US2556878A

US2556878A - Fireproofed flanged structural member and a precast shoe therefor

Info

Publication number: US2556878A
Application number: US530519A
Authority: US
Inventors: John V Kohlhaas
Original assignee: Individual
Current assignee: Individual
Priority date: 1944-04-11
Filing date: 1944-04-11
Publication date: 1951-06-12
Anticipated expiration: 1968-06-12

Description

June 12, 1951 J. v. KOHLHAAS v FIREPROOFED FLANGED STRUCTURAL MEMBER AND A PRECAST SHOE THEREFOR- Filed April 11, 1944 INVEN OR.

JOHN KOHLl-IAAd.

' ATTORNEY.

Patented June 12, 1951 UNITED STATES TENT OFF-ICE THEREFOR John V. Kohlhaas, PhiladelphieuPa.

Application April 11, 1944, Serial No. 530,519

4 Claims. 1

For optimum fire protection it is requisite that the metallic beams, girders and columns of a building be enclosed in concrete or the like with avoidance as far as practicable of joints in the enclosing material so that the metal is fully protected from contact by flames, and it is therefore customary practice to erect suitable forms about the steel members after they are in position and pour the concrete into the forms which must then be left in place until the concrete has suitably hardened. This practice, however, is objectionable in that, among other things, the construction and subsequent removal of the forms are time consuming and expensive operations and when the forms are associated with non-vertical members such as girders or beams they must be maintained in position by suspending them from superjacent elements or by supporting them on suitable scaffolding which has to be left in place during the hardening period and so encumbers the floor subjacent the forms and interferes with further constructional activity as long as it is in place.

In consequence attempts have been made to suitably enclose the steel structural members after-erection by means of precast elements of concrete, but these procedures have not satisfactorily solved the problem for upon the occurrence of .a fire the mortar which is used to close the joints between the elements quickly disintegrates under the intense heat or is washed out by high pressure water discharged onto the fire and the flames can then penetrate through the joints and impinge on the structural members.

In accordance with the present invention, however, the difficulties hitherto inherent in the use of precast fireproofing elements are obviated and a solid flame andiwater. impermeable covering provided for the metallic structural members Without the expense and inconvenience incident to the erection and maintenance of forms preparatory to the pouring of the concrete in situ and the necessity of keeping them in place during, and of removing them after, the hardening period.

It is thus a principal object of the invention to provide a novel building construction and method thereof of the character to which brief reference has just been made, which may be utilized for fireproofing either vertical or nonvertical structural members.

Other objects, advantages and novel features of design, construction, arrangement and assembly comprehended by the invention are hereinafter more particularly'pointed. out or will be apparent to those skilled in the art as the following description of the invention proceeds, reference being had to the accompanying drawing in which:

Fig. 1 is a fragmentary side elevation, partially broken away into section, of a beam or girder with its lower portion fireproofed in accordance with the invention;

Fig. 2 is a transverse section on the line 2-2 inFig. 1;

Fig. 3 is likewise a transverse section of the beam illustrating the first step in the application of a precast shoe to its lower portion;

Fig. 4 is a, similar view showing the shoe applied and temporarily secured to the beam preparatory to pouring the concrete and keying the shoes toeach other and to the beam;

Fig. 5 shows the manner of fireproofing a vertical column in accordance with the invention, the figure being a side elevation of the fireproofed column with parts broken away into vertical section;

Fig. 6 is a transverse section on line 6--6 in Fig. 5, and

Fig. 7, generally corresponding to Fig. 3, but in horizontal section through the column illustrates the first step in applying one of the precast shoes thereto.

Corresponding parts are designated by like reference characters in Figs. 1-4 and 5-7 respectively.

Referring first to Figs. 14 inclusive, B is a typical I-beam or girder, such as is commonly used in building construction, which, for 'example when constituting a sustaining member for a floor, is supported at its ends on other structural members in the usual way. In fireproofing such a beam in accordance with the invention I prepare a suitable number of concrete shoes I which may be cast in molds in any convenient location and then transported to the job; they are desirably made about three feet long so they can be readily handled and may be reinforced with reinforcing material such as mesh 2 or metal rods. Each shoe is preferably rectangular in transverse section and about twice as wide as it is deep, and in one of its wider faces is provided with a channel 3 the mouth of which is of less width than the width of the flange 1 of the beam with which the shoe is to be associated, while the bottom of the channel comprises a central recess 4 of a width and depth to snugly receive the flange. The side walls of the recess thus preferably approximate the depth of the flange at its edges and above the recess the channel is widened out laterally for a short distance in each direction and its walls 5 then carried upwardly parallel to each other, thence inwardly inclined as at 6 and finally again carried upwardly to define the mouth of the channel between the lips I. A channel of substantially the shape just described and best illustrated in Figs. 3 and 4 is normally most satisfactory although the exact shape of the undercutting is more or less a matter of choice as long as the mouth of the channel is narrower than flange f, while it is desirable, though not perhaps absolutely essential, that the bottom of the channel be provided with the recess 4 approximating the width of the flange to insure proper alignment of the shoe with the beam and prevent any lateral shifting of the shoe after it is in position.

In each end of each shoe is formed a depression or countersink 8 preferably an inch or more in depth which is bounded at all points by a rib projection on the end of the body of the shoe save for a short distance, below the plane of the recess, 4 where it is carried outwardly to one of the lateral faces of the shoe to form a gate 9 for a purpose to be hereinafter described; the width of the marginal boundary of this countersink should be sufficient to afford adequate strength yet not so great as to unduly restrict the area of the countersink itself. It is also desirable if mesh or like material is employed as a reinforcement for the shoe to dispose it substantially as indicated and thus with its ends projecting for a short distance into the undercut portion of the channel but not sufficiently to interfere with the application of the shoe to the beam as now to be described; if desired the shoe may also be reinforced by transversely extending rods 2a.

After the beam has been suitably erected one of the shoes is applied to its lower flange ;f substantially as shown in Fig. 3, the shoe being held in a somewhat angular position so that one of the lips I at the side of its channel can be hooked over the proximate edge of the flange and the latter thus entered in the undercut part of the channel. The shoe is then swung upwardly so that its lower face is substantially horizontal and shifted sufficiently to bring flange 1 into the recess 4; if desired it may also be slid endwise so as to bring one of its extremities against the column which supports one end of the beam. The shoe is then temporarily held in place in any suitable way as by bolts l0 having L-shaped heads adapted to engage over the edges of the flange, the shanks of the bolts, of which only enough are used to support the shoe, being passed downwardly through preformed slots II in its bottom to receive nuts and washers on their lower project ing extremities so that the parts now appear as in Fig. 4 registering slots H in abutting shoes forming holes about the bolts.

After the first shoe is applied as just described, conveniently adjacent one end of the beam, a second shoe is similarly secured to the latter with its end in abutting relation with the proximate end of the first shoe and so on until the lower flange of the beam is entirely covered by the series of shoes.

It results that a groove is defined on each side of the web w of the beam extending substantially for its full length and into this groove concrete or like material C is now poured until the groove is filled flush with the upper faces of the shoes, thereby imbedding flange f and the lower part of the web in a mass of fireproof material with which these portions of the beam are in intimate contact. Because of its relatively high viscosity when poured, comparatively little of the concrete passes over the edges of the flange into the chambers formed by the juxtaposed countersinks 8 at the abutting ends of the shoes, and other concrete c is next forced under pressure into these chambers through the openings formed by the juxtaposed gates 9 so as to entirely fill the chambers and gates, whereby a solid block or band of concrete is provided between adjacent shoes and extending partly over the beam flange to bridge the joint between the shoes which, after it is hardened, not only keys them and the beam together but prevents the access of flame or water to the beam in the vicinity of the joint. Any concrete projecting through the gates is of course preferably smoothed off flush with the lateral face of the shoes before it sets.

After the concrete C which has been poured into the groove as well as that (c) injected into the chambers and gates has fully hardened, bolts I0 are no longer required to support the shoes since the latter are firmly and permanently attached to the beam, and the washers and nuts on their lower ends thus can either be left in place or cut off in any suitable way. Preferably, however, and to save the labor of cutting off the bolts, the shanks of the latter are nicked or otherwise weakened slightly at appropriate points before they are placed in position and can thus be broken off substantially flush with the lower face of the shoes by setting up very tightly on the nuts.

It will now be apparent that in accordance with the invention and without the necessity of erecting, supporting and ultimately stripping the customary forms, the lower flange and adjacent portion of the web of a non-vertical beam may be enclosed in a substantially monolithic structure of concrete comprising a plurality of precast shoes of convenient size applied to the beam and 'keyed together and to the beam in such way that all portions of the latter within the limits of the shoes are in intimate contact with concrete, and those portions of the beam in alignment with the joints between the shoes are fully protected from access of flame and the joints themselves made impermeable to water.

As indicated in Fig. 2 in broken lines, the exposed portion of the beam may then be enclosed by precast slabs S disposed between the upper surface of the shoes, the upper beam flange if and the superjacent floor F which latter may be formed of precast reinforced slabs or poured in situ as preferred, slabs S being preferably cemented to the shoes and beam in the customary way; the details of theses-operations, however, form no part of the invention.

Moreover, the principles of the invention are equally applicable to the fireproofing of vertical columns as more particularly shown in Figs. 5-7 to which reference will now be made.

The metallic column X which is to be fireproofed may be of the usual I-beam type and it will be assumed it has been erected in substantially vertical position. A plurality of precast preferably reinforced shoes 20 of the general character of those previously described are prepared, each such shoe thus comprising a longitudinal channel 2| with a central recess 22 at its bottom to receive one of the flanges f of the column. Above this recess the channel is widened and its walls 23 preferably carried up at right angles to the bottom of the recess to meet the inwardly overhanging lips 24 which define between them apassage of less width than the width of the flange, while the under faces 25 of the lips are inclined in such manner that the extremity of each lip is thinner thanits base; moreover, the depth of the channel is made less than one-half the distance between the outer faces of the flanges f, f, of the column so that when a pair of the shoes are disposed about it in opposed relation hereinafter described a space will be left between their ljuxtaposed'inner faces. As in the case of shoes I aco-untersink 26 is formed in each end of'each shoe and a gate 21 extended outwardly therefrom at or near'that part of the countersink remote from the rnouth of the channel.

A plurality of precast preferably reinforced concrete keys 2-8 are also prepared, all of these keys save two which-are desirably made somewhatlonger than-the others, approximating the shoes in length and being ofgenerally T-shaped cross section, the leg 29 of each key being of a width to fit fairly snugly between the shoes after the latter are applied to the column while the head part 30 is provided at its extremities with longitudinal ribs 3! having their inner faces in--- clined correspondingly to the faces 25 of the lips so they will fit snugly thereagainst when the key is in place between them.

One-of shoes 28- is now applied to one flange of the column, preferably at its base, substantially'in the manner illustrated in Fig. 7, that is, by engaging one edge of the column flange in the channel beneath one of the overhanging lips 24 while the shoe is held at an angle to the column web and then swinging the shoe about the flange until its opposite edge passes into the channel when by slightly shifting the shoe the flange can be seated in recess 22. Another shoe is then applied to the opposite flange of the beam in a generally similar way and while both shoes are temporarily held in position, first one and then the other of a pair of the keys 28 are slid downwardly between them in such manner that the extremities of their heads will engage over lips 24 of the shoes and thus by coaction of the inclined faces of the keys with the correspondingly inclined surfaces 25 on the shoes firmly tie the latter together.

Mention has been made of the fact that two of the precast keys may be made somewhat longer than the others and, in such case this pair of keys 28 is used in conjunction with the lowest pair of shoes so that after the keys are in place they will project somewhat above the upper ends of the latter (Fig. 6); it results that when the second and next higher pair of shoes is similarly applied and keyed together, the subjacent keys will extend into the space between them with consequent br aking of the joint between the superposed pairs of shoes and, correspondingly, that the next pair of keys will extend above the second pair of shoes so as to break the joint with the third pair and so on until the upper end of the column is reached. Of course when this procedure is followed the upermost pair of keys will extend somewhat above the uppermost shoes unless cut off to suitable length before being placed in position or initially made shorter than the other keys.

Concrete or other like material C is then poured into the space proximate each side of the beam web so as to fill it and other concrete injected under pressure through the openings formed by the juxtaposed gates 27 to thereby fill the countersinks 26 at the juxtaposed ends of 6 the shoes and effect'the bridging of the joints and key-ingof the parts to the column as hitherto explained in connection with the form. of' the invention shown in Figs. 1-4.

Thus in accordance with the invention, a column X may be very readily encased in a substantially monolithic structure of concrete devoid of joints penetrable by flames or water and the columnthus fully protected and fireproofe'd, all parts of the column being in intimate contact with the concrete surrounding it.

While I have: herein described the invention with considerable particularity and have illustrated preferred ways of utilizing it in the fireproofing of horizontal and vertical metallic structural elementsxof usual type, I do not thereby desire or intend to restrict or limit its application to structural elements of any specific character, or to confine myself to any precise details of'construction or method of assembly of the instrumentalities employed as they are capable of modifications and changes in numerous particulars without departing from the spirit and scope of the invention as defined in the appended claims.

Having thus described my invention, I claim and desire to protect by Letters Patent of the United States:

1. In building construction, a flanged beam and a plurality of precast shoes extending longitudinally of the beam, each shoe comprising an elongated base having a longitudinal recess in which the flange is seated with the sides and bottom of the recess intimately engaging the face and side edges of the flange and side walls integral with the base and on opposite sides of the recess, said side walls having outer surfaces substantially paralleling the beam web and inner surfaces spaced outwardly from the recess extending parallel to the web for a short distance from the base and thence upwardly and inwardly toward the web defining channels on opposite sides of the beam, the inner upper edges of the side walls being spaced apart a distance less than the transverse distance between the sides of the recess seating the flange, adjacent shoes being bonded together at their ends.

2. In building construction, a flanged beam, a plurality of precast shoes extending longitudinally of the beam, each shoe comprising an elongated base having a longitudinal recess in which the flange is seated with the sides and bottom of the recess intimately engaging the face and side edges of the flange and side walls integral with the base and on opposite sides of the recess, said side walls having outer surfaces substantially paralleling the beam web and inner surfaces spaced outwardly from the recess extending parallel to the web for a short distance from the base and thence upwardly and inwardly toward the web defining channels on opposite sides of the beam, the inner upper edges of the side walls being spaced apart a distance less than the transverse distance between the sides of the recess seating the flange, ribs projecting from the ends of the shoes respectively defining with the corresponding rib of a juxtaposed shoe a chamber and a gate communicating therewith, and concrete mix filling the channels, chambers and gates.

3. A precast shoe adapted for application to a flanged beam in building construction comprising an elongated base and opposed upstanding side walls integral with and extending longitudinally of the base defining a channel extending for the full length of the shoe, each of said walls having an inner surface a portion of which extends a short distance from the base substantially normal thereto and another portion which extends thence upwardly and inwardly toward the inner upper edge of the wall, said edges of the walls being spaced apart a less distance than the first mentioned portions of said surfaces, the base at the bottom of the channel having a central longitudinal recess provided with upwardly directed sides spaced apart a less distance than said first mentioned portions and. a greater distance than said edges, the recess being adapted to receive the beam flange.

4. A precast shoe adapted for application to a flanged beam in building construction comprising an elongated base, opposed upstanding side walls integral with and extending longitudinally of the base defining a channel extending for the full length of the shoe, each of said walls having an inner surface a portion of which extends a short distance from the base substantially normal thereto and another portion which extends thence upwardly and inwardly toward the inner upper edge of the wall, said edges of the walls being spaced apart a less distance than the first mentioned portions of said surfaces, the base at the bottom of the channel having a central longitudinal recess provided with upwardly directed sides spaced apart a less distance than said first mentioned portions and a greater distance than said edges, the recess being adapted to receive the beam flange, and an integral rib at each end of the shoe cooperable with a corresponding rib at an adjacent end of another like shoe when disposed in abutting relation therewith to define a chamber for reception of concrete mix to form a joint between such shoes, said rib being interrupted to define an access gate for such chamber.

JOHN V. KOHLI-IAAS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 598,702 Gander Feb. 8, 1898 646,192 Purdy Mar. 27, 1900 947,590 Franson Jan. 25, 1910 1,597,167 Pace Aug. 24, 1926 2,074,463 Davis Mar. 23, 1937 2,102,231 Zoettl Dec. 14, 1937 2,238,514 Weeks et a1 Apr. 15, 1941 2,294,554 Henderson Sept. 1, 1942 2,352,338 Muirhead June 27, 1944 FOREIGN PATENTS Number Country Date 3,714 Great Britain Nov. 15, 1873 536,326 France Apr. 29, 1922 202,572 Great Britain 1923 676,335 France 1930 40,949 France 1932 470,651 Great Britain Aug 19, 1937 467,551 Great Britain June 18, 1937 538,483 Great Britain Aug. 6, 1941