A CRITICAL ANALYSIS OF THE DONGHAI BRIDGE, SHANGHAI, CHINA

Proeedings of Bridge Engineering Conferene 008 3 April 008, University of Bath, Bath, UK A CRITICAL ANALYSIS OF THE DONGHAI BRIDGE, SHANGHAI, CHINA Ci Song University of Bath Abstrat: This paper provides a ritial analysis of the Donghai Bridge whih inludes aesthetis, loading, struture, onstrution, durability, vandalism, future hanges and improvements. It gives the idea how to look a bridge from an aestheti view and also how a bridge is atually built. Espeially for a rossing-sea projet, the speial onstrution methods are designed due to harsh site onditions and limited onstrution period. Keywords: rossing-sea projet, able-stayed bridge, prefabriation Bakground information Donghai bridge is loated at north of Hangzhou Bay in East Sea of China. It an also be alled as the East Sea Bridge. By being one of the three ollaboration works, part of Shanghai international shipping enter, Donghai Bridge is the onnetion in Yangtze Delta vest area (i.e. Shanghai City, Jiangsu Provine and Zhejiang Provine). It servies for the overland transport of ontainers of Yangshan Deep Water Port of International Shipping Center and it offers water supply, eletriity supply and ommuniations, et. The Yangshan Deep Water Port is China s first free-trade port upon its ompletion in 00. The Donghai Bridge starts from the Luhao Port in Shanghai and goes aross north area of Hangzhou Bay, and finally, reahes the small Yangshan Island in Zhejiang Provine. The loation of site is shown in Fig. Donghai Bridge is the first truly offshore bridge in hina s bridge history and it is also the longest ross-sea bridge in the world. The total ost of projet is about.8 billion CNY (.64 billion USD). The overall length of Donghai Bridge is 3.5km and width of the bridge is 3.5m. It is designed to be a motorway bridge whih arries 6 lanes of traffi. This inludes 3.7km onshore setion (Luhao Port, Shanghai), 5.3km offshore setion (between Luhao Port and Big Tortoise Island) and 3.5km sea embankment inluding another able stayed bridge Kezhushan Bridge (between Big Tortoise Island and Kezhushan Island). The Kezhushan Bridge is not analyzed in this paper. Figure : Loation of Donghai Bridge In Marh 00, the deep water port projet in Shanghai is formally agreed by the nation. After one year, in Marh 00, the State Counil examined and passed the feasibility researh on the first phase of this projet. The onstrution ommened in June 00 and ontinued for three and half years. In De 005, Donghai Bridge was ompleted together with the deep water port (Phase I) and opened to traffi. Ref. [] Innovative anti-orrosion tehnique is used to prevent the marine orrosion in Donghai Bridge. So the bridge is designed to stand for 00 years. Aesthetis of the Bridge The aesthetis of bridges plays a very important role in the overall suess of building a bridge. Fritz Leonhardt, the most famous bridge engineer of the 0 th

entury, defined ten aspets of aesthetis of bridges, whih are used to analyze the aestheti design of Donghai Bridge.. Fulfillment of Funtion The struture of Donghai Bridge is very simple and learly shown to the publi. The main span of the bridge is a able-stayed bridge with double pylons. The dek is held by groups of ables onneting to two pylons. Two inverse Y- shaped massive pylons give onfidene in stability of the bridge. Cable-stayed bridges are very often hosen for large span rossing-sea projets due to its simple onstrution and learly fulfillment of funtions. Simpliity leads to the suessful design of funtion of Donghai Bridge. beause different thikness of dek is used for the auxiliary navigation span whih is shown in Fig 3. This an be overed by varying the box girder setion thikness internally, but it is very ineffiient and huge waste of materials.. Proportions Proportions have signifiant effet on designing bridges. All balanes between masses and voids, depths and spans need to be ahieved. As shown in Fig, Donghai Bridge displays exellent proportions aross the sea. The masses and voids are perfetly balaned. The height of pylons also mathes the maximum span. The thikness of dek is just orret to the breath of piers. Everything are balaned and perfetly fit to eah other. All these balanes give an impressive aestheti view of the bridge. Figure 3: Various thikness of dek at auxiliary navigation spans.4 Refinements There are only two piers at eah support aross the width of dek so that no views of opaque barrier will appear from oblique angles. Not muh more refinements have been done to reate the aesthetis of Donghai Bridge. For the improvement of the refinements to the bridge, tapering piers an be used rather than a straight one..5 Integration into the Environment As shown in Fig, Donghai Bridge is a able-stayed bridge whih gives a wonderful pleased view aross a wide span of water. Donghai Bridge has a great suess in integrating its own struture into the surrounding features and environment..3 Order Figure : Proportions of bridge Some able-stayed bridges may have potentially ugly view from oblique angles due to the rissrossing of ables. This problem only happens when two or three planes of ables were designed to support the struture. In order to prevent the rissross ables, Donghai Bridge is designed to have only one plane of ables. But the single-plane system redues the torsional strength of the struture. So the dek needs to be substantially stiffened to take the additional torsion and this result very deep dek whih is ineffiient. To overome this problem, an inverse Y-shaped tower is used instead of just one vertial pylon. The top of the inverse Y-frame is made vertial and all ables attahed along this part of the pylon with a fan onfiguration. The fan onfiguration of ables gives most effiient effet to the struture. Therefore, this system gives maximum benefit for a single plane of ables while unpleasant oblique views avoided. For a good ordered bridge, there should be non-stops or an unbroken line as eyes moving through the entire length of bridge. The Donghai Bridge fails in this field.6 Surfae Texture Surfae texture is very important in bridges, but often ignored. Ref. [] Same as all other onrete bridges, the surfae texture of Donghai Bridge is a matt finish. Rough finishing is very often used in piers, but in this ase, most strutural elements are prefabriated and have muh finer finishing than ast in-situ. Therefore, a signifiant aestheti appeal has been added to Donghai Bridge by its smooth finishing..7 Colour and Charater Blak ables have been used in Donghai Bridge to aentuate the ertain ables in day times. Beause all ables of bridge are in blak, so they disappear at night. Only the dek and two pylons are high-lighted with blue artifiial lighting at night. Contributing with two lines of lamp lighting, the bridge is just like a dragon floating on the sea when looking from far away.

γ =.5 (ULS ombination ) γ =.0 (ULS ombination ) f 3 The dead load of dek = Wd. γ. f 3 γ =497.4 kn/m.9 Complexity Figure 4: Night sene of bridge The main reason for designing a able-stayed bridge is beause simple onstrution an be arried out over a relatively long span. There is not muh omplexity in the Donghai Bridge. The most omplex setion is the main navigation span whih has two inverse Y-shaped pylons with stays ables attahed at top..0 Inorporation of Nature From bird s eye view, Donghai Bridge is urved in an S shape. This shape inorporate better into the nature rather than a straight line shape for a struture built on water. It is learly shown in Fig 5. The olour of East Sea in China appears brown instead of blue. It has muh better effet as dark gray appearane of bridge fitting into natural olour of deep water. 3 Loading Figure 5: Bird s eye view of Donghai Bridge All loadings in this onferene paper are alulated aording to BS5400. 3. Dead Load The ross-setion of main navigation setion able stayed bridge is omposite box setion whih is too ompliated for onsideration. The other type of ross-setion, onrete twin box setions are used to define the dead load. Assume the ross-setion area of onrete twin box setions is 6.7m². The unit weight of reinfored onrete is 400kg/m³. The weight of dek Wd = 400 9.8 6.7=393. kn/m 3. Superimposed Load The superimposed load is mainly the road fill. The fill for Donghai Bridge is asphalt. Assume the thikness of the asphalt is 00mm. The unit weight of asphalt is 300kg/m³. The weight of road Wr = 300 9.8 0. 30 = 67.7kN/m γ =.75 (ULS ombination ) γ =.0 (ULS ombination ) f 3 The superimposed load = Wr. γ. γ f 3 =30.3 kn/m 3.3 HA Traffi Live Load Carriageway = 4.5m wide Dek Span = 60m Design for a meter width of dek: Number of notional lanes = 4 Notional land width = 5.75/4 = 3.94m From Table 3 BS5400: W = 3.6 kn/m (per notional lane) Knife Edge Load (KEL) = 0 kn (per notional lane) For a meter of width of dek: W = 3.6/3.94 = 3.45 kn/m KEL = 0/3.94 = 30.46 kn γ =.50 (ULS ombination ) Design HA Loading for a meter width of dek: W =.50 3.45 = 5.75 kn/m KEL =.50 30.46 = 45.69 kn Maximum mid span bending moment with KEL at mid span = M ult M ult = (5.75 60 )/8 + (45.69 60)/4 = 8387.6 knm γ =.0 for ULS onrete bridge f 3 M ult =.0 8387.6 = 06.36 knm 3.4 HB Traffi Live Load Nominal load per axle = 45 units 0kN = 450kN The maximum bending moment will be ahieved by using the shortest HB vehile. i.e. with 6m spaing. The maximum moment for a simply supported span ours under the inner axle when the vehile is positioned suh that the mid span bisets the distane between the entriod of the load and the nearest axle. With a 60m span and the 6m HB vehile with equal axle loads, the inner axle is plaed at.5m from the mid span. Fig 6 Figure 6: HB loading

RL = 450(73.7+75.5+8.5+83.8)/60 = 884.5 kn RR = 4 450 884.5 = 95.5kN Moment at X = 884.5 8.5 450.8 = 776.75 knm The HB vehile oupies one lane with HA load in the adjaent lane. Assume that the HB load is arried by a notional lane width of dek. Hene the moment per meter width of dek = 776.75/3.94 = 8090.55 knm γ =.30 (ULS ombination ) Design HB moment for a meter width of dek: M ult 3.5 Wind Load =.30 8090.55 = 357.7 knm The wind load is analysis by other standards whih is quite different from British Standards. But in this onferene paper, all the loadings are defined aording to BS5400. The maximum wind gust, v, whih would strike the bridge is given in equation as v = vk S S () Assume the mean hourly wind speed is 35m/s and the Donghai Bridge is 5m above the ground and horizontal wind loaded length is 340m, so that the gust fator S is found from table as.37 and the funneling fator S is.00 generally. Ref. [] v is alulated by Eq. () whih v =5.3 m/s The horizontal wind load ating at the entriod of the part of the bridge under onsideration is given by equation () as Where t P = qa C () D q=0.63 v (3) Using the value of v from Eq. () and alulate q, whih is the dynami wind pressure from Eq. (3), then m q=.6kn/. The solid horizontal projeted area A =400 m. is the drag oeffiient whih is read CD from graph by alulated b/d value. Ref. [] C D =. for the dek. Other elements suh as parapets and piers must also be onsidered aording to wind load. The wind load results for 350m span are shown in Table below: Table : P t values of different elements of bridge q(kn/ m ) A ( m ) C D P t (kn) Dek.6 400. 705 Piers.6 6 60. 696 Parapets.6 350 0.3. 03 Another more important ation by wind is uplift of a vertial downward fore. This nominal fore is alulated as Eq. (4) Ref. [] P = qa C (4) v The dynami pressure, q is same as alulated before. The plan area A 3 =05 m. Beause the ross-setion of dek is a twin box-setion, the lift oeffiient C =0.75 3 is taken. Calulate Pt from Eq. (4), gives that P t =3339kN. 3.6 Temperature Effets Temperature effets are an important onsideration during bridge design. The simple approah is used here to onsider the temperature flutuations of Donghai Bridge. The overall length of Donghai Bridge is 3.5km and has a mixing of onrete and omposite deks. There are quite lot expansions joints have been put in different positions of bridge. Assume the maximum distane between two expansion joints is 40m and the entire bridge ross setion inreases in temperature by 5. The distane of bridge will move longitudinally at the expansion joints is alulated using Eq. (5) L e = Τ. l.α (5) The oeffiient of thermal expansion for steel and -6 onrete is a= 0 /. The applied length l =00m. The total extension e = 30mm and 5mm for eah expansion joint to move in longitudinally. If the expansion joints are logged, some longitudinal ompressive stress is whih will be built up and the stress an be alulated using Eq. (6) σ = Τ.α.E (6) Steel will expand more than onrete under same inreased temperature. So use the Young s Modulus for steel to alulate the stress. The Young s Modulus for steel E = 00,000 N/mm². σ =60N/mm² 4 Design of Strutures The bridge is designed in S-shape from the plan view with the minimum radius 500m. This is not only due to the aestheti appeal, but also for the onstrution requirements of highway bridge. Firstly, too long straight setion will ause drivers visual fatigue and inrease the aidents. Seondly, the entral axis of eah setion should perpendiular to the diretion of rising tide and falling tide. This method not only redues water influene to the bridge, but also helps safe navigation for ships when passing the Donghai Bridge. 4. Main Navigation Setion The width of the beam is 33m and the depth is 4m. It is a single box with three hambers. The Main span is L

40m. Large span indued huge moment and shear on the dek. If using onrete box-setion, the thikness of flanges and webs will be muh larger than other spans to take the moment and shear. Therefore, the weight of eah box-setion will be extremely massive and annot be lifted by rane boat. Even onrete box-setion an be stiffened by adding steel inside the amber, but still not very effiient and eonomi. Steel box setions are hosen to use instead of onrete. The problem of steel box setions is bukling and this may lead to ollapse. In order to overome this problem, the top flange is stiffened by asting a onrete slab on the top. This forms a onrete-steel omposite box setion. The top onrete flange is treated as a ontinuous slab and webs arry the shear. The bottom flange is in ompression in hogging regions. Other steel plates are also stiffened by adding steel profile and braings inside. As shown in Fig. 7, all steel plates are surprising thin and lightweight. box-setions. The depth of dek is muh thiker at supports than where else. The thikness of dek varies along the span with the minimum thikness at mid-span and maximum at supports. Stiffer setion attrats bending moment. So the dek on the support is built thiker to resist the bending moment. All onrete box-setions are prestressed by internal prestressing. 4.4 Main Navigation Span Cable -stayed Bridge Figure 7: Cross-setion of omposite box girder of main navigation setion 4. Offshore Non-navigation Setion The preast ontinuous beam with the span of 60m or 70m is used for offshore non-navigation setion. Instead of single box setion, two idential box setions with one hamber are seleted. The ross-setion of box girder is shown in Fig. 8. All box setions have same thikness along entire span. Conrete box setions are prefabriated in segments in island near the site. Eah setion is mate-ast, so that the previous segment beomes part of the formwork for the next one. Ref. [] Box setion segments are then transferred to the site and all prestressed by internal prestressing to hold all segments bak in positions. Extra defletors are also added to the box setion for external prestressing in advane. They are not used until any deviation ours during onstrution or in future servies. Figure 9: Inverse Y-shaped double pylons with stay ables in fan onfiguration There are several reasons to hoose a able-stayed bridge rather than suspension bridge rossing a wide span. Cable-stayed bridges display a more diret load-path from dek to pylon through the stay ables. Ref. [] The onstrution method of able-stayed bridges is easy and eah able is relatively thin and replaeable. The main element of this bridge is the double pylons with single plane of ables. Two inverse Y-shaped pylons are seleted with many losely-spaed stays attah to the top vertial part of pylons as shown in Fig. 9. The height of pylon is 48m. The most effiient onfiguration fan system is used without any ugly oblique views resulting. This form of struture not only has the aestheti benefit, but also has the advantage that torsional stiffness is added to the bridge by reating a triangular losed setion. The height of pylon is 48m. Cable stay is high strength Pre-fabriated parallel wire strand (PPWS). PPWS is fabriated by high strength galvanized wire whih is totally paralleled with a setion of hexagon or other shape. Ref. [4] The wire bundle is wrapped with high strength polyurethane tape and fixed sokets at both ends of able. The standard distane of ables on the pylon is m and 8mon the beam. The elevation of main navigation setion able-stayed bridge is shown in Fig. 0. Figure 8: Cross-setion of offshore non-navigation setion 4.3 Auxiliary Navigation Setion There are 3 auxiliary navigation bridges with main span of 0m, 40m, and 60m respetively. Two idential single box setions with single hamber are also hosen for these setions. Three auxiliary navigation setions are atually built as a antilever bridge with Figure 0: Elevation of main able-stayed bridge 4.5 Expansion Joints and Bearings

Beause the dek of able-stayed bridge mostly made of steel, so as the temperature inreasing, the dek of main span will expand largely. So expansion joints are put in the middle of span to allow any horizontal movements up to 40mm. The normal servie life for expansion joints is longer than 0 years. Ref. [] Both steel hinge (roker) bearings and rubber pot bearings are used in Donghai Bridge at different positions. The steel hinge bearing ats as a pin onnetion and no horizontal movement is allowed but it an rotate. The rubber pot bearing is the most popular used one, whih is slightly heaper than others. 5 Constrution 5. Complex Constrution Conditions Donghai Bridge is loated in site whih has subtropial oeani monsoon limate. It is on the south edge of north subtropial zone and east-asia monsoon region. Mainly wind is North wind and east-south wind throughout whole year. Strongly influened by the monsoon, the site has learly four seasons; old in winter and hot in summer. The annual average temperature is 5.3-6. C and annual average rainfall is 053.9mm.Ref. [3] The tidal type of sea area belongs to shallow tide with irregular and half day harateristis. Two rising tides and two falling tides happen eah day with distint aspets of bak and forth tide. Ref [] Table : Charaters of tide in east sea of Shanghai Ref. [3] Little Yangshan Luhao Port Station Station (08/997-/00 (978-994) ) Average sea level (m) 0.3 0.8 Average high tide level (m).86.5 Average low tide level (m) -.34 -.3 Maximum level differene (m) 5.4 5.03 Average level 3.0.75 differene (m) Average duration of rising tide Average duration of falling tide 5 hours 6minutes 7 hours 5 hours 5minutes 6 hours 34minutes Aording to Table, the bridge onstrution is hugely influened by typhoon, wave, tide, old-air and other bad onditions. Aording to the apaities of equipments have been used in reduing effet of wind and urrent, the average workable days is less than 80days per year over three hand half years total onstrution period. Therefore, another ritial issue need to onsider is the limited onstrution period. The onstrution period of Dong Hai Bridge is only 4 months omparing to the large sale of the bridge. Beause it serves for the Yangshan Deep Water Port, so it needs to be ompleted together with the first phase of Little Yang-shan Port. By onsidering the short onstrution period and overall length of Donghai Bridge, travelling formwork method is used in onstrution of onshore setion. For the offshore setion whih is about 98% of the Donghai Bridge, neither travelling formwork method nor inremental launhing method is appliable due to its ineffiieny and different offshore onditions. So preast onrete onstrution is muh more preferred with launhing and balaned antilever onstrution methods. At four navigation setions, spans of dek are very large and launhing girder method is uneonomi sine building temporary supports in deep water is very expansive. So only balaned antilever method is applied. When onstrution goes to the area near the bank of island where water is very shallow and full of submerged roks, the floating ranes annot reah there, so those setions are onstruted by travelling formwork method or inremental launhing method. 5. Soil Conditions and Foundations There are layers of different soils in the site of Donghai Bridge. Soils have been defined up to seven layers from top to bottom as shown in Table 3. Table 3: 7 layers of soil from top to bottom Ref. [3] Layer Colour Soil type Compres -sibility Grey Mud High Loose Yellow to grey Sandy silt 3 Grey Muddy silty lay High Loose 4 Grey Silty lay High Loose 5() Grey Clay Loose to medium to high loose 5(4) 5(4) 6 Greygreen Grey-gr een Dark green to yellow Sandy lay Silty lay loose dense to dense Silty lay 7() Yellow Sandy silt 7() Yellow Silty sand 7() 7(t) Greyyellow to yellow Grey Silty fine sand Interbedded silty lay and sandy silt to low to low dense dense to dense dense to dense loose

As shown in Table 3, the soil ondition of site is quite bad, so that pile foundation is hosen for the bridge. Layer 7() and Layer 7() both have low impressibility and are formed by good quality dense sands. They are also stably distributed along the whole site. The depth and thikness of the soil is also ideal for the pile foundation, so layer 7 is hosen to arry the bearing apaity the pile foundation 5.. GPS systems Driving piles into the sea bed is very largely influened by the urrents and waves. It is very diffiult for driving ships to get to the exat positions. There are not as many monitoring points an be set out as on land. Therefore, the normal onshore surveying methods are not very appliable and not aurate enough for the onstrution. Aording to the offshore pile driving tehnology, new innovative GPS-RTK tehnique is used in this projet, known as The Offshore GPS Pile Driving Position System. This system an monitor the position of ship and aurate any errors from alulations. By the monitoring of GPS system, the high auray is ahieved and the problem is solved. 5.. Pile aps The outer shell of pile aps are also prefabriated in island. Eah shell is transported to the site and ereted to the pile groups as shown in Fig.. One finished onneting to piles, the reinforement is left for the pier, and the top of pile ap is overed in-situ with onrete. forward and onstrution ontinuous. Main installation proess of able-stayed bridge is shown in Fig.. Figure : Eretion proess of able-stayed bridge Figure 3: Balaned antilever onstrution for able-stayed bridge Figure : Eretion of pile ap 5.3 Main Navigation Setion Cable Stayed Bridge Tow inverse Y-shaped tower is asted in-situ in the site. After ompleted the main tower and auxiliary piers, one temporary support is installed at eah side of tower along bridge axis to support the first several segments of preast box setions above. The first five segments are lifted into position by floating boat rane and ereted and onneted on the two temporary supports. Another segment is lifted into position and first able is installed from tower to the dek. After this, the mobile rane is assembled on the dek and used for further lifting work. The onstrution is done by balaned antilever method. As the onstrution reahes the auxiliary pier, the temporary supports are removed from pylon and side temporary support is added to the auxiliary pier. One segment is ereted to the top of auxiliary pier first and then onneted to the dek from pylon. Another stay able is added to hold the dek. Then the mobile rane moves 5.3. Composite dek The main navigation span of bridge dek is onstruted using preast onrete topped steel omposite box setions. The profile of box-setion is single box with triple hambers whih is shown in Fig 6. The top flange of box-setion is stiffened with prestressed onrete and bottom flange and web are steel. Eah box-setion is prefabriated in large sale prefabriate site on island, then transported to the onstrution site and raned and ereted into plae. All asting work should be done in prefabriate site, inluding assembling and welding steel box setion, asting in-situ onrete top flange to the steel struture, et. After all prefabriation steps have been done, the box-setions are moved to storage to stay for 90 days before using. Proess of balaned antilever onstrution for the dek:. Preast box setion is transported to site by ship and lift up into position by rane.. Adjust spae between last segment. As in position, start onneting two segments and also fill in an epoxy resin to the joint to further aid smooth onneting. 3. Add the tendons for prestressing and ast in-situ 0m wide onrete top slab. 4. When strength onrete is over 90%, pull bak the tendons to prestress the segment. 5. Move rane forward

6. Install stays from tower to the segment to pull the dek up in position. 7. Crane lift next segment on and repeat all the steps from step The span of offshore non-navigation setion is either 60m or 70m. All the segments are prefabriated on the prefabriate site on island and transport to the wharf eah as a whole setion by the way of transverse moving and longitudinal moving. All the piers and girders are transported to the site by boats. The 60m box girders are lift to the position and ereted using rane boat and Herules (500 tonnes apaity). The 70m box girders are lift to the position and ereted using rane boat and Little Swan (3000 tonnes apaity), shown in Fig. 6. Eah box setion is first lift to the top of pier and supported by temporary supports. All onnetion works are done in-situ on the temporary supports. After all segments onneted to eah other, the dek is onverted into a ontinuous beam. Figure 4: Composite box girder lift by mobile rane As two spans meet about to meet together, the key segment is prefabriated speially that the steel setion is slightly longer. Beause steel dek annot ast in-situ, so the losure of the span beomes triky. One side of key segment is onneted as usual by bolting to the pervious one. At the other side, use the temporary onnetion plate to adjust the position. One it is in the orret position, a permanent plate is replaed and losure finished. 5.4 Onshore Setion Setion near the Luhao Port selets 50m span ontinuous box girder. It is onstruted in-situ using travelling formwork method. 50m span ontinuous box girder is also seleted for the setion near bank of Big Tortoise Island. Beause the rane boat annot work in shallow water, so that inremental launhing method is used for this setion. 5.5 Offshore Non-navigation Setion Figure 6: 70m box girder is lift by Little Swan 5.6 Auxiliary Navigation Setion The other three auxiliary navigation hannels are onstruted using different methods. The span of auxiliary navigation setion is 0m, 40m and 60m respetively. The pier is preast to box setion of enforement onrete thin wall. The first box girder segment is ast in-situ on the top of eah pier by formwork. All other segments are also ast in-situ using balaned antilever onstrution whih is shown in Fig. 7. The dek is built outwards in both diretions from a pier by mobile arriages and suspended formwork. The thikness of dek varies along the span. As the onreting ontinuous and the dek tapers, the arrangement of formwork adapted to get smaller dimensions. Figure 5: Eretion of piers There are two piers at eah support. All the piers for non-navigation setion are preast on island and transported to site. Eah pier is lift to the top of pile ap and onneted to the foundations as shown is Fig. 5. Figure 7: Cast in-situ using balaned antilever onstrution

6 Durability Donghai Bridge is loated at wreth marine environment. In order to make sure the bridge an stand for 00 years, a serial of ompletely, eonomial and reasonable antiorrosion system is drafted and applied to the onstrution of the bridge. Eah element of bridge has its own strategy and orresponding system due to the variation of strutures, materials and environments. All the tehnologial requirements are drafted as well. E.g. raw materials of high performane onrete, ratios of mixture, prodution proesses, onstrution methods, et. So the site onstrution an all be guided by these standards. 6. Antiorrosion Strategies for Different Elements: 6.. PHC (Prestressed High Strength Conrete) piles High performane onrete + steel reinforement protetion layer + FRP (Fiber Reinfored Plastis) wrapping reinforement + filling ore reinforement method 6.. Steel piles Sarifiial anodes protetion method (replaement every 35 years) + heavy-duty antiorrosive oating protetion (000µm, life-time 0 years) + filling ore reinforement method + predited steel piles orrosion amount (7mm). Ref. [3] Temporary anode piees are installed during onstrution and they are left on it (life-time years). 6..3 Drilling piles Conrete with mineral admixture + steel protetive anister + steel reinforement protetion layer 6..4 Pile aps, piers and girders High performane onrete + steel reinforement protetion layer The surfaes of piers in splash zone are oated by waterproof painting. 6..5 Stay Cables All the ables are made by galvanized steel wires whih are oated by a layer of zin to prevent orrosion. Hot extrusion HDPE (High Density Polyethylene) able jaket is wrapped to eah able and sealed to prevent storm water logging. 6..6 Bearings Triple anti-orrosion methods are used on bearing: weathering steel (inluding 09CuPCrNiA, 5CrCuMn and ZG0Mn) + metal oating + heavy-duty antiorrosive painting. Ref. [3] 6..7 Expansion joints and handrails Expansion joints and handrails are proteted by hot dip galvanizing antiorrosive method. 6. Exposed Testing Station: The reason for setting the exposed testing station is to monitor the atual effets of antiorrosive systems in Donghai Bridge. It also provides important basis and testing results for future maintenanes of bridge. On the other hand, the exposed testing station ollets data of offshore antiorrosive tehnique used in Donghai Bridge and aumulates experienes for the future appliations with improvements. The exposed testing station is built at north-west of Big Tortoise Island. 7 Protetion from vandalism 7. Anti-ollision system In order to protet the bridge from vandalism by boats and ships, both of VTS (Vessel Traffi Administrative System) and safety protetion system are applied. Some independent anti-ollision piers are arranged at both sides of main navigation hannel around tower bases. The light ollision an be absorbed and resisted diretly by the anti-ollision piers. But for the heavy ollisions, anti-ollision piers are not strong enough, so that the pier foundation together with other anti-ollision failities will restrit the impat. Aording to the navigation standard, boats shapes, ollision fores and anti-ollision failities, for the auxiliary navigation hannel, a speial orange olour protetive box is adopted. The pile ap of eah pier is wrapped by the orange protetive box. There are lots little holes on the protetive box whih an absorb and redue the impat. This system is very eonomi beause no extra protetive piers are required. Figure 8: Orange protetive box 7. Anti-ollision Parapets Donghai Bridge servies for the ports. High standard requirements for safety are very important and must be ahieved. Speial researhes have been done to the anti-ollision system of parapets. The anti-ollision parapets are designed for standard ontainers whih have a weight up to 55 tones. Designed maximum olliding speed is 60km/h and olliding angle is 5 degree. After several tests and omparisons, the steel-onrete omposite material is seleted for parapets. 8 Future Changes and Improvements: There are 4 navigation hannels in Donghai Bridge. One is loated in the main navigation setion. It is for 5000DWT vessel and the learane is 300x40m. It is a single hannel with double diretions. One is for 000DWT vessel and the learane is 00x5m (double hannels single diretion);and Two are for 500DWT vessel, the learane is 56x7.5m (double hannels single diretion), loated near the Luhao harbor and little Wugui Island. Ref [] Considering the overall length of Donghai Bridge is 3.5km, 4 navigation hannels may not enough for the

future. One of the solutions is that one more able-stayed bridge is added to the route of bridge on the Luhao Port side. But this will make the struture very omplex beause another able-stayed bridge, Kezhushan Bridge, whih is onnet to the Donghai Bridge already. The maximum span of Kezhushan Bridge is 33m and it onnets the end of Donghai Bridge to the Yangshan Deep Water Port. In fat, Kezhushan Bridge does not have any navigation requirements, so it is quite a waste to having a long span able-stayed bridge there. 9 Summery For a bridge have overall length 3.5km, the Donghai Bridge is exellently designed and dramatially onstruted in three and half years. It also gives impressive aestheti feeling while the philosophy of simpliity applies. Referenes [] http://dorim.mokpo.a.kr/~kwer/data_file/symposiu m/session/zeng-huan%0zhang.pdf [] Ibell, T.,. 997. Bridge Engineering leture notes, University of Bath [3] Deep Water Port and Donghai Bridge Projet http://o.63.om/neteaseivp/forum/dirsearh.jsp [4] http://en.sp.om/website/searhprodutsingle.ati on?proid=808080806e8306f670ed000 [5] Lin, Yuanpei. Shanghai Lupu Bridge and Donghai Bridge