GB2123873A - Reinforced concrete slabs, and concrete structures formed therefrom - Google Patents

Abstract

A concrete structure, and reinforced concrete slabs 1 for producing it, in which each slab has reinforcing bars 4 with projecting portions at those edges of the slabs which abut, the slabs being aligned and held in position by clamping together of the projecting portions. There are gaps between the slabs sufficient to allow thermal expansion of the slabs and/or bars, and to allow access to the clamping means 8, 10. The projecting portions of one slab may lie above those of the adjacent slab. <IMAGE>

Description

SPECIFICATION Reinforced concrete slabs, and concrete structures formed therefrom This invention relatesto reinforced concrete slabs, and to concrete structures formed therefrom.

It is a problem, in producing concrete structures, such as roadways, hard standing, concrete tunnel linings, and such like, to ensure that the adjacent sections are co-planar, and also to allowforthermal expansion and contraction. If expansion and contraction are not possible, this leads to destructive forces acting on the structure and very expensive repair work (see e.g. "Concrete International", Sept 1980, pp 90-98, published by The American Concrete Institute).

On the other hand using discrete concrete slabs so as to allow expansion, makes it difficult to ensure thatthe slabs do not present raised edges which are then hammered by every vehicle which passes overthem.

Accordingly, the invention proposes a concrete structure formed by a plurality of discrete slabs of concrete, each slab having reinforcing bars with projecting portions which projectfrom at least one edge of the slab, the projecting portions ofthe bars of adjacent slabs being clamped together with the surfaces of said slabs being substantially co-planar and with gaps between the slabs sufficient to allow thermal expansion of the slabs and/or bars.

For executing such structures, the invention also proposes a reinforced concrete slab, having reinforcing barswith projecting portions projecting from two opposite edges of the slab, wherein said portions are mututally displaced as between said opposite edges, whereby when two slabs are placed adjacentto and aligned with one anothertheir respective projecting portions will lie closely adjacent for clamping together.

Such slabs and structures are much improved in the respects mentioned, and can be used for roadways, in place of sleepers for railways, as iining fortunnels, as vertical barriers, e.g. against snow-slips or sand movement, and in many other circumstances. It will be seen that these uses are ones which lead to greater safety for both public and workers, and by their nature are liable to save great sums of money in the reduction of repairs and maintenance, and in avoiding accidents.

Preferably, the reinforcing bars used are as described in British Patent 1031180. The slabs are preferably factory produced, thus minimising work on site, and can be pre-stressed as desired.

In orderthatthe invention shall be clearly understood, several exemplary embodiments thereof will now be described with reference to the accompanying drawings, in which: Fig. 1 shows a cross-section of a three-lane carriage way of a road; Fig. 2 shows a plan view thereof; Figs. 3,4 and 5 show a detailed plan and sectional views of one slab according to the invention; Figs. 6,7 and 8 show a plan view, a side view and a perspective view of a corner of a slab with the clamping means; Figs. 9,10 and 11 show an end view, a plan view and a longitudinal section of a concrete structure according to the invention used for laying a railway track; Figs. 12 and 13showviewsofanalternative clamping means employing a wedge;; Figs. 14to 17 show method and apparatus for aligning railway track mounted as shown in Figs 9to 11; Figs. 18 to 23 show a concrete structure according to the invention used as a vertical barrier; Figs. 24 to 27 show details of a concrete structure according to the invention used as a tunnel lining; Figs. 28 and 29 show detail of linkage means between reinforcing bars.

Figure 1 shows the section of a three-line carriageway, each carriageway being covered with a slab 1 according to the invention.

Figure 2 illustrates that the transversal joints of a carriageway alternate with the whole slabs ofthe contiguous carriageway, orwith the whole curbstone 2; so that interrupted, i.e. weaker parts of one carriageway become reinforced by the whole, the strongest, parts of the contiguous carriage or curbstone. The dash line indicates the slab 1 which is being connected to the previously placed slabs.

Figure3demonstratesthe plan view ofthe slab 1, reinforced with transversal star pitted bars 3 and with longitudinal ones 4, (calculated from greater, positive flexural moments provoked by heavy wheels in the slab supported by elastic subbase).The ends of these bars 3,4 are bent and rebenttowards the midthickness oftheslab-and rigidly attached to blocks7 on one slab edge and with blocks 7' on the opposite edge, blocks 7 lying above blocks 7'.

The bentand rebent main bars 3,4 and the upper and lower nails 7, 7' arevisible in the longitudinal section of the slab, figure 4, and in its transversal section, figure 5. The upper slab zone is reinforced with weaker, repartition bars 5, 6; they shall resist to eventual smaller negative moments. These bars are straightand don't exceed from the slab board.

Thefigure 6 shows the plant view of the connection oftwo contiguos slabs 1 and theirjoining with the r.c.

cu rbstone 2 of a highway.

The figures 7 and 8 illustrate this connection in a vertical section and in a perspective view. In this example the nails 7 and 7' are fixed on the transversal bars 3 and on the longitudinal 4 by screwing . At the assemblage underthe lower nails 7' ofthe placed slabsinthe jointstherearewelded longitudinal and transversal strip steels 9, connected in their encounter with a screw. On the lower nails 7' there are placed the upper nails 7 ofthe newly assembled slab (1).

Between the nails and the previously placed slabs there are left dilatation spaces, as between the strip steels and the slab boards. Each couple ofthe nails 7' and 7 is clasped by means of a short strip steel 8 and two long screw bolts 10 turned into the lower, long strip steel 9. This connection ofthe nails 7 and 7' allows the longitudinal dilatation ofthe slabs, but it ensures the required equal level ofthe contiguous slab edges, when heavy wheels pass over the joint.

The serviceability ofthe highway will be very prolonged when all the connection articles beyond the slabs are from stainless steel.

The head ofthe screw bolts arethinned in order to make possible their rotation in the reduced space of the joint (20-30 mm).

For curves of great and medium radius the slabs of standard length and width serve; the small difference between the outside and internal perimeters can be compensated in the joints, eventually by longer and shorter nails in these joints. Only for highways of small radius, i.e. exceptionally, slab of special measureswill be necessary.

The same joining system can be applied for pavements of large areas, e.g. squares, aerodromes.

Here the very heavy wheels require thicker slabs reinforced with strongerstar pitted bars and connected by means of stronger nails, strip steels and screw bolts.

As all the constructions also these pavements require a reliable ground; when the soil is humid e.g., it must be continuously drained and solidificated.

The application of the slab according to this invention forthe Railways is illustrated in the figures 9 upto 13; the rectification ofthe rails assembled in plants into their exact horizontal and vertical position on the plots and theirfixing can be done by means of the apparatus visible in the figure 14 up to 16 and according to the figure 17.

The figure 9 shows the front of a slab 1 according to this invention with two couples of nails 7', 7, (fixed on the longitudinal starpitted bars 4), nearthe rails 13.

The levels ofthese nails alternate underhand overthe slab middepth; their surface towards this middepth is inclined alternatively to the right and to the left. On the backfrontthe positions and the inclinations ofthe nails to the middepth are opposite to the above specified. So, when at assemblage a new slab will meet the previously placed slab, their nails leave transversal spaces for wedges, alternatively inclined to the left and to the right. The finger pressure on these wedges suffices to fix the nails and through them the slabs in their exact vertical and transversal position, whilstthe longitudinal dilatation possibility remains assured; the length ofthe nails and the width of the wedges shall be slightly less than the joint width.

Thefigure 10 demonstrates a plan view on parts of the rails 13, on fixing plates 22, on two contiguous slabs according to this invention 1 and on a joint between these slabs with the two couples of nails and wedges 14. There are visible the lowertransversal star bars 3, the longitudinal 4; on the latterthe stainless nails 7',7 are fixed; they exceed into the joint. The holes 11 serve for an exact connection of the rails with the slab. The hole 12 is madeforfixation of the rectification apparatus, described hereafter.

Thefigure 11 illustrates the longitudinal section of the slab 1. The transversal star pitted bars 3,6 are calculated from the same flexural moments and dynamic coefficient as the sleepers which are replaced bythese slabs. Butthe maximum load of a locomotie axle is supported by a slab length which is equal to the distance of two contiguous axles, usually200 cm, about 3 times the width of 3 replaced sleepers; so the slab tracks cost about 20% lesserthan the replaced sleeper tracks. On the longitudinal bars4there are fixed alternatively the lower and the upper nails 7', 7 embraced with the wavy bar 3'. Sometimes there are repetition bars 5.

Thefigure 12 shows the connection of the lower nail 7' with the upper one 7 by means of wedge 14, including to the left, in perspectiveview.Thesame, but in longitudinal view, is visible in thefigure 13. The plate 16 and the screw bolt 15 stabilises the wedge against vibrations. By this connection one half of the nails resists to the heavy wheels, running from the right orfrom the left, onlythrough reciprocal compression. Any tensile stress, which is much more dangerous, when repeated many millions times, does not exist. Therefore this connection is the most secure.

The nails tryto split the slab front; the wavy-line star bar 3' impedes the splitting. This connection is the simplest, quickest for execution in the narrow joints and the most economical, thus preferable.

The traffic security and the comfort of passengers require reduction of the joints on minimum, i.e. slabs the length of which equals with thatofthe rails (about 1 8m), as well as staggering ofthe slab and rail joints, augmenting the slab depth and reinforcement under each rail joint. Connection ofthe rails with the long slabs immediatelyafterthe manufacture ofthe latter (intheplant) makes possiblesuretranslations, transport and assemblage of the slabs of small depth and weight.

The continuous support ofthe rails by the long slabs reduces the dangerous fatigue stresses in the rails; so these can be lighter, cheaper and serve longer, i.e.

traffic interruptions and amortization costs can be reduced.

The tracks in curves can be performed as described at highways.

This long slabofferssupportto an appartusfor rectification ofthe rail in its exact horizontal and vertical final position, as it is illustrated in the figures 14, 15, 16. The figure 17 shows the fixation ofthe rail of the slab. At manufacture ofthe slab both the holes 11 and 1 forthe fixation ofthe rails and the apparatus are made; the holes have conic walls more conical in the lowest part, as it is visible in thefigure 17. Herethe hole is closed with a c.stopper 17. Into the upper part ofthis hole there is inserted the tube 18 of smooth surface, with the nut 19 on its lower end. On this tube and nut there are inserted two greater nuts 20, welded together attheir congruent threads. Then,th rough the upper end 21 ofthetube 18there is impressed laitance with few fine sand into the low and lateral partofthe hole; so all the nuts are fixed; after having unscrewed thetube 18from the nut 19, into the nuts 20 there can be screwed the screw boltwhich fixes the plate 22 and the rails, ofthe screw bolt 33 which supports the rectifying apparatus. The bolt 33 is provided with the ring 34 which can rotate in (ball) support, created by the lower plate 34", welded to base-plate 27 and by the upper plate 34', screwed on the base 27. To this there is welded the support 28 with a screwed hole. On the opposite board ofthe base 27 there is welded another support 28' with a smooth hole, coaxial to the preceding hole.Into these holes the mandrel 31 is inserted; its one end is screwed and provided with the handwheel 31', its opposite end is made, to catch the rail 13through two ball bearings 29 and the nut 30 and to place the rail into the required position; vertically by turning the vertical screw bolt 33 with the ending, upper handwheel and horizontally byturning the horizontal mandrel 31 with the handwheel 31 '. This rectification ofthe rails is continuous, without any shock, exact and economical.

Underthe exactly rectified rail there is injected a rapid hardening cement35 (orotherresisting mass), stopped on one side of the rail by the (gummy) strip 36, (seethefigure 14).

The right part of the figure 17 showsthefixing of the rail 73tothe slab 1 by means of the shaped plate 22, the screw bolt 23 with a safety rosette. The same fixing is made on the left side ofthe rail. In curved tracks the position ofthefastening plates 22 and the rail can be strengthened, connecting the screw bolts 23 on both rail sides with the stirrup 24 which passes through a hole in the rail, is ensured with the little screw bolt25 and a rosette and welded at its end 26.

The particular connection of the slabs according to this invention makes them useful for construction of Sand-Fences in sandy deserts and of Snow-Fences in cold territories. The main details ofthe sand4ence are illustrated bythefigure 18 up to 23. In this casethe slabs have horizontal crevices they are jalousies. Their vertical star pitted bars 4 reinforce the vertical boards only, they don't exceed from the slab; they are calculated fortransportonly. The main reinforcing ars are the transversal ones 3 which excesd from the siabtowardsthe columns.

in figure 18the slabs l form a zigzag lineto resist so better against sandstorms (from the left in the designed case3.Thes3abs aresupportedalsobythe columns inserted profoundly into the sand.

Thefigure 19shows in vertical section and the figure 20 in horizontal section the preceding ofthis column placing. The large tube 38 with a welded spiral on its extemal surface is bored progressively into the sand. On the internal wall ofthe tube 38, diametrical ly there are welded two conducts 41, with protection sheet-irons 43 at their bottom. The prog ressive penetration ofthe tube 38 is followed by the internal tube 39 with the shade 40 at its bottom, introducing vacuum in this tube, exhausting the sand with airthrough the upper aperture 42 from the bottom shade 40; the air pressed from the conducts 41 .facilitatesthis sand sucking and the sinking ofthe tube 42 with the shade 40 up to the required profundity of foundation.Then the tube 39 and the shade40 is replaced through the precast column 37, visible in the figures 18,21,22,23. Successively laitance is pressed through gummy tubes, inserted into the conducts41, at a simultaneous contrarotation ofthe tube 38 with the external spiral, lifting it slowly. The sand which surrounds the bottom ofthe lifted tube 38, penetrates towards the column; mixed with the laitance from the conducts 41, it creates a reliable lateral concrete support for the column, progressively from its bottom up to the soil surface.

Otherwise, the free space between the column 37 and the tube 38 can be filled in with concrete cast and vibrated from soil surface.

The figure 21 illustrates the connection of the jalousieslab 1 with two columns 37, in horizontal section. Through holes 44 there passes the U-iron 45, opened upwards to receive the transversal bar3 exceeding from the slab. That is visible also in the figure 22 and 23. In the latterthe bar3 is covered by the square iron 46 and clamped with the short strip plate 47 and with two screws 10.

In the frontal view (figure 22) on the jalousie slab 1 and two columns 37 the slab ends cuneiformly, at bottom to be strengthened from the soil, upward from eventual super-slab, when described sandfence would be overflowed by sandstorms. For such eventuality the longitudinal r.bars 50 ofthe columns 37 exceed upwards. There are visible the horizontal crevices 48 in the jalousie slab; two vertical crevices are between the slab and the contiguous columns.

They reduce the violent squale ofsandstorms on the fence, its velocity producing the settling down ofthe sand behind the fence and so the protection of the railway.

As itwas mentioned already,theslabs according to the invention strengthen the walls and vaults of Tunnels. Moreover these slabs augment the worker security during their construction and reduce the costs of execution as well as ob maintenance, also of the programmed Channel tunnel.

The lower part ofthefigure 24 illustrates the section of two finished blocks with the corresponding joint; its upper part shows two other blocks during ccnstruction. The figures 25 and 26 represent the frontal viewon the longitudinal section ofthe th3&commat; slab 1, svith its penrnetral r.bars4and horizontal ones 3; all these bars end screwed.Already during the r manufac- ture of these slalds two central bars4are bound with the bars 3 by means of four U-stirrups 51 , exceeding orthogonallywith their screwed ends from the slab surface, inwards the wall or vault forshuttering of which the slabs serve. First the back slab 1 nearthe mount is fixed to the previously term inated wall slab 1, as the midpart of the figure 24 shows it. Equal connection is performed between the bars 3 ofthe slab in placing and that of the previousiyterminated horizontally contiguous slab. The transversal view on this connection is visible in the figure 27.To the back bar4 exceeding from the preceding slab, there is fixed a long strip plate 59, with two screwed holes near teach exceeding bar 4. Between the exceeding bar ends 4a plate with two smooth holes 60 is put Overthe bar4 in placing a short plate 61 with two smooth holes is fixed with two rosettes and screw bolts 10. Then into the screwed sockets 54 ofthe precedinglyterminated wall slabs, the short bars 53 and 52, with screwed ends and opposite screwed sockets are screwed; binding the bars 52,53 together and with the stirrups 51 by means ofthe strip plate 55 and two nuts 56 an efficient longitudinal and perimetral continuous reinforcementforthe backpart ofthetunnel arises. Equally efficient, continuous reinforcement is achieved also forthe fore-part ofthe tunnel wall or vault repeating the described operations, only in the inverse order, i.e. connecting the bars 52',53',the bars 4,4', the stirrups 51'. This continuous longitudinal and perimetral reinforcing barsstrengthenthetunnel walls and vaults also against unforeseen forces, caused e.g. by landslides, earthquakes, unexpected local pressure on the tunnel, by vibrations from many heavy trains during many years of service, in its long internal part.But in both the entrances the greattemperaturevariations don't allow any impediment to the longitudinal dilatation by the continuous longitudinal r.bars 53, 53'; therefore in the (relatively short) tunnel entrances also these main longitudinal bars must be interrupted and connected, as the longitudinal slab bars 3, in order to make possible the longitudinal dilatation of single ring of the wall and vault. The lacking favourable effect ofthe continuous longitudinal reinforcements 53,53' is to be compensated by thicker walls and vaults. The manual fixation ofthe bars 52', 53' with the stirrups 51' behind thefore-slab 1 requires to limittheslab width on 50cm, its length can be 100 cm.Between the hinderand fore-slabs 1 the precast concrete block 57 is inserted; it has an appropriate shape, (designed with the thick outline), which creates the shuttering forthefine concrete; this unites all these members into a strong continuous tunnel tube, although it is composed from small handy bodies which can be handed in the restricted tunnel space by a sole or two workers, reducing so also the numbers of accidents. The use ofthe back-slabs as the permanent (reinforcing) tunnel part minimises (in space, time) effects of water or sand which sometimes vehemently press from the mount and case great and expensive difficulties.

Thefigure 28 shows the longitudinal section ofthe screwed socket from star pitted bar 54 and the view on the main reinforcing star bars 52, on their screwed ends which meet in the midsocket 58.

The figure 29 shows the frontal view on the screwed socket made from the star pitted bar 54 and the cross-section ofthe star bar 52 near this socket front

Claims (15)

1. A concrete structure formed by a plurality of discrete slabs of concrete, each slab having reinforcing bars with projecting portions which projectfrom at least one edge ofthe slab, the projecting portions ofthe bars of adjacent slabs being clamped together; with the surfaces of said slabs being substantially co-planarwith gaps between the slabssufficientto allowthermal expansion of the slabs andlor bars.

2. A structure as claimed in claim 1,wherein the projecting portions in each slab are positioned so that when slabs are aligned said portions of one slab lie closelyadjacentthose ofthe adjacentslab.

3. A structure as claimed in claim 2,wherein said portions of one slab lie above said portions ofthe adjacent slab.

4. A structure as claimed in any preceding claim wherein said projecting portions of adjacent slabs are clamped together by a pair of bars and bolts.

5. A structure as claimed in claim 4, wherein a wedge is used to assisttightening ofthe clamping action.

6. A structure as claimed in any preceding claim, wherein the end surfaces of the projecting portions are spaced from the edge surfaces ofthe slabs.

7. A reinforced concrete slab, having reinforcing bars with projecting portions projecting from two opposite edges ofthe slab, wherein said portions are mutually displaced as between said opposite edges, wherebywhen two slabs are placed adjacentto and aligned with one another their respective projecting portions will lie closely adjacentforclamping together.

8. A slab as claimed in claim 7, wherein the projecting portions are on opposite ends of single bars, which bars are shaped to produce the mutual displacement ofthe projecting portions.

9. Aslab as claimed in claim 7 or8,whereinthe bars are profiled, and have a star-shaped crosssection.

10. Aslab as claimed in claim 7,8 or9, wherein the reinforcing barshaverectangularblocksrigidlyfixed at their ends, said blocks forming the projecting portions.

11. Aslabasclaimed in claim 10,wherein said rectangular blocks are cast partially into the slab.

12. Aslabas claimed in anyofclaims7to 11, wherein holes are provided bywhich railsfor locomotives can be fixed thereto.

13. A slab as claimed in claim 12, wherein additionai holes are provided for locating rail displacing devices.

14. Aconcrete structure as claimed in claim 1, employing slabs as claimed in any of claims 7 to 13.

15. A concrete structure substantially as herein described with refereceto the accompanying drawings.