Pot Bearing Research Articles

Effect of Pot Bearing Aging on the Seismic Response of a Three-span Continuous Girder Bridge

Effect of Pot Bearing Aging on the Seismic Response of a Three-span Continuous Girder Bridge

Research on the Mechanical Properties and Temperature Compensation of an Intelligent Pot Bearing for a Pipe-Type Welding Strain Gauge.

As an important component connecting the upper and lower structures of a bridge, bridge bearings can reliably transfer vertical and horizontal loads to a foundation. Bearing capacity needs to be monitored during construction and maintenance. To create an intelligent pot bearing, a portable small spot welding machine is used to weld pipe-type welding strain gauges to the pot bearing to measure strain and force values. The research contents of this paper include the finite element analysis of a basin bearing, optimal arrangement of welding strain gauges, calibration testing, and temperature compensation testing of the intelligent basin bearing of the welding strain gauges. Polynomial fitting is used for the fitting and analysis of test data. The results indicate that the developed intelligent pot bearing has a high-precision force measurement function and that after temperature compensation, the measurement error is within 1.8%. The intelligent pot bearing has a low production cost, and the pipe-type welding strain gauges can be conveniently replaced. The novelty is that the bearing adopts a robust pipe-type welding strain gauge and that automatic temperature compensation is used. Therefore, the research results have excellent engineering application value.

Seismic performance of isolated buildings with friction spring damper

The main objective of this paper is to introduce a new combination of passive seismic response control devices containing Friction Spring Damper (FSD) and Pot Bearing (PB) for buildings and compare this system with conventional seismic isolators such as Lead Rubber Bearing (LRB) and Friction Pendulum System (FPS). For this purpose, two benchmark buildings with different structural systems have been considered for implementing the devices. To capture the flag-shaped and self-centered behavior of FSD, new uniaxial material has been developed for OpenSees, and numerical verification of the material has been done based on a past experimental study. Nonlinear dynamic time-history analyses have been used to extract the seismic responses of models, including fixed-base structures, and isolated structures by FSD along with PB, LRB, and FPS. The results show that not only the proposed isolation system has the capability of reducing base shear and inter-story drift as well as both conventional seismic isolation systems compared to fixed-base structures, but also the system has even better performance than the isolated structures with LRB. Moreover, due to the self-centered behavior of FSD, the residual displacement of the proposed system is much lower than conventional isolation systems, which can lead to lower maintenance costs of isolators.

EFFECT OF USING LEAD RUBBER BEARING ON A STEEL ARCH BRIDGE

A study was conducted to evaluate the application of Lead Rubber Bearing (LRB) on bridge structures. The length of steel arch bridge is 80 m, width of 10 m, and height of 19.6 m. The bridge is simply supported with two bearings on each support. Structural analysis reveals that the lateral force on the bearing is more than 400 tons (835 tons in longitudinal direction). The original designer’s intention is to use pot bearings. However, the pot bearing was required to undergo some mechanical test to verify its properties prior to installation. Due to its size, this scheme is not applicable due to the limitations of the testing facility. Therefore, an alternative design was evaluated using LRB to reduce the reaction force, hence downsize the bearing size. The LRB used is of LRB 7500 characteristics, and the calculation refers to AASHTO Guide Specifications for Seismic Isolation Design (GSID), 4th edition 2014.The analysis shows that applying LRB on the bridge lengthened the structural period from 0.76 seconds to 1.67 seconds. It also increased the damping ratio from 5% to 43 %. With these significant changes in structural parameters, lateral forces due to earthquake loads on the bearing and foundation can be greatly reduced. The study found that replacing pot bearings with LRBs can reduce the lateral force to 80 tons, approximately one fifth from the previous design. Correspondingly, the internal forces of some major structural components of the bridge can be reduced due to the application of LRB.

EFFECT OF USING LEAD RUBBER BEARING ON A STEEL ARCH BRIDGE

A study was conducted to evaluate the application of Lead Rubber Bearing (LRB) on bridge structures. The length of steel arch bridge is 80 m, width of 10 m, and height of 19.6 m. The bridge is simply supported with two bearings on each support. Structural analysis reveals that the lateral force on the bearing is more than 400 tons (835 tons in longitudinal direction). The original designer’s intention is to use pot bearings. However, the pot bearing was required to undergo some mechanical test to verify its properties prior to installation. Due to its size, this scheme is not applicable due to the limitations of the testing facility. Therefore, an alternative design was evaluated using LRB to reduce the reaction force, hence downsize the bearing size. The LRB used is of LRB 7500 characteristics, and the calculation refers to AASHTO Guide Specifications for Seismic Isolation Design (GSID), 4th edition 2014.The analysis shows that applying LRB on the bridge lengthened the structural period from 0.76 seconds to 1.67 seconds. It also increased the damping ratio from 5% to 43 %. With these significant changes in structural parameters, lateral forces due to earthquake loads on the bearing and foundation can be greatly reduced. The study found that replacing pot bearings with LRBs can reduce the lateral force to 80 tons, approximately one fifth from the previous design. Correspondingly, the internal forces of some major structural components of the bridge can be reduced due to the application of LRB.

Tarumanagara University Campus 1 Sky-bridge Structure Evaluation

In this study an evaluation of the structure of the sky-bridge at Tarumanagara University campus 1 on earthquake regulations SNI 1726 : 2019. The sky-bridge connects the two buildings, parking building (8 floors) and the main building (21 floors). Type of support on the sky-bridge in the parkirng building is multidirectional pot bearing and in the main building is fixed pot bearing. The modeling of pot bearings in the ETABS program is modeled as a link property element. Based on the evaluation results, checking on the dimensions of installed pot bearing components have qualified the requirements set by AASHTO LRFD Bridge Design 2012. Based on earthquake redundancy factors, pot bearing on the 7th floor cannot be adjusted lateral deformation required is greather than maximum deformation limit provided by pot bearing, while based on earthquakes with strong factors, pot bearing on the sky-bridge are incorrect due to the lateral deformation that occurs. From the results of the study concluded that use pot bearings as support of sky-bridge 7th floor is not appropriate when checked against earthquake regulations SNI 1726: 2019.

Investigation and Analysis of Bridge Pot Bearing

The paper present describes the investigation and analysis of bridge pot bearing. A technical solution to the problem of unavoidable movements in bridge structures is the use of bridge bearing. The road engineering consists of three major structure, road embankments, bridges, and tunnels. In consideration of the cost of land acquisition in urban areas, the trend of road engineering migrating to hilly or mountain areas has been developed. Pot bearing has many advantages the extremely long service year in addition to the correct installation the routine inspection and maintained of pot bearing in the service time are necessary for them to fully function. Current domestic research mainly concentrates of rubber bearing and has only few discussion and analysis on pot bearing.

Seismic design method analyses of an innovative steel damping bearing for railway bridges

The bearing sliding effect of the pot bearing and plastic deformation of a low-yield steel damper has been proven to be effective in mitigating the seismic response of railway bridges during earthquakes. However, both the sliding effect and plastic deformation require large bearing and pier dimensions to avoid unseating damage during earthquakes, leading to higher costs during construction of the railway bridge. On the basis of bearing sliding and energy dissipation, a novel steel damping bearing is developed by using “function separated design”. The steel damping bearing is composed of a pot bearing to support the vertical loads and a series of low-yield steel dampers to bear the horizontal seismic loads. In this paper, both the force-based and displacement-based design methods for the steel damping bearing are analysed by using the equivalent linearization method. Then, a 1:7 scale two-span simply supported railway bridge model is tested on a shaking table under different ground motions to estimate the design method results for the steel damping bearing. Additionally, a bridge model with pot bearings is tested as a benchmark model. Finally, the prototype bridge is modelled by numerical analysis to evaluate the effectiveness of each design method. The experimental and numerical results reveal that both design methods can effectively simulate the response of the bridge model. Moreover, a comparison between the models with steel damping bearings and with pot bearings reveal that the steel damping bearing can greatly mitigate the pier forces and displacement with an acceptable displacement between the pier and girder.

Load-Measuring Pot Bearing with Built-In Load Cell —Part I: Design and Performance

This paper presents the underlying principle and the results of various performance evaluations for a load-measuring pot bearing with built-in load cell. The pot bearing composed of a pot made of steel in which an elastomer disk is inserted is a bearing supporting larger loads than the elastomeric bearing and accommodating rotational movement. Owing to a Poisson’s ratio close to 0.5, elastomer withstands hydrostatic pressure when confined in a rigid body. Accounting for this principle, the vertical load applied on the pot bearing can be obtained by converting the pressure acting on the elastomer. Therefore, a load-measuring pot bearing is developed in this study by embedding a load cell exhibiting remarkable durability in the base plate of the bearing. The details for the insertion of the load cell in the base plate of the pot were improved through finite element analysis to secure sufficient measurement accuracy. The evaluation of the static performance of the pot bearing applying these improved details verified that the bearing exhibited sufficient accuracy for the intended measurement purpose. The dynamic performance evaluation results indicated that accurate measurement of the dynamic load was also achieved without time lag.

Load-Measuring Pot Bearing with Built-In Load Cell —Part II: Fatigue Performance and Experimental Temperature Correction

This paper presents the results of fatigue performance tests performed up to 10 million cycles on a load-measuring pot bearing with built-in load cell to verify its field applicability and proposes an empirical temperature correction formula. In Part I of this work, various measurement performances of the load-measuring pot bearing were evaluated through static and dynamic loading tests. Bridge bearings are subjected to the effect of fatigue caused by the repeated application of moving loads and exposed to harsh site conditions including cold and hot weathers differently to laboratory conditions. Accordingly, the durability of the load-measuring pot bearing with built-in load cell shall be secured and the environmental effects like temperature shall be minimized for its application on field. This study conducted fatigue tests up to 10 million cycles on a load-measuring pot bearing with the capacity of 1000 kN to examine eventual degradation of the measurement accuracy with respect to the number of fatigue loading cycles. In addition, the experimental temperature correction procedure is proposed to obtain the temperature correction formula enabling to correct the effect of temperature on the load measurement.

Feasibility of a Multi-Functional Bridge Bearing with Built-in Piezoelectric Material

This paper presents a multi-functional bridge bearing conceived by introducing a piezoelectric (PZT) element within conventional pot bearing or rubber elastomeric bearing. Bridge bearings are devices that transfer loads and movements from the deck to the substructure and foundations of a bridge. Bearings are thus continuously subjected to the loads of vehicles crossing the superstructure, and they are also subjected to the weight of the superstructure. The proposed bearing has been developed to respond to the increasing demand for self-powered sensing devices for the monitoring of bridges by using the vibration-based mechanical energy produced by the traffic load. This PZT element not only supplies the electrical power required for the operation of the embedded sensing and lighting systems but can also be used to perform real-time monitoring of the traffic by adopting built-in load measuring functions such as those in bridge-weigh-in-motion (BWIM) systems. The feasibility of the proposed system is discussed through its application to an example bridge.

C형 강재 지진격리장치의 성능시험

기존의 교량받침으로 많이 사용되고 있는 폴리우레탄 디스크를 적용한 POT형식에 C형 강재감쇠장치를 추가적으로 적용한 새로운 형태의 지진격리장치에 대한 명확한 정적 성능검증과 동적특성을 파악하기 위하여 최대 극한 수직하중 시험, 최대 회전 시험, 동적재하 시험 및 동적재하 극한 반복시험을 시행하였다. 해석적 결과와 성능시험 결과를 비교분석한 결과, 충분한 감쇠능력을 보유하고있을 뿐만 아니라, 설계기준에도 적합하다는 결론을 얻을 수 있었다. 또한, EDC 및 유효강성값의 시험치가 이론치와 유사하여 시험 결과값의 분석이 유효함을 보였다. This paper introduces the performance of a newly developed base isolation system made from the combination of a polyurethane disk - attached pot bearing and C-shape steel dampers. Ultimate compressive load tests, ultimate rotation tests, dynamic tests, and dynamic load repeat tests have been completed to determine dynamic characteristics and to verify performance characteristics. The experimental results are compared with the analytic results. It is determined that all requirements for bridge bearing in the specifications are satisfied, and that adequate energy dissipation has occurred. The EDC and effective stiffness estimated by tests are similar to the theoretical values.

Full-scale pseudo-dynamic test for bridge retrofitted with seismic isolations

The authors examine retrofitted bridge pier performance with a seismic isolation present. Retrofitted bridge seismic performance experimental validation was done through fabrication and testing of four full-scale reinforced concrete bridge piers with fixed support conditions. To simulate the superstructure dead load, a static vertical load was applied to the bearing top and several different bearing systems were installed. Conventional pot bearing was also considered in addition to lead rubber bearing (LRB) and rubber bearing (RB) systems. To simulate earthquake loading, a horizontal loading was applied to the specimen using a pseudo-dynamic testing method. Isolated RB and LRB system specimen seismic response was compared to that of the conventional pot bearing specimen. That the seismic isolation system this study considers is effective in magnitude reduction of transferred substructure forces and period bridge shifting is shown in the results. The peak acceleration transmitted to the structure can be effectively reduced by the LRB structure, which under earthquake loading is less than those with RB system. That the proposed seismic retrofit method was found to be valid can be concluded through the test results.

Collapse during Construction of a Precast Girder Bridge

This paper describes the collapse during construction of a precast concrete girder bridge crossing Highway 15, north of Montreal. The bearing conditions for the girders at the time of collapse are discussed. The tie rods that were used to restrain the movement of the girder top flanges were tested to determine their effective stiffness and strength. Rotational and sliding tests were also performed on the pot bearing units. These experimental results were used in an analytical study to confirm the sequence of collapse of the girders. Bracing requirements during construction for precast girder bridges supported on pot bearings are discussed.

적층고무받침으로 내진보강된 교량의 유사동적실험

도로교의 내진설계기준이 국내에 도입되어 적용된 것은 10여년에 불과하므로 아직 많은 교량에 내진성능 보강이 필요하다. 본 논문에서는 받침이 노후된 교량의 내진성능 보강방법으로서 적층고무받침으로 교체하는 방법의 타당성에 관하여 논하였다. 이를 위하여 내진상세가 없는 실물크기 RC교각 시험체를 제작하고 POT받침, 적층고무받침(RB), 납-적층고무받침(LRB)를 각각 설치하였다. 유사동적 실험을 통하여 이들 시험체의 지진시 거동을 모사하고 성능을 비교하였다. 실험결과로부터 제안된 내진보강기법의 타당성을 확인하였다. Many highway bridges in Korea need seismic retrofit because only one decade has passed since the seismic design criteria was introduced. For the highway bridges of which bearings are worn and dysfunctional, the validity of seismic retrofit method using laminated rubber bearings was discussed in this study. Real scale RC pier specimens without seismic details were constructed. And then, Pot bearing, Rubber bearing (RB), Lead-rubber bearing (LRB) were applied to these specimens. Through pseudo dynamic test method, dynamic behavior of these RC piers under earthquake was simulated and compared. From the test results, proposed seismic retrofit method was found to be valid.