GB2026585A - Shuttering for casting bridge decks - Google Patents

Abstract

A shuttering panel 10 for use in making a concrete bridge deck is made by spraying glass fibre reinforced cement (g.r.c) onto a former. The panel has a flat periphery 12, an upwardly convex channel section section central portion 14 with sloping ends 16, and upstanding flanges 18 at its edges whereby several such panels can be adjoined. A removable closure 50 provides an opening in the cast deck 26 giving access to telescopic support beams 38. The panel may have upper and lower parts 28,30 interconnected by corrugated part 32 all of g.r.c. and filled with expanded plastics 34,35,36. <IMAGE>

Description

SPECIFICATION Method of making a concrete span and shuttering panels therefor This invention relates to the construction of concrete spans, for example in bridges.

In the construction of concrete bridges it is known to provide a support structure comprising longitudinal elongate members side-by-side and spaced apart (usually parallel) and bridged by a series of spaced apart transverse elongate members. The openings defined by the longitudinal and transverse members then have to be closed by some sort of shuttering before the concrete can be poured. The nature of the shuttering, and its cost both in terms of materials and on-site work, have generally been unsatisfactory hitherto.

In one aspect the present invention provides a method of making a concrete span which comprises providing a support structure comprising longitudinal elongate members sideby-side and spaced apart and bridged by a series of spaced apart transverse elongate members; placing shuttering panels, preferably of glass fibre reinforced cement (g.r.c.), over the openings defined by the longitudinal and transverse members, so that the openings are closed thereby and the panels rest peripherally on both the longitudinal and transverse members, the region of each panel within its periphery comprising one or a series of parallel upwardly convex channelsection top surface portions which extend substantially between a pair of said elongate members; if necessary arranging reinforcing elements over the panels; and pouring concrete over the panels and support structure and allowing it to cure.

Preferably a said opening defined by two adjacent longitudinal members and two adjacent transverse members is closed by two or more panels side-by-side. In this case the adjacent panels are preferably secured together along their adjacent edges. The panels may be provided with upstanding flanges along those edges for this purpose. Each panel may comprise a single sheet of g.r.c., but in another form it may comprise an upper and a lower layer of g.r.c. joined by an intermediate corrugated layer, the interstices between the layers being filled by low density preformed elements, for example of expanded polystyrene. The lower layer is preferably substantially flat.

In another aspect the invention provides a shuttering panel for the use described above, the panel having substantially flat edge portions, the region of each panel within its periphery comprising one or a series of parallel upwardly convex channel-section top surface portions which extend substantially between two opposite edges of the panel but terminate short of those edges. The panel is preferably provided with upstanding flanges along its edges parallel to the upwardly convex region or regions.

In order that the invention may be more clearly understood, various embodiments will now be described with reference to the accompanying drawings, wherein: Fig. 1 shows a perspective view of a panel of the present invention, Fig. 2 shows a cross-sectional longitudinal view through a panel in use, Fig. 3 shows a cross-sectional transverse view through the structure shown in Fig. 2, Fig. 4 shows a cross-sectional transverse view through a second embodiment of panel, Fig. 5 shows a perspective view of one end portion of a third embodiment of panel, and Fig. 6 shows a cross-sectional longitudinal view, similar two Fig. 2, illustrating a modified method of constructing the span.

Referring to the drawings, and firstly to Fig. 1; the shuttering panel 10 comprises a single layer of g.r.c. made by conventional spraying on a suitably shaped former. The panel 10 has a flat continuous peripheral region 12 surrounding an inner upwardly convex region 14 which extends substantially the length of the panel but terminates just short of the opposite end edges by reason of the flat peripheral strips 12 at those edges. The upwardly convex region has sloping end faces 16, as can best be seen in Fig. 2. The two opposite side edges of the panel are provided with upstanding flanges 18.

Referring to Figs. 2 and 3; a bridge span is constructed starting in conventional manner using a pair of longitudinal beams 20 between which extend a series of smaller section spaced apart transverse beams 22, the top surfaces of the transverse beams 22 being substantially flush with the top surfaces of the longitudinal beams 20.

The rectangular openings thus defined by the longitudinal and transverse beams are closed by shuttering.panels 10: in the example illustrated each such space is closed by three such panels.

However, any number of panels from one upwards can be used depending upon the dimensions of the space. All the panels closing one opening bridge one pair of the support members, in this case the transverse members 22, the upwardly convex regions 1 4 extending substantially between those support members.

Where two or more shuttering panels are used, as in the present instance, their adjacent edges are secured together through their adjacent flanges by bolts, clips or other suitable securing devices. The flat peripheral regions of the group of panels rest on the support members 20 and 22, as can be seen in Figs 2 and 3, thus effectively closing the space between the support members. Suitable steel reinforcing elements are then arranged over the shuttering panels and support members. The precise nature and arrangement of the reinforcement will depend upon the nature of the structure concerned, but is exemplified by the steel rods 24 extending lengthwise in the valleys alongside adjacent raised regions 14, and steel light gauge rod or mesh reinforcement layers 25.

Shuttering (not shown) is provided outwardly of the longitudinal members 20 so as to form parapets. Then concrete is poured over the shuttering and support structure, as indicated at 26 in Fig. 3, and is allowed to cure.

As well as providing relatively inexpensive, easily produced, transported and placed shuttering, the panels 10 by reason of their upwardly convex regions reduce the amount of concrete which is required. For example, if the total thickness of concrete is 250 mm, the central region 14 might rise 1 50 mm, so that only 100 mm of concrete lies over the topmost portions of this raised region.

Referring to Fig. 4; an alternative form of panel is shown, which comprises an upper g.r.c. layer 28 and a lower g.r.c. layer 30 joined by a corrugated intermediate g.r.c. layer 32. A flat marginal region 12 is provided with upstanding flanges 18 on two sides, as in Fig. 1. The upper layer 28 together with the marginal region 12 and flange 1 8 has the same general configuration as the panel shown in Fig. 1. However, it is constructed rather differently.

Initially, g.r.c. is sprayed onto a former to provide the flat lower layer 30, including the peripheral region 12 and flanges 18. Then performed triangular section fillets 34 and trapezoidal section fillet 35 of lightweight material such as expanded polystyrene are laid on the lower layer 30 over the central region which is to be raised. Then g.r.c. is sprayed over the fillets 34 and 35 to provide the corrugated intermediate layer 32. Thereafter further lightweight fillets 36 are inserted into the channels in the intermediate layer 32, the fillets 36 being of a suitable trapezoidal cross-section so as to substantially fill those channels. Then, a further layer of g.r.c. is sprayed over the fillets 36 to provide the top layer 28. The composite panel thus formed has considerable flexing strength, and can use a lower total quantity of g.r.c. than the single layer panel of Fig. 1.

Referring to Fig. 5, this shows a g.r.c. shuttering panel which can be a single layer of g.r.c., and comprises a flat marginal strip 12 as in Fig. 1, but with a series of parallel upwardly convex regions 14. By this configuration, the tptal upward arching of the raised regions is lower than in the case of the panels of Fig. 1, although the total volume of the raised regions may be substantially the same.

The panel of Fig. 5 can alternatively be regarded as a number of panels of Fig. 1 constructed integrally side-by-side. Upstanding flanges 1 8 can be provided along opposite longitudinal edges of the panel of Fig. 5 if desired, but it is envisaged that this panel will be more useful with smaller structures, such as foot bridges, where a single panel can close an entire opening between longitudinal and transverse support members.

Instead of being a single layer of g.r.c. it could be a composite structure, somewhat similar to that of Fig. 5, but with a single lightweight fillet within each of the raised regions 14.

Referring to Fig. 6; in this modification of the process described in relation to Figs. 2 and 3, before placing the panels 10 in position, special extendable support devices 38 are laid between the transverse members 22 at spacings corresponding to the crests of the raised regions 14 of the panels 10. Each device 38 comprises two beams 40, 42, one of which fits telescopically within the other. The ends of the beams remote from each other are provided with flanges 44 which rest on the transverse members 22. The peripheral regions 12 at the ends of the panels 10 can have recessed undersurfaces to accommodate these flanges. The device 38 is provided with suitable means, such as a hydraulic ram or a screw device, operable from above for extending and retracting the two beams.The beams carry a number of spacer elements 46 on their top surfaces which support the raised regions 14 of the panels 10 which are laid over them, thus preventing them from unduly flexing or collapsing under the weight of concrete which is poured on them. The raised region 14 of each panel 10 has an opening 48 which provides access from above to the mechanism for extending and retracting the beams of the device 38. Before the concrete is poured, a box 50 is placed over the opening 48, and after the concrete has cured the box is moved so that a workman from above can reach through the opening 48 and retract the device 38 and then lower it on a line to the ground. Thereafter a plug is put into the opening 48 and the space left by the box 50 is filled with concrete. In this way, under-support for the shuttering panels can be provided by workers operating from on top of the support structure rather than from underneath.

Claims (7)

1. A method of making a concrete span which comprises providing a support structure comprising longitudinal elongate members sideby-side and spaced apart and bridged by a series of spaced apart transverse elongate members; placing shuttering panels over the openings defined by the longitudinal and transverse members so that the openings are closed thereby and the panels rest peripherally on both the longitudinal and transverse members, the region of each panel within its periphery comprising one or a series of parallel upwardly convex channelsection top surface portions which extend substantially between a pair of said elongate members; if necessary arranging reinforcing elements over the panels; and pouring concrete over the panels and support structure and allowing it to cure.

2. A method according to claim 1 wherein a said opening defined by two adjacent longitudinal members and two adjacent transverse members is closed by two or more panels side-by-side.

3. A method according to claim 2 wherein the adjacent panels are secured together along their adjacent edges.

4. A method according to claim 3 wherein the panels are secured together through upstanding flanges along their adjacent edges.

5. A method according to claim 1 wherein the shuttering panels are made from glass fibre reinforced cement.

6. A method according to claim 5 wherein each panel comprises a single sheet of glass fibre reinforced cement.

7. A method according to claim 5 wherein each panel comprises an upper and a lower layer of glass fibre reinforced cement joined by an intermediate corrugated layer.

8. A method according to claim 7 wherein the corrugated layer is formed by laying preformed elements over the lower layer to define a corrugated surface, and spraying glass fibre reinforced cement over them; and the upper layer is formed by inserting further preformed elements into the channels defined by the corrugated layer, and spraying glass fibre reinforced cement over them.

9. A method according to any one of the preceding claims wherein an extendable support device is laid in its extended condition between two adjacent elongate members so as to support the corresponding shuttering panel from beneath; and after the concrete has been poured and cured the support device is retracted and removed.

10. A method according to claim 9 wherein the extendable support device comprises two beams one of which is received telescopically inside the other.

11. A method according to claim 9 or claim 10 wherein the support device is retractable by means operable from above, and wherein the shuttering panel has an opening and a corresponding hole is left when the concrete is poured, the support device being retracted by operating said means from above through said opening and hole.

12. A method according to claim 11 wherein the opening and hole are subsequently filled with concrete.

13. A method of making a concrete span, substantially as described herein with reference to the accompanying drawings.

14. A bridge having a concrete span rhade by a method according to any one of the preceding claims.

1 5. A shuttering panel for use in making a concrete span, the panel having substantially flat edge portions, the region of each panel within its periphery comprising one or a series of parallel upwardly convex channel-section top surface portions which extend substantially between two opposite edges of the panel but terminate short of those edges.

1 6. A shuttering panel according to claim 1 5, wherein the panel is provided with upstanding flanges along its edges parallel to the upwardly convex region or regions.

17. A shuttering panel according to claim 1 5 or claim 1 6, made of glass fibre reinforced cement.

18. A shuttering panel according to claim 17, comprising a single sheet of glass fibre reinforced cement.

19. A shuttering panel according to claim 17, comprising an upper and a lower layer of glass fibre reinforced cement joined by an intermediate corrugated layer of glass fibre reinforced cement, the interstices between the layers being filled by relatively lower density preformed elements.

20. A shuttering panel according to claim 19 wherein the preformed elements are of expanded polystyrene.

21. A shuttering panel according to claim 19 or claim 20 wherein the lower layer is substantially flat.

22. A shuttering panel according to any one of claims 1 5. to 18 for use in a method according to claim 11, the panel having an opening therein through which the retraction means can be operated.

23. A shuttering panel for use in making a concrete span, substantially as described herein with reference to Figs. 1 to 3, Fig. 4, Fig. 5 or Fig.

6. A method according to any one of the preceding claims wherein the shuttering panels are made from glass fibre reinforced cement.

1

7. A shuttering panel according to claim 15 wherein said convex top surface has a curved profile.

6 of the accompanying drawings.

New claims or amendments to claims filed on 9 October '79 Superseded claims 5 New or amended claims New Claim 2 Original claims 2 to 4 renumbered 3 to 5 and appendancies corrected.

New Claim 6 Original claims 6 to 1 5 renumbered 7 to 16 and appendancies corrected.

New Claim 17..

Original claims 1 6 to 23 renumbered 18 to 25 and appendancies corrected.

2. A method according to claim 1 wherein said convex top surface portions have a curved profile.