US2740335A - Grating for bridge floors and the like - Google Patents

Description

April 3, 1956 G. G. GREuLlcH 2,740,335

GRATING FOR BRIDGE FLOORS AND THE LIKE med June 27, 1951 4 sheets-sheet 1 mf l /n imm/V Ny V @VW W l. L I i I. i

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@RATING FOR BRIDGE FLOORS AND THE LIKE Filed June 27, 1951 4 Sheets-Sheet 2 IN V EN TOR.

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@RATING FOR BRIDGE FLOORS AND THE LIKE Filed June 27, 1951 4 sheets-sheet 3 E i INVENTOR.

Aprilk 3, 1956 G. G. GREuLlcH 2,740,335

GRATING FOR BRIDGE FLOORS AND THE LIKE Filed June 27, 1951 4 'sheets-sheet 4 LPM /c//m Az @Maw @Ra/D Gee-11.121,44

ilnited States Patent O GRATING FOR BRIDGE FLOORS AND THE LIKE Gerald G. Greulicll, Pittsburgh, Pa.

Application June 27, 1951, Serial No. 233,732

3 Claims. (Cl. 94-30) This invention relates to open gratings that are used as floors or decks for bridges or airplane runways and the like, or as traffic supporting covers for subways, ditches or vaults.

Gratings of this character have been formed from bars crossing one another at right angles to form rectangular openings. Such gratings, with bars at right angles to the direction of traiiic, have been more eicient in pre venting forward skidding or sliding of vehicles and somewhat less eiiicient in preventing sidewise skidding than gratings in which the cross members are replaced by diagonal members that form triangular openings having their bases relatively long and parallel to the direction of traic. To overcome the poor resistance of gratings with rectangular openings to lateral or diagonal skidding, a number of expedients have been tried, such as placing the tops of the grating bars at different levels or notching their upper surfaces to produce serrations. I have found that when the long sides of a grating opening are parallel to the sides of a vehicles tires lateral skidding is greatly reduced. This is because the tires can project down into the opening farther than when the short sides of an opening are parallel to the tire sides. Since a tire has to rise up out of a grating opening before it can start to skid sidewise, an easy way to increase the anti-skidding characteristics of grating would appear to be to make the openings square and larger. However, such an increase in size produces a rough and bumpy ride over the grating. A smooth ride can be produced by using triangular openings, because they have relatively long sides without excessive open areas. On the other hand, if the grating is of the type provided with triangular openings having their bases parallel only to the direction of traic and without any cross bars at right angles to the direction of tratic, forward skidding is increased and a very annoying and at times unsafe front wheel wobble is produced.

It is among the objects of this invention to provide an open grating which reduces skidding of vehicles in any direction over it, which does not produce a bumpy ride nor wobbling of the front wheels of vehicles, which is stronger than previous gratings of comparable weights, which can be used with wider spans, which is formed with a minimum of welds, which can be used equally well with the longitudinal members parallel or transverse to the direction of traflic, which does not require bottom bracing of the beams, and which can be formed from prefabricated slabs that are connected side by side in adjustable relation.

In accordance with this invention, a plurality of parallel metal longitudinal members are held in predetermined spaced relation in vertical notches in parallel cross members, with the tops of all of the members lying in substantially the same plane. The cross members are preferably disposed substantially the same distance apart as the longitudinal members to form therewith a plurality of substantially square openings of relatively large size, but the openings can be oblong if desired. Extend- ICE ing across each of these openings is a diagonal member, which is secured to the longitudinal and cross members at its opposite ends. The diagonal members are arranged to form a repetitive square or parallelogram pattern superimposed on successive groups of four adjacent square or oblong openings, thus forming an arrangement of triangular openings with their bases extending in four directions. The cross members extend through trans verse openings in at least some of the longitudinal members. These openings are of such shape as to provide the maximum amount of material between adjacent openings in the same member. The openings require the cross members to be inclined when they are inserted in the openings and then rotated on a longitudinal axis into upright position. It is preferred to form the diagonal members between each pair of longitudinal members from a metal bar extending lengthwise of the latter and reversely bent to extend back and forth between them. The notches in the cross members are wide enough to receive the bars where they intersect the cross members, and welds are made at the notches to join all of the members together and to the bars. The bars are so arranged that their diagonal portions on opposite sides of a longi tudinal member radiate therefrom in four directions at the intersections of that member with alternate cross members. Preferably, the upper portions of the notches are upward to provide inclined weld-receiving surfaces, and the tops of the diagonal bars at the intersections are provided with shallow notches which also receive the welds. The grating is formed in slabs of convenient size for handling, and the cross members preferably project beyond the outermost longitudinal members of each slab for connection to the slabs on opposite sides of it.

The preferred embodiment of the invention is illustrated in the accompanying drawings, in which Fig. 1 is a somewhat diagrammatic plan View of a complete grating slab with portions of like slabs connected to it; Fig. 2 is an enlarged fragmentary plan view of one of the slabs; Fig. 3 is a vertical section taken on the line III-III of Fig. 2; Fig. 4 is a vertical section taken on the line IV-IV of Fig. 2; Fig. 5 is a fragmentary side view of the cross bar shown in Fig. 3; Fig. 6 is a side view of the cross bar shown in Fig. 4; Fig. 7 is a longitudinal vertical section taken on the line VII-VII of Fig. 2; and Fig. 8 is a fragmentary perspective view showing the intersections of two of the diagonal bars with a cross bar beside a longitudinal member before welding.

Referring to the drawings, each grating slab is formed from a plurality of parallel longitudinal metal members A and B of any desired length, alternating parallel cross bars C and D and zigzag bars E extending lengthwise between the longitudinal members. The longitudinal members preferably are of two types alternating with each other. One type is a relatively heavy beam A which has flanges 6 extending along its lower edge to rest on the girders 7 or the like that support the grating. Each beam as a Wide web 8 terminating at its upper end in a thick head 9. The other type of longitudinal member B is a narrow fiat bar which is disposed on edge midway between the heads of each pair of beams. The number of beams A and middle bars B in each slab depends upon the width of slab desired. For very light loads, one heavy beam A may be alternated with two or three bars B. Also, it is optional whether both of the outermost longitudinal members of a slab are beams, both middle bars or a beam at one side and a middle bar at the other side. In any event, the cross bars C and D preferably project a short distance beyond the outermost longitudinal members of thepslab. The intersecting cross bars and longitudinal members provide the slab with a large number of rectangular openings. Most suitably the cross members are spaced substantially the same distance apart as the longitudinal members to form substantially square openings, preferably about three or four inches square, which is larger than is feasible for conventional gratings.

The middle bars B are supported by cross bars C and D, the upper portions of which are provided with vertical notches 12, through which the middle bars extend. These notches are of such depth that the tops of the middle bars and the cross bars all lie in the same plane. The depth (width) of the cross bars is considerably greater than that of the middle bars, but considerably less than that of the beams. Consequently, the beams have to be provided with transverse openings 13, through which the cross members can extend. The upper portions of the cross bars are provided with additional notches 14 for receiving the portions of the beams above openings 13, such portions being formed chiefly from the heads 9 of the beams, so that the tops of the beams will lie in the same plane as the tops of the bars.

The beam openings 13 through which the cross bars extend have a special shape which, along with the positions of the openings, forms part of this invention. Each opening or slot (Fig. 7) extends substantially equal distances from opposite sides of the cross bar that extends through it, the combined distance being great enough to permit the cross bar to be inserted in the slot when tilted laterally at quite an angle. One half of the slot has a horizontal bottom wall 16 on which the cross bar rests. It also has a vertical wall 17 engaged by one side of the lower portion of the bar. The other half of the slot has a horizontal top wall 18 substantially in engagement with the bottom of the cross bar notch 14 that receives the head of the beam, and it also has a vertical wall 19 engaging a portion of the side of the cross bar opposite to the lower vertical wall 17. The top wall 21 of the lower half of the slot is inclined downward from the lower end of upper vertical wall 19, and the bottom wall 22 of the upper half of the slot is inclined upward from the upper end of lower vertical wall 17. The two inclined walls 21 and 22 are disposed in substantially parallel planes which are slightly farther apart than the thickness of the cross bar. The outer ends of the two inclined walls are connected to the adjacent horizontal walls of the slot by short end walls.

After the cross bar has been laid on its side in an inclined position and inserted in the slot, the upper edge of the bar can be swung upward as its lower edge is swung in toward the lower vertical wall 17 of the slot. The notch 14 in the upper portion of the cross bar will permit it to straddle the head of the beam as the bar is swung into upright position. The lower portion of the cross bar then can be welded to the beam beside the lower vertical wall of the slot, although it is not necessary to so weld every bar to every beam. The shape and inclination of beam slots 13 is such that a maximum of solid metal is provided between the closest points of adjacent slots for a given depth of cross bar, because those points are spaced diagonally from each other. Also, by having only half of each slot directly below the beam head, and the other half of the slot at a lower level, considerably more support is given to the beam head. That is, with only half of the slot directly below the beam head, there is a considerable body of supporting metal between the beam head and the lower halt of the slot.

Extending lengthwise of the slab between each pair of longitudinal members is a continuous zigzag bar E that most suitably is the same width and thickness as middle bars B. Each E bar is reversely bent at uniformly spaced points to provide it with diagonal portions 24 that extend back and forth between the adjoining beam and middle bar, diagonally across a series of the rectangular openings in the gratings to divide each one into two triangular openings. At each bend in the bar its diagonal portions are connected by a short portion that is parallel to and engages the adjoining longitudinal member at an intersection with a cross bar. It is another feature of this invention that the cross bar notches, through which the diagonal bars extend, are the same notches that receive the beams and middle bars. For this purpose these particular cross bar notches, which are staggered lengthwise of the slab, are made wide enough to also accommodate the E bars. The tops of the diagonal bars lie in the same horizontal plane as the rest of the bars. It will be seen that the directions of the diagonal portions of each E bar are reversed relative to the E bar on its opposite sides, so that each intersection of the E bars with the cross bars there are four diagonal members which radiate in four directions from the intersection. It also will be seen that the diagonal members form squares around the alternate cross bar notches which they do not extend through.

A still further feature of this invention is that all of the bars and the beams are welded together at the notches in the cross bars. To provide adequate surface area for butt welding, the upper portions of the notches are flared to provide inclined surfaces that form tapered pockets.

beside the members extending through the notches. Welding material 26 is deposited in these pockets to weld the different members together. By providing each diagonal bar, where it lits in the notches, with downwardly tapered shallow notches 27 (Fig. 8), the welding material can extend across the notches in the E bars and unite with the adjoining middle bar or beam, as the case may be. Consequently, only two welds at each intersection of the diagonal bars with the cross bar welds four members together and those welds can be made from the top. These welds also help hold the cross bars upright in beam slots 13, by helping to prevent the bars from pivoting on the lower ends of the upper vertical walls 19. Lower vertical walls 17 of the slots prevent the bottoms of the cross bars from moving in the opposite direction.

It is preferred to taper the upper portion of each beam head transversely so that its upper surface will be no wider than the different bars. v This improves the appearance of the grating from above and also reduces the width of the beam surface on which rain and ice can accumulate.

For connecting these grating slabs side by side, the ends of the cross bars projecting from one side of each slab are bent laterally, as at 28, to oiset them the thickness of the bars. They then will overlap the straight projecting ends of the cross bars of the next slab. This overlapping permits the two slabs to be moved toward or away from each other within limits, and then the overlapping cross bar ends can easily be welded together by welding the end surfaces of some of the bars to the sides ofthe overlapping bars. One end of each slab may be provided with a transverse trim bar 29 welded to the projecting ends of the longitudinal members and diagonale. When the slabs are laid, the projecting members at the end of the next slab are welded to this trim bar.

lf desired, cross bars C and D can be provided along their neutral axes with holes 31, through which reinforcing rods 32 can be inserted in case it is desired to fill the upper portion of the grating with concrete. In such a case supporting pans 33 (Fig. 3) are mounted on ribs 34 extending along opposite sides of the beams a short distance below the cross bars. The spaces .between these pans and the top of the slab then can be filled with concrete.

This design of grating, with triangular openings throughout, permits greater space between cross bars C and D than with conventional designs, because the zigzag bars E separate each rectangular space into two triangles, each ot which necessarily has no more than half the area of the rectangular space. This greater spacing of the cross bars allows deeper cross bars to be used without sacricing horizontal shear strength in the beams A, since the wider spacing of the cross bars means that a greater amount of metal can be left between adjacent slots 13 through any beam. Because deep cross bars can be used,

any need for conventional bottom bracing of the beams is eliminated and its weight and cost thereby saved. Also, when it is realized that the section modulus of the cross bars goes up as the square of their depth, it is apparent that any increase in depth effects a much greater increase in transverse strength. This increase in transverse strength provides a much wider load distribution so that more beams A are effective in carrying the load. Therefore, the individual beams are required to carry less load per unit, andthe length of'spans (the distance between girders 7) over which the grating is used may be increased appreciably without a comparable increase in weight of metal required in the beams.

The diagonal bars E carry their full complement of ange compression stress in proportion to the cosine of the angle with the beam head 9. They also make the middle bars B effective in full cross section as supplemental area to the beam head. These bars form, in effect, a Y

laterally extending trussed ange system on each side of the beam head. It is thus seen that the diagonal bars perform the dual function of bridging the space between beam heads and of helping the beams A in resisting bending moment.

One of the reasons for the economy of this grating is that several elements are joined together by means of a single weld. Less than half as many welds are required as are used in conventional welded grating now in wide use having a comparable area or size and number of openings in the upper or supporting surface. By making the diagonal bars continuous, a much smaller weld is required to retain them in position and to function structurally than would be the case if they were short individual pieces. Fewer and smaller welds result in less warpage and twist in the finished product, due to proportionately less shrinkage during the cooling of the weld metal. This not only eliminates much of the cost of subsequent straightening and alignment, but it provides economically a better appearing and more acceptable product.

Economy inherent in my invention lies further in the fact that the slabs are universal in application. That is, due to the pattern formed by the members in the grating surface, the slabs can be laid with the beams either parallel or transverse to the direction of traic movement without altering the appearance or surface characteristics ofthe grating.

According to the provisions of the patent statutes, I have explained the principle of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

l claim:

1. An open grating for bridge floors and the like, comprising a plurality of parallel longitudinal metal members, a plurality of spaced parallel metal cross members disposed on edge and having their upper portions provided with vertical notches receiving portions of said longitudinal members to hold the latter in predetermined spaced relation to form rectangular openings the upper portions of said notches being wider than their lower portions, a metal bar extending lengthwise between each pair of longitudinal members and reversely bent to extend back and forth between them diagonally across each of said openings, the notches in said cross members where those members are intersected by said bars being wider than the longitudinal members and each of those notches receiving two of the bars separated by the longitudinal member in the same notch, whereby the diagonal portions of bars on opposite sides of a longitudinal member radiate therefrom in four directions at the intersections of the bars with cross members, the bars being provided with shallow notches where they intersect the cross members, and a pair of welds at the top of the grating at each of said intersections joining the longitudinal member to the adjoining bars and cross member, each of said welds filling one of said shallow notches.

2. An open grating for bridge floors and the like, comprising a plurality of spaced parallel metal beams disposed on edge and adapted to rest on suitable supports, each of said beams being provided at longitudinally spaced points with transverse slots, a plurality of parallel cross bars disposed on edge and extending through said slots, the upper portions of the bars being provided with vertical notches receiving the portions of the beams above said slots, each of the slots having portions extending from opposite sides of the cross bar therein, one of said slot portions having a horizontal bottom wall on which the cross bar rests and a vertical wall engaging one side of the bar, the other portion of the slot having a vertical wall engaging the other side of the bar above said one portion of the slot and also having a horizontal top wall substantially in engagement with the bottom of the cross bar notch, the top wall of said one portion of the slot being inclined downward from the lower end of said last-mentioned vertical wall, the bottom wall of the other portion of the slot being inclined upward from the upper end of said lirst-mentioned vertical wall, said inclined walls being disposed in substantially parallel planes slightly farther apart than the thickness of the cross bar to require the cross bar to be inclined when inserted in the slot and then rotated on a longitudinal axis into upright position against said vertical walls of the slot, and welds at said notches joining the bars to the beams.

3. An open grating for bridge tloors and the like, cornprising a plurality of parallel longitudinal metal members, a plurality of spaced parallel metal cross members disposed on edge and having their upper portions provided with vertical notches receiving portions of said longitudinal members to hold the latter in predetermined spaced relation to form rectangular openings, a metal bar extending lengthwise between each pair of longitudinal members and reversely bent to extend back and forth between them diagonally across each of said openings, the notches in said cross members where those members are intersected by said bars being wider than the longitudinal members of each of those notches receiving two-of the bars separated by the longitudinal member in the same notch, whereby the diagonal portions of bars on opposite sides of a longitudinal member radiate therefrom in four directions at each bar-receiving notch to form eight angles, and welding metal deposited on top of each bar where it intersects a cross member and joined to that member at one side of the bar and to the longitudinal member at the opposite side of the bar.

References Cited in the file of this patent UNITED STATES PATENTS 1,264,758 Berson Apr. 30, 1918 1,612,236 Thomson Dec. 28, 1926 2,128,753 Liehard l Aug. 30, 1938 2,190,215 Nagin Feb. 13, 1940 2,275,104 Greulich Mar. 3, 1942 2,425,054 Tarof Aug. 5, 1947 2,645,985 Beebe July 21, 1953

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