Steel bridge bearings may be divided into three general types. In general, there are two types of supports shown on plans, fixed f or expansion e. In situations where bridge skew angles exceed 30 degrees, consult the bearing and expansion joint specialist and the bridge design engineer for recommendations and approval. If the specific bearing type is not known, reference the index in the back of the guide for the page number where the bearing is listed. However, the span restriction for sliding bearing utilization can be disregarded when it is used in combination with other bearing types. Rocker and pin bearings are primarily used in steel bridges. Rough translation of the german original version november 2010. Bridge bearings indian association of structural engineers. A bearing is a machine element which supports another moving machine element known as journal.
The construction layout sheet in the plans will show the designers intent. Similar with pot bearing, spherical bearing also can be divided into three types. Bridge bearings until the middle of this century, the bearings used consisted of following types. Substructure guidelines bridge substructure types are determined during the preliminary design phase of the bridge design. Bearings in this catalog are arranged by bearing type, with a size andor numerical listing. Ccl advanced solutions help create innovative bearings that anticipate. A sole plate may also be embedded into the bottom flange of a prestressed concrete girder. The designer must determine which bearing type is best suited to cost. Collectively, these bearings are known as high load multi. In highway bridge bearings movements are accommodated by the basic mechanisms of internal deformation elastomeric, sliding ptfe, or rolling. The separator, which retains the balls or rollers, is also called the cage. Sole plate the sole plate is a steel plate that is attached to the bottom of girders or beams or truss chords. Expansion joints and bearings september 2017 where practical and where additional protection for bearing assemblies and hinges is warranted, provide a secondary sealing system below the expansion joint assembly.
For example, this means when bridge traffic runs east and west, the north and south track plates must be completely parallel. Seismic isolation bearing systems bridge the world with leading infrastructure solutions bridges 300 east cherry street north baltimore, oh 45872 telephone. With high strengthened steel body, spherical bearing is especially designed for high vertical, horizontal. Linear bearing types range from ball bearing cagesessentially bare cages holding balls that are often used as diepost bushingsto recirculating ball designs where the balls roll linearly along the shaft and then return to their starting points through channels on the nonshaft sides of the bearings. Bearings can be fixed in both the longitudinal and transverse directions, fixed in one directi on and expansion in the other, or expansion in both directions. The obstacle to be crossed may be a river, a road, railway or a valley. The oldest form of bridge bearing is simply two plates resting on top of each other. Integral bridge with frame abutments acts like portal frame where moments, shear force and axial loads transfer directly to the supporting structure from deck of bridge. Load load aa b ad ae g h kn kn mm mm mm mm mm mm kg. All bearings do, however, have at least the bearing or bearing surface. The designer must determine which bearing type is best suited to cost effectively accommodate the design requirements. Bearing is the component of bridge on which the girder in case of girder bridge, or solid slabin case of slab bridge rests. Types of elastomeric bearing pads plain and laminated elastomeric bearings pads. A bearing is ideally required to provide six degrees of freedom.
Each bearing listing includes the appropriate dimensions. The frame abutments retains the backfill behind it like retaining walls. The three new bearing types most widely used today in the united states are pot, spherical and disk. Spherical bearing, also called spherical bridge bearing, is one type of bridge bearings with large rotation capacity. The purpose of a bearing is to allow controlled movement and thereby reduce the stresses involved. Bridge bearings support structures at a constant elevation, carrying forces from the superstructure into the substructure and allowing necessary superstructure motions to take place. Bridge rehabilitation an overview sciencedirect topics. A roving bridge, changeline bridge or turnover bridge is a bridg e over a canal constructed to allow a horse towing a boat to cross the canal wh en the towpath changes sides. Bearings gives the supporting conditions to super structure. Bearings can be fixed in both the longitudinal and transverse directions, fixed in one directi on and expansion in the other, or expansion in.
There are several different similar types of bridge bearings that include neoprene bearing pads, neoprene bridge bearings, laminated elastomeric bearings and seismic isolators, which are all generally referred to as bridge bearing pads in the construction industry. The layout of each track must be completely parallel on one side of the bridge versus the other. In recent years considerable progress has been made in the mechanical design of the fixed and moving components. These early concrete piles were the castinplace type. Steel bridge design handbook bearing design volume 15. A support with a f will have a bearing device that will resist longitudinal movements. Pot bearings are special types of bearing pads for taking larger loads, translation and rotation in confined areas. A bridge bearing is a component of a bridge which typically provides a resting surface between bridge piers and the bridge deck.
Jun 21, 2017 bearing is the component of bridge on which the girder in case of girder bridge, or solid slabin case of slab bridge rests. Translational and rotational movement of bridge superstructure may be due to shrinkage of concrete elastic shortening of concrete due to prestressing. Elastomeric bearings for construction industry in neoprene and natural rubber compound laminated rubber bearings provide the simplest method of isolation and are most suitable for high frequency ground motions. There are several different similar types of bridge bearings that include neoprene bearing pads, neoprene bridge bearings, laminated elastomeric bearings and seismic isolators, which are all generally referred to as bridge bearing pads in the construction industry they are designed and manufactured.
We have been focusing on research and development in recent years and we have made great achievement in this industry. Bridge bearings are used to transfer forces from the superstructure to the substructure, allowing the following types of movements of the superstructure. Bridge bearing bearing is a mechanical device placed between superstructure and substructure to transmit vertical and horizontal load allowing some translational and rotational movement. Spread footing or embedded wall footing is preferred as foundation for the frame abutments.
Bearing pads are either plain or reinforced with respect to the loads defined. It permits a relative motion between the contact surfaces of the members, while carrying the load. Information on bridge bearings is available in various technical literatures but it is scattered. The average bearing pressure on the concrete is 20 mpa. Lead rubber bearings used for higher energy dissipation. This module provides practical information for efficient bearing design and detailing. A large variety of bearings have evolved using various combinations of these mechanisms. It typically consists of a pin at the top that facilitates rotations, and a curved surface at the bottom that accommodates the translational movements.
Bridge bearings types of bearings for bridge structures. Bridge bearings types of bearings for bridge structures and. Pot bearings for bridges and structures plain bearing products. The following case studies show three recent bridge bearing replacement projects designed by wsdot. Bearings are important elements in large infrastructures such as bridges, heavy buildings and high rise buildings, ensuring load transfer, movement, rotation, vertical or horizontal restraints as required by the design at. Plain and reinforced elastomeric bearings have become the most common type of bearing in recent years because of their desirable performance characteristics, durability, low maintenance requirements, and relative economy.
A common form of modern bridge bearing is the elastomeric bridge bearing. Bearing types include no bearing required integral or continuous frametype bridge modern isolation bearings aashto 2010, guide specifications disktype. There are many factors to consider when deciding on the most appropriate substructure. In the years immediately preceding the turn of the twentieth century, several types of concrete piles were devised. Bearings transfers loads from super structure to sub struc. Geometrical design find overall length, breadth and thickness b o, h o, l o of elastomeric pad. Bridge bearings types of bearings for bridge structures and details. The rolling elements distinguish the two basic bearing types ball bearings and roller bearings. Another type of bridge bearing is the mechanical bridge bearing. There are several types of mechanical bridge bearing, such as the pinned bearing, which in turn includes specific types. Pot bearings are often regarded as suitable for use when bridge bearing rotations are too large. Maurer elastomeric bearings can be fitted with additional steel plates and restraints. Find number of steel plates n, thickness of steel plates h s.
Bridge bearings are devices for transferring loads and movements from the deck to the substructure and foundations. While covering the subject of bridge bearings during various courses at iricen the absence of a document covering all aspects of different types of bridge bearings was acutely felt. Seismic isolation bearing systems bridge the world with leading infrastructure solutions bridges. Bridge bearings introduction aashto defines a bearing as a structural device that transmits loads while facilitating translation andor rotation. Movement could be thermal expansion or contraction, or movement from other sources such as seismic activity. These include rockers, rollers, pins, pots, steel girder hangers, ptfeelastomeric, and elastomeric pads. Elastomeric bearings for construction industry in neoprene and natural rubber compound. Apr 23, 2015 bridge bearings until the middle of this century, the bearings used consisted of following types. The elastomeric bearings of type 1 and 2 are set between steel plates. Effective isolation in all seismic zones and soil types no corrosion, stickslip, wear or aging effects. We have established long term cooperation relationship with many companies and our products have.
Steel bridge bearing selection and design guide steel building. A roving bridge, changeline bridge or turnover bridge is a bridg e over a canal constructed to allow a horse towing a boat to cross the canal wh en the. Wisdot bridge manual chapter 27 bearings wisconsin dot. Trbs second strategic highway research program shrp 2 report s2r19arw2. Tp sq hole ctrs hole ctrs hole dia height mass reference no. Laminated rubber bearings provide the simplest method of isolation and are most suitable for high frequency ground motions. An elastomeric bridge bearing is a commonly used modern bridge bearing. This iricen publication is a result of the desire to fill the gap. Bridge bearings are structural equipment or devices installed between. Bearings are elements transferring vertical loads from. Integral bridges types, advantages and limitations. The bridge designer will prohibit movement in some bearings and allow movement in others.
A rocker bearing is a type of expansion bearing that comes in a great variety. In a tapered roller bearing, the center lines do not converge at a common point. Different types of bridges with pdf file engineering. Section 2 special design requirements for different bearing types. The submerged timber piles of this bridge, which were driven in 900 ad, were found in good condition and were reused. Bridge design bridge design and assessment bridge bearings. The required passage may be for a road, a railway, pedestrians, a canal or a pipeline. Although many different types of bridge bearings have been used by the nysdot, elastomeric and multirotational bearings are the. Rocker and pin bearings for bridge structures rocker is an expansion bearing composed of curved surface at the bottom, which accommodate translational movement and a pin at the top makes room for rotation. Types of elastomeric bearing pads construction rubber. The maximum horizontal load can only be applied if it is less than 33% of the simultaneous vertical load. It permits a relative motion between the contact surfaces of. Fhwa bridge inspection manual section 9 bridge bearings. Pin bearing a pin bearing is a type of fixed bearings that accommodates rotations through the use of a steel translational movements are not allowed.
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