Preparation and characterization of natural rubber–based new elastomers for high-damping base isolation systems

Abstract

Natural rubber (NR)–based vulcanizates have been used as base isolation materials for many years. Combining good damping properties, low cost, and availability with acceptable mechanical and aging performance, these materials have always been the first choice for base isolation applications. In this research, we try to formulate a natural rubber base recipe with increased damping properties, which can fulfill mechanical and aging requirements of base isolation systems. For this purpose, a series of blends have been formulated by incorporating chloroprene (CR) or butadiene (BR) and acrylonitrile butadiene rubber (NBR) into the natural rubber base. Filler content accelerator type and vulcanization system have been chosen to optimize damping while maintaining a reference point. All vulcanizates have been tested for their mechanical properties. Moving die rheometer (MDR) and rubber process analyzer (RPA) have been used to obtain general cure data as well as storage (G′) and loss modulus and loss angle (η). Crosslink densities have been calculated using RPA and Lee and Pawlowsky’s Coran approach. Dynamic material tests have been performed to obtain dynamic shear properties, equivalent damping ratio, and shear modulus. The results indicated that NR/NBR and NR/CR compounds with viscous damping values of 10.4% and 8.9% at frequency of .5 Hz can lay bases for formulating high-damping rubber (HDR) materials for base isolation systems due to their increased damping and rather good mechanical and relaxation performance.

Numerical Assessment of Bidirectional Roller Bearing Isolators under Near-Fault Earthquakes

“…Natural rubber bearings (NRB), lead rubber bearings (LRB), high-damping rubber bearings (HDRB), slider bearings, and mono-, double-, and triple-friction pendulum (FP) systems stand out for their design simplicity and effectiveness. Some isolated structure projects and the development of new materials were described by De Luca and Guidi (2019) and Nobari Azar et al (2022). An isolation seismic layer must provide (i) low lateral stiffness, (ii) re-centering capacity, and (iii) supplementary damping.…”

Study on the seismic response of new staggered story isolated structure under different parameters

“…Research shows that both Friction Pendulum System (FPS) and Lead Rubber Bearing (LRB) isolation frames can effectively increase the seismic performance of structures (Zhao et al, 2022). Research shows that the pulse signal in pulsed ground motion will amplify the response of LRB base isolation structure (Nobari Azar et al, 2022). found that natural rubber base isolation can effectively meet the requirements of base isolation system (Rabiee and Chae, 2022).…”