Fiber-Reinforced Elastomeric Bearings for Vibration Isolation

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
James M. Kelly ◽  
Niel C. Van Engelen
Keyword(s):  
Seismic Isolation ◽  
Vibration Isolation ◽  
Fiber Reinforcement ◽  
Compression Modulus ◽  
Additional Parameter ◽  
Fiber Reinforced ◽  
Elastomeric Bearings ◽  
Vertical Stiffness ◽  
Elastomeric Bearing ◽  
Fiber Materials

Fiber-reinforced elastomeric bearings were originally proposed as an alternative to conventional steel-reinforced elastomeric bearings for seismic isolation applications. The flexible fiber reinforcement is a light-weight and potentially cost saving alternative to steel reinforcement which is assumed rigid in the design process. The variety of fiber materials available also serves as an additional parameter for designers to tailor the vertical stiffness of the bearing. In this paper, the analytical solution for the vertical compression modulus of a rectangular elastomeric pad including the effects of bulk compressibility and extensibility of the fiber reinforcement is used to investigate the achievable decrease in vertical frequency. It is shown by an example that the extensibility of the fiber reinforcement can be used to significantly reduce the vertical stiffness in comparison to an equivalent steel-reinforced elastomeric bearing. The resulting decrease in the vertical frequency means that fiber-reinforced elastomeric bearings may have an advantage over steel-reinforced bearings in the vibration isolation of buildings.

scholarly journals Finite Element Analysis for Nonlinear Unbonded Circular Fiber-Reinforced Elastomeric Bearings

2021 ◽  
Vol 5 (7) ◽  
pp. 170
Author(s):  
Pablo Castillo Ruano ◽  
Alfred Strauss
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Carbon Fiber ◽  
Seismic Isolation ◽  
Nonlinear Viscoelasticity ◽  
Fiber Reinforcement ◽  
Special Focus ◽  
Fiber Reinforced ◽  
Element Analysis ◽  
Elastomeric Bearings

In recent years, interest in low-cost seismic isolation systems has increased. The replacement of the steel reinforcement in conventional elastomeric bearings for a carbon fiber reinforcement is a possible solution and has garnered increasing attention. To investigate the response of fiber-reinforced elastomeric bearings (FREBs) under seismic loads, it is fundamental to understand its mechanical behavior under combined vertical and horizontal loads. An experimental investigation of the components presents complexities due to the high loads and displacements tested. The use of a finite element analysis can save time and resources by avoiding partially expensive experimental campaigns and by extending the number of geometries and topologies to be analyzed. In this work, a numerical model for carbon fiber-reinforced bearings is implemented, calibrated, and validated and a set of virtual experiments is designed to investigate the behavior of the bearings under combined compressive and lateral loading. Special focus is paid to detailed modeling of the constituent materials. The elastomeric matrix is modeled using a phenomenological rheological model based on the hyperelastic formulation developed by Yeoh and nonlinear viscoelasticity. The model aims to account for the hysteretic nonlinear hyper-viscoelastic behavior using a rheological formulation that takes into consideration hyperelasticity and nonlinear viscoelasticity and is calibrated using a series of experiments, including uniaxial tension tests, planar tests, and relaxation tests. Special interest is paid to capturing the energy dissipated in the unbonded fiber-reinforced elastomeric bearing in an accurate manner. The agreement between the numerical results and the experimental data is assessed, and the influence of parameters such as shape factor, aspect ratio, vertical pressure, and fiber reinforcement orientation on stress distribution in the bearings as well as in the mechanical properties is discussed.

Seismic Isolation Systems for Developing Countries

2002 ◽  
Vol 18 (3) ◽  
pp. 385-406 ◽  
Author(s):  
James M. Kelly
Keyword(s):  
Developing Countries ◽  
Theoretical Analysis ◽  
Earthquake Engineering ◽  
Seismic Isolation ◽  
Low Cost ◽  
Fiber Reinforcement ◽  
Fiber Reinforced ◽  
Public Buildings ◽  
Shape Factors ◽  
Engineering Research

This paper describes an experimental and theoretical study of the feasibility of using fiber reinforcement to produce lightweight low-cost elastomeric isolators for application to housing, schools and other public buildings in highly seismic areas of the developing world. The theoretical analysis covers the mechanical characteristics of multi-layer elastomeric isolation bearings where the reinforcing elements, normally steel plates, are replaced by a fiber reinforcement. The fiber in the fiber-reinforced isolator, in contrast to the steel in the conventional isolator (which is assumed to be rigid both in extension and flexure), is assumed to be flexible in extension, but completely without flexure rigidity. This leads to an extension of the theoretical analysis on which the design of steel-reinforced isolators is which accommodates the stretching of the fiber-reinforcement. Several examples of isolators in the form of long strips were tested at the Earthquake Engineering Research Center Laboratory. The tested isolators had significantly large shape factors, large enough that for conventional isolators the effects of material compressibility would need to be included. The theoretical analysis is extended to include compressibility and the competing influences of reinforcement flexibility and compressibility are studied. The theoretical analysis suggests and the test results confirm that it is possible to produce a fiber-reinforced strip isolator that matches the behavior of a steel-reinforced isolator. The fiber-reinforced isolator is significantly lighter and can be made by a much less labor-intensive manufacturing process. The advantage of the strip isolator is that it can be easily used in buildings with masonry walls. The intention of this research is to provide a low-cost lightweight isolation system for housing and public buildings in developing countries.

scholarly journals Analytical and Experimental Overview of Fiber Reinforced Elastomeric Isolator

2021 ◽  
Vol 9 (VII) ◽  
pp. 3906-3911
Author(s):  
Afroz Qureshi
Keyword(s):  
Seismic Isolation ◽  
Seismic Waves ◽  
Base Isolation ◽  
Low Cost ◽  
Fiber Reinforced ◽  
Effective Response ◽  
Isolation System ◽  
Vertical Stiffness ◽  
Base Isolation System ◽  
Fiber Reinforced Elastomeric Isolator

There has been many researches in order to further improve the Base Isolation system by trying various combinations and alternative materials. In that fiber reinforced isometric isolators are emerged as a viable solution, because for the low cost and effective response to seismic waves as compared to the conventional isolators. Studies further shows that it provides high vertical stiffness and low horizontal stiffness, also having effective damping over the conventional one. Developing countries who doesn’t have proper seismic protection solutions have found this convenient as they are comparatively less in cost and doesn’t require complex installation. Studies also shows Un-bonded FREI has lower horizontal stiffness and considerably lower stress demand on rubber material as compared to the B-FREI and hence significantly higher seismic isolation efficiency.

scholarly journals VERIFICATION OF ELASTOMERIC BEARINGS FINITE-ELEMENT MODELS IN CALCULATING SOFTWARE PACKAGES

2019 ◽  
pp. 4-4
Author(s):  
Oleg V. Mkrtychev ◽  
Artem A. Bunov
Keyword(s):  
Finite Element ◽  
Seismic Isolation ◽  
Nonlinear Models ◽  
Element Model ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Limit Values ◽  
Elastomeric Bearing ◽  
Software Packages ◽  
Work Model

Introduction. While designing buildings and constructions with an elastomeric bearing with a lead core as a seismic isolation system, it is necessary to make calculations concerning effectiveness and reasonability of its usage. These demands lead to necessity to construct bearings in a common finite-element model, in order to consider how a bearing and a construction work together. Though a calculator has a lot of different variants of elastomeric bearing’s construction, which are connected to their implemented work model. To prove that obtained calculation results are sufficient and accurate, selection criteria of elastomeric bearings implemented work models are necessary. Materials and methods. To get accurate results we will compare elastomeric bearing’s work diagrams and free periods of motion when there are different variants of their numerical modelling with the help of software packages with factory tests results. Results. The researches have shown that lateral force’s and shear’s limit values are the same for all of the observed cases, although free periods of motion and work diagrams differ. Usage of more accurate bearing work model in software package Ansys/LS-Dyna can explain these differences, it can be seen if compare their work’s diagrams. Conclusions. Analysis of constructions with elastomeric bearings’ work, which function according to the idealized linear model, can be possible only for II level constructions. Idealized nonlinear models should be used for I level constructions.

scholarly journals VERIFICATION OF ELASTOMERIC BEARINGS FINITE-ELEMENT MODELS IN CALCULATING SOFTWARE PACKAGES

2019 ◽  
pp. 4-4
Author(s):  
Oleg V. Mkrtychev ◽  
Artem A. Bunov
Keyword(s):  
Finite Element ◽  
Seismic Isolation ◽  
Nonlinear Models ◽  
Element Model ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Limit Values ◽  
Elastomeric Bearing ◽  
Software Packages ◽  
Work Model

Introduction. While designing buildings and constructions with an elastomeric bearing with a lead core as a seismic isolation system, it is necessary to make calculations concerning effectiveness and reasonability of its usage. These demands lead to necessity to construct bearings in a common finite-element model, in order to consider how a bearing and a construction work together. Though a calculator has a lot of different variants of elastomeric bearing’s construction, which are connected to their implemented work model. To prove that obtained calculation results are sufficient and accurate, selection criteria of elastomeric bearings implemented work models are necessary. Materials and methods. To get accurate results we will compare elastomeric bearing’s work diagrams and free periods of motion when there are different variants of their numerical modelling with the help of software packages with factory tests results. Results. The researches have shown that lateral force’s and shear’s limit values are the same for all of the observed cases, although free periods of motion and work diagrams differ. Usage of more accurate bearing work model in software package Ansys/LS-Dyna can explain these differences, it can be seen if compare their work’s diagrams. Conclusions. Analysis of constructions with elastomeric bearings’ work, which function according to the idealized linear model, can be possible only for II level constructions. Idealized nonlinear models should be used for I level constructions.

scholarly journals Lateral Response Comparison of Unbonded Elastomeric Bearings Reinforced with Carbon Fiber Mesh and Steel

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Ali Karimzadeh Naghshineh ◽  
Ugurhan Akyuz ◽  
Alp Caner
Keyword(s):  
Classical Equation ◽  
Experimental Tests ◽  
Elastic Behavior ◽  
Fiber Reinforced ◽  
Elastomeric Bearings ◽  
Cyclic Shear ◽  
Vertical Stiffness ◽  
Elastomeric Material ◽  
Lateral Response ◽  
Fiber Mesh

The vertical and horizontal stiffness used in design of bearings have been established in the last few decades. At the meantime, applicability of the theoretical approach developed to estimate vertical stiffness of the fiber-reinforced bearings has been verified in different academic studies. The suitability of conventional horizontal stiffness equation developed for elastomeric material, mainly for steel-reinforced elastomeric bearings, has not been tested in detail for use of fiber-reinforced elastomeric bearings. In this research, lateral response of fiber mesh-reinforced elastomeric bearings has been determined through experimental tests and the results have been compared by corresponding values pertaining to the steel-reinforced bearings. Within the test program, eight pairs of fiber mesh-reinforced bearings and eight pairs of steel-reinforced bearings are subjected to different levels of compressive stress and cyclic shear strains. Fiber-reinforced elastomeric bearings may be more favorable to be used in seismic regions due to lower horizontal stiffness that can result in mitigation of seismic forces for levels of 100% shear strain. Damping properties of these types of fiber mesh-reinforced bearings depend mostly on the selection of elastomeric material compounds. Suggestions have been made for the lateral response of fiber-reinforced elastomeric bearings. It has also been determined that the classical equation for lateral stiffness based on linear elastic behavior assumptions developed for elastomeric bearings does not always apply to the fiber-reinforced ones.

Shear strength of reinforced concrete beams with a fiber concrete matrix

2006 ◽  
Vol 33 (6) ◽  
pp. 726-734 ◽  
Author(s):  
Fariborz Majdzadeh ◽  
Sayed Mohamad Soleimani ◽  
Nemkumar Banthia
Keyword(s):  
Shear Strength ◽  
Reinforced Concrete ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Fiber Reinforcement ◽  
Shear Capacity ◽  
Fiber Reinforced Concrete ◽  
Rc Beams ◽  
Fiber Reinforced ◽  
Fiber Volume

The purpose of this study was to investigate the influence of fiber reinforcement on the shear capacity of reinforced concrete (RC) beams. Both steel and synthetic fibers at variable volume fractions were investigated. Two series of tests were performed: structural tests, where RC beams were tested to failure under an applied four-point load; and materials tests, where companion fiber-reinforced concrete (FRC) prisms were tested under direct shear to obtain material properties such as shear strength and shear toughness. FRC test results indicated an almost linear increase in the shear strength of concrete with an increase in the fiber volume fraction. Fiber reinforcement enhanced the shear load capacity and shear deformation capacity of RC beams, but 1% fiber volume fraction was seen as optimal; no benefits were noted when the fiber volume fraction was increased beyond 1%. Finally, an equation is proposed to predict the shear capacity of RC beams.Key words: shear strength, fiber-reinforced concrete, RC beam, stirrups, energy absorption capacity, steel fiber, synthetic fiber.

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