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悬索桥Cable Stayed Bridges.pdfCABLE STAYED BRIDGE
ylonsandstays
Erection of each bridge may be summarised as follows: placing of the main beams on temporary propping from the bed of the Rhone concreting of the running surface and the pylon stressing of the stays
GB/T 41993-2022 家用和类似用途的声音信号装置Operationaldate Tune1987
8.4Railwaybridges
Characterisics
Operational date 1968
CABLE STAYED BRIDGES
Fig.8.54.Bridge over the Neckar at Unterturkheim
Fig 8.55.Anchorages for stays and run over the pylon heac
Pylonandstays The pylon, with two vertical arms, is built into the deck, the
ylon, with two vertical arms, is built into the deck, the
whole resting on reinforced concrete piers (Fig 8.57).The Section at the foot is 1 52m × 1 52 m, increasing towards the head to make room for four anchorage housings and transverse prestress (Fig8.58) The stays, each made up of 79 parallel wires of 7 mm dia., are designed to take up only the loads due to traffic Connection of each cable to the deck is through twelve bars of 32 mm dia
CABLE STAYED BRIDGES
Fig.8.59 Pretoria Aqueduct
Operational date 1979
Fig.8 60.Aqueduct and pedestrian walkway over arwon
853. Canal bridge over the Neto.* Italy,1973
In the winter of 1973, the four centre bays of an aqueduct with multiple 20 m spans, crossing the River Neto in Italy, were washed away by an exceptional flood.The failure of the water supply to the large agricultural zone served by
this aqueduct called for rebuilding to be as swift as possible A solution crossing the bed of the watercourse in one single span quickly became the obvious answer, largely due to the inaccessibility during the course of the work
General design
Ihe stayed part of the deck consists of a steel box section, 1735 m deep and 3.70 m wide.It is stiffened around the perimeter and provided with wind bracing on theupper face. The anchorages are fixed outside the side walls. Watertightness between.the existing reinforced concrete part and the stayed part, in steel, is ensured by a Sika joint.
iecthion 1735 m deep and 3.70 m wide. It is stffened around the perimeter and provided with wind bracing on the upper face. The anchorages are fixed outside the side walls. Watertightness between.the existing reinforced concrete part and the stayed part, in steel, is ensured by a Sika joint.
Pylons and stays
CABLE STAYED BRIDGES
Fig.8.61.Aqueductover the Neto
Characteristics Total length of the structure 16760 m ●Main span 81·60 m Width of the water channel 3.70 m :Depth of thechannel 1735m
Fig.8.63 Erection stages
Fig. 8.64 Aqueduct and footbridge over the Bremdarten
CABLE STAYED BRIDGES
Fig.8.66.Aberfeldy Footbridge geometry
B.54.Agueduct and footbridge over theHeuss at Bremgarten,Switzerland,1975 The structure is shown in Fig. 8 64
General design
Fig. 8.67. The Aberfeldy Footbridge
Operational date Completed in 1980
E8.68 AberfeldyFootbridge deck arrangeme
F868AberfeldyFootbridgedeck arrangement
braferences
9. Model tests of a cable stayed bridge with a slender concrete deck
CABLE STAYED BRIDGES
213 9.3. Test results 217 214 9.3.1. Preliminary tests (test on half of the 214 bridge) 217 9.3.2. Load disposition near cables 217 9.3.3. Principal tests 217 215 9.3.4. Bearing capacity tests 220 215 9.3.5. Dynamictests 220 215 216 9.4. Conclusions 221 216 Reference 224
MODELTESTS
Fig 9.1 Main characteristics of the tesi
CABLE STAYED BRIDGE
Fig.93 Anchorage of the stays
9.12.Measuring equipment In order to be able to follow the development of the internal forces,the support reactions and the displacements in a precise manner,measuring instruments were placed at a total of 400 points The strains on each cable,the deck anc measurements of the deflection of the deck and the pylon
MODEL TESTS
Fig.9.4.Staticalsystemandjointatmidspan
ig.95 Concreteblockstosimulatedeadweighi
were carried out with electrical transducers. All of the eight supports were equipped with pressure cells in orderto neasure the reactions
9.2.1.Preliminarytests First, both tunconnected bridge halves were load tested as preliminary investigations only A point load of 3kN (Fig 9.6) was applied at different points on the deck along the bridge axis This corresponded to a service load of 1200 kN on the prototype. A force couple was applied to the bridge deck in order to determine the torsional stiffness as shown in Fig 9.7
9.2.2Concentratedloadsnearcables It is important to know how a concentrated point load near a cable is distributed among that cable itself and those near it for the economical design of a cable stayed bridge with a slender deck Therefore, a concentrated load of about 0.6 kN
CABLE STAYED BRIDGES
wasapplied toa supporting plateapproximately9 cmlong directly beside the cables (Fig 9.8), which in reality corresponded to an axle load of approximately 240kN.
9.23 Distributed load
For these tests, an equivalent load of 4.5 kN/m on the prototype was assumed, which corresponded to a uniformly
Fig 9.6 Point load for preliminary tesi
Fig.g.7.Load arrangement for torsional preliminary test
weighing 540 kN. These loads were applied to the model using a total of 29 hydraulic jacks, spaced 0.64 m apart Distributionbeamswereplaced underthejackson neoprene pads in order to guarantee as uniform a load distribution as possible. As the bridge model had an available total width of0.7m,a linearloadof0.7m×45kN/m²=3.15kN/m was produced, ie.a maximum press force of 0.64m x315 kN/m2kN. Variousload intensities(15g,1.0q,0.75g,05g)with different symmetric and asymmetric load placements (entire bridge, middle section, edges)were investigated The chosen load configurations as well asthe limit conditions for the pylon and the expansion joint are shown in the graphical presentation of the measured results
.8.Concentrated point load near a cable
Figs.9 9 and 9 10. Distributed load arrangement applied by jacks
93.Testresults
MODEL TESTS
It may be seen that only 22 or 24%, respectively, of the applied load is taken up by the affected cable pair when this load is applied in the first quarter of the main span (Fig 9 11(c) or in the middle of the lateral span (Fig 9.11(d) If the load is placed on the end of the cantilever (Fig 9.11(e) some 47% of it is taken up by the longest cable, as a loading of the second half of the bridge cannot take place due to the joint. Similar results were obtained for a strain in torsion (Fig 9.11(f), (g) and (h) Thus it may be seen that a slender deck is itself capable of distributing loads over a large number of cables.
9.3.3 Principal tests
Fiq 9 11.Results of preliminary tests
Fig.912 Results of the principal tests
CABLE STAYED BRIDGES
whichcorrespondistoavalueof 36mmorL/290when expressed in terms of 1.Og.The correspondence between measured and calculated values was also less good, due to a slight upliftof the support and an overestimate of thepylon stiffness.It may be seen once again that for large cable stayed bridges the serviceability state should be calculated for the expected and not on hypothesised load intensity and placement
93.4Bearing capacity tests
9.3 5. Dynamic tests
9.3.5.1 Tests on a freely oscillating system The results of the oscillation tests are presented in Table 9 2 and Figs 9.16 and 9.17; these take into account the similitude lawsconcerningfrequency The values in parentheses refer to the properties of the actual structure which served as a reference for the model For the first natural frequency, the measured and calcul ated values are very similar (155Hz and 1.58Hz for the fixed joint, 1.53 Hz and 1.44 Hz for the expansion joint) The deck thickness of the model as well as the hanging
93.5.2.Test with constrained oscillations for the investigation of the physiological effects due to traffic In this test, the dynamic displacement of the structure caused by a lorry weighing 250 kN at various speeds was determinedexperimentally Two measurement series were carried out, the first without wooden batten in order to simulate a good driving
Table9.2.Resulis ofvibrationtesis
MODEL TESTS
Fig.9.16.Natural frequency in bending (fa)and torsion (f)
94 Concusions
Ihe tests have proven conclusively that cable stayed bridges with very slender concrete decks and closely spaced cables are perfectly capable of satisfying all the criteria of serviceability and safely The ultimate bearing capacity depends mainly on the strength of the stays,whereas the deck itself is in general not critical with respect to
CABLE STAYED BRIDGE
Fig.9.18.Testswithsmooth surface
7.9.18.Testswithsmooths
9.19.Tests with rough surface (wooden batten)
GB／T 51347-2019 农村生活污水处理工程技术标准（完整正版扫描）static instability (buckling) The required thickness of the deck results, in the first place, from the longitudinal and ransverse bending moments as well as,although of lesser importance, from the normal forces introduced by the
cables. These forces reach their maximum values in the section near the pylon and therefore for large spanned bridges of this type it may be reasonable to increase the
able 9.3.Results of the dynamic tests withconstr scillations(convertedforprototvpe)
MODEL TESTS
ABLE STAYED BRIDGES
Walther R.Ponts haubanes tablier mince. IBAP,Ecole Polytechnique Federale de Lausanne (EPFL)
Photographic credits
Photographic credits
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