How to select suitable type of Bridge Bearing? Guidelines BS 131 Spherical, POT PTFE, Elastomeric скачать в хорошем качестве

How to select suitable type of Bridge Bearing? Guidelines BS 131 Spherical, POT PTFE, Elastomeric

Selection of Bearings Welcome to another video on bridge Engineering on All About Bridges Youtube channel. In this video we will discuss which type of bearing should be adopted for a certain type of railway girder or road over bridge girder. The discussion will be based upon the guidelines issued by RDSO in this regard through BS-131 that is Guidelines for selection of bridge bearings for railway bridges and road over bridges. Bearings are crucial components in bridge construction as they facilitate movement, accommodate loads, and help in the longevity and stability of the structure. BS-131 further contains table 2, titled “Suggested Bearing Types for Particular Girder Types,” which provides guidance on selecting appropriate bearing types for different bridge girder structures based on their material and span length. 1. Steel Plate Girder (Railway Bridge) – Spans up to 24.4 meters Recommended Bearing Types: 1. Steel Sliding Bearing – This type of bearing is suggested for areas with low corrosion risks. However, in regions where corrosion is prevalent, proper corrosion mitigation measures need to be implemented to extend the service life of the bearings and prevent structural deterioration. 2. Steel Reinforced Elastomeric Bearing with Anti-Slip Devices – This is a more robust and flexible option, incorporating an elastomer (rubber-based material) reinforced with steel plates. The anti-slip feature ensures that the bearing remains in place under dynamic loads and prevents excessive movement, which is crucial for railway applications. Double asterisk note says Steel sliding bearing should not be replaced by elastomeric bearing in existing spans where already sliding bearing is there. Elastomeric bearing should be provided in cases of construction/replacement of superstructure. 2. PSC (Prestressed Concrete) Girder (Railway Bridge) – Spans up to 24.4 meters Recommended Bearing Types: 1. Steel Reinforced Elastomeric Bearing – This bearing is designed to provide flexibility while supporting heavy loads. The elastomeric material allows for small deformations and helps in absorbing vibrations caused by train movement. 2. POT-PTFE Bearing – This is a high-performance bearing that consists of a pot (housing an elastomeric disc) and PTFE (Polytetrafluoroethylene) to allow smooth sliding movement. It is ideal for bridges that require meaningful rotation and translation movements while accommodating high loads. 3. Steel Concrete Composite I Girder (Railway Bridge) – Spans up to 30.5 meters Recommended Bearing Type: 1. Steel Reinforced Elastomeric Bearing – Similar to the recommendation for PSC girders, this bearing type is suggested for steel-concrete composite girders. It provides load distribution, flexibility, and shock absorption, which is essential for railway bridges that experience dynamic train loads. 4. Steel Open Web Girder (Through & Underslung Girder) – Spans 30.5 meters and above Recommended Bearing Types: 1. Steel Rocker and Roller Bearing – This type is suggested for areas with less corrosion risk. However, in corrosion-prone zones, additional protective measures should be implemented to ensure longevity. 2. Spherical Bearing with PTFE (Polytetrafluoroethylene) or Similar Material at the Sliding Interface – This bearing facilitates smooth movement while distributing loads efficiently. To prevent deterioration, corrosion protection measures must be applied to exposed portions. 5. Rail cum Road Bridges Recommended Bearing Type: 1. Spherical Bearing with PTFE or Similar Material at Sliding Interface – Since rail cum road bridges experience combined vehicular and railway loads, a spherical bearing with PTFE is recommended to accommodate multi-directional movements and high loads. As these bearings may be exposed to harsh environmental conditions, corrosion protection should be ensured. 6. Steel Concrete Composite I Girder (Road Over Bridge - ROB) – Spans up to 36 meters Recommended Bearing Types: 1. Steel Reinforced Elastomeric Bearing – This bearing is flexible, durable, and provides excellent load distribution, making it suitable for composite structures. 2. POT-PTFE Bearing – A high-capacity bearing designed to withstand large vertical loads and accommodate horizontal movements and rotations. If exposed to a corrosion-prone environment, additional protective measures should be taken. 7. Bow String Girder (ROB) – Spans 42 meters or more Recommended Bearing Types: 1. Spherical Bearing with PTFE or Similar Material at the Sliding Interface – This bearing helps in distributing loads efficiently and facilitates smooth movement. However, exposure to corrosive conditions requires protective measures. 2. POT-PTFE Bearing – Given the large span of 42 meters or more, these girders require a bearing that can support high vertical and horizontal forces while permitting necessary movements. Corrosion mitigation should be implemented where required.