94 results about "Lightering" patented technology

The invention relates to a method for measuring the weight center of gravity of a super-large structural member, which adopts a suspension method to hoist the super-large structural member and performs calculation by matching with the following formula: obtaining a vertical center ZG value of the super-large structural member. According to the measuring method, a mode of combining horizontal hoisting and inclined hoisting is adopted, and the average value is calculated in a mode of taking the average value through three times of hoisting, so that the weight center-of-gravity data of the super-large structural member can be obtained, and accurate data values are provided for ocean transportation, subsequent lightering, installation and other work of the super-large structural member.

The utility model discloses a marine steel pipe pile transport frock, including two frock stand columns, multiple pairs of layer branch leg, bottom layer support pad and multiple high layer support pads, bottom layer support pad is the horizontal strip beam body of setting, and its top surface has multiple arc through grooves along its length direction equidistance and is set up, two frock stand columns are fixed at the both ends of bottom layer support pad, multiple pairs of layer branch leg are set up on the opposite side wall of two frock stand columns from bottom to top interval, and multiple high layer support pads are set up on multiple pairs of layer branch leg respectively, every high layer support pad includes a horizontal strip beam body, and its top surface and bottom surface have multiple arc through grooves along its length direction equidistance and are set up respectively, and the both ends of beam body are equipped with the connecting lug board connected with a pair of layer branch leg, this marine steel pipe pile transport frock can realize the layering of batch steel pipe pile on barge, not only good integrity and stability, and be applicable to different diameter or the steel pipe pile of variable diameter, and the barge operation efficiency is high, and the cost is low.

The embodiment of the application discloses a bridge anti-ship collision device impact force-impact depth model construction method, comprising the following steps: determining the total potential energy of the system in the process of the barge impacting the anti-collision device, wherein the total potential energy comprises the plastic strain energy of the outer panel of the anti-collision device, the compression energy consumption of the internal structure of the anti-collision device, the energy absorption of the bow of the barge and the work of the external impact force; each item in the total potential energy is expressed as a function of the impact force and / or the impact depth of the anti-collision device; each function is substituted into the minimum potential energy principle equation satisfied by the total potential energy, and an impact force-impact depth model for representing the relationship between the impact force and the impact depth of the anti-collision device is obtained. The embodiment can establish a clear mechanism model for the dynamic response of the anti-collision device under the ship collision.

The application discloses a kind of offshore bridge section float installation method based on SPMT, the installation method includes the following steps: S1: barge carries bridge section and SPMT reaches the front of installation pier, by dinghy, mooring rope is fixed on pier;S2: barge gradually tightens mooring rope, tail is aimed at the gap between pier;S3: barge winch tail is pulled into the gap between pier, ensure that the tail installation area is enough to accommodate bridge section and SPMT and is fixed using fender and float ball;S4: before installation, remove the bridge section binding, SPMT enters the bridge section below and lifts the bridge section from temporary support, is transported to tail, and is positioned by translation rotation etc. Action carries out bridge section installation position rough positioning.The present application uses SPMT to transport and install bridge section in position, which can achieve millimeter-level fine adjustment, has higher installation precision, reduces the impact of wave impact on barge, ensures the horizontal state of goods when barge is inclined, and reduces the time cost loss caused by bad weather.

This application relates to a cargo hold and its control method for rapid loading and unloading of cargo on a transshipment barge, belonging to the field of marine technology. It includes a W-shaped cargo hold with two symmetrical unloading ports along the bow and stern lines of the barge at its bottom, each port equipped with an adjustable-opening hatch assembly; and a cargo distribution detection module installed inside the cargo hold to acquire surface area information of the cargo stack within the hold, calculate the center of gravity position of the hold based on this information, and calculate the opening degree distribution of the unloading ports at the bottom of the hold based on the center of gravity position information; and a controller whose data input terminal is connected to the data output terminal of the cargo distribution detection module, and whose signal output terminal is connected to the signal input terminals of several hatch assemblies, for receiving the opening degree distribution results and adjusting the opening degree of the unloading ports at the bottom of the hold. This application ensures the stability of the barge during the unloading process.

To provide a construction method of a monopile type foundation capable of constructing the monopile type foundation constituting a large-sized monopile type offshore wind power generation facility without using a corresponding large-sized self-elevating barge or self-navigating work barge.SOLUTION: A self-elevating barge 40 is stopped in a water area, and a transporting barge 20 loaded with a monopile 3 is moored in the water area. A lower part of the monopile 3 laid down sideways is supported by an erecting device 30 mounted on a carrying barge 20, and a crane 43 of a self-elevating barge 40 and the erecting device 30 are used to submerge and erect a lower end part side 3b of the monopile 3. A monopile 3 erected in a water area is moved to a pile guide part 51 of a driving auxiliary device 50 mounted on a self-elevating barge 40 by a crane 43. The monopile 3 is driven into the water bottom ground SB using the crane 43 and the driving device 45 in a state in which horizontal movement of the monopile 3 is restrained by the pile guide part 51.SELECTED DRAWING: Figure 14

A deck support device for shallow water platform module float-over installation, comprising a slide, a slide shoe, a buffer assembly, a support assembly and a diagonal brace, etc. The support assembly is a split structure, which is connected by electromagnetic suction cups and inserts. The top of the buffer assembly can be connected with the inserts. The load of the platform module is transmitted to the barge through the double-cone contact surface of the support assembly and the buffer assembly. This design can provide higher stability during the operation process. The buffer assembly further provides necessary buffering during the load transfer process of the platform module, avoiding rigid collision. During the float-over installation barge withdrawal process, the platform module can be quickly separated through the split structure of the support assembly. Meanwhile, the gap between the barge and the platform module is increased after the separation of the insert of the support assembly, ensuring the safe withdrawal of the float-over barge and greatly shortening the offshore operation time.

The application discloses an efficient transport barge for inland river material transfer, relates to the field of logistics transfer equipment, and comprises a ship body, a load carrying mechanism for carrying goods is locked to the ship body, a docking mechanism for receiving the load carrying mechanism is arranged on a target wharf of the ship body, the docking mechanism comprises two parallel docking column units, the load carrying mechanism comprises receiving assemblies located on both sides of the ship body, each receiving assembly is locked with a corresponding docking column unit, and the load carrying mechanism is unlocked with the ship body, the ship body drives away from the wharf to complete unloading, the load carrying mechanism and the docking mechanism are arranged, so that the ship body is docked during approaching the wharf, unloading is completed during driving away from the wharf, and the ship body does not need to stay at the wharf for too much time, thereby greatly shortening the unloading time at the wharf and improving the overall cargo carrying efficiency of the ship body.

The present invention provides a pile driving method, a self-lifting barge, and a guide frame, which enable the precise driving of piles. [Solution] When driving piles 10 using a self-elevating barge 1, the following steps are performed: navigating the self-elevating barge 1 to the pile driving point in the water and inserting the legs 3 into the seabed; positioning a three-dimensional guide frame 5 in a guide frame arrangement section 6 provided on the self-elevating barge 1 so that its top is above the water and its bottom is resting on the seabed; and driving the piles 10, positioned inside the guide frame 5, into the seabed 50.

This invention discloses an autonomous vessel and a method for maintaining a precise position or trajectory during offshore operations (e.g., cable or pipe laying or offshore construction installation). The vessel includes multiple externally anchored mooring lines, a winch system with tension sensors, a position sensor, and a control system. The control system processes position and tension data to detect deviations caused by environmental forces such as wind, waves, or ocean currents. In response, the control system activates the winch system to adjust the length of the mooring lines, counteracting forces caused by different environmental factors and achieving controlled maneuvering within the mooring area. An optional artificial intelligence module can learn from historical data to predict dynamics and optimize adjustments along predetermined waypoints. Compared to traditional dynamic positioning systems, this reduces fuel consumption, improves accuracy, and minimizes risk. It is applicable to vessels such as barges or installation platforms.

1. The name of the design product: pile positioning barge. 2. The use of the design product: used for positioning steel pipe piles in offshore limited space and auxiliary buoy. 3. The design points of the design product: in shape. 4. The picture or photo that best indicates the design points: perspective view. 5. Other circumstances that need to be explained: A part of the enlarged view is the main view A area of the local enlarged view; B part of the enlarged view is the left view B area of the local enlarged view; C part of the enlarged view is the rear view C area of the local enlarged view; D part of the enlarged view is the top view D area of the local enlarged view.

The invention discloses offshore composite beam transporting and erecting integrated construction equipment and a construction method thereof, and belongs to the technical field of bridge construction. Comprising a barge platform, the barge platform is provided with a lifting sling, the lifting sling comprises a vertical truss, one end of the vertical truss is fixed to one end of the barge platform, the other end of the vertical truss is provided with a first truss beam perpendicular to the vertical truss, one end of the first truss beam is fixed to the other end of the vertical truss, and the other end of the first truss beam is provided with a second truss beam perpendicular to the first truss beam. A first truss beam is arranged at one end of the barge platform, a second truss beam is arranged at the other end of the first truss beam, one end of the second truss beam is hinged to the other end of the first truss beam, the other end of the second truss beam is arranged towards the other end of the barge platform, and a bolt hinge is arranged at the connecting position of the first truss beam and the second truss beam. The bolt hinge is used for adjusting the connecting angle of the second truss beam relative to the first truss beam. According to the technical scheme, the transportation and erection construction problem of the offshore composite beam is solved, and integrated operation of the offshore composite beam from transportation to erection is achieved.

The application discloses a whole-segment steel box girder sliding on-ship-lifting integrated construction method without floating crane intervention, a whole-segment steel box girder assembling and sliding platform is arranged on the land area of the bank side of a bridge to be built, and two groups of sliding tracks are arranged in parallel on the assembling and sliding platform; a deck barge with an adaptive tonnage is selected, and ship-borne sliding tracks with the same specification and spacing as the sliding tracks on the bank side are arranged on the deck of the barge; the application greatly reduces the approach and operation of large lifting equipment, reduces fuel consumption and carbon emission of mechanical equipment, shifts the main construction operation to the land area to reduce the water operation time, effectively avoids water pollution caused by construction sewage, welding slag, waste and the like entering a river, dust and noise in land operation can be effectively controlled through conventional protection measures, the influence of construction operation on surrounding residential areas, crops and ecological environment is greatly reduced, and the application meets the relevant requirements of green construction and ecological environment protection.

The invention discloses a hoisting method of an offshore heavy precast beam, which comprises the following steps of: constructing an integrated operation platform for connecting a precast field area and a hoisting operation area, and pre-anchoring and positioning a crane ship in a water area near the mounting position of the precast beam, so that the position and orientation of the ship body are kept fixed in the whole course; a lifting appliance of the crane ship is pre-positioned to be in a pre-taking state capable of covering the precast beam on the transportation equipment; transporting the precast beam to a preset hoisting position of a hoisting operation area through the integrated operation platform by transportation equipment; precast beams are taken, moved and placed on a path between a preset lifting position and a mounting position only by controlling pitching of the cargo boom to perform variable amplitude motion and cooperatively controlling lifting motion of the lifting appliance; and resetting and circulating to finish subsequent hoisting of the precast beam. The problems of high construction cost of temporary wharfs, many barge transportation links, long consumed time for moving and positioning of crane ships and high risk in the hoisting process of offshore heavy precast beams are solved.

The utility model relates to an electric double-body barge which comprises a barge body. The middle parts of the sheet bodies are connected into a whole through a connecting bridge, and each sheet body comprises a deckhouse and a container type power supply; the bridge type container crane is composed of a bridge and a container hoisting mechanism; the bridge frame comprises a metal box type supporting structure and a track; the shore power connection equipment comprises a rotating base mounted on the sheet body, an electric capstan wound with a cable is mounted on the rotating base, the shore power connection equipment further comprises a telescopic arm, one end of the telescopic arm is mounted on the rotating base, and a cable conveying device for releasing the cable is mounted at the other end of the telescopic arm; the electric catamaran barge adopts a catamaran type layout, has a larger deck operation space, can store more container type power supplies, has better stability, is beneficial to carrying out hoisting operation under complex sea conditions, meets the multi-scene power supply requirements, and also meets the green and environment-friendly requirements.

The present application belongs to the field of ocean engineering, and particularly relates to a weighing DSU device for floating installation of a large offshore platform and a use method thereof. The device comprises a weighing system and an energy absorption system. The energy absorption system comprises a tension outer cylinder, a DSU elastic body, a tension flange A and a tension flange B. The tension outer cylinder internally contains the retractable DSU elastic body. The outer surface of the tension outer cylinder is provided with the tension flange A. The tension flange B is linked with the DSU elastic body. The lower end of the weighing system is connected with the tension flange B. The offshore platform is placed at the upper end of the weighing system. The tension flange B is connected with the tension flange A before the offshore platform is built. The DSU elastic body is in a compressed state. The tension flange B is disconnected with the tension flange A before the offshore platform is transferred to a barge. The tension flange B and the weighing system can be displaced along the vertical direction through the stretched DSU elastic body. The present application omits the working process of transferring the platform block to the DSF after the platform block is built and weighed, and reduces the construction process of platform weighing and center of gravity calibration.

This application provides a powder unloading terminal structure based on a screw unloader, including an unloading terminal and a screw unloader. The unloading terminal includes an offshore waterway and a canopy. The offshore waterway is built in the water, avoiding the occupation of shoreline resources, and is suitable for special scenarios where land reclamation is restricted and the construction of impermeable projects is prohibited. Both sides of the offshore waterway have the capacity for ship berthing, and there are at least two offshore waterways, providing support for the canopy structure. The canopy spans the two offshore waterways, and the water area below the canopy is the unloading area. The canopy effectively resists the impact of severe weather, making unloading operations no longer restricted by weather conditions, and also prevents dust from spreading to the outside. The water area outside the canopy serves as a barge area, enabling orderly scheduling and berthing of ships, further improving the operational efficiency of the terminal. The screw unloader is located inside the canopy and can directly unload powder from the ship's hull.

A testing device and method used on pressure relief valve while installed on an inland cargo barge to open the pressure relief valve and to determine its set lift pressure. Use of the testing device does not require the testing to be performed at a shipyard. The testing device includes a lift unit that mounts to the top of the valve's spring housing and engages the valve stem. Hydraulic pressure applied to pistons on the lift device moves the valve stem. Proper separation of plates on the lift unit indicates proper opening of the valve. The pressure reading for the applied hydraulic pressure is then correlated to the lift pressure set for the valve under test.

The invention relates to a vibration sinking installation method for a steel cylinder, in particular to a vibration sinking installation method for an underwater steel cylinder with uneven soil distribution, which comprises the following specific installation steps: 1, a crane ship is fixedly connected with a vibratory hammer group through a hoisting lock, the vibratory hammer group is hoisted to be right above the steel cylinder, the steel cylinder is clamped through a hydraulic clamping jaw, and the vibratory hammer group is hoisted to be right above the steel cylinder; hoisting the steel cylinder to a preset position on the water surface; secondly, the steel cylinder slowly descends until the steel cylinder and the vibratory hammer set are all submerged below the water surface; thirdly, the steel cylinder is lowered step by step to make contact with the seabed surface, the E-shaped hook head is deloaded step by step and slowly falls, the steel cylinder enters mud by means of self weight, and the perpendicularity of the steel cylinder is adjusted after the steel cylinder is stabilized; fourthly, the vibratory hammer set is started, the steel cylinder is vibrated into mud, and the perpendicularity of the steel cylinder is adjusted again after the steel cylinder is stabilized; and fifthly, the operation in the fourth step is repeated, the steel cylinder descends to the designated mud entering depth, the hydraulic clamping jaw is loosened, and the vibratory hammer set is lifted and placed on the deck of the transportation barge.

Spreewald barge for passenger transport, wherein at least one area without persons, except the ferryman, is provided and in the area of ​​the ferryman a housing with a power source with ventilation is provided and that a power supply to a respective electrical device on the barge from the battery to the device is flexibly fixed and detachable installed and heating of a passenger seating area is provided.

An autonomous vessel and method for maintaining precise position or trajectory during marine operations, such as cable or pipe laying or offshore construction and installation, are disclosed. The vessel includes multiple mooring lines anchored externally, a winch system with tension sensors, a position sensor, and a control system. The control system processes positional and tension data to detect deviations caused by environmental forces like wind, waves or currents. In response, it actuates the winch system to adjust mooring line lengths, counteracting forces and enabling controlled maneuvering within the mooring spread. An optional artificial intelligence module learns from historical data to predict dynamics and optimize adjustments along predefined waypoints. This reduces fuel use, enhances accuracy, and minimizes risks compared to conventional dynamic positioning systems. Applicable to vessels like barges or installation platforms.

The invention discloses a self-installation type installation method for an ocean module drilling machine, which comprises the following steps: firstly, a constructor climbs on a platform, and assembles a first-stage small crane by utilizing manpower and a simple tool; then, the installed crane is used as a hoisting means, and a second-stage crane, a third-stage crane and a fourth-stage crane with higher hoisting capacity are sequentially installed; the fourth-stage crane is used for installing a deck fifth-stage crane serving as a platform main crane; then, a drilling support module and a larboard fifth-stage crane are installed through a deck fifth-stage crane, and a starboard fifth-stage crane is installed on the basis of the drilling support module and the larboard fifth-stage crane; and finally, the fifth-stage cranes on the left board and the right board are used for combined operation, and installation of all the remaining drilling machine modules is completed. The method thoroughly gets rid of the dependence on large floating cranes and barges through the platform self-building hoisting capacity and the step-by-step lifting installation logic, and has the advantages that the construction cost is low, the cycle arrangement is flexible, the limitation of external resources and sea conditions is small, and all cranes and modules can be repeatedly used for different platforms.

The invention relates to the technical field of ship butt joint, and discloses an inland ship pushing, connecting and locking device which comprises a pushing ship and a barge, a pushing frame is fixedly connected to the side wall of the pushing ship, a positioning groove is formed in the inner wall of the barge, the outer wall of the pushing frame is slidably connected with the inner wall of the positioning groove, a containing groove is formed in the inner wall of the barge, and a locking device is arranged in the containing groove. An electric telescopic rod is started to retract, a sliding plate and a sliding disc are driven to ascend, a positioning rod is made to ascend, arc-shaped supporting blocks are made to make contact with positioning holes of a pushing frame through a supporting assembly, the positioning rod is made to move in multiple directions through an inserting assembly, and the multiple arc-shaped supporting blocks make contact with the positioning holes of the pushing frame synchronously. The positioning rod is quickly and accurately inserted into the positioning hole, so that the problem that the positioning rod and the positioning hole are difficult to align due to shaking of the pushing boat and the barge, so that the pushing boat and the barge are difficult to butt is effectively prevented, the difficulty of repeatedly finely adjusting the position of the pushing boat by an operator is reduced, and the butt joint time of the pushing boat and the barge is shortened.

The embodiment of the invention discloses a collision force-collision depth model construction method for a bridge ship collision prevention device, and the method comprises the steps: determining the total potential energy of a system in the process that a barge collides with the collision prevention device, the total potential energy comprises plastic strain energy of an outer panel of the anti-collision device, compression energy consumption of an internal structure of the anti-collision device, barge bow energy absorption and external impact force acting; each item in the total potential energy is expressed as a function about the impact force and / or the impact depth of the anti-collision device; and substituting each function into the minimum potential energy principle equation satisfied by the total potential energy to obtain a collision force-collision depth model for representing the relationship between the impact force and the impact depth of the anti-collision device. According to the embodiment of the invention, a clear mechanism model can be established for the dynamic response of the anti-collision device under ship collision.

The invention provides an automatic container wharf barge loading system which comprises an automatic barge matching module used for inputting barge and production business data; the intelligent arrangement module for container discharge of the storage yard is used for intelligent arrangement of container discharge of the storage yard after container selection is completed, so that multi-dimensional score aggregation is completed; the intelligent storage yard box discharging arrangement module executes a plurality of rules: a performance cost coefficient score calculation rule of a work queue, a performance cost coefficient score calculation rule of a channel, a turnover score calculation rule and a time window score calculation rule; and the equipment control module is used for controlling a plurality of IGVs, at least one storage yard rail-mounted crane and at least one shoreside bridge crane of the automatic container wharf after dispatching container selection and storage yard intelligent cabinet delivery are finished. The operation efficiency and the transportation accuracy of automatic container wharf barge shipping are improved.

The application discloses a high-window self-adaptive land-water transfer loading device for offshore booster stations, which is designed by innovative combination of multifunctional components such as machinery, electricity, hydraulic pressure, sensors and controllers, and realizes stepless continuous self-adaptive transfer loading of offshore booster stations and other equipment within a long time window period through preset level ballast strategy of the barge body and multi-point same-surface integrated elevation adjustment strategy of the land-water transfer loading device. In order to promote land-water transfer loading work of offshore booster stations and other super-large-volume and super-heavy marine equipment platforms, reduce the limitation of the transfer loading window period caused by tides, effectively expand the effective transfer work time, reduce the possibility of forced temporary rescheduling due to insufficient remaining time caused by delay of the transfer loading work caused by weather and other natural factors or other sudden factors, and improve the utilization efficiency of the transfer wharf.

The utility model discloses a protective shell fixing structure for a mud barge oil cylinder, and relates to the technical field of mud barge oil cylinders, the protective shell fixing structure comprises an oil cylinder body and a protective shell, the protective shell comprises two groups of connecting shells, the two ends of one group of connecting shells are fixedly connected with connecting plugs, the two ends of the other group of connecting shells are provided with slots matched with the connecting plugs, and the connecting plugs are inserted into the slots. The connecting plugs are inserted into the inserting grooves, side sliding grooves are formed in the two ends of each connecting plug, a movable inserting block is slidably connected into each side sliding groove, the two connecting shells are installed on the outer surface of the oil cylinder body in a combined mode, and under the action of the connecting plugs, the inserting grooves, the side sliding grooves, the movable inserting blocks and the second springs, the connecting plugs are inserted into the inserting grooves. The two connecting shells are rapidly combined, the protective shell is fixed to the oil cylinder body, when an outer protective plate of the protective shell is impacted, impact force is buffered under the action of the first buffering mechanism, and the impact resistance of the oil cylinder body is improved.

The utility model discloses a dredging engineering offshore barge loading platform, including the hull, the first pipeline is fixedly arranged on the hull, and a plurality of second pipelines are fixedly communicated on the both sides of first pipeline, and the plurality of second pipelines are fixedly arranged with Z type elbow pipe away from first pipeline one end, and the Z type elbow pipe is rotatably arranged with the branch pipe away from second pipeline one end, and the branch pipe is fixedly arranged with the discharge pipe away from Z type elbow pipe one end, and the box is fixedly arranged on the hull and is located at a plurality of branch pipes, and the both sides of box are respectively provided with the round mouth for Z type elbow pipe and branch pipe's penetration, and the motor is fixedly arranged in a plurality of box inboard bottom, and the output of a plurality of motor all is provided with the gear assembly of driving branch pipe rotation. Motor drives branch pipe rotation through gear assembly, and branch pipe drives discharge pipe rotation, makes discharge pipe rotate certain angle, and then adjusts the angle position of sand loading, avoids sand barge sand uneven and does not fill the condition of loading, improves the working efficiency of barge loading platform.

The invention discloses a mounting structure of a stern ramp and a roll-on and roll-off platform type barge, and relates to the technical field of ships. The mounting structure comprises a tail end wall, a transverse auxiliary bulkhead and a plurality of longitudinal enclosure bulkheads. The transverse auxiliary bulkhead and the multiple longitudinal enclosure bulkheads are arranged to be matched with the tail end wall, so that the tail end wall, the transverse auxiliary bulkhead and the internal longitudinal enclosure bulkheads form a whole, the strength of the mounting structure is improved, and in the using process, the situation of structural deformation or failure caused by insufficient strength of the mounting structure is avoided; the stability of the stern ramp is improved, the situation that the stern ramp inclines, is blocked and even falls off is avoided, and the safety of passing vehicles and operators is improved. The roll-on and roll-off platform type barge comprises the stern ramp, the hinge and the mounting structure, the stern ramp is connected with the mounting structure through the hinge, the situation that the stern ramp inclines, gets stuck and even falls off is avoided, and the safety of passing vehicles and operators is improved.

The application provides a kind of intelligent combination fleet cooperative stability control method and system, it is related to shipping transport technical field, the method includes: step 1, in the installation position of mechanical-hydraulic lock buckle deployment pressure sensor, in barge deck deployment deformation sensor, in ship bow and stern deployment attitude sensor, real-time acquisition lock buckle hydraulic pressure value, barge structure deformation variable and ship pitch angle data;Step 2, hydraulic pressure value, structure deformation variable and ship pitch angle data, according to each barge and associated lock buckle generation ship state parameter set, the ship state parameter set includes lock buckle stress peak, barge load distribution gradient and pitch angle offset amount.The application effectively improves the cooperative stability of combination fleet in complex sea conditions by real-time sensing, dynamic adjustment and cooperative control, reduces the risk of dynamic instability of connecting structure.