GB2223785A - Deck panel for panel bridge - Google Patents

Abstract

A deck panel (2) for a bridge formed from prefabricated panels comprises a deck plate (6) secured to and supported by a series of parallel spaced beams (4), known as stringers, and a plate (18) secured transversely to and across each end of the beams (4) in such a way that a portion (20) of the plate (18) extends below the beams (4) on the opposite side from that to which the deck plate (6) is secured. In a bridge incorporating the deck panel each end plate (18) rests on a transom, as close as possible to the strongest part thereof. <IMAGE>

Description

IMPROVEMENT IN AND RELATING TO DECK PANELS This invention relates to bridges and in particular to deck panels for bridges constructed from pre-fabricated panels which are assembled on site.

In known bridges, I-section cross girders, known as transoms, span between the main girders of the bridge which are formed from pre-fabricated panels. The transoms carry the roadway which consists of deck panels which span between the transoms and comprise a series of spaced, parallel, I-section beams known as stringers which support a steel or Limber deck plate, the stringers running transversely to the transoms.

For a given size of stringer the transverse stiffness of the deck panel and consequently its load carrying capacity is fixed. This means that a large number oE deck panels of varying degrees of strength will be required so that for any given situation with a given maximum load, the deck panel with the least weight which will support that load can be used.

Another problem which has been found with such bridges is that when a load is applied to one of the two deck panels whose ends are attached to a particular transom, the transom tends to rotate and/or the transom flange beneath the loaded panel bends. This wealcens the transom and deck panels thereby reducing the strength of the roadway.

The object of this invention is to provide a deck panel which overcomes these problems.

In accordance with one aspect of the invention a deck panel for a bridge formed from pre-fabricated panels comprises a deck plate secured to and supported by a series of spaced parallel beams and a plate secured transversely to and across one end of the beams in such a way that a portion of the plate extends beyond the beams on the opposite side from that to which the deck plate is secured.

This allows two deck panels to be positioned on a supporting transom with the protruding plate portion resting on the transom, thereby causing any load on one of the panels always to be applied in the same place on the transom. This reduces the tendency of the deck to rock and of the transom to bend since the plates can be positioned as close as possible to the strongest part of the transom, for example, if the transom is I shaped the web.

Preferably each deck panel is provided with two plates1 each attached to respective ends of the beams.

The plates are secured to the beams with one edge abutting the deck plate.

In accordance with another aspect of the present invention a deck panel for a bridge formed from pre-fabricated panels comprises a deck plate secured to and supported by a series of spaced parallel beams and means whereby at least one stiffener may be mounted transversely to the beams.

The transverse stiffness and therefore the load carrying capacity of the deck panel can thus be varied by mounting stiffeners to the beams which increases the versatility of the deck panel and consequently reduces equipment costs.

Preferably the means for mounting a stiffener comprises aligned aperture(s) provided in the beams and dimensioned so as to receive the stiffener(s). If the beams are I-sections, the apertures may be provided in the web of the I-sections.

The stiffeners can therefore be readily inserted in the panel through the apertures making variation of panel transverse stiffness a quick and simple operation.

If a bridge is formed from pre-fabricated panels and has at least two deck panels each of which has at least one stiffener mounted transversely thereto, the stiffeners being aligned, it is preferable to provide means for connecting the stiffeners.

The connecting means serve to spread a load applied to one panel between it and the panel to which it is connected via their stiffeners. The overall transverse stiffness of the bridge is increased and the connector(s) causes the upper surfaces of both panels to be in the same horizontal plane since they cause both panels to move an equal distance downwards under the applied load.

The connecting means may comprise a tube member secured to one of the panels, preferably to an end beam thereof, and dimensioned so as to receive the stiffener.

As an alternative to jointing the stiffeners on adjacent deck panels it is possible to vary the edge stiffness of each deck panel by adding a strengthening plate to the underside of the outer two stringers. By varying the edge stiffness and transverse stiffeners of the deck panels a variety of loading cases can be accommodated without changing the stringer size or jointing adjacent deck panels.

The invention will now be further described by way of example with reference to the accompanying drawings in which: Figure 1. is a plan view partially cut away of a deck panel in accordance with one aspect of the invent ion; Figure 2. is a view in direction of arrows II-II of the deck panel of Figure 1; Figure 3. is a side view in the same directions as Figure 2 of part of two deck panels of Figure 1; Figure 4. is a view similar to Figure 3 showing the effects of loading of one of the panels; Figure 5. is an end view of two deck panels in accordance with another aspect of the invention and Figure 6. is a similar view to Figure 5 showing prior art deck panels.

The deck panels 2 shown in the drawings comprise a series of spaced parallel I-sect ion beams 4, known as stringers, which support a steel or timber deck plate 6 which is secured to the flanges 7 of the stringers. The deck panels 2 when employed in roadways span between I-section cross girders 8 known as transoms, which themselves span between the main girders of the bridge which are formed from pre-fabricated panels.

As is shown in figures 1 to 4 the deck panels 2 are provided with stiffeners 10 which pass through apertures in the webs 11 of the stringers 4 transversely thereto. The number of stiffeners 10 dictates the transverse stiffness of the deck panel 2 and this can therefore be varied by adding or removing stiffeners 10. This increases the versatility of the deck panel permitting it to be employer with different maxt'muu1 loadings. The strength of the stiffeners can also be varied thereby further increasing the versatility of the deck panel.

The stiffeners 10 of the two adjacent panels can be coupled by suitably dimensioned members 12 (see Figures 3 and 4) into which the ends of the stiffeners 10 are inserted. An end of the member 12 is welded (see 14) to one of the panels. When a load is applied to one of the panels as shown by arrows 15 in Figure 4, the members 12 transmits part of the load across the joint between the panels to spread it between the two panels and moreover causes both panels to move downwards together by similar amounts as shown in Figure 4 where the unloaded position is indicated by dotted line 16.

The couplers therefore maintains transverse stiffness of the roadway across the width of the bridge (the transoms running widthwise across the bridge) and cause the deck panels to act essentially as single units.

The alternative method of stiffening the edge of the deck panel is also shown on Figures 1 and 2.

Strengthening plates 29 are welded to the underside of the outer two stringers on both edges of the deck panels. This maintains the strength of the deck panels without the need for jointing adjacent deck panels.

The two deck panels 2 shown in Figures 5 and 6 are adjacent lenghthwise along the bridge, that is, they are viewed in a direction transverse to that of Figures 2 to 4. A plate 18 is secured transversely to and across the ends of the stringers 4. One end of the plate 18 abuts the overhanging portion of the deck plate 6 and the other end 20 extends below the bottom flange of the stringers 4 and rests on the supporting transom 8. The length of the stringers 4 and deck plates 6 are arranged so that the plates 18 rest as close as possible to the web 22 of the transom whilst still leaving a gap between the deck plates 6 to allow for correct fit of the deck panels.

The plates 18 serve to transmit a vertical load on one or both of the panels to the web 22 of the transom. In known decking systems (see Figure 6) the stringers 4 rest directly on the transoms 8 and when a load is applied to one of the panels, the right-hand panel in Figure 6, the transom beam tends to rotate as shown by the dotted outline 24 as the panel moves down (see deflected outline 26) and /or the flange has a tendency to bend which weakens the transom and deck panels.

With the panel shown in Figure 5 the short distance of the plates 18 from the transom web 22 reduces the lever arm of the transom thereby reducing the tendency of the panel and transom to rotate and preventing weakening of the transom by reducing the load on the transom flange as far as possible. The point at which the load is applied on the transom is known since it will always be at the place the plate 18 rests on the transom and therefore this can be arranged to be as near to the transom web as practicable. Loading of one of the panels causes the transom to move almost vertically downwards (see outline 28) rather than in a downwards rotating fashion.

A roadway formed from the panels shown in Figures 1 to 6 can therefore have different transverse stiffnesses depending on the loading by varying the number of stiffeners and strengthening plates, the transverse stiffness being maintained across the width of the bridge by the couplers (where used). Loading which moves along the bridge will not cause rocking of the panels or weakening of the transoms due to the vertical end plates which rest on the transoms. The panels are therefore versatile, strong and stable in use.

Preferably each deck panel is provided with two plates, each attached to respective ends of the beams.

The plates are secured to the beams with one edge abbuting the deck plate.

Claims (5)

CLAIMS:

1. A deck panel for a bridge formed from prefabricated panels comprising a deck plate secured to and supported by a series of spaced parallel beams and at least one end plate secured transversely to and across at least one end of the beams in such a way that a portion of the plate extends below the beams on the opposite side from that to which the deck plate is secured.

2. A deck panel as claimed in Claim 1 wherein one edge of the end plate abuts the deck plate.

3. A bridge comprising at least two parallel girders, each girder consisting of a plurality of pre-fabricated panels connected end-to-end, the girders being spaced apart by a plurality of parallel transoms which extend between the girder and support a number of deck panels as claimed in Claim 1 wherein each end plate rests on a transom as close as possible to the strongest part of the transom.

4. A bridge as claimed in Claim 3 wherein the transoms are I section beams and the end plates rest on the top flange above its web.

5. A deck panel substantially as described herein with reference to the accompanying drawings.