Classifications

• • E—FIXED CONSTRUCTIONS
  • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
  • E01D—CONSTRUCTION OF BRIDGES, ELEVATED ROADWAYS OR VIADUCTS; ASSEMBLY OF BRIDGES
  • E01D21/00—Methods or apparatus specially adapted for erecting or assembling bridges
  • E01D21/10—Cantilevered erection

Definitions

• the present invention relates to an arrangement for the casting in sections of a prestressed concrete bridge in accordance with the cantilever construction method, comprising a cantilever construction carriage (casting carriage) with a front jib and front and rear runners rolling on a rail track with preferably dualtraversing rails on a previously cast bridge section or bridge pier, having two rear runner units each of which comprises two runner sets co-operating with the rails on the same side of the rail track and equipped to abut the top or underside of the said rails, every rear runner unit comprising a frame to which the rear part of the casting carriage is attached.
• Casting arrangements of the said type have been previously known, and such an arrangement is e.g. described in Patent 138855 which is the applicants property.
• the anchoring frame between the rear end section of the casting carriage and the runner unit is made rigid and incapable of being displaced longitudinally and to the sides. Since the rear end section of the carriage is anchored to the frame it is also not possible to displace (e.g. with a view to adjustment) the end section of the carriage in the lateral direction. The required lateral adjustments must therefore be carried out direct on every one of the formwork panels.
• the bearing frame between the rear end section of the casting carriage and the runner unit as a parallelepiped, with joints in all four corners and with the joint axes extending in the longitudinal direction of the rail track, the frame being capable of being swung sideways about its two lower joint axes.
• the bearing frame comprises preferably two parallel supports and a horizontal crossbeam at the top, the height of the beam being variable in relation to the support.
• the crossbeam has suspended tie-rods for attachment to the cast bridge deck so as to relieve the rear runners.
• a tensioning device or jack adjustable in height to be fitted between the underside of the casting carriage's rear section and the cast section of the concrete bridge and for the rear tie-rods of the carriage or/and tensioning device to be adjusted in such a way that the tie-rods are stressed at least 10% above the calculated maximum load.
• the latter embodiment has the advantage that load-dependent displacement in height of the front section of the carriage and the formwork is avoided while at the same time the tie-rods subject to tension are relieved as the load acting on the front section of the carriage increases, which is the opposite to what has been the case so far.
• the arrangement in accordance with the invention is provided with a tensioningdevice or jack capable of being regulated in height and possibly equipped with a force measuring device, this being provided between the rear bearing frame supports under the rear section of the carriage, extending downward to about the lower ends of the runners and extendable down to the top surface of the concrete deck.
• cantilever construction proceeds in two opposite directions from the pier and use is made of an arrangement comprising two cantilever construction carriages (casting carriages) each carrying its formwork and capable of running on rails located on a previously cast section of the bridge.
• Each casting carriage can be subdivided into a front section comprising a jib and a rear section.
• the arrangement also comprises a system of bars for releasable coupling of the two front sections of the carriages when the latter are at a distance from one another in the longitudinal direction facing away from one another in symmetrical fashion.
• An arrangement of this type is described in the said Patent 138 855.
• the system of bars comprises a stiff frame so designed that the relative position of the carriages (to be precise the front sections of the carriages) cannot be changed and that the carriages are always in line with one another.
• Such a design is hardly efficient when it comes to casting a curving bridge.
• the known arrangement does not enable casting along curves since the carriages are separate from one another and can move independently.
• a further intention of the present invention consists in bringing about an arrangement enabling the casting in sections along curves - starting from a bridge pier - it being possible to adjust the relative position of the carriages following their location on the pier head.
• the system of bars comprises two roughly level coupling frames which together with the carriages in the coupled state extend between the end sections of the carriages at a mutual distance which substantially corresponds to the distance between the traversing rails (track gauge) and link the carriages with one another in an adjustable manner, inasmuch as each coupling frame has an upper and a lower basically horizontal flange of adjustable length.
• the flanges can be linked with one another by means of diagonal threaded tie-rods of adjustable length and they can be so designed as to be capable of telescoping into one another.
• the advantage of the said design consists in the fact that the carriages (the front sections) can be angled in relation to one another in order to match the curvature of the bridge.
• Another advantage consists in the fact that the same coupling frame can be used for different bridge constructions inasmuch as this can be adapted to the local conditions.
• Fig. 1 is an elevation partly in section of a previously cast bridge section with the arrangement in accordance with the invention
• fig. 2 is a front section of the arrangement and a section of a support bridge viewed in the direction of the arrows II-II in fig.
• fig. 3 is an end section which on a larger scale shows detail A of fig. 1 viewed in the direction of arrow III comprising an embodiment of the invention
• fig. 4 is an end section corresponding to fig. 3 but showing detail A viewed in the direction of arrow III with a different embodiment of the invention.
• Fig. 5 shows an arrangement for casting bridge sections starting from a previously cast bridge pier of the kind described in the applicants' Patent 138 855
• fig. 6 illustrates the casting method at a later stage of the work
• fig. 7 shows an arrangement of the kind presented in figs. 5 and 6 but carried out in accordance with the invention
• fig. 8 is a lateral section or elevation of the same arrangement as shown in fig. 7 but drawn in a larger scale.
• Figs. 1 and 2 show a recently cast bridge section 1 which may be the top of a bridge pier and on which are placed paralleltraversing rails 2.
• a casting carriage 3 with a front jib 4 and lower and upper runners 15 and 5 respectively, which co-operate with the traversing rails 2.
• To the front end of jib 4 are attached supporting tie-rods 6 extending downward, to the lower ends of which are secured two lower traversing rails 7 freely extending backward, the mutual distance between which is considerably smaller than the width of the inner formwork (see fig. 2).
• the rear section of traversing rails 7 is rollably suspended in brackets 8 with runners 9 so that the rails 7 can be advanced together with carriage 3.
• the front section of casting carriage 3 is designated 22 and the rear section 23.
• the traversing rails 7 support a formwork carriage 10 with inner formwork 11,12,13.
• the carriage has runners 14 and can be displaced forward and rearward on the rails 7.
• Fig. 2 shows that the cross-section of the bridge sections 1 is roughly box-shaped, with the side walls and the top of the box being cast between the inner formwork 11,12,13 and the outer formwork 16,17.
• the carriageway of the bridge is designated 18.
• the formwork has vertical sections suspended from hangers 20 and 21 respectively.
• the -inner formwork 11,12,13 comprises a steel construction 11,12 arranged on the said formwork carriage 10 so that it can be transported along the rails 7 and displaced irrespective of the outer formwork 16,17 connected with the same carriage 3 as well as with the aid of the schematically drawn tie-rods 19.
• Fig. 1 does not show the outer formwork.
• Fig. 1 shows that a support 8 is provided at the front end of the last section cast with a view to supporting the rails 7. The required reinforcing work has been carried out at an earlier stage when the insides of the outer formwork and the inner formwork were free, and fig. 1 shows carriage 10 for the inner formwork advanced to such a point that it is immediately above the outer formwork 16,17 (not shown in fig. 1).
• Fig. 3 shows detail A in figs. 1 and 2 seen from the back (or from the front).
• the traversing rail track 2 comprises two rails 2a and 2b arranged at a distance from one another, which are secured to the previously cast bridge deck 18 with the aid of anchoring units 34 and anchor bolts 35.
• the rear section 23 of casting carriage 3 comprises inter alia a longitudinal girder 33, a frame unit 36 and a horizontal crossbeam or end beam 30 which are rigidly linked with one another.
• Two supports or suspended beams 28,29 are suspended, in a rotatable manner and at a distance from one another, with the aid of pivot bolts 31,32 from crossbeam 30, with their lower ends connected with trolley yokes 24,25 so as to be capable of being swung to and fro, the said trolley yokes having from the rear the appearance of an inverted U with the vertical legs 37 bearing at their lower ends the previously mentioned runners 15a,15b.
• the distance between supports 28,29 substantially corresponds to the distance between the rails 2a, 2b.
• the runners 15,15a normally roll along the underside of the flanges of rails 15a,15b.
• a tie-rod 38 for attachment to bridge deck 18 hangs from the end sections of crossbeam 30.
• the tie-rods are threaded and provided with nuts 39,40.
• the joints 26,27,31,32 constitute a parallelepiped.
• the supports 28,29 will be in the initial position, i.e. they will be substantially vertical as shown in fig. 4.
• the supports 28,29 will be subject to tension owing to the weight of the front section 22.
• the lateral position of rear section 23 may if required be fixed with the aid of devices not shown in fig. 3.
• the formwork elements are suspended at the front of the casting carriage (roughly at 4,6) and roughly at the edge of the preceding cast bridge section.
• the rear end section 23 of the casting carriage with crossbeam 30 is displaced sideways, with the aid of the arrangement shown in fig. 3. from the position shown in fig. 4 to the position shown in fig. 3. e.g. to the left as shown in fig. 3, the formwork panels at the front of the casting carriage will move correspondingly in the opposite direction, i.e. to the right, since in this case the casting carriage will pivot an axis located at a point between the upper runners 5 ( see fig. 1) .
• Fig. 4 corresponds substantially to fig. 3.
• a tensioning device 42 is suspended in a bracket 41, the said tensioning device extending in its normal, unloaded state nearly down to the anchoring plates 44 for rails 2a, 2b but which are also capable of serving as a base for the device 42.
• the tensioning device is shown with a threaded spindle 43 and can with the aid of the latter be made to abut the concrete deck 18 so that the tensioning device is clamped between the longitudinal girder 33. i.e. the rear section 23 of the casting carriage, and the concrete deck.
• the tie-rods 38 are located in position between crossbeam 30 pertaining to this section and bridge deck 18.
• a tensioning jack with a force indicator as shown at 45.
• a mechanical tensioning device 42 use may be made of a hydraulic jack with a cylinder (42) and a ram (43).
• the tensioning device 42,43 is adjusted in height so that the longitudinal girder 33 lies roughly horizontal . Then the tie-rods 38 are tensioned so as to achieve a prestress which is about 10% higher than the effective loading. Application of this stress ensures that the extension of tie-rods 38 is taken up already when adjusting and releasing the casting carriage and not as used to be the case, when the extension came about gradually in the course of time as the casting process proceeded.
• the advantage of the design consists in the fact that the downward deflection at the front of casting carriage 3 is considerably reduced. In addition it offers greater safety against total damage.
• the tie-rods 38 take up all anchoring forces at the rear as the casting proceeds.
• the arrangement 42,43 according to fig. 4 is preferably not in the same cross-sectional plane as the arrangement in accordance with fig. 3.
• the tensioning arrangement in accordance with fig. 4 can be used with casting carriages equipped with the arrangement in accordance with fig. 3 but also with casting carriages having a rigid rear runner suspension, e.g. of the type shown in Patent 138855.
• Figs. 5 and 6 illustrate stepwise casting of bridge sections from a previously cast pier 101 using two casting carriages of the type described above, and the figures show an arrangement as discussed in the above Patent 138855.
• fig. 5 101 designates the top of a previously cast pier serving as an anchoring section for the bridge spans to be cast, which bear traversing rails 102.
• On pier 101 are mounted the front sections 122 of two casting carriages 103 each with its own front jib 104.
• the formwork carriage for the inner formwork and its lower traversing rails are not shown.
• the two casting carriage sections 122 are linked with the aid of a rigid coupling frame 121, and a part of the rear end sections 123 of the carriages has therefore been removed in order to enable such coupling without the two carriages together taking up more space than is available on top of pier 101.
• the first bridge sections already cast are designated 101a and 101b in fig. 6.
• Fig. 6 shows the situation after removal of coupling frame 121.
• Each carriage 103 has a front support leg 161, which during erection supports the front section 122 of the carriage on the previously cast section (via traversing rails 102).
• Figs. 7 and 8 show a coupling frame 150 designed in accordance with the invention.
• the coupling frame comprises an upper flange which consists of two flange sections 151,152 longitudinally displaceable in relation to one another and capable of being locked with the aid of bolts 155 which pass through holes 156 in the parts 151,152.
• the lower flange comprises in corresponding manner two flange sections 153,154 designed in the same way.
• pivot bolts 162 for fasteners 159 serving to anchor threaded tie-rods 157,158 which link the diagonally opposite corners or fasteners of the flanges with one another.
• supports as indicated at 160 but these are strictly speaking not necessary since at the erection stage the flanges are anchored in adjacent rigid rear sections 122 of the casting carriages 103.
• both the diagonal rods and the flanges are designed with a view to modifying the length.
• the two coupling frames 150 When erecting the carriages for casting curved bridge sections the two coupling frames 150 are so fitted that the frame at the outer side of the bridge is longer as a result of the fact that the carriages are angled in relation to one another.
• the two coupling frames are in plane 50 as are the side walls of the casting carriage, see fig. 2, i.e. virtually straight above the traversing rails.
• the frame lengths and as a result the relative position of the casting carriages can be adjusted if required whereas previously it was not possible to adapt the carriages to the curvature of the bridge prior to separation from one another of the carriages, i.e.

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• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Bridges Or Land Bridges (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

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ID=19886596

Family Applications (1)

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Cited By (14)

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Citations (4)

• 1982
  • 1982-06-01 NO NO821820A patent/NO150289C/no unknown
• 1983
  • 1983-06-01 DE DE19833390026 patent/DE3390026T1/de active Granted
  • 1983-06-01 WO PCT/NO1983/000020 patent/WO1983004274A1/en active Application Filing
  • 1983-06-01 NL NL8320159A patent/NL8320159A/nl unknown
  • 1983-06-01 GB GB08400112A patent/GB2129854A/en not_active Withdrawn
  • 1983-06-01 JP JP58501782A patent/JPS59501465A/ja active Granted

Patent Citations (4)

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