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 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.

scholarly journals Influence of Elastomeric Bearings in Tension on the Seismic Performance of Base-Isolated r.c. Buildings

2020 ◽  
Vol 11 (1) ◽  
pp. 82
Author(s):  
Fabio Mazza ◽  
Mirko Mazza
Keyword(s):  
Base Isolation ◽  
Nonlinear Models ◽  
Vertical Component ◽  
Computer Code ◽  
Nonlinear Phenomena ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Near Fault ◽  
Base Isolation System ◽  
Near Fault Earthquakes

Elastomeric bearings are commonly used in base-isolation systems to protect the structures from earthquake damages. Their design is usually developed by using nonlinear models where only the effects of shear and compressive loads are considered, but uncertainties still remain about consequences of the tensile loads produced by severe earthquakes like the near-fault ones. The present work aims to highlight the relapses of tension on the response of bearings and superstructure. To this end, three-, seven- and ten-storey r.c. framed buildings are designed in line with the current Italian seismic code, with a base-isolation system constituted of High-Damping-Rubber Bearings (HDRBs) designed for three values of the ratio between the vertical and horizontal stiffnesses. Experimental and analytical results available in literature are used to propose a unified nonlinear model of the HDRBs, including cavitation and post-cavitation of the elastomer. Nonlinear incremental dynamic analyses of the test structures are carried out using a homemade computer code, where other models of HDRBs considering only some nonlinear phenomena are implemented. Near-fault earthquakes with comparable horizontal and vertical components, prevailing horizontal component and prevailing vertical component are considered as seismic input. Numerical results highlight that a precautionary estimation of response parameters of the HDRBs is attained referring to the proposed model, while its effects on the nonlinear response of the superstructure are less conservative.

scholarly journals Low Cost Frictional Seismic Base-Isolation of Residential New Masonry Buildings in Developing Countries: A Small Masonry House Case Study

2017 ◽  
Vol 11 (1) ◽  
pp. 1026-1035 ◽  
Author(s):  
Ahmad Basshofi Habieb ◽  
Gabriele Milani ◽  
Tavio Tavio ◽  
Federico Milani
Keyword(s):  
Finite Element ◽  
Seismic Vulnerability ◽  
Base Isolation ◽  
Low Cost ◽  
Element Model ◽  
Shaking Table ◽  
Fe Model ◽  
Isolation System ◽  
Finite Element Software ◽  
Non Linear

Introduction:An advanced Finite Element model is presented to examine the performance of a low-cost friction based-isolation system in reducing the seismic vulnerability of low-class rural housings. This study, which is mainly numerical, adopts as benchmark an experimental investigation on a single story masonry system eventually isolated at the base and tested on a shaking table in India.Methods:Four friction isolation interfaces, namely, marble-marble, marble-high-density polyethylene, marble-rubber sheet, and marble-geosynthetic were involved. Those interfaces differ for the friction coefficient, which was experimentally obtained through the aforementioned research. The FE model adopted here is based on a macroscopic approach for masonry, which is assumed as an isotropic material exhibiting damage and softening. The Concrete damage plasticity (CDP) model, that is available in standard package of ABAQUS finite element software, is used to determine the non-linear behavior of the house under non-linear dynamic excitation.Results and Conclusion:The results of FE analyses show that the utilization of friction isolation systems could much decrease the acceleration response at roof level, with a very good agreement with the experimental data. It is also found that systems with marble-marble and marble-geosynthetic interfaces reduce the roof acceleration up to 50% comparing to the system without isolation. Another interesting result is that there was little damage appearing in systems with frictional isolation during numerical simulations. Meanwhile, a severe state of damage was clearly visible for the system without isolation.

scholarly journals Seismic Vulnerability Evaluation of a Three-Span Continuous Beam Railway Bridge

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Chongwen Jiang ◽  
Biao Wei ◽  
Dianbin Wang ◽  
Lizhong Jiang ◽  
Xuhui He
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Seismic Isolation ◽  
Seismic Vulnerability ◽  
Element Model ◽  
Seismic Demand ◽  
Continuous Beam ◽  
Railway Bridge ◽  
Demand Model ◽  
Probabilistic Seismic Demand

In order to evaluate the seismic vulnerability of a railway bridge, a nonlinear finite element model of typical three-span continuous beam bridge on the Sichuan-Tibet railway in China was built. It further aimed at performing a probabilistic seismic demand analysis based on the seismic performance of the above-mentioned bridge. Firstly, the uncertainties of bridge parameters were analyzed while a set of finite element model samples were formulated with Latin hypercube sampling method. Secondly, under Wenchuan earthquake ground motions, an incremental dynamic method (IDA) analysis was performed, and the seismic peak responses of bridge components were recorded. Thirdly, the probabilistic seismic demand model for the bridge principal components under the prerequisite of two different kinds of bearing, with and without seismic isolation, was generated. Finally, comparison was drawn to further ascertain the effect of two different kinds of bearings on the fragility components. Based on the reliability theory, results were presented concerning the seismic fragility curves.

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 Modelling lead-rubber seismic isolation bearings using the unified mechanics theory

2021 ◽  
Vol 4 (4) ◽  
pp. 213-226
Author(s):  
Hernán Martín Hernández Morales
Keyword(s):  
Finite Element ◽  
Curve Fitting ◽  
Seismic Isolation ◽  
Damage Mechanics ◽  
Element Model ◽  
Hysteretic Behavior ◽  
Newtonian Mechanics ◽  
Element Analysis ◽  
Lead Rubber Bearing ◽  
Period Lengthening

Lead-rubber seismic isolation bearings (LRB) have been installed in a number of essential and critical structures, like hospitals, universities and bridges, in order to provide them with period lengthening and the capacity of dissipating a considerable amount of energy to mitigate the effects of strong ground motions. Therefore, studying the damage mechanics of this kind of devices is fundamental to understand and accurately describe their thermo-mechanical behavior, so that seismically isolated structures can be designed more safely. Hitherto, the hysteretic behavior of LRB has been modeled using 1) Newtonian mechanics and empirical curve fitting degradation functions, or 2) heat conduction theories and idealized bilinear curves which include degradation effects. The reason for using models that are essentially phenomenological or that contain some adjusted parameters is the fact that Newton’s universal laws of motion lack the term to account for degradation and energy loss of a system. In this paper, the Unified Mechanics Theory – which integrates laws of Thermodynamics and Newtonian mechanics – is used to model the force-displacement response of LRB. Indeed, there is no need for curve fitting techniques to describe their damage behavior because degradation is calculated at every point using entropy generation along the Thermodynamics State Index (TSI) axis. A finite element model of a lead-rubber bearing was constructed in ABAQUS, where a user material subroutine UMAT was implemented to define the Unified Mechanics Theory equations and the viscoplastic constitutive model for lead. Finite element analysis results were compared with experimental test data.

Finite Element Simulation of Stability and Resistance to Extreme Loads of Braced Shell with Elastomeric Bearings

2014 ◽  
Vol 709 ◽  
pp. 190-195
Author(s):  
Alexander M. Belostotsky ◽  
Andrei S. Pavlov
Keyword(s):  
Finite Element ◽  
Finite Element Simulation ◽  
Elastomeric Bearings ◽  
Elastomeric Bearing ◽  
Extreme Loads ◽  
Element Simulation

This article reviews the experience of modeling and evaluation stability of braced shell with elastomeric bearing under static, seismic and extreme loads.

The Behavior of Bearings Used for Seismic Isolation under Rotation and Axial Load

1999 ◽  
Vol 15 (2) ◽  
pp. 225-244 ◽  
Author(s):  
Atsushi Mori ◽  
Peter J. Moss ◽  
Nigel Cooke ◽  
Athol J. Carr
Keyword(s):  
Seismic Isolation ◽  
Axial Loads ◽  
Isolation System ◽  
Elastomeric Bearings ◽  
Lead Rubber Bearings ◽  
Combined Action ◽  
Lift Off ◽  
Rubber Bearings ◽  
Bearing Behavior ◽  
Angle Of Rotation

The investigation described in this paper looked at both laminated elastomeric bearings and lead-rubber bearings in order to obtain a better understanding of the real bearing behavior under the combined action of rotation and axial loads when used in a seismic-isolation system. In particular, the investigation focused on the distributions of vertical pressure on the bearing faces and the degree of lift-off of the edges of the bearings as the angle of rotation increased.

scholarly journals A Study on Seismic Isolation of Shield Tunnel Using Quasi-Static Finite Element Method

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Can Li ◽  
Weizhong Chen ◽  
Wusheng Zhao ◽  
Takeyasu Suzuki ◽  
Yoshihiro Shishikura
Keyword(s):  
Finite Element ◽  
Shear Modulus ◽  
Seismic Isolation ◽  
Transverse Direction ◽  
Longitudinal Direction ◽  
Isolation Effect ◽  
Poisson's Ratio ◽  
Shield Tunnel ◽  
Isolation System ◽  
Isolation Layer

Using a quasi-static method based on an axisymmetric finite element model for seismic response analysis of seismically isolated tunnels, the seismic isolation effect of the isolation layer is studied, and the seismic isolation mechanism of the isolation layer is clarified. The results show that, along the longitudinal direction of the tunnel, the seismic isolation effect is mainly affected by the shear modulus of the isolation material. The smaller the shear modulus is, the more evident the seismic isolation effect is. This is due to the tunnel being isolated from deformation of its peripheral ground through shear deformation of the isolation layer. However, along the transverse direction of the tunnel, the seismic isolation effect is mainly affected by the shear modulus and Poisson’s ratio of the isolation material. When Poisson’s ratio is close to 0.5, a seismic isolation effect is not evident because the tunnel cannot be isolated from deformation of its peripheral ground through compression deformation of the isolation layer. Finally, a seismic isolation system comprising a shield tunnel in which flexible segments are arranged at both ends of an isolation layer is proposed, and it is proved that the seismic isolation system has significant seismic isolation effects both on the longitudinal direction and on the transverse direction.

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