portion
of the beam may be selected or increased without substantially increasing
the weight of the beam, thereby taking advantage of the fact that
the strength of the beam increases as the square of the web height.
Each of the beam embodiments also provides flange portions having
large flat outer surfaces which are highly desirable for attaching
the beams to a frame and for attaching overlying corrugated sheet
metal panels to the beams with threaded fasteners.
The beam embodiments described in connection with FIGS.
16-23 provide additional desirable features. For example, the strut
members used in these embodiments include portions which project
laterally into and between the ribs of the corrugated web portion
and in conforming relation to the corrugations so that the corrugated
shape of the web portion is positively maintained when the beam is
loaded. As a result~ the conforming strut members provide for minimizing
- the thickness of the sheet metal panel forming the corrugated web
portion. The separate upper and lower outer flange portions in these
beam embodiments also provide for selecting the gauge for the outer
flange portions according to the design loading on the beams. The
outer flange portions are also positively secured to the correspondinq
inner flange portions and to the strut members to provide a substantially
rigid beam construction.
In the embodiments shown in FIGS~ 21 and 23t the overlap
of the flange portions is effective to reduce the roll-over moment
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l~Z~Z~l~
Docket 2589
. .
and thereby improve the load carrying ability oF a Z-shaped beam with
only a srriall decrease in the nesting compactness of the beams in a
stack. It is also apparent that each of the beams may be joined
end-to-end with adjacent end portions in overlapping relation. In
addition, the longituclinally spacing between adjacent strut members
may be selected according to the design loads on the beam. As also
disclosed in connection with FIGS. 16-23, the conforming strut members
may be formed of sheet metal, die cast metal or injection molded plastics
material, according to the particular use and load bearing requirements
! for the beam.
The sheet metal strut member 190 also provides complete
access for spot welding each strut member to the web portion and
to the outer flange portions or for attaching rivets or other fasteners.
While an I-beam is illustrated in FIG. 20, it is apparent that the
construction could be used for producing C-beams, for example, to
replace conventional C-beams used in the construction of metal buildings.
As another feature, the longitudinally spaced pairs of double strut
members in opposing relation not only function to clamp the corrugated
web portion therebetween, but also Function to carry the column loading
20 between the upper and lower flange portions.
While the forms of beams herein described constitute preferred
embodiments of the invention, it is to be understood that the invention
is not limitei to these precise forms of beams, and that changes may
be made therein without departing -From the scope and spirit of the
invention, as defined in the appended claims.
The invention having been described, the following is claimed:
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