US2084100A - Expansion joint - Google Patents

Description

J 1937. F. .J. MCHUGH 2,084,100

EXPANSION JOINT Filed Jun '7, 1955 1 15 EIIMG. HUGH FIG.4. I BY ATTORNEY Patented June 15, 1937 UNITED ST'i'g PATENT orriee EXPANSION JOINT Frederick J. McHugh, Lachine, Quebec, Canada Application June '7, 1935, Serial No. 25,460

10 Claims.

This invention relates to expansion joints for bridges and similar structures and especially to joints consisting of two sets of joint bars arranged between adjacent bridge fioor sections with the bars of one set slidably fitted.- between the bars of the companion set.

In joints of the above type as heretofore constructed the bars of each set are firmly anchored to move with one of the floor sections between which the two sets of bars are interposed. In very cold weather it frequently happens that the bars of one set will freeze to the bars of the companion set so that relative movement between the two sets of bars thus becomes impossible with the result that contraction of the floor sections to which the bars are attached causes these sections to tear away from the bars at their points of anchorage thereto. To overcome this difficulty the present invention proposes to connect the bars of each set to its associated bridge floor section by means permitting said section and bars to have a limited relative movement sufiicient to take care of expansion and contraction of the floor sections during the period that the bars of one set are frozen or stuck to the bars of the companion set. Another feature consists in connecting the bars to the floor sections so that contraction of the floor sections during the period that the two sets of bars are frozen together serves to raise the bars above the general road surface level of said sections so that the two sets of bars are thus subjected to a more severe pounding action by passing trafiic and are soon freed from each other.

Proceeding now to a more detailed description reference will be had to the acompanying drawing in which Fig. 1 is a vertical sectional view showing the improved expansion joint embodied in the floor or roadway structure of a bridge.

Fig. 2 is a View similar to Fig. 1 but showing the parts in a different position.

Fig. 3 is a view similar to Figs. 1 and 2 but showing a still further position of the parts.

Fig. 4 is a fragmentary plan View of the joint structure per se with certain parts broken away to disclose elements that would otherwise be concealed from View.

In this drawing the expansion joint is generally indicated at A and is shown bridging the gap between adjacent bridge floor sections 5 and 6 on which the roadway l is constructed. The joint comprises two sets of interfitting joint bars 8 and 9 welded to separate supporting frames l0 and H. Frame I0 is pivotally carried by the upper ends of suitable supporting links i2 having their lower ends pivoted to brackets I3, anchored to the bridge section 5. Frame H is similarly carried by the upper ends of supporting links M having their lower ends pivoted to brackets l5 anchored to the bridge section 6.

The ends 8a of the bars 8 project beyond the adjacent side of frame in and are slidably received in the spaces between the bars 9. The ends 9a of the bars 9 are similarly projected beyond the adjacent side of the frame II and received in the spaces between the bars 8. The extent to which the bars 8 and 9 are thus overlapped is predetermined so that the overlapping relation is maintained when the bridge sections 5 and 6 are separated to the maximum extent by relative movement due to contraction. Suitable cover plates l6 and I! are preferably welded to the upper edges of the bars 8 and 9 to partly close off the spaces between adjacent bars of each set.

Assuming maximum expansion of the bridge sections 5 and E, which occurs at temperatures of the order of +120 F., the parts described in the foregoing will be positioned as illustrated in Fig. 1. As here shown the inner opposing sides of the two frame members It and H are practically butted together so that the extensions 8a. of the bars 8 are completely received in the spaces between the bars 9, whose extensions to. are likewise received in the spaces between the bars 8. The two sets of bars thus overlap to the maximum extent with the outer ends of these bars contacting the adjacent edges 5a and 6a of the bridge sections 5 and 6. In this position of the parts the links [2 are inclined so that the upper pivots 12a. are closer to the bridge section 5 than the lower pivots I227. The links M are similarly inclined so that the upper pivots Idaare closer to the bridge section 6 than the lower pivots [4b.

Fig. 2 illustrates the arrangement of the parts when the bridge sections 5 and 6 are separated to the maximum extent by relative movement due to contraction such as may occur, for example, at temperatures of the order of 40 F. In this case it will be noted that the frame members It and II have not changed their positions with respect to the bridge sections 5 and 6 but have been separated from each other so that there is only a slight overlapping of the bars 8 and 9 at the tips of the extensions 8a and 9a.

Fig. 3 illustrates the conditions obtaining when the extensions 8a of the bars 8 are frozen to the extensions 9a of the bars 9 so that relative sliding movement between the two sets of bars becomes impossible. In this case the links I 2 and I4 permit the bridge sections A and B to move away from each other independently of the bars 8 and 9 since the links will then swing from the in- 5 clined position shown in Figs. 1 and 2 to the substantially vertical position shown in Fig. 3. This movement of the'links l2 and It also serves to elevate the bars 8 and 9 above the general level of the roadway I with the result that the 10 two'sets of bars are soon freed from each other by the more severe pounding action to which they arethus exposed by the traffic passing thereover. Suitable stops l8 and 19 are provided for limiting the swinging movement of the links I2 and I4 in one direction so that even in the position shown in Fig. 3 the upper endsof the links are closer to the bridge sections by which they are carried than the lower ends. Due to the provision of these stops the frame sections l0 and II, to 20 which the joint bars 8 and 9 are secured, will gravitate from the position shown in Fig. 3 back to the position shown in Figs. ('1 and 2 as soon as the two sets of bars are freed from each other by the pounding action of the trafiic. The supporting links of the frames I0 and H are arranged in pairs as shown in Figs. 1 to 4 inclusive. The upper ends of links l2 are secured between transverse plates 20 and 2| of frame H) by means of the upper pivots I2a. As 0 shown more clearly in Fig. 4 one end of each pivot lZa is formed with a head I20 bearing against plate 20 while the other end projects beyond plate 2| and is provided with an annular groove 12d receiving one end of a retaining plate 22. Plate 22 is fastened by bolts 23 or other fastening means to the outer side of plate 2|. .The upper ends of each pair of links 14 are similarly secured between plates 24 and 25 of frame II, the pivots Ma of these links having heads I 40 engagingthe plate 24 and grooves Md receiving the ends of a retaining plate 26 bolted to the plate 25. As will be understoodfrom Fig. 3 the lower ends of the links l2 are secured by their pivots lZb between side portions l3a of the .45 brackets l3 while the lower ends of links M are similarly secured by their pivots Mb between the side portions |5a of the brackets 15. The pivots i212 and Mb are provided at one end with heads (not shown) adapted to bear against one of the side members l3a and l5a of the brackets 13 and I5, the opposite ends of said pivots being grooved to receive the ends of retaining plates 2! corresponding to the previously mentioned retaining plates 22 and 26. k An important advantage of the joint described herein is that the freezing of the bars 8 and 9 does not give rise to any objectionable stressing of the bridge structure. This is due to the fact that the link connections 12 and I4 provide for maximum expansion of the bridge structureeven when the bars 8 are tightly frozen to the bars 9. Having thus described what I ,now conceive to be the preferred embodiment of this invention it will be understood that various modifications may be resorted to within the scope and spirit of the appended claims. 7

Having thus described my invention, what I claim is:-

1. An expansion joint comprising two sets of joint bars bridging a gap between two structures which are subject to relative movement due to expansion and contraction, the bars of each set being carried by but movable relative to one of said structures and being slidably fitted between the bars of the companion set.

2. An expansion joint as claimed in claim 1 in which each set of bars isconnected to one of said structures by a plurality of swinging links.

3. An expansion joint as claimed in claim 1 in which each set of bars is connected to one of said structures by a plurality of links each having one end pivotally connected with said bars and the remaining end pivotally connected to a bracket carried by said structure.

4. An expansion joint as claimed in claim .1 in which the bars of each set are entirely free of connection to the bars of the companion set,

5. An expansion joint as set forth in claim 1 in which the said structures comprise adjacent sections of a roadway between which the two sets of bars are horizontally arranged so that their upper surfaces are normally'level with the roadway surface. 7

6. An expansion joint for bridge structures comprising two sets of horizontally arranged bars bridging a gap between adjacent floor sections of said structure, the bars of each set being carried by but movable relative to one of Said sections and being disposed in overlappingsliding relation with the bars of the companion set.

'7. An expansion joint comprising two sets of horizontally arranged joint bars bridging a gap between adjacent sections of a roadway structure, the bars of each set being disposed in overlapping sliding relation with the bars of the companion set and being secured to one of said sections by connecting means permitting said section to move relatively tothe connected bars when the latter are stuck or frozen to the bars of the companion set.

8. An expansion joint as claimed in claim 7 in which the connecting means between the bars of each set and the associated roadway section functions to raise the bars above the general level of the roadway whenever there is relative stuck or frozen together.

10'. An expansion joint as recited in claim 9 in which the means linking the bars to said sections normally serves to support the bars with their upper surfaces flush with the upper surfaces of said sections, said means functioning during movement of said sections away from each other and relative to the bars connected therewith to raise said bars above the general level of said sections to permit said bars to re turn to their normal lower position when said sections again move toward each other.

, FREDERICK J. MCHUGH.

.45 movement between said. section and bars in one

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