US2637421A

US2637421A - Stabilized beam construction

Info

Publication number: US2637421A
Application number: US129384A
Authority: US
Inventors: Merl R Wolfard
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-11-25
Filing date: 1949-11-25
Publication date: 1953-05-05
Anticipated expiration: 1970-05-05

Description

May 5, 1953 M. R. WOLFARD I v STABILIZED BEAM CONSTRUCTION 2 SHEETS-SHEET 1 Filed Nov. 25, 1949 C(ttorneg Merl I? ISnnentor um m M y 1953 M. R. WOLFARD STABILIZED BEAM CONSTRUCTION 2 SHEETS-SHEET 2 Filed Nov. 25,- 1949 Merl R. l'mventor m AR attorney Patented May 5, 1953 UNITED STATES PATENT OFFICE STABILIZED BEAM CONSTRUCTION Merl R. Wolfard, Cambridge, Mass.

Application November 25, 1949, Serial No. 129,384

5 Claims.

This invention relates to the stabilization of construction members, such as beams. More particularly the invention is directed to the minimizing of undulatory and vibratory movements which agitating loads tend to produce in such beams.

In one aspect, this invention is an improvement on the invention set forth in my Patent 2,333,136, in which I disclose the value of certain arrangements of struts of substantially V-form interposed between a compression element and a tension element. One aim of that invention was to attain maximum load carrying capacity with a minimum weight of material, in which instance, the suitability of the compression element was considered from the standpoint of its capacity to carry the compression load resulting from the endwise thrust applied to its ends by the tension element, this tension element itself being considered as the fundamental load-sustaining element and the element requiring control.

In this invention the primary concern is with the stabilization of a beam which in itself is sufiicient, or nearly sufficient when the beam is static, to carry the loadings which may be applied to it.

The present invention is applicable to the stabilization of such beams when already in place in existing structures, for example, bridges or buildings. The invention is particularly advantageous where a bridge or building floor is required to carry loadings that produce greater vibratory disturbances than those for which such structures were designed.

It is well known that in structures which are designed for carrying expected loads, such structures may vibrate or undulate more than can be tolerated when certain agitating loadings are applied to them. For example, when a body of soldiers cross a bridge, they are always instructed to break step to prevent what might be destructive vibration. Likewise, light bridge structures will safely carry the weight of traffic intended to pass over them provided the speed of travel is not too great, as is evidenced by the stationing of policemen at such bridges to prevent a prescribed limit of speed from being exceeded. Again, a bridge may carry the expected normal traffic but an occasional truck, loaded beyond the normal capacity of the bridge, may cause excessive vibration injurious to the bridge.

Also, agitating loadings carried on the floor of buildings may cause undesirable vibrations of the whole building as well as the floor itself. For example, where machinery causing vibrations is installed on one floor of a building the vibration permissible on that floor may exceed that which can be permitted on other floors of the building. 01' indeed, when factory machinery is installed on all of the floors of a building, the building itself may be severely damaged and its usefulness destroyed by reason of the accumulation of vi- ;rations of the plurality of floors.

By the present invention such undulatory and vibratory movements are so effectively minimized that these and similar structures are rendered substantially immune to agitating forces which otherwise would result in destructive vibrations.

In carrying out the present invention, wherever a beam member extending across a span between supporting means is to be stabilized, an auxiliary member is usedin conjunction with said beam member, the said auxiliary member extending lengthwise of the beam member and normally below it. The invention is applicable for stabilizing a beam in any other plane but will hereinafter be described as loaded from above to facilitate a clear description of the invention.

The auxiliary member is supported from the end portions of the beam member. There are struts disposed between the beam member and the auxiliary member, one in each second-fifth portion of the span from the end of the span. Preferably there is also tying means intermediate of said struts for applying a structure-loading, that is, a loading applied by the structure to the beam member intermediate of said struts for the purpose of deflecting the beam member downwardly relative to said struts when the construction is static.

The auxiliary member preferably is a tension member, but it may be or include a beam-like member possessing resistance to bending. In a preferred embodiment of the invention the auxiliary member is a tension member with the ends thereof connected to the beam member over a substantial lengthwise region of the end portions of the beam member. The innermost point of supporting contact of each connecting means with said beam member is in the range of about 4 to about 16% of the length of the span from its respective end of the span.

There is a strut disposed between the beam member and the tension member in each secondand is inclined toward the center of the span to the beam member, and is there attached to the beam member. The ties have a relative length in said construction such that, when the construction is static, they apply a structure-loading to the beam member, thereby downwardly deflecting the mid-region of the beam member relative to said struts.

In the drawings,

Figure l is a side elevation of a stabilized beam construction embodying fundamental principles of this invention;

Fig. 2 is an enlarged transverse vertical section taken on line 22 of Fig. 1;

Fig. 3 is a side elevation of a stabilized beam construction wherein the beam member and a beam-like member are of wood;

Fig. 4 is a side elevation of a preferred embodiment of the invention for stabilizing a wooden beam;

Fig. 5 is an enlarged transverse vertical section on line 5-5 of Fig. 4;

Fig. 6 is an enlarged bottom view of an end portion of the construction shown in Fig, 4;

Fig. '7 is a side elevation of a preferred embodiment of the invention for stabilizing a steel beam;

Fig. 8 is an enlarged transverse vertical section on line 8-8 of Fig. '7;

Fig. 9 is an enlarged bottom view of an end portion of the construction shown in Fig. 7;

Fig. 10 is a side elevation of a construction of the invention as applied to the stabilization of steel beam and in which the struts are of substantially V-form;

Fig. 11 is an enlarged transverse vertical section taken on line ll|l of Fig. 10; and

Fig. 12 is an enlarged bottom view of an end portion of the construction shown. in Fig. 10.

In the embodiment of the invention illustrated in Figs, 1 and 2, a beam member 2, which is to be stabilized in accordance with the present invention, extends across the span between the supports 3. The beam member 2 is composed of two structural steel channels 4 with their flanges facing outwardly, spaced apart by the spacers 5 and secured together by suitable means such as bolts 8. A beam-like member H] is similarly composed of structural steel channels [2 with spacers l4, and joined together by suitable means such as bolts H5. The channels [2 are shown as being of greater cross-sectional dimensions than the channels 4. The beam-like member Iii extends lengthwise of and below the beam member 2 through the mid-portion of the span. Links it are secured to the beam-like member l2 at 29, adjacent to its ends, and extend thence at an incline outward and upward to the beam member 2, where the links are connected to the beam member at 22. The beam-like member ID and the links l8 together constitute an auxiliary member supported at connections 22. These connections 22 as shown are located inwardly at a distance from the supports 3, and preferably are located at a distance of about 4% to about 16% of the length of the span from the end of the span.

Struts 24 are disposed between the beam member 2 and the beam-like member it at locations each within the respective second-fifth of the length of the span from the end of the span. In other words, each strut 24 is placed between onefifth and two-fifths of the length of the span from each respective support 3. The optimum location for each strut 24 isin the neighborhood of three-tenths of the length of the span from the endof the span. Intermediate of the struts 24 any convenient tying means for drawing the 4 beam member 2 toward the tension member I0 may be used, such as bolts 26.

In assembling the structure of Fig. 1, for best results the beam member 2 and the beam-like member [0 should be slightly pressed apart, by a jack or similar means, when the struts are placed in position, so that structure-loading is applied to the beam member 2 at the connections 22. By increasing the tension on the bolts 26 the beam member 2 is structure-loaded intermediate of the struts 24, whereby the mid-region of the beam member 2 is deflected downwardly. This downward deflection also somewhat increases the structure-loading of the beam member 2 at the connections 22, by reason of the lever action of the beam member 2, on the top of each strut 24 as a fulcrum, tending to lift the adjacent connecting point 22. The effectiveness of this structure-loading for stabilization of the beam construction is enhanced if the resistance to bending of the beam-like member H3 is greater than the resistance to bending of the beam member 2. This follows because when, for example, a live loading is imposed on the beam member 2 intermediate of the struts 24, the first result is thatit tends to reduce the tension in the bolts 26, and no substantial deflection of the beam member occurs until that tension is reduced to zero, provided that the upward deflection of the beam-likemember it is negligible as compared with the downward deflection of the beam member 2. It follows, therefore, that the optimum eifectiveness is provided when the lower ends of the bolts 26 do not move upward as the beam member 2 isdefiected downward during the assembly of the structure.

Fig. 3 shows a form of the invention in which a wooden beam member 30 extends across the span between the supports 3! and is stabilized by means of a wooden beam-like member 32. The beam-like member 32 here extends from the location of its supporting connection to the beam member at one end to the supporting connection at its other end. As illustrated, these supports are bolts 34. The struts 36 hold the beam member 30 and beam-like member 32 apart from each other and are preferably somewhat nearer the end of the span than the struts shown in Fig. l, but yet within the second-fifth of the length of the span. As illustrated, the bolts 38 for-defleeting downward the mid-region ofthe beam member 30 are inclined upward and inwardfrom their location in the beam-like member .32 through the beam member 30. This provides that, when the tension on the bolts 38 is increased, the upward force applied to the-beam lie member 32 by the lower ends of thebolts, is nearer to the respective struts 38 than is the downward force applied to the beam member 30' by the upper ends of the bolts 33.

Figs. 4, 5 and 6 show apreferredconstruction for stabilizing a wooden beam member. extending across the span between the supports, ll.

of the span. Preferably also the means holding the tension member against slip toward the center of the span is separate from andnearer A tension member 52, preferably of metal such as steel, extends lengthwise of and belowaeemr plates against separation from each other constitute a yoke resisting the downward component of the loading applied to the beam member 40 by the tension member 42.

Within each second-fifth of the length of the span there is a strut 52 disposed between the beam member 48 and'the tension member 42, and holding those members apart from each other. A tie 54 is attached to the tension member 42 at the lower end of each strut 52, and extends thence upwardly and inwardly to an attachment to the beam member Ml. trated, the attachment of each tie' 54 at its lower end is a hook 56 extending through an aperture in the tension element 42. The ties 54 are attached to the beam'member 4!! in any convenient manner, as by the lag screws 58. Preferably also the ties 54 have means for adjusting their length, such as turnbuckles 59.

In this construction, for best results each strut 52 should have a length such that it applies some structure-loading to the beam member 40, at the location of the bolts 50, before the turnbuckles 59 are tightened.

Figs. '7, 8 and 9 illustrate a preferred construction for stabilizing a steel beam member 60 extending across the span between the supports 6|. A tension member 62 extends lengthwise of and below the beam member til with connecting means supporting said tension member 62 from said beam member 50 within each endsixth of the span, and preferably having the innermost point of supporting contact $3 of each said connecting means in the range of about 4% to about 16% of the length of the span from the end of the span. Preferably also, the means holding the tension member against slip toward As illusthe center of the span is separate from, and

nearer to, the end of the span than is that portion of the connecting means which is in the vicinity of said point of innermost contact 63 with the beam member 60. As illustrated, bolts 64 extend through tension member 62 and through the lower flange of beam member 68, and hold the tension member 62 against slip toward the center of the span. Bolts 66 also extend through the tension member 52 and the lower flange of the beam member 60. The bolts E55 preferably pass through holes somewhat larger than the bolts so that they act primarily to resist the downward component of the loading applied to the beam member by the tension member 62 at each respective end connection. There may be a plate 68 below the tension element 62, through which the bolts 66 pass, for preventing localized stress at the location of the bolts.

A strut 10 is disposed between the beam member 60 and the tension member 62 in each secend-fifth of the length of the span from the end of the span and holds those members apart from each other. A tie I2 is attached to the tension member 62 at the lower end of each strut m and extends thence upwardly and inwardly to an attachment to the beam member 60. As illustrated the attachment of each tie 12 at its lower end is a longitudinal line of beam 6 welding 13 on each side of the tie 12. The tie 12 is shown as attached to the beam member 60 also by lines of seam welding 15 on each side of the tie 12.

In assembling a construction such as illustrated in Fig. 7, the ends of the ties H! are first located in fixed position by means of the seam welds l3 and 15, and the struts 10 are then positioned or inserted after employing, for example, an offset jack or other equivalent means to provide sufiicient space ,for the struts between the beam member 60 and tension member 62. The length of the struts 1|], when in position, should be such that they deflect the beam member 60 upwardly. Thus the beam member 60 is structure-loaded intermediate of the struts 10, and also at the lengthwise locations of the bolts 66.

Figs. 10, 11 and 12 show a construction wherein a steel beam member extends across the span between the supports 8|. The steel beam member 80 is shown as being of H-cross section and as placed with its flanges vertical and with. its web in horizontal position and resting upon the support 8|. With this arrangement the beam member 88 is relatively stiff laterally by reason of its cross-sectional shape and the beam member 80 is stabilized vertically by reason of the construction now to be described. A tension member 32 extends lengthwise of and below the beam member 8|] with connecting means supporting said tension member 82 from the web of the beam member 80 within each end-sixth of the span and preferably having the innermost point of supporting contact 83 of each said connecting means in the range of about 4% to about 16% of the length of the span from the end of the span. Preferably also the means holding the tension member against slip toward the center of the span is separate from and nearer to the end of the span than is that portion of the connecting means which is in the vicinity of said point of innermost contact 83 with the beam member 80. As illustrated, bolts 84 extend through the tension member 82 and through the web of beam member Bil, and hold the tension member 82 against slip toward the center of the span. Bolts 86 also extend through the tension member 82 and the web of the beam member 80. These bolts preferably pass through holes somewhat larger than the bolts so that they act primarily to resist the downward component of the loading applied to the beam member 80 by the tension member 82 at each respective end connection.- There may be a plate 88 below the tension element 82 through which the bolts 86 pass, for preventing localized stress at the location of the bolts.

Within each second-fifth of the length of the span from the end of the span there is a strut Bil disposed between the beam member 35 and the tension member 82, and holding those members apart from each other. As illustrated, each strut 90 is of substantially V-form with the point of the V based on the tension member 82, and the arms 9i of each V extending outwardly and upwardly to the beam member 80 where they are secured against lengthwise slip. As shown in the drawing this is accomplished by the transverse seam welds 92. The lengthwise location of each strut as being in each second-fifth of the length of the span, refers to the location of the median line of the V-strut, that is, the lengthwise location of the point of the V. This median line, as illustrated in Fig. 10, will also be the vertical line of each bolt 94 which extends through the tension member 82 at the point of t e V I- m u wardl an .t sht1 w 9. h b a i be 'jflfl inc easi he ten on th' t o t' fprov de tc am i sa q iw s e ten'ds to dra'WWhe beam member 80, 'atthe iotationof each of thebolts 94, toward thepoint of t or e c stru s! a ar macne "a h s embe 8. a th il e fid-o ea h strut 90 and extendsfth'ence upwardly and in: war-c115" to; an attachment to the beam member 80'; fisillustra'te ach tieisa-flatfbar having at it's lowe'r'endfa o d-throug hichthe" bolt s3 passes and has f at "i u per end a hole 1 through which'the bolt asv enus and ecures it to" as web 'of thefbea'm member 85. Asfshown each tie 9'5" has at'gitsrnid portion a turnbuckle'tl" y means of which' theteiision in theitiefiQ mayfbe adjusted.

a m lill ith constru ie t i-str may" be placed: in positionwith a snug; tit hetween the beam and tension members; and {the bolts 94 are-then tightened? This defiectsthe i l w i of YE' FQ' b l 5. an s iu u loading to the m member 30. at thelocationof the bo'1tsf8tf' 'I ows'flbyreasonof'the level" actionon the upper end of those year'ms s l which are'adja centfl to jthe b'olts as. Thy-turnbuckles "531 mf'ay1then" b'e tightened to structure.- load the beam memb rtfi" intermediate or said strut-519D.

' It sh ld .b xinoo e tha b this n enti n until that 1 live-loading [exceeds the" tensionv in];

tiallyi. incorporated in the structure-loading ties,

in contradistinction to ,a 1 simple beam whose movement is greatest finfits mid-region. Further more; ifthe agitating'forc'e imposed on a sane:

tnrejof the'invejntionisof such ma'gnitudeythatitjdoes cause some mov'ement, the effect or'that movementflislocalized' by'reason of the effective arrangementfof fparts'inthe structure of them vention, and travel of undulatory movements from onefllocationto another along. the beam member is prevented; As 'atvholc, the invention provides an eifect'ivenessin minimizing vibratory and unduiatoryfmove'mehts which; so tar 'as 4I am aware, has hithertobeen unapproached.

1. A stabilized beam'construction comprising, in combination, a beam member extending a fess a span between supporting means; an auxiliary m mbe w. z a ali s en t w s of d el ai ta t r mie in ma u o ti d an iliaryi'niemberfl from'said beam member with in o sfigth of the span, the innermost point of 'stlppoi ting contact of each said con necting meansbeing inthe range of about f1% toabout 15% (if the' lengthof the span from theieiidof't'hespan; a strut disposed between thbea'mand auxiliaryfmembers in each secondfi fth' of the length of the span from the end o fithe span, and holding said members apart fiftimeachother; and a tie' attached to" the auxil-' iarymem emr the vicinity of the lower end'of each said strut, each 'fiaid tie" thence extending upwardly at an incline toward the center of the sjo'an t'o'jtheb'eam member and there attached th that member'f each said tie'having a relative length in said construction such that, when the conjstifuctionis sta n; the beam member inter'me'diatejof "said" struts is structure-loaded,

' thereby producing downward deflection of the mid-region'of the beam member relative to said struts.

2. A' stabilized beamconstruction as in claim 1, further characterized in that each'said tie inmil ews-insanemeans, thereby providing for predetermination of the structure-loading at the mid-region of the" span.

3. fstabilized'beam construction as in claim tl, further characterized in that the connecting means sulr iportirfig, thetensionmember in each end-sixth". of "the span joins "the tension member to the beam In'ember 'over a substantial lengthwise portion of said membe s;

4;. A stabilized beam construction as in claim 3 further characterized ,in that that portion of the connecting means'whi'ch is toward the end of the'spa'n' comprises means holding the tension member against-slip'towai'd the center of the span; and that portion'of the connecting meansjvhich' i ihth vicinity of the innermost point of suppt'irt'ir' g contact with the beam member' vcom p rises means resisting the downward component of thefloading' applied to the beam member by the {tension member.

-;5. A stabihz'edbeam construction as in claim 4, further characterized"infthat the means resisting the downward commenter the loading applied to the beam member by the tension member is adyok'efi MERL R. WOLFARD.

.lj'eferences cit d-in the file'of this patent UNITED STATES 'PATEN'I'S