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Design Proposal for Luyang Sea Crossing in Phase I Project of Yang Shan Deepwater Port Chapter IXChapter IX Bridge Supporting Projects91 Maintenance and health Monitoring System of BridgeAfter the bridge is opened to traffic, it will be damaged due to the influence of climate, oxidize, corrosion and aging and also under the stress caused by dead-load and live load for a long term, leading to reduction in strength and rigidity as time goes by. This will not only affect the safety of traffic, but also shorten the operational life of bridge. Therefore, it is necessary to establish and develop a monitoring system to monitor and evaluate the bearing capacity, operational status and durability of bridge structure during its operation. Meanwhile, necessary maintenance facilities should be installed to carry out required maintenance of bridge structure on a regular basis. Monitoring scope of bridge structural health monitoring system includes: Monitoring of bridge working condition:- include wind velocity and wind direction at bridge site, environmental temperature and temperature distribution on bridge structure, traffic load distribution, seismic load, etc.Monitoring of overall bridge performance:- include dynamic characters of bridge structure, stress and deformation of critical parts on main girder.Structure assessment:- evaluate the structural reliability of the bridge at any time.The structural health monitoring of bridge mainly consists of 4 systems and operates through network connection. These 4 systems are detector system, information collection system, information handling and analysis system, system operation and computer control system.911 Environmental Monitoring of Bridge Site Wind velocity and direction monitoring at bridge siteThis is mainly done by wind velocity indicator installed on main bridge and top of the bridge tower. Works include measuring average wind velocity and wind direction, drawing wind rose map of bridge site, determining average wind velocity, wind direction and recurrence frequency. These information will be used as reference when reviewing the wind resistance design and making out bridge traffic control measures during strong wind period. Monitoring of environmental temperature and temperature spread on bridge structureThis is done by temperature indicator installed inside bridge body and tower. Monitoring items include environmental temperature at bridge site, temperature distribution on cross-section of concrete deck and tower, temperature distribution on road surface. Monitoring of traffic load and its distributionThis is mainly completed by axle velocity indicator and camera installed on specified location of the lane, works include: measuring of axle weight and vehicle velocity, deducing real-time bridge traffic load, recording/observing traffic congestion and vehicle distribution condition on bridge, measuring of proportion of lorry and flow of all vehicle types.(4) Monitoring of underwater conditionLocal scour will occur at the seabed around the bridge foundation due to the influence of stream current. Therefore underwater landform adjacent to bridge pier should be regularly observed to record cut-and-fill variations of seabed, thereby ensuring the reliability of foundation during operation. (5)Corrosion monitoringCorrosion monitoring probes shall be arranged as below:a. Permanent embeddable reference electrodes (either silver/silver chloride or manganese/manganese dioxide), reinforcement connections, reference electrode distribution boxes and monitoring facilities. These permanent reference electrodes will be used to monitor the corrosion condition of reinforcement.b. Embeddable corrosion monitoring probes will be installed to monitor the ingress of aggressive chloride ions.912 Monitoring of Overall Bridge Performance Dynamic Character monitoring of bridge structureDynamic character of bridge structure is related with the rigidity, weight, damping value and their distribution. Dynamic character monitoring is mainly to measure bridge vibration nature, such as auto-oscillation frequency, oscillation modal and damping value, by method of environmental casual vibration. Stress and deformation monitoring of critical parts on girder Monitoring is done by the strain and level instrument installed on critical parts inside the bridge, draw relevant stress/deformation influential line and plane, to determine the stress and deformation condition of critical parts. Such information will provide bases for assessing the bearing capacity, operational status and durability of the bridge. Stayed-cable force monitoringCable force condition is an important index to judge whether or not the bridge is under normal operation. Stayed-cable force monitoring is to measure the auto-oscillation frequency and oscillation modal of the cable first, mainly by method of environmental casual liberation, and then deduce cable force accordingly.913 Bridge structural evaluationBridge structural evaluation mainly includes 3 aspects, i.e. bearing capacity, operational status and durability.914 Bridge Maintenance Facilities Movable inspection trolley will be installed to help staff inspect and maintain bridge structure. Rail fence will be installed on all tops of main bridge piers to falicitate the inspection of bearing performance on pier tops.Rail fence will be installed every 140-160 meters on pier top and ladder leading down to the pier top will be installed on deck. Manhole will be set at the bottom slab of box girder to provide access into the box, for inspection of pipelines inside.92 Pavement and ParapetAll deck pavement will adopt asphalt concrete featuring comfortable traveling and quick construction. Pavement thickness of asphalt concrete is 10cm, doublelayer structure. The base layer is 6.0cm thick medium particle layer; and the upper layer is 4.0cm thick small particle layer. Damp-proof course will be installed between asphalt concrete and deck. Regarding clash parapet, the concrete bridge will adopt compound concrete parapet, and the cable stayed bridge will adopt steel parapet.93 Deck Emergency Cross PassageThe total length of this crossing is 28.136km. It is unavoidable that vehicle failure and pavement maintenance will occur during operation. To prevent traffic interruption due to above circumstances, emergency cross passage will be set on bridge deck with reference to central barrier arrangement of expressway.Emergency cross passage will be set as below: connect the deck structure of up-bound and down-bound viaduct for every certain distance (about 4km), i.e., set a opening section (cross passage) at the central barrier to allow vehicles on one viaduct traveling to the other when necessary, forming a dual 1 lane traffic mode. Thereby, barrier removal and maintenance works can be carried out on the closed section of the viaduct at other side. Because water pipe is set at central barrier between up-bound and down-bound bridge, the water pipe shall be placed under the deck where emergency cross passages are set. Steel hanging frame and ladder shall be set under the deck for water pipe installation, maintenance and displacement. There are 6 deck emergency passages on the whole bridge, so little negative effecting will occur to the water pipe.9.4 Pipeline, Power and Lighting9.4.1Pipeline Fully completion of the services like water, electricity and communication is a key issue of the development of Yang Shan Deep Water. For placing such pipes/cables from mainland to island, via bridge crossing is the best option. In this project, there will be water mains, 110KV HV cable, HV and LV cable required by bridge, communication optical cable, etc. passing through the bridge. Considering the cost-effectiveness and convenient maintenance, all utility pipes will be placed into the internal space of the viaducts or on deck. Layout is shown in figure below:The water mains will be located at the central barrier of the bridge deck, for easy installation and maintenance. 110KV high voltage cable will be set inside the single box girder to provide larger work space for placing and maintenance; LV cable and communication, broadcast/television cable of the bridge will be set inside the same box girder with steel cable tray relatively. Enough safe distance between the cable trays should be ensured, to prevent communication, broadcast television signal from disturbed by electric cable.(1) Water Mains A DN500 water pipe with 440 m3 /h design flow is required to be carried by the bridge according to solicitation document. Total head pressure loss of the crossing distance is about 43m. Generally, elevation difference between deck and land is 40m, while at the opening bridge the water pipe will have to either climb up to the bridge tower or lay down to the seabed, which leads to a level difference of 30-50m. Taken into consideration the difficulty of maintenance and anti-corrosion for placing the water pipe on seabed, it is proposed to adopt the elevated crossing via the towers of opening bridge. Thus, level difference between highest point of water pipe and land is about 60m, which means the starting pressure of the water pipe should 1.1Mpa.Spheroidal graphite iron pipe will be adopted for water main, and the dead-load of DN500 pipe plus water weight is 340kg/m in total. A flexible joint will be installed every 300m alongside water pipe, to cater the pipe deformation.Asphalt coating is adopted onto the external surface of the pipe to resist corrosion. (2) 110KV HV CableIt is quite common to place HV cable on bridge, and there were such experiences in America, Japan and some other countries early 1980s. There are also such experiences in China, for example, an 110KV cable had been placed inside the box girder of Xiang Jiang Northern Bridge and worked well since early 1990s. In 1991, Shanghai Construction Committee and Shanghai Science/Technique Committee organized a detailed study on the feasibility of placing 220KV cable on Shanghai Yang Pu Bridge, and drew following conclusions:Temperature and magnetic field caused by super HV cable on bridge will not exert harmful affection to bridge structure.Damage to super HV cable on bridge due to bridge vibration and deformation can be prevented by relevant technical measures, which has been proven by successful experience.According to relevant regulation in “Cable Design Standard for Electrical Engineering -GB50217-94”, placing cable on bridge shall make sure the cable be protected from hurt of mechanical force, overheat, corrosion, etc., and must be easy to place and maintain. The total length of Lu Yang Sea Crossing is about 28Km, consisting of continuous box girder bridge, cable stayed bridge and opening bridge, with continuous box girder accounting for over 98% of the whole bridge length, whose cross-sectional internal clearance is 4.5m2.5m. Such type of structure provides favorable conditions for cable crossing. The space inside box girder is a natural cable corridor, which not only enables smooth crossing of cable but also provides access for inspection. On box girder, vent holes will be set on web and manhole will be provided at bottom slab for every 140-160m to facilitate air circulation. Cable inside the box girder will not only be free from weather affection, but also avoid the damage caused by traffic accident on deck.In consideration of demand increase of power of Yang Shan Port and cable replacement after its working life henceforth, another corridor for placing additional 110KV HV cable is provided inside the box girder. Cable placing inside box girder can be either opening (on-ground) or in cable tray. Method I: Opening placing in the airCable fixing components will be installed inside box girder every certain distance. To cater the deformation of bridge and to satisfy the requirement of cable length reserve, the total reserve will be distributed throughout the whole crossing and cable will be placed in snake form. Layout of opening placing is shown as figure 2. To prevent cable wearing, anti-abrasion and damping pad will be inserted between cable and bottom slab of box girdr.Method II: Placing with Cable TrayCable will be placed inside box girder with hot galvanized steel cable tray. Cable tray should not be made too wide in order not to affect the inspection access. Cable will be straightly placed within usual section. For the area where exists the expansion joint, wider cable tray can be applied for cable length reserve. Placing arrangement is as shown in figure 3:Compared with Method II, Method I is easier to install and it is more cost effective. Placing cable in the air is good for heat elimination thus good to safe operation of cable. However, exposed cable is possible to be damaged by small creature; As for Method II, some placing details are difficult to handle. Cable tray can provide protection to cable inside, but raise the cost greatly at the same time. Therefore, Method I incorporated with necessary protection measures for creature invasion is recommended. For opening bridge section, the 110KV cable will be placed along the lifting tower. Its layout is shown in figure 4. For easy maintenance, inspection ladder/access are set along the cable tray. To ensure the safety of both bridge and cable, following points should be taken into consideration during cable design and selection:The 110KV HV cable on bridge should adopt dry fire retarding insulation cable made of cross linkage polyethylene.Minimize the amount of cable joints on bridge, and no cable joint and crossing interconnected box are allowed to be set on the cable stayed bridge and opening bridge.Ensure the quality of HV cable and accessories.Take into account the preformed holes required by cable placing during bridge structure design.(3) Communication and broadcast television cable Steel cable tray will be placed inside continuous box girder and box girder of cable stayed bridge. Cable at opening bridge section should be placed along the lifting tower, details can be referred to figure 4. To prevent communication and broadcast television signal from disturbance, measures listed below shall be adopted:Distance between communication cable and electric cable should meet the requirements of related national standard.Use steel cable tray with cover, which can provide shielding.To facilitate cable installation and maintenance, an inspection access will be provided beside tray, and manhole will be set at the bottom slab of the box girder for every 140-160m. 942 Lighting and Power Supply(1) Lighting and its ControlLu Yang Sea Crossing is bridge of super large scale, the lighting system should be designed in accordance with normal regulation. Lights will be symmetrical arranged mainly, with incorporation of one-sided layout. Lighting pole will be located at the clash parapet of the central barrier with spacing of 30m. The light is about 10m high and 250W high voltage sodium lamp will be used. Average illuminance of bridge deck should be no less than 20Lx.Lighting system of the whole bridge includes whole-night light and late-night light, which can be controlled in step-down station or on site of loading center. Layout of power supply system is shown as figure 5. Advantages of such control method are as below:When all or part of the lights on bridge deck are not lightened, the supplying transformer will be power-off, so there will not be any no-load consumption of transformer, resulting in saving of electricity.When vehicle flow is reduced late night, late-night light could be switched off to save energy.Best power supply system, easy to achieve automatic monitoring, representing advanced maintenance/management level.(2) Placement of lighting wiresMedium-voltage cable will be placed inside continuous box girder and box girder of cable stayed bridge with cable tray. For opening bridge section, cable placing method is the same with that of 110KV HV cable; Trunk lighting cable will be placed in tube, lying next to the parapet of the central barrier. Pluggable electric appliance will be installed at the interface of movale deck and fixed deck of the opening bridge, to enable circuit shutdown before lifting of opening section. (3) Power SupplyThe objects of the permanent bridge power supply include: deck lighting, navigational signal light, electrical equipment inside main tower of cable-stayed bridge, lifting equipments and elevator of opening bridge. Power will be supplied to above objects with reference to the second rate loading, except lifting equipments of opening bridge and navigational signal light, which will be power supplied with reference to the first rate loading.Bridge in this project is of super length, with deck lighting system of long distance dispersity. According to similar projects in China and abroad, electric energy transmission system of medium voltage developed by France will be adopted. Overseas projects of France-Italy Expressway, Normandy Bridge, etc. adopted such system. In China, there are also projects as Yangtze River No.2 Bridge of Nan Jing, Yangtze River Bridge of Chong Qing, Xiao Shan International Airport, etc. adopting such system. And such electric energy transmission system of medium voltage has been more and more widely used domestically. According to low loading and dispersing character of special fields of long distance and large scope, this system selects a sufficient electric voltage (5.5KV) which can reduce the cross-section of power transmission cable and number of substation, reaching a balance between saving in inve