Home  About us  Contact
 

Elastomeric Bearings (elastomeric + bearing)

Distribution by Scientific Domains
Engineering100%

Selected Abstracts

The eigenvalues of isolated bridges with transverse restraints at the end abutments

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2010
Nicos Makris
Abstract This paper examines the eigenvalues of multi-span seismically isolated bridges in which the transverse displacement of the deck at the end abutments is restricted. With this constraint the deck is fully isolated along the longitudinal direction, whereas along the transverse direction the deck is a simple-supported beam at the end abutments which enjoys concentrated restoring forces from the isolation bearings at the center piers. For moderate long bridges, the first natural period of the bridge is the first longitudinal period, while the first transverse period is the second period, given that the flexural rigidity of the deck along the transverse direction shortens the isolation period offered by the bearings in that direction. This paper shows that for isolated bridges longer than a certain critical length, the first transverse period becomes longer than the first longitudinal period despite the presence of the flexural rigidity of the deck. This critical length depends on whether the bridge is isolated on elastomeric bearings or on spherical sliding bearings. This result is also predicted with established commercially available numerical codes only when several additional nodes are added along the beam elements which are modeling the deck in-between the bridge piers. On the other hand, this result cannot be captured with the limiting idealization of a beam on continuous distributed springs (beam on Wrinkler foundation),a finding that has practical significance in design and system identification studies. Finally, the paper shows that the normalized transverse eigenperiods of any finite-span deck are self-similar solutions that can be represented by a single master curve and are independent of the longitudinal isolation period or on whether the deck is supported on elastomeric or spherical sliding bearings. Copyright © 2009 John Wiley & Sons, Ltd. [source]

A mechanical model for elastomeric seismic isolation bearings including the influence of axial load

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2009
Sachie Yamamoto
Abstract For the purpose of predicting the large-displacement response of seismically isolated buildings, an analytical model for elastomeric isolation bearings is proposed. The model comprises shear and axial springs and a series of axial springs at the top and bottom boundaries. The properties of elastomeric bearings vary with the imposed vertical load. At large shear deformations, elastomeric bearings exhibit stiffening behavior under low axial stress and buckling under high axial stress. These properties depend on the interaction between the shear and axial forces. The proposed model includes interaction between shear and axial forces, nonlinear hysteresis, and dependence on axial stress. To confirm the validity of the model, analyses are performed for actual static loading tests of lead,rubber isolation bearings. The results of analyses using the new model show very good agreement with the experimental results. Seismic response analyses with the new model are also conducted to demonstrate the behavior of isolated buildings under severe earthquake excitations. The results obtained from the analyses with the new model differ in some cases from those given by existing models. Copyright © 2008 John Wiley & Sons, Ltd. [source]

Erdbebenertüchtigung des Feuerwehrgebäudes in Basel durch schwimmende Lagerung

BAUTECHNIK, Issue 8 2009
Hugo Bachmann Prof. Dr. sc. techn.
Baumechanik; Bauwerkserhaltung/Sanierung; Structural Mechanics; Maintenance and Renovation Abstract Kürzlich wurde das Hauptgebäude der Berufsfeuerwehr Basel-Stadt aus dem Jahre 1943 auf spezielle Erdbebenlager aus Gummi und auf Gleitlager gestellt. Es handelt sich um die erste derartige Erdbebenertüchtigung eines bestehenden Gebäudes nördlich der Alpen. Im Vergleich zu einer konventionellen Verstärkung waren die Baukosten bedeutend geringer, und es war keine temporäre Ausquartierung des Betriebes in ein teures Provisorium erforderlich. Zudem ist die resultierende Erdbebensicherheit erheblich größer und die Schadensanfälligkeit bei schweren Erdbeben wesentlich geringer als es bei einer konventionellen Verstärkung der Fall wäre. Seismic upgrading of the fire brigade building in Basel by base isolation. Recently, the main building of the professional fire brigade of the city and canton Basel-Stadt built in the year 1943 was placed on special seismic elastomeric bearings and on sliding bearings. This is the first such seismic upgrading of an existing building in the north of the Alps. Compared to a conventional strengthening the buildingcosts were significantly smaller, and no temporary transfer of the operation into an expensive provisional building was necessary. Moreover, the resulting seismic safety is considerably higher and the vulnerability to a severe earthquake essentially smaller than in case of a conventional strengthening. [source]

Bewehrte Elastomerlager , Erkenntnisstand und Defizite

BAUTECHNIK, Issue 1 2006
Helmut Eggert Dr.-Ing.
Bewehrte Elastomerlager werden seit etwa 50 Jahren im Brükkenbau verwendet. Sie wurden in der Vergangenheit mit einfachen, in DIN 4141 Teil 14 formulierten Regeln bemessen. In der künftigen Europäischen Norm EN 1337 Teil 3, die die deutsche Norm ablösen wird, sind die Regeln deutlich komplizierter, ohne daß neue Erkenntnisse vorliegen. Im vorliegenden Beitrag wird der vorhandene Kenntnisstand skizziert und auf noch vorhandene offene Fragen als Anregung für künftige Forschungen hingewiesen. Laminated elastomeric bearings , the level of knowledge and the deficits. Laminated elastomeric bearings have been installed in bridges for nearly 50 years. The simple design rules in Germany, DIN 4141 Part 14, will now relieve from EN 1337 Part 3, which are more complicated. But there is not new knowledge. Nevertheless not to this day have all facts which are necessary for construction design been sufficiently clarified. This lack of knowledge concerns, among other things, the design of the reinforcing plates, the size of restoring moment, the interaction of compression, shear and rotation and the quantity of creep and relaxation. [source]