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rocker-bearing-in-bridge Bridge Bearings -Types of Bearings for Bridge Structures and Details

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This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form rocker bearing in bridge anyone is expressly forbidden. They are of two basic types: fixed bearings and expansion be.

The most commonly used types of bearings in bridges are: sliding plate bearings, rocker and roller bearings, elastomeric bearings elastomeric pads and pot bearings. Sliding steel plane or curved bearings are used for spans less than meters. Rocker bearings are ma. In this situation, the analysis of behaviour of bearings in service seem to be indispensable. This paper presents the results of theoretical and field investigations of deficient rocker bearings often observed in existing bridges.

Various failures of bearings were observed often causing malfunction or deterioration of structures [ 1, 2. Corrosion of steel components, including the con. Fig 1. Deterioration of bridge girder corbel due to faulty positioning and rusting of steel sliding bearing rocker bearing in bridge and excessive tilting of rocker bearing b.

At present, design of translation of expansion bearings is based on as. The problem results from non-uniform seasonal and daily time-dependent ambient. The vertical and transverse temperature rocker bearing in bridge in bridge deck are non-linear over the cros. The combined actions due to prestress, dead loads and thermal loads leading to creep of superstructure may exceed the.

The movements of segmental rolb. Tilting rocker bearing in bridge single a and multiple b rocker bearings. It seems that observed intensive rusting of the contact surfaces leads. Fig 4 shows diagrammatically the deflection of a bridge girder and a horizontal translation of the be.

Expansion bearings are used at. Over each pier. The total movement of segmental rocker bearing in bridge is equal.

Excessive rocker bearing in bridge was observed during detailed ins. Fig 4. Deflection diagram and rotation of the sections adjacent to supports No 4 and No 3. The longitudinal movements of bearings can be evaluated at any time according to Eqif the mag. The factors influencing the expansion bearings behaviour are temperature variation, as well as shrinkage. Bridge inspection and rehabilitation. A practical guide. New York, Gelzbetoninill tiltl!

Vilnius: Technika, Yanagihara, T. Matsuzawa, M. Kudo, T. The determination of long-time movements is complex because these factors produce a constantly changing strain and stress distribution over the depth rocker bearing in bridge span of the bridge decks. Table 2. Horizontal translation of bearings No 4. Pateikiamas trijq tarpatramiq nekarpyto is anksto itempto dezinio skerspjiivio tilto su neleistinai pasvirusiais atraminiais guoliais pavyzdys.

Santrauka Rocker bearing in bridge pagrindiniai veiksniai, kurie turi itakos tiltq segmentiniq paslankiqjq atraminiq guoliq posvyriams. Pateikiama metodika atraminiq guoliq horizontaliesiems poslinkiams apskaiciuoti. Paslankiqjq atraminiq guoliq darbas priklauso nuo aplinkos temperatiiros pokyciq, tilto perdangos rocker bearing in bridge ir valksnumo deformacijq del isankstinio armatiiros itempimo bei nuolatines apkrovos.

Ilgalaikius atraminiq guolitt poslinkius nustatyti sudetinga, nes del minetq veiksniq nuolatos kinta itempimq ir deformacijq biivis isilgai ir skersai tilto perdangos. Doctor Habil, Professor. Director of International Study Centre.

Vilnius Gediminas Technical University, Sauletekio rocker bearing in bridge. E-mail: tscts. Doctor Expert member of Lithuanian Academy of Sciences. Author and co-author of more than! Research interests: concrete structures and bridges, materials, durability, monitoring, and refurbishment.

Rocker Bearings in Bridge Structures. Functions and Properties of Lubricating Oil on Rocker bearing in bridge. Kamaitis Vilnius Gediminas Technical University temperature change; shrinkage and creep of concrete m deck beams; 1. Introduction Bearings in a bridge transmit the vanous rocker bearing in bridge deflections of deck beams; substructure movements or foundation settlements; applied from the superstructure to the piers.

They are of two basic types: fixed bearings and expansion be- horizontal bracing and acceleration forces of heavy Downloaded by [ Both types need to accommodate the rotations. Expan- wind actions. The facts are not sufficiently understood and re- sion bearings allow rotation as well as horizontal movement of the superstructure.

Rocker bearings are ma- flected in the design of bearings. Defects of bearings and their causes frequently in bridge construction, where the bearings are designed to transfer relatively large horizontal mo- Classification of bearings defects is presented m vements.

There are rocker bearing in bridge types of plain elastomeric table. Two main causes of faulty functioning of be- bearings used to transfer relatively large vertical and arings can be mentioned: faulty positioning or alignment of bearings during horizontal loads including also movements due to chan- construction; ges in temperature or improper positioning of bridge insufficient maintenance.

To keep the bearings in a good state, periodic Various failures of bearings were observed often causing malfunction or deterioration of structures [ 1, 2, maintenance is required.

Unfortunately, often no pre- 3]. The rocker bearing in bridge of bearings and hinges are not ventive maintenance for long periods of time is envi- important on the condition of the bearing itself but of saged leading to restriction of normal functioning of some other damages in the structure.

They are located bearings. In some cases we found the bearings not ac- where movement has to take place so that if they do cessible for visual inspection and maintenance. In these not function the eccentric loading appears and the cases the disfunctions of bearings can be detected only structure may suffer excessive stress. If the movements by observing the signs of distress in the adjacent struc- are restricted, the restraint rocker bearing in bridge which are not considered in the design, could cause cracking and spalling tures.

Rainwater with de-icing chemicals, including sand of the concrete in the girders or substructure cap m and dirt, penetrates from the roadway through the le- the vicinity of bearings.

Types of defects of bridge bearings Types of bearing Sliding plat Rocker and roUer Types of defect and damage Most common causes corrosion of plates and sliding surfaces chemical deterioration restricted movement frozen bearings leakage of the deck joints; lack rocker bearing in bridge maintenance accumulation of dirt and debris, no lubrication and painting ; excessive horizontal translation tearing of plates from concrete seat or superstructure inadequate design; resnicted movement on the sliding surfaces convsion, debris, dirt corrosion of bearing components excessive tilting leakage of the deck joints; lack of maintenance; inadequate design or positioning of bearings constntction misalignment ; the effect of creep and shrinkage not considered; inadequate design cracking or crumpling of contact surfaces pins, rollers Downloaded by [ Aggressive rocker bearing in bridge removes the proper provision at the time of bearing installation can lubricants and corrosion protection coatings from be- cause special problems.

Figure 1, a shows the cracking aring components. A common problem in steel bearings and crushing of concrete due to eccentric loading on IS bearing with sliding steel plates. The excessively tilted moisture with chemicals causing rusting. Corrosion of steel components, including the con- rocker bearings were observed in some prestressed con- tact surfaces, which cannot be protected by paint, in- tinuous beam bridges Fig 1, b.

The excessive transla- duces additional rocker bearing in bridge effect. Preventing translation tion of sliding plate or segmental rollers can lead to will cause excess movement at another bearing, pre- overstress of masonry plate and concrete under the venting rotations can induce large moments.

Design considerations Llcon The roller bearings must be designed for vertical Thus, the total tilt of roller bearing is therefore: and horizontal loads. Allowance should be given for 4 rotation and horizontal movement.

Downloaded by [ The problem results from non-uniform seasonal and daily time-dependent ambient a Superstructure climatic effects. The vertical and transverse temperature distributions in bridge deck are non-linear rocker bearing in bridge the cros- Sole plate ssection of a girder leading to plastic Rotation prevented plate hogging or sagging curvatures and rotaSegmental roller Substructure tions and translations of the sections.

The combined actions due to prestress, dead loads and thermal loads leading to creep of superstructure may exceed the Masonry plate horizontal displacement levels calculated by Eq 1. The movements of segmental rolb lers of expansion bearings should not exceed the values determined from the rocker bearing in bridge conditions Fig 2 : permissible contact pressure on the h rocker b.

Tilting of single a and multiple b rocker bearings Horizontal translation versus time for the bearing No 4 position of reaction from superstructure masonry plate concrete creep rocker bearing in bridge prestress and sustained loads cau- must maintain full contact with the concrete substruc- ses continual increase in tilting of bearings Fig 3.

It ture, ie the contact stress at the extremity shall be gre- is important to note that the rockers do not return to ater than zero their initial position after winter seasons.

Fig 4 shows diagrammatically the deflection of a bridge girder and a horizontal translation of the be- 4. Case studies arings. The rotation of sections as well as displace- The bridge investigated is a structure of It is divided into two parts: val- on the effect of prestressing force and long-term ver- ley and rocker bearing in bridge. The valley section an approach viaduct tical loads.

distance or, in the worst-case scenario, to fall off of the bridge seat. Steel rocker bearings also require periodic maintenance to ensure their performance. This bearing type is no longer used on new bridges. Steel Sliding Bearings (Type S.S.) Steel sliding bearings consist of a pinned joint to accommodate rotation and a sliding element to accommodate longitudinal movement. The bearing should bear directly on the concrete substructure. Anchor rods are not required for expansion bearings. Lateral forces are restrained by means of friction, concrete keeper blocks, or keeper angles. In certain cases, such as high movement expansion bearings, anchor rods may be required. rocker bearings are seismically vulnerable and are re­ placed with more stable bearings. As shown in the sec­ ond case study, removal and replacement of nonfunc­ tioning bearings can be included as part of bridge rehabilitation or seismic retrofit projects. Replacement bearings include multirotational disc bearings, .

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