US20200056374A1

US20200056374A1 - Structural reinforcement

Info

Publication number: US20200056374A1
Application number: US16/541,180
Authority: US
Inventors: Matthew GREENHALGH
Original assignee: Taziker Industrial Ltd
Current assignee: Taziker Industrial Ltd
Priority date: 2018-08-15
Filing date: 2019-08-15
Publication date: 2020-02-20
Also published as: GB202103395D0; GB201813326D0; GB2590334B; GB2582840B; GB201911730D0; GB2582840A; GB2590334A

Abstract

The present invention relates to a boss 1000 for assembly with a part, the boss 1000 having a roughened portion for engaging a face of the part. The present invention also relates to a kit of parts, or an assembly, comprising such a boss 1000, and a bolt, a kit of parts, or an assembly, comprising such a boss 1000, and said part, preferably wherein the part is a strengthening member, and a method of structurally reinforcing a girder, the method comprising determining a section of the girder that requires strengthening and fastening to the girder a strengthening member without removing said section.

Description

RELATED APPLICATION

This application claims the benefit of priority of United Kingdom Patent Application No. 1813326.4 filed Aug. 15, 2018, the contents of which are incorporated herein by reference in their entirety.

FIELD AND BACKGROUND OF THE INVENTION

This invention relates to structural reinforcement. More specifically, the invention relates to a boss for assembly with a part, and a method for structurally reinforcing a girder.
In the construction of girder bridges, a plate of the girder, or a splice connection between multiple beams of a girder, may be under strengthened and thus require structural reinforcement. Existing methods of structural reinforcement require the girder(s) to be propped from below and/or the live load on the bridge to be restricted, while the under strengthened plate or splice connection is removed and a replacement is fitted, so as to ensure the bridge does not collapse.
The requirement that the bridge be propped in this way means that the structural reinforcement process is labour-intensive and time consuming. Furthermore, when the bridge being reinforced spans a road or a railway, the propping process will cause major disruption to the traffic on the road or railway below, as a propping mechanism must be set up beneath the bridge. Similarly, when the bridge being reinforced carries traffic, the requirement that the live load on the bridge be restricted (for example closing the bridge to road and rail traffic) is inconvenient and disruptive.

SUMMARY OF THE INVENTION

Aspects and embodiments of the present invention are set out in the appended claims. These and other aspects and embodiments of the invention are also described herein.
According to one aspect of the invention there is provided a boss for assembly with a part, the boss having a roughened portion for engaging a face of the part.
Preferably, the boss comprises a flange. Preferably, the roughened portion is a roughened surface positioned on the flange.
Preferably, in use, the flange is arranged to abut the face of the part thereby to engage the face of the part. Preferably, the roughened portion is positioned on a surface of the flange that abuts the face of the part in use. Preferably, the roughened portion covers more than 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of the surface of the flange that abuts the face of the part in use.
Preferably, the roughened portion of the boss is formed by machining. Preferably, the roughened surface comprises at least one groove. Preferably, the at least one groove is machined into the roughened surface. Preferably, the at least one groove comprises a spiral groove. Preferably, the at least one groove comprises a circular groove.
Preferably, the boss is manufactured using a lathe, preferably a CNC lathe. Preferably the groove is machined into the roughened surface using a lathe, preferably a CNC lathe. Preferably, the lathing or the boss and the lathing of the groove are performed sequentially simultaneously while the boss is mounted on the lathe.
Preferably, the roughened portion has a knurled surface.
Preferably, the roughened portion has a surface roughened to a surface preparation grade of between Sa 1 and Sa 3, more preferably between Sa 2 and Sa 3, and yet more preferably Sa 2½. Preferably, the surface is roughened by abrasive blasting, preferably by sandblasting.
Preferably, the boss has a through hole, and preferably the through hole is arranged to receive a bolt.
Preferably, the bolt has a tolerance fit within the through hole of the boss.
Preferably, the boss has a collar, and preferably the collar surrounds the through hole. Preferably, in use, the boss is inserted into the part. Preferably, in use, the collar of the boss is inserted into the part.
Preferably, the boss has a flange, and preferably the flange is arranged at one end of the collar.
Preferably, the roughened portion is on the flange.
Preferably, the roughened portion is on a surface of the flange.
Preferably, the boss is arranged to engage a face of the part via the flange.
Preferably, the roughened portion of the surface of the flange is arranged to engage the face of the part.
Preferably, the engagement of the boss with the face of said part inhibits relative moment between the boss and the part.
According to another aspect of the invention there is provided a kit of parts, comprising: a boss, as described herein, and a bolt.
Preferably, the bolt is a tension control bolt, and preferably the bolt is arranged to fit within the boss via a tolerance fit.
According to another aspect of the invention, there is provided a kit of parts comprising a boss, as described herein, and a part.
Preferably, the part is a strengthening member.
Preferably, the strengthening member has a roughened portion arranged to engage with the roughened portion of the boss.
Preferably, the roughened portion of the strengthening member is roughened to substantially the same degree as the roughened portion of the boss.
Preferably, the roughened portion of the strengthening member has a surface roughened to a surface preparation grade of between Sa 1 and Sa 3, more preferably between Sa 2 and Sa 3, and yet more preferably Sa 2½.
Preferably, the strengthening member is a strengthening plate.
Preferably, the strengthening plate has at least one through hole arranged to receive a portion of the boss.
According to another aspect of the invention there is provided an assembly or kit of parts comprising: a boss, as described herein, and a bolt.
Preferably, the bolt is a tension control bolt, and preferably the bolt is arranged to fit within the boss via a tolerance fit.
According to another aspect of the invention there is provided an assembly or kit of parts comprising: a boss, as described herein, and a part.
Preferably, the part is a strengthening member.
Preferably, the strengthening member has a roughened portion arranged to engage with the roughened portion of the boss.
Preferably, the roughened portion of the boss is arranged to engage with the roughened portion of the strengthening member thereby to inhibit relative movement between the boss and the strengthening member.
Preferably, the roughened portion of the strengthening member is roughened to substantially the same degree as the roughened portion of the boss.
Preferably, the roughened portion of the strengthening member has a surface roughened to a surface preparation grade of between Sa 1 and Sa 3, more preferably between Sa 2 and Sa 3, and yet more preferably Sa 2½.
Preferably, the strengthening member is a strengthening plate.
Preferably, the strengthening plate has at least one through hole arranged to receive a portion of the boss.
The terms ‘assembly’ and ‘kit of parts’ may be used interchangeably.
According to another aspect of the invention there is provided a structure, such as a bridge, comprising an assembly as described herein.
According to another aspect of the invention there is provided a girder comprising an assembly as described herein.
According to another aspect of the invention there is provided a structure, such as a bridge, comprising said girder.
According to another aspect of the invention there is provided a structure, such as a bridge, incorporating an assembly as described herein; preferably wherein said assembly is coupled to a girder.
According to another aspect of the invention there is provided a method of structurally reinforcing a girder, the method comprising: determining a section of the girder that requires strengthening; and fastening to the girder a strengthening member without removing said section.
Preferably, said section is coupled to the girder via a plurality of coupling points.
Preferably, the strengthening member is fastened to the girder via said coupling points while said section remains coupled to the girder.
Preferably, said plurality of coupling points are a plurality of rivets.
Preferably, at least one of said plurality of rivets is replaced with a bolt, preferably wherein the bolt is a tension control bolt.
Preferably, the girder is surveyed to identify the position of each coupling point.
Preferably, the strengthening member is fabricated, wherein the strengthening member comprises at least one through hole.
Preferably, the fabricating includes drilling a plurality of through holes in the strengthening member, and wherein the positions of the through holes correspond to the identified coupling points.
Preferably, at least one of the rivets is removed through the corresponding through hole in the strengthening member.
Preferably, a boss is assembled with the strengthening member.
Preferably, the strengthening member is arranged to receive a portion of the boss.
Preferably, the boss comprises a roughened portion, and wherein the assembly of the boss with the strengthening member includes the boss engaging a face of the strengthening member, preferably thereby to inhibit relative moment between the boss and the strengthening member.
Preferably, said face of the strengthening member is roughened so as to engage with the roughened portion of the boss.
Preferably, a bolt is assembled with the assembled boss and strengthening member, wherein the boss is arranged to receive the bolt thereby to fasten the strengthening member to the girder.
Preferably, the boss is a boss as described herein.
According to another aspect of the invention, there is provided a structure which has been reinforced using the method as described herein.
Any apparatus feature as described herein may also be provided as a method feature, and vice versa. As used herein, means plus function features may be expressed alternatively in terms of their corresponding structure.
Any feature in one aspect of the invention may be applied to other aspects of the invention, in any appropriate combination. In particular, method aspects may be applied to apparatus aspects, and vice versa. Furthermore, any, some and/or all features in one aspect can be applied to any, some and/or all features in any other aspect, in any appropriate combination. It should also be appreciated that particular combinations of the various features described and defined in any aspects of the invention can be implemented and/or supplied and/or used independently.
The invention extends to methods, system and apparatus substantially as herein described and/or as illustrated with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

One or more aspects will now be described, by way of example only and with reference to the accompanying drawings, in which like parts have like reference numerals, and in which:

FIGS. 1, 2, 3 a, 3 b, 4 and 5 are views of a boss for assembly with a part.

FIG. 6 is a girder which requires structural reinforcement.

FIG. 7 shows the first step in a method of structurally reinforcing a girder.

FIG. 8 shows the third step in the method of structurally reinforcing a girder.

FIG. 9 shows the fourth step in the method of structurally reinforcing a girder.

FIG. 10a shows the fifth step in the method of structurally reinforcing a girder.

FIG. 10b is an exploded view of the girder.

FIG. 11 shows the sixth step in the method of structurally reinforcing a girder.

FIG. 12 is a cross sectional view of the girder which requires structural reinforcement.

FIG. 13 is a cross sectional view of the girder, showing the result of the method.

FIG. 14 is a cross sectional view of the girder which requires structural reinforcement.

FIG. 15 is a cross sectional view of the girder, showing the result of the method.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

FIG. 1 shows a boss 1000. The boss 1000 has a collar 1002 and a flange 1004. The collar 1002 and flange 1004 define a through hole 1006 through their centres. The through hole 1006, has a given central axis, and has dimensions appropriate to receive a bolt. The flange 1004 has a flat upper surface 1008. The flange 1004 is arranged at one end of the collar 1002 and the flat upper surface 1008 extends perpendicular to the axis of the through hole 1006. The flange 1004 is a hollow cylinder having an axis aligned with the axis of the through hole 1006.
FIG. 2 shows the boss 1000. The collar 1002 of the boss 1000 is a hollow cylinder having an axis aligned with the axis of the through hole 1006. The hollow cylinder of the collar 1002 has a lower surface 2002. The flange 1004 has a lower surface 2004.
FIG. 3a shows the boss as viewed from below. The lower surface 2004 of the flange 1004 has a roughened surface, which is shown by the hatching in FIG. 3a . In the preferred embodiment the entire lower surface 2004 is roughened, although only a lesser portion may be. In the case where the boss 1000 is inserted, or at least part of the boss is inserted, in a through hole of a plate, and where the flange 1004 is arranged to contact a surface of the plate, the roughened lower surface 2004 provides friction grip between the flange 1004 and the plate. The friction grip between the boss and the plate inhibits relative movement of the boss 1000 and the plate.
One method for preparing the roughened surface is to use abrasive blasting (such as sand or grit blasting) to roughen a surface of the boss 1000. The abrasive blasting roughens the surface 2004 of the boss, preferably to a surface preparation grade Sa 2 Z. The roughened surface of the boss 1000 is a faying surface for assembly of the boss with a part, such as a plate of a girder.
Abrasive blasting causes peaks and troughs to be formed, on a small scale, on the faying surfaces being blasted. Over time, the peaks may be worn away and become less prominent, and the troughs may fill with material such as rust and become less prominent. Therefore, roughening the faying surface by abrasive blasting is particularly effective if the surface is abrasively blasted immediately prior to boss being assembled with a part, or as late as possible before being assembled with a part.
Roughening a surface of the boss by abrasive blasting is also particularly effective where no surface protection coating is applied to the boss (for example by galvanising, zinc plating, painting or applying Greenkote®). If a surface protection coating is applied to the boss, the coating might fill the troughs and therefore cause the surface to become smoother.
If a surface protection coating is to be applied to the boss, is it preferable to use alternative roughening methods which create more pronounced features in the roughened surface that will still be present even after a surface protection coating is applied to the boss. One such alternative method is to machine surface features onto the faying surface that are more pronounced than the peaks and troughs generated by abrasive blasting. The surface features may include for example one or more grooves machined into a surface of the boss to roughen the surface.
The machining may involve knurling the faying surface. The knurling may involve the use of a handheld knurling tool in which case pressure of the knurling tool on the surface indents the surface to form grooves which make up a knurled texture on the surface. The knurling may involve machine knurling in which case grooves are cut into the surface, for example using a lathe, to form a knurled texture on the surface. The grooves formed by the knurling are deep enough and wide enough that a surface protection coating applied to the surface follows the groove rather than filling them thereby preserving the surface roughness even after the coating is applied.
It can be difficult to effectively roughen the whole of the faying surface by knurling without interfering with other parts of the boss 1000. For example, it can be difficult to knurl the whole lower surface of the flange 2004 without interfering with the collar 1002, particularly the parts of the surface proximal to the collar.
Therefore, the machining may alternatively or additionally involve cutting grooves into the faying surface, for example using a lathe, preferably a computerised numerical control (CNC) lathe.
In one example, a lathe is used to cut a spiral groove into the lower surface 2004 of the boss. FIG. 3b shows the boss 1000, as viewed from below, with such a spiral groove 3002 cut into the lower surface 2004 to roughen the surface. The spiral groove 3002 is right handed in FIG. 3b , but could instead be left handed. When the boss 1000 is inserted into a part, for example a plate of a girder, the lower surface 2004 of the flange 1004 is arranged to abut a face of the plate. The lower surface 2004 achieves a friction grip with the face of the plate by way of the spiral groove 3002. The friction grip restricts relative movement between the boss 1000 and the plate.
The spiral groove is particularly effective in preventing rotation of the boss with respect to the part with which the boss is assembled. This is advantageous when a bolt is inserted through the through hole 1006 and tightened. The bolt will be rotated within the through hole 1006 to tighten it, which could tend to cause the boss to rotate. The friction grip that the spiral groove achieves with the part inhibits such rotation of the boss with respect to the part.
In another example, a lathe is used to cut at least one ring groove into the surface 2004. When there are multiple ring grooves, they are arranged on the surface 2004 concentrically.
In both the spiral and concentric ring examples, the grooves are cut into the surface 2004 during the same lathing process as that which forms the boss itself. The boss is formed using a lathe. Firstly, a piece of material is cut to one radius to form the flange part of the boss. Secondly, the material below the flange part is cut to a shorter radius to form the collar part of the boss. Thirdly, a central through hole 1006 is bored through the centres of the collar and flange parts.
The spiral groove is formed by turning the boss in the lathe, and moving a cutting tool between a first position where it contacts the surface 2004 at the inner edge (where the surface 2004 meets the collar 2002) and a second position where it contacts the surface 2004 at its outer edge. As the boss is turning in the lathe, the cutting tool moving continuously from the first position to the second position (while in contact with the surface) causes a spiral groove to be cut into the surface. The direction of rotation of the boss in the lathe determines whether the spiral is right handed or left handed.
The ring groove is formed by turning the boss in the lathe, and contacting the surface 2004 with a cutting tool at a certain radial position on the surface 2004. The cutting tool remains in contact with the surface 2004 for at least one full rotation of the boss to cut a ring groove in the surface. To cut multiple concentric rings, the cutting tool contacts the surface 2004 at a second radial position for at least one full rotation of the boss to cut a second ring concentrically inside or outside the first, and so on.
Making the boss in this way is particularly efficient, as it uses a single piece of machinery, and only requires the raw material to be mounted on the machinery once. Once mounted, all cutting operations necessary to form the boss and cut the groove(s) may be executed, and the fully formed boss removed from the lathe.
In yet another example, the machining involves cutting at least one radial groove into the surface 2004, each groove extending from the outer edge of the collar 2002 to the outer edge of the surface 2004. When there are multiple grooves, they are preferably distributed equally around the surface 2004 (for example, if there are four grooves, they are positioned at 90° intervals around the surface 2004). Each radial groove is formed by a milling operation, after the boss itself has been formed using a lathe as described.
The spiral groove, concentric ring grooves, or radial grooves are deep enough and wide enough that a surface protection coating applied to the surface would follow the grooves rather than fill them thereby preserving the surface roughness even after the coating is applied.
The surface protection coating is preferably Greenkote®. The Greenkote® coating can be painted on to the boss without the need for an etching primer layer being used, which provides two advantages over zinc based plated coatings, which do require an etching primer layer. Firstly, applying fewer layers of coating to the roughened surface of the boss reduces the likelihood that the coating fills the surfaces features (grooves or troughs) and thus reduces the smoothing effect of the coating as described. Secondly, etching primers typically contain acid which, if applied to the roughened surface, can erode the roughened surface features and reduce their prominence causing the surface to become smoother. In addition, bolts (specifically, tension control bolts which are preferably used for assembly of the boss with a part) are typically also coated with Greenkote®.
Instead of Greenkote®, the following surface protection coatings could be used: hot dip galvanising; spun galvanising; bright zinc plating; electro plating; and painting.
The methods of roughening the faying surface of the boss described above apply equally to the roughening of a corresponding faying surface of the part into which the boss is inserted. The faying surface of the part is a face of the part. Roughening both faying surfaces increases the relative friction between the surfaces when they are in contact to achieve an optimal friction grip between the boss and the part. Preferably the two faying surfaces are roughened by the same method to produce corresponding roughened surfaces that achieve an optimal friction fit together. If the surfaces are roughened by abrasive blasting, the two faying surfaces are preferably roughened to the same degree as each other (i.e. both to a surface preparation grade Sa 2½) as this achieves a particularly effective friction grip.
FIG. 4 shows a side view of the boss 1000, while FIG. 5 shows the boss as viewed from above. In the case where the boss 1000 is inserted within a through hole of a plate, the height of the collar 1002 is the same as the thickness of the plate, so that the lower surface 2002 of the collar 1002 is flush against the bottom surface of the plate. The flange 1004 engages with a surface of the plate so as to retain the boss 1000 in position. The outer diameter of the collar 1002 is substantially the same as the diameter of the through hole of the plate. The inner diameter of the collar 1002 is substantially the same as the bolt which is received within the through hole so that the bolt has a friction or close tolerance fit within the boss 1000.
While FIGS. 1 to 5 show the flange 1004 of the boss 1000 being circular, the flange could instead be any other appropriate shape, preferably a tessellatable shape. In one example, the circular flange could have segments removed from opposing sides of the circle. In another example, the flange could be square or hexagonal. In these given examples, the distance from the centre of the boss to the outer edge of the flange is reduced in certain directions. Reducing the distance from the centre of the boss 1000 to the outer edge of the flange 1004 provides the advantage of reducing the necessary spacing between two bosses which are positioned next to one another, thereby allowing for a higher density of bosses. The central through hole 1006 would still have a shape and dimensions appropriate to receive a bolt irrespective of the shape of the flange.
FIG. 6 shows a girder 6000 prior to strengthening; the girder comprises first and second beams 6002 and 6004. The beams each have web plates 6008 and two flange plates 6010 and 6012, where 6010 are the upper flange plates and 6012 are the lower flange plates. The flange plates 6010 and 6012 are coupled to the web plates 6008 by means of angled sections 6014. The angled sections 6014 are coupled to the upper flange plates by means of a plurality of rivets 6016 and the lower flange plate by means of a plurality of rivets 6018. For each flange plate, the rivets 6016 and 6018 which couple the angled sections 6014 to the flange plates 6010 and 6012 are arranged in two columns, where one column of rivets is arranged to couple one of the angled sections 6014 to the flange plate on one side of the web plate 6008, and the other column of rivets are arrange to couple one of the angled sections 6014 to the flange plate on the other side of the web plate 6008.
The two beams 6002 and 6004 are connected via first and second splice connections 6020 a and 6020 b. The splice connections 6020 a and 6020 b comprise multiple splice plates which overlap with, and are fastened to, existing plates of the beams 6002 and 6004.
Taking the first splice connection 6020 a as an example, the connection comprises a splice plate 6024 which is positioned on the top surface of upper flange plates 6010 of each of the two beams 6002 and 6004. The splice plate 6024 overlaps with the upper flange plates 6010 and the left hand portion of the splice plate 6024 is coupled to the upper flange plate 6010 of the first beam 6002 while the right hand portion of the splice plate 6024 is coupled to the upper flange plate 6010 of the second beam 6004. The second splice connection 6020 b also comprises a similar splice plate (not shown) which is positioned on the bottom of the lower flange plates 6012 of the two beams 6002 and 6004.
Taking the second splice connection 6020 b as an example, the connection comprises at least one additional splice plate 6026 which is positioned on the upper surface of the lower flange plates 6012 so as to overlap with both lower flange plates 6012. The left hand portion of the additional splice plate 6026 is coupled to the lower flange plate 6010 of the first beam 6002 while the right hand portion of the additional splice plate 6026 is coupled to the lower flange plate 6010 of the second beam 6004. The first splice connection 6020 a also comprises similar additional splice plates (not shown) which are positioned on the bottom of the upper flange plates 6010 of the two beams 6002 and 6004.
The splice plate 6024 is coupled to the upper flange plates 6010 of the two beams 6002 and 6004 via a plurality of rivets 6028, which form two columns, one column on either side of the rivets 6016 which couple the flange plates 6010 to the web plates 608 via the angled sections 6014. The additional splice plate 6026 is coupled to the lower flange plate 6012 via a plurality of rivets 6030 which form a single column adjacent the column of rivets 6014 which couple the lower flange plate 6012 to the web plate 6008.
In construction, a girder such as is shown in FIG. 6 may require structural reinforcement, for example because the splice connection between the two beams may be under strengthened. When the girder is used in the construction of a bridge, and the splice connection requires structural reinforcement, the beams may need to be propped from below, and/or the live load on the bridge may need to be restricted, in order to prevent the bridge from collapsing when removing the under strengthened splice plates to fit stronger splice plates.
While FIG. 6 shows a girder comprising two beams which are connected by a splice connection, the girder could instead comprise one single beam. In this case, the girder may require structural reinforcement if either the upper or lower flange plate is under strengthened. Again, when the girder is used in the construction of a bridge, the beam may need to be propped from below, and/or the live load on the bridge may need to be restricted, in order to prevent the bridge from collapsing when removing the under strengthened flange plate in order to fit a stronger flange plate.
Similarly, while FIG. 6 shows the two beams to have a splice connection between their upper and lower flange plates, the two beams could instead have a splice connection elsewhere, for example between their web plates.
FIG. 7 shows a girder 7000. The girder 7000 is the result of the first step of a method of structurally reinforcing a girder being performed on the girder 6000 of FIG. 6, where the splice connection 6020 a between the upper flange plates 6010 of the beams 6002 and 6004 is under strengthened.
In the first step of the method, every other row of rivets 6016 and 6028 is replaced by bolts 7002. The bolts 7002 replace the rivets 6016 and 6028, which couple the upper flange plates 6010 to the web plate 6008 (via the angled sections 6014), and the splice plate 6024 to the upper flange plates 6010, respectively. In order to ensure that the upper flange plates 6010 and the splice connection 6020 a are not weakened by the removal of the rivets 6016 and 6028, the rivets 6016 and 6028 are replaced individually so that, when one rivet is removed, a bolt 7002 is fitted in its place before the next rivet is removed. In this way, the rivets 6016 and 6028 can be removed and replaced with bolts 7002 without weakening the bridge, thereby negating the need for the bridge to be propped from below, or for the live load on the bridge to be restricted. Alternatively, one row of rivets 6016 and 6028 may be removed before bolts 7002 are fitted in their place. The rivets 6016 and 6028 are removed by drilling, and the replacement bolts 7002 are installed and tightened in accordance with the manufacturer's specifications before the next rivet is drilled out.
The girder 7000 has remaining rivets 6016 and 6028 and bolts 7002 positioned in alternate rows along the girder 7000. The bolts 7002 are tension control bolts of approximately the same diameter as the removed rivet, so that the bolts 7002 have a close tolerance fit within the hole left by the removed rivet. In this example, the bolts are M24 high strength friction grip bolts. The bolts are secured from below by a nut, as will be described in more detail with reference to FIGS. 13 and 15.
In the case where the method is used to structurally reinforce a girder of a road or rail bridge, where the bridge carries traffic such as cars or trains, this step of the method provides the advantage of reducing the amount of time the bridge needs to be closed to that traffic. This is because the rivets are replaced individually with bolts 7002 while the under-strengthened portion of the girder remains attached. Therefore, the structural integrity of the bridge is not compromised while the rivets 6016 and 6028 are replaced. In this way, the process of replacing the rivets 6016 and 6028 can be interrupted, or completed in stages, so as to allow traffic to flow when required and thus negating the need to restrict the live load on the bridge. In one example, where the bridge is a rail bridge, the process of replacing the rivets 6016 and 6028 with bolts 7002 can be completed across multiple nights during the period where trains are not running over the bridge.
Additionally, in the case where the method is used to reinforce structurally a girder of a bridge that spans a road or a railway, this step of the method provides the advantage that the bridge does not need to be propped or supported from below while the rivets 6016 and 6028 are replaced with bolts 7002. Therefore, the traffic flowing on the road or railway beneath the bridge need not be interrupted during this step of the method.
In addition to the replacement of rivets 6016 and 6028 with bolts 7002, this step of the method may include, or be preceded by, a surface preparation of the upper flange plates 6010. The surface preparation may include the application of a self-levelling compound to the top of the upper flange plates 6010.
In the second step of the method, the girder 7000 is surveyed to locate the positions of the rivets 6016 and 6028 and the bolts 7002.
FIG. 8 shows a girder 8000. The girder 8000 is the result of the third step of the method of structurally reinforcing a girder being performed on the girder 7000 of FIG. 7.
In the third step of the method of structurally reinforcing a girder, two spacer plates 8002 and 8004 are positioned on the top surface of the upper flange plates 6010. The spacer plates 8002 and 8004 are substantially identical to one another, where one plate is positioned on one side of the splice plate 6024 and one plate is positioned on the other side. The spacer plates 8002 and 8004, along with the splice plate 6024, provide a level surface upon which additional plates may be positioned.
The spacer plates 8002 and 8004 have an array of holes 8006 through the plates. The locations of the holes 8006 correspond to the locations of the rivets 6016 and 6028 and the bolts 7002 of the upper flange plate 6010. The locations of the rivets 6016 and 6028 and bolts 7002 are determined by the surveying of the beam as described with reference to step two of the method. The rivets 6016 and 6028 and the bolts 7002 have heads which form projections above the top surface of the upper flange plates 6010. When the spacer plates 8002 and 8004 are positioned on the top surface of the upper flange plates 6010, the heads of the rivets 6016 and 6028 and bolts 7002 protrude into the holes 8006 of the spacer plates 8002 and 8004 thereby to retain the spacer plates 8002 and 8004.
The holes 8006 of the spacer plates 8002 and 8004 are circular, and have a diameter which is larger than the diameter of the heads of the rivets 6016 and 6028 and bolts 7002. In this way, the heads of the rivets 6016 and 6028 and the bolts 7002 are able to protrude into the holes 8006 thereby to retain the spacer plates 8002 and 8004 without the need for additional fasteners. Furthermore, the rivets 6016 and 6028 and the bolts 7002 can be removed through the holes 8006 while the spacer plates are in place. In one example, a rivet 6016 can be drilled out by accessing the rivet 6016 through one of the holes 8006. In another example, a bolt 7002 can be unfastened by removing the corresponding nut, and the bolt 7002 can be extracted through the opening provided by the hole 8006. The spacer plates 8002 and 8004 are fabricated, including the drilling of the array of holes 8006, prior to their being transported to the girder to be strengthened.
As well as the addition of the spacer plates 8002 and 8004 at this step of the method, any gaps between the existing upper flange plates 6010 and the added spacer plates 8002 and 8004 are filled with a self-levelling compound to ensure that any areas of the corrosion of the upper flange plates 6010 are filled to provide a level surface upon which the spacer plates 8002 and 8004 can be fixed.
In the case where a plate of the girder, rather than a splice connection, requires structural reinforcement, this step of the method may not be necessary, as the plate to be strengthened should already have a level surface.
FIG. 9 shows a girder 9000. The girder 9000 is the result of the fourth step of the method of structurally reinforcing a girder being performed on the girder 8000 of FIG. 8.
In the fourth step of the method of structurally reinforcing a girder, a strengthening member, which is a strengthening plate 9002, is positioned on top of the level surface provided by the splice plate 6024 and spacer plates 8002 and 8004. The strengthening plate 9002 is shaped so as to cover exactly the surfaces of the splice plate 6024 and the spacer plates 8002 and 8004.
The strengthening plate 9002 has an array of holes 9004 through the plate. The locations of the holes 9004 correspond to the locations of the rivets 6016 and 6028 and the bolts 7002 of the upper flange plate 6010, and are thus aligned with the holes 8006 of the spacer plates 8002 and 8004. The locations of the rivets 6016 and 6028 and bolts 7002 are determined by the surveying of the beam as described with reference to step two of the method. The rivets 6016 and 6028 and the bolts 7002 have heads which form projections above the top surface of the upper flange plates 6010. The heads of the rivets 6016 and 6028 and bolts 7002 may protrude into the holes 9004 of the strengthening plate 9002 when it is in place, thereby to retaining the strengthening plate 9002.
The holes 9004 of the strengthening plate 9002 are circular, and have a diameter which is larger than the diameter of the heads of the rivets 6016 and 6028 and bolts 7002. In this way, the rivets 6016 and 6028 and the bolts 7002 can be removed through the holes 9004 while the spacer plates are in place. In one example, a rivet 6016 can be drilled out by accessing the rivet 6016 through one of the holes 9004. In another example, a bolt 7002 can be unfastened by removing the corresponding nut, and the bolt 7002 can be extracted through the opening provided by the hole 9004. The strengthening plate 9002 is fabricated, including the drilling of the array of holes 9004, prior to it being transported to the girder to be strengthened.
This step of the method provides a number of advantages over existing methods of structural reinforcement. Firstly, as the holes 9004 of the strengthening plate 9002 are large enough that the rivets 6016 and 6028 and the bolts 7002 can be removed through the holes 9004, the strengthening plate 9002 can be fixed to the girder without removing the under strengthened section of the girder (for example, the splice plate 6024 or upper flange plate 6010) and thus without weakening the bridge. Therefore, the girder does not need to be propped from below while the strengthening plate is fitted. This is particularly advantageous in the case where the girder is part of a bridge which spans a road or railway, as a propping structure will not have to be erected below the bridge and thus the road or railway will not need to be closed. This is also advantageous where the bridge spans a body of water. Similarly, the live load on the bridge need not be restricted while the strengthening plate is fitted, therefore avoiding the inconvenience and disruption which would be caused by closing the bridge to traffic.
Secondly, as the under strengthened section of the girder does not need to be removed for the strengthening plate 9002 to be attached, the structural integrity of the girder is not compromised at any step of the method. Therefore, the method can be performed in stages or interrupted at any point. In the case where the girder is part of a bridge which carries car or rail traffic, this is particularly advantageous because the method can be carried out over multiple nights meaning the bridge will not need to be closed at times when traffic is not flowing.
It should be noted that the advantages provided by the pre-fabricated strengthening plate 9002 apply equally to the pre-fabricated spacer plates 8002 and 8004 as described with reference to FIG. 8.
FIG. 10a shows a girder 1100. The girder 1100 is the result of the fifth step of the method of structurally reinforcing a girder being performed on the girder 9000 of FIG. 9.
In the fifth step of the method of structurally reinforcing a girder, the bolts 7002 are removed through the holes 9004 of the strengthening plate 9002. Each bolt 7002 is removed individually. Once a bolt 7002 has been removed, a boss 1000 is inserted into the hole 9004 in the strengthening plate 9002 left by the removal of the bolt 7002. As described previously, the boss 1000 has a through hole 1006 which is arranged to receive a bolt. Once the boss 1000 has been inserted, another bolt 1102 is inserted into the through hole of the boss 1000 and secured from below by a nut (not shown). This process is completed before another bolt 7002 is removed so as not to compromise the structural integrity of the girder. As previously described, the through hole 1006 of the boss 1000 has a diameter which is substantially the same as the hole of the upper flange plate 6010 through which the bolt 7002 was previously attached.
Once this fifth step of the method has been completed, the girder has assemblies 1104 of bolts 1102 and bosses 1000 at every other row of holes along the top surface of the girder.
As only the bolts 7002 are removed, the splice plate 6024 remains fastened to the beams 6002 and 6004 by the rivets 6016 and 6028 which were not replaced by bolts 7002 in the first step of the method. Furthermore, each bolt 7002 is removed individually, and another bolt 1102 is fitted before the next bolt 7002 is removed. In this way, the splice connection 6020 a is not weakened while the strengthening plate 9002 is attached. Therefore the strengthening plate 9002 can be fastened to the girder without removing the splice plate 6024 and thus the girder does not need to be propped from below nor does the live load on the bridge need to be restricted.
FIG. 10b shows an exploded view of the girder 1100. FIG. 10b shows a section of the girder which is not part of the splice connection 6020 a. FIG. 10b shows the upper flange plate 6010 being coupled to the angled section 6014 via rivets 6016. There are also vacant holes 1106 in the upper flange plate 6010 which are left by the removal of the bolt 7002. The spacer plate 8002 is shown having holes 8006 which are aligned with the location of the rivet and bolt holes in the upper flange plate 6010. The strengthening plate 9002 is shown also having holes 9004 which are aligned with the holes 8006 of the spacer plate 8002. The boss 1000 is arranged to be received in a hole 9004 of the strengthening plate 9002, and the bolt 1102 is arranged to fit within the through hole 1006 of the boss 1000. The through hole 1006 of the boss has substantially the same diameter as the holes 1106 in the flange plate 6010 which were previously occupied by rivets 6016.
As previously described, the surface of the flange 1004 of the boss 1000 is roughened so as to provide a friction grip with the upper surface of the strengthening plate 9002. The upper surface of the strengthening plate 9002 may also be roughened so as to cooperate and with the roughened portion of the boss 1000. In this way, the boss 1000 will be engaged by the surface of the plate 9002 so that it cannot rotate within the hole 9004. This is particularly advantageous when a bolt 1102 is fitted within the boss 1000 as the rotational movement of the bolt 1102 will not cause the boss to rotate.
FIG. 11 shows a girder 1200. The girder 1200 is the result of completing all of the steps of the method of structurally reinforcing a girder. The girder 1200 has a number of additional bolts 7002 which strengthen further the coupling between the strengthening plate 9002 and the girder 1200. In this step of the method, the holes 9004 which do not host a boss 1000 and bolt 1102 assembly 1104 are optionally filled with metal repair putty, or a similar substance, and levelled off prior to the application of paint onto the girder.
FIGS. 12 and 13 show cross sectional views of a part of the girder which is not part of the splice connection 6020 a.
FIG. 12 shows the girder 6000 of FIG. 6, before any steps of the method of structurally reinforcing a girder have been performed. FIG. 12 shows the upper flange plate 6010 having rivets 6016 which couple the upper flange plate 6010 to the angled sections 6014. The angled sections 6014 are coupled to the web plate 6008 via a rivet 1202.
FIG. 13 shows the girder 1200 of FIG. 11, after all steps of the method of structurally reinforcing a girder have been performed. FIG. 13 shows the girder 1200 therefore having the upper flange plate 6010, the spacer plate 8002, and the strengthening plate 9002. The holes 8006 of the spacer plate 8002 and the holes 9004 of the strengthening plate 9002 are aligned so as to form a through hole. The rivets 6016 have been removed and replaced with bolts 1102, which are fastened through the through holes and secured from below by nuts 1302.
Referring back to the fourth step of the method as described previously, the holes 8006 of the spacer plate 8002 and the holes 9004 of the strengthening plate 9002 have diameters which are larger than the diameters of the heads of the bolts 7002. This is because the bolts 7002 are extracted through the holes 8006 and 9004. The holes 8006 and 9004 shown in FIG. 13 are therefore wider than the heads of the bolts 7002 and 1102.
The collar of the boss 1000 has a height which is equal to the combined thickness of the spacer plate 8002 and strengthening plate 9002. The flange of the boss 1000 engages the top surface of the strengthening plate 9002 via the roughened portion of the flange, thereby to inhibit rotation of the boss 1000 when the bolt 1102 is fitted. Additional bolts 7002 are fitted towards the edges of the girder; as the bolts do not pass through as many plates they are not as long as the bolts 1102. The bolts 1102 and 7002 are arranged to secure the spacer plate 8002 and strengthening plate 9002 to the girder via the same coupling points that were previously occupied by the rivets which secured the flange plate 6010 to the girder. In this way, the strengthening plate 9002 is secured to the girder without removing any existing sections of the girder.
FIG. 13 also shows the boss 1000 providing a through hole which receives the bolt 1102. The boss 1000 is required to line the holes 8006 to 9004 and thereby narrow the diameter of the holes to the appropriate diameter so that the bolts 1102 form a close tolerance within the through hole of the boss 1000.
FIGS. 14 and 15 show cross sectional views of a part of the girder which is part of the splice connection 6020 a.
FIG. 14 shows the girder 6000 as in FIG. 6, before any steps of the method of structurally reinforcing a girder have been performed. FIG. 14 shows the upper flange plate 6010 having rivets 6016 which couple the upper flange plate 6010 to the angled sections 6014. The angled sections 6014 are coupled to the web plate 6008 via a rivet 1202. The flange plate 6016 is also coupled to the splice plate 6024 and the additional splice plate 6026 via the rivets 6028.
FIG. 15 shows the girder 1200 as in FIG. 11, after all steps of the method of structurally reinforcing a girder have been performed. FIG. 15 shows the girder 1200, having the strengthening plate 9002 fastened to the girder. Referring to the steps which were performed to transform the girder 6000 into the girder 1200, the rivets 6016 and 6028 were firstly removed and replaced by bolts 7002 (as described in the first step of the method with reference to FIG. 7). The strengthening plate 9002 was then positioned on top of the splice plate 6024 (as described with reference to FIG. 9). The bolts 7002 were then removed and extracted through the holes 9004 and a boss 1000 was inserted into the holes 9004 so as to narrow the holes and restore the through hole to a diameter appropriate to receive the bolts 1102 (as described with reference to FIG. 10). The bolts 1102 were secured from below using the nuts 1302. In this way, the splice plates 6024 and 6026 remain coupled to the upper flange plate 6010 and the additional splice plate 6026 while the strengthening plate 9002 is fastened to the girder.
It will be understood that the invention has been described above purely by way of example, and modifications of detail can be made within the scope of the invention.
In particular, although the invention has been described with reference to the structural reinforcement of a splice connection, the invention could also be applied to the structural reinforcement of any other plate of a girder, for example a flange plate. In this case, the strengthening plate is attached directly to the flange plate without the need for spacer plates.
Similarly, while the invention has been described with reference to the use of such girders in bridges, the invention could also be applied to other structures which incorporate girders, such as office buildings.
Furthermore, while the boss has been described as being arranged to receive a bolt via a friction or close tolerance fit, where the bolt is secured by a nut, the boss could also be arranged with a screw thread interior of the through hole where the bolt is threaded through the through hole.
Each feature disclosed in the description, and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.
Reference numerals appearing in the claims are by way of illustration only and shall have no limiting effect on the scope of the claims.
All publications, patents and patent applications mentioned in this specification are herein incorporated in their entirety by reference into the specification, to the same extent as if each individual publication, patent or patent application was specifically and individually indicated to be incorporated herein by reference. In addition, citation or identification of any reference in this application shall not be construed as an admission that such reference is available as prior art to the present invention. To the extent that section headings are used, they should not be construed as necessarily limiting. In addition, any priority document(s) of this application is/are hereby incorporated herein by reference in its/their entirety.

Claims

What is claimed is:

1. A boss for assembly with a part, the boss having a roughened portion for engaging a face of the part.

2. A boss according to claim 1, wherein the boss comprises a flange.

3. A boss according to claim 2, wherein the roughened portion is a roughened surface of the flange.

4. A boss according to claim 3, wherein in use the flange is arranged to abut the face of the part in use thereby to engage the face of the part via the roughened surface.

5. A boss according to claim 1, wherein the roughened portion comprises at least one groove.

6. A boss according to claim 5, wherein the at least one groove comprises at least one of: a spiral groove; a circular groove; and/or a radial line groove.

7. A boss according to claim 1, wherein the roughened portion is formed by machining.

8. A boss according to claim 1, wherein the roughened portion has a knurled surface.

9. A boss according to claim 1, wherein the roughened portion has a surface roughened to a surface preparation grade of between Sa 1 and Sa 3, preferably between Sa 2 and Sa 3, and more preferably Sa 2½.

10. A boss according to claim 9, wherein the surface is roughened by abrasive blasting, preferably sandblasting.

11. A boss according to claim 1, the boss having a through hole, preferably wherein the through hole is arranged to receive a bolt.

12. A boss according to claim 11, the boss having a collar, preferably wherein the collar surrounds the through hole.

13. A boss according to claim 1, wherein in use the boss is inserted into the part.

14. A boss according to claim 1, wherein the engaging of the boss with the face of the part inhibits relative movement between the boss and the part.

15. An assembly, comprising a boss according to claim 1, and a bolt, preferably wherein the bolt is a tension control bolt, and preferably wherein the bolt is arranged to fit within the boss via a tolerance fit.

16. An assembly, comprising a boss according to claim 1, and a part, preferably wherein the part is a strengthening member, and more preferably a strengthening plate.

17. An assembly, according to claim 16, wherein said part has at least one through hole arranged to receive a portion of the boss.

18. An assembly, according to claim 16, wherein said part has a roughened portion arranged to engage with the roughened portion of the boss, preferably thereby to inhibit relative movement between the boss and said part.

19. An assembly, according to claim 18, wherein the roughened portion of said part is roughened to substantially the same degree as the roughened portion of the boss.

20. A structure incorporating the assembly of claim 15, preferably wherein said assembly is coupled to a girder.

21. A method of structurally reinforcing a girder, the method comprising:

determining a section of the girder that requires strengthening; and

fastening to the girder a strengthening member without removing said section.