Special Equipment Bailey Pontoon Floating Bridge With Light Weight For Convenient

Floating Pontoon Bridge Description:

Floating pontoon bridge by boat or tank instead of bridge pier, the float bridge. Army together a using standard equipment, military pontoon bridge, says pontoon bridge. Its structure is not complex, open and convenient, bridge construction has the characteristics of simple, fast, but the high cost of maintenance. At ordinary times could be used in the emergency disaster relief or as a temporary traffic facilities.

The erection of pontoon bridge is a special specialty, which involves a lot of professional knowledge. This paper mainly introduces the structure, construction method and simple design method of pontoon bridge erected by highway steel bridge equipment.

Floating pontoon bridge design basic scheme consideration points

Road condition, performance, pontoon structure, pontoon drawings, environment

Basic design principle of floating pontoon bridge

Principles to be followed: the performance objectives are consistent with the purpose, safety, durability, quality, ease of maintenance and management, harmony with the environment, economy and other indicators.

Choosing the type of structure: topographic, geological and geographical conditions should be considered.

The number of pontoon structures and the overall system should meet the requirements of strength, deformation and stability.

Below table gives the classification of the status performance levels of the floating pontoon bridge. A state performance level of 0 is mainly compared to other performance levels 1-3. For traffic loads, storm waves, tsunamis and earthquakes, the pontoons are designed in several performance levels.

According to the importance factor, the design of the floating bridge should ensure that it has the corresponding target performance level listed in table, such as load, storm wave, tsunami and earthquake.

Construction of bridge foundation of Floating pontoon bridge 

The bridge base of prefabricated truss pontoon bridge is usually constructed according to the following requirements:

1. Bridge base position: Depending on the nature of the soil and the distance from which the bridge base position may be moved when the pontoon bridge is blocked, it is usually not less than 1.5m from the riverbank edge.

2. Since the end of the prefabricated truss pontoon bridge is connected to the river bank through the end columns of the two sides of the truss, the soil of the river bank bears a large local pressure. If the pressure per unit area of the seat plate exceeds the allowable bearing capacity of the soil, dense pillow materials must be used to expand and strengthen the foundation of the bridge. The length of the pillow is generally 1~1.5m, and the section is not less than 15cm × I5cm.

3. The height of the upper surface of the pillow material above the water surface is generally 30cm lower than the height from the top surface to the water surface of the bridge foot boat.

Features of Floating pontoon bridge 

1. The pontoon bridge can generally only form a single-lane, and the width for the vehicle is 3.7m. When the double lane bridge is needed, two bridge span devices are used side by side.

2. The main beam of the pontoon bridge is mainly hinged cantilever beam system. That is, the bridge gate bridge is connected with the main beam with an articulated connector.

3. Local strengthening and connection is usually required between the main beam of the pontoon bridge and the boat (boat) body.

The erection of pontoon bridge is a special specialty, which involves a lot of professional knowledge. This paper mainly introduces the structure, construction method and simple design method of pontoon bridge erected by highway steel bridge equipment.

Limit state of the floating pontoon bridge

The floating pontoon bridge should be have sufficient capacity to face potential hazards such as ships, debris, wood, floods, mooring rope failure, and complete separation of the bridge after lateral or oblique fracture.

Although the water provides buoyancy for the floating pontoon bridge, if the water leaks into the interior of the floating pontoon bridge, it will gradually damage the floating pontoon bridge and eventually lead to the sinking of the bridge. This is the current research problem facing the floating pontoon bridge.

Specific design and analysis of floating pontoon bridge

Stability: refers to the ability of the ship to tilt under the action of external forces, and to return to the original balance position after the external forces disappear.

Three equilibrium states:

1) Stable balance: G is under M, and gravity and buoyancy form a stability torque after the tilt.

2) Unstable equilibrium: G is above M, and gravity and buoyancy form an overturning moment after tilting.

3) Accidental balance: G and M coincide, and gravity and buoyancy act on the same vertical line after tilt, without torque.

The relationship between stability and ship navigation:

1) The stability is too large, and the ship swings violently, causing discomfort to personnel, inconvenient use of navigation instruments, easy damage to hull structure, and easy displacement of cargo in the hold, thus endangering the safety of the ship.

2) The stability is too small, the ship's anti-capsizing ability is poor, it is easy to appear large inclination Angle, slow recovery, and the ship is tilted on the water surface for a long time, and the navigation is ineffective.

As with boats, the overturning of pontoons is related to their static stability.

Floating pontoon bridge body design:

General pontoons mainly consider the separate pontoon tank. As explained earlier, the hydrodynamic characteristics of each tank can be studied individually, and then the results obtained can be used for global system analysis. 

Design of wind speed and effective wave height: the effective wave height of 2.5m is a key point of the pontoon type bridge. In order to ensure that the effective wave height is below 2.5m, it is necessary to set up a wave barrier. The viscous effect and the potential flow effect are two important factors in the analysis of the incident water wave motion and the stress of underwater structures. For potential flow theory, it is mainly the scattering and radiation effects of water waves around the structure.

Application of floating pontoon bridge:

Pedestrian, road and railway.

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