Lead-rubber bearings

Figure 1. Bilinear hysteretic model of the lead rubber bearings used in this study...

Herein, the material non-linearity of the isolator bearings has been taken into account by assuming that the lead rubber bearings have been used. For simplification, the non-linear hysteretic curve of the bearings, as shown in Figure 1, is divided into two linear parts (bilinear models). 

By considering the nonlinearity of the lead-rubber bearings and optimizing their parameters using GAs, further reduction can be obtained for the building s top story horizontal displacement. However, due to the lead-rubber bearings plastic deformation, the horizontal displacement of the base system increases. 

Lead-Rubber Bearings with Emphasis on Their Implementation to Structural Design... 

Code-Based Design Seismic Isolation of Buildings, Fig. 7 Typical lead rubber bearing with cutaway showing internal construction (courtesy of Takenaka Corp., Japan)... 

Base isolation Bridge bearings Elastomeric bearings Lead-plug bearings Lead-rubber bearings Rubber bearings Seismic isolation... 

Lead-rubber bearings are one of various existing types of seismic isolation devices and have been used for years for the protection of structures from the damaging effect of earthquakes. This entiy presents summarized information regarding the use, benefits, properties, and applications of lead-rubber bearings along with literature sources for further reading on the subject. 

Lead-Rubber Bearings with Emphasis on Their Implementation to Structural Design, Fig. 1 Typical installation of a seismic isolator in a... 

Lead-Rubber Bearings Short Description and Historicai Background... 

The lead-rubber bearing (LRB) was invented in 1975 by W. H. Robinson in New Zealand (Skinner et al. 1993 Kelly 2004 Robinson and Tucker 1977, 1983). It has been extensively used... 

The elastomer rubber layers serve as the isolation (i.e., stiffness and fundamental structural frequency reduction) component lead also contributes to the stiffness of the bearing, but this contribution is relatively minor. The steel shim plates assist with vertical load support. The lead core mainly serves as the damping (i.e., energy dissipation) component. A typical hysteretic (force-displacement) loop for a lead-rubber bearing is shown in Fig. 4 (Constantinou et al. 2007b). 

Section Lead-Rubber Bearing Properties and Structural Design provides a more detailed description of the properties of lead-mbber... 

Lead-Rubber Bearings with Emphasis on Their impiementation to Structurai Design, Tabie 1 Lead-rubber bearing components/properties and environmental/other effects... 

Constantinou et al. 1999, 2007a, b Kalpakidis and Constantinou 2009a, b Kalpakidis et al. 2010). Some of these effects and a summary of lead-rubber bearing properties and components along with the significance of these components are outlined in Table 1. 

Subsequently, several studies were performed resulting in seismic isolation retrofit work that was completed in 1995 (Walters 2003). 42 lead-rubber bearings and 69 natural rubber bearings were utilized for the retrofit (MCEER). 

Consider an M-story base-isolated shear building model as shown in Eig. 18. A simple model is used here to present an essential feature of the robustness evaluation method. Since the use of natural rubber bearings (NRB) only as isolator elements may lead to a higher level of acceleration at the top story, both NRB and lead rubber bearings (LRB) are used here. Eurthermore, an additional damping in the base-isolation story is to be given by oil dampers. 

LRB (lead rubber bearing) Plastic stiffness Upper +10 +6 +11... 

Seismic Anaiysis of Concrete Bridges Numericai Modeiing, Fig. 16 Lead rubber bearing (rectangular section) and corresponding hysteresis law... 

Lead-rubber bearings (laminated bearings with lead core)... 

---