scholarly journals Performance comparisons of triple friction pendulum bearings with different sliding surface properties

2021 ◽  
Vol 4 (3) ◽  
pp. 151-162
Author(s):  
Muhamad Zulfakar ◽  
Ali İhsan Karakaş
Keyword(s):  
Friction Coefficient ◽  
Surface Properties ◽  
Friction Surface ◽  
Time History ◽  
Radius Of Curvature ◽  
Sliding Surface ◽  
Base Shear ◽  
Finite Element Program ◽  
Element Program ◽  
Friction Pendulum

In this study the time history analyses are carried out three dimensionally for a simple five-story concrete structure seismically isolated incorporating triple friction pendulum bearings with different sliding surface properties with the help of the ABAQUS finite element program. The altering friction surface properties are friction coefficient and radius of curvature. The performances of the various isolators are compared with each other as well as with those of a fixed based structure. For this purpose, maximum relative story displacements, story accelerations and column base shear forces are investigated as seismic reactions. According to the analysis results it can be stated that the seismic reactions of isolated structures are significantly reduced when compared to those of the fixed supported structure. Additionally, when triple friction pendulum bearing isolators with different friction coefficients and friction surface radii are compared, it can be observed that increasing the friction coefficient increases the reactions of the structure while increasing the friction surface radii decreases the reactions

scholarly journals Steel Frames Exposed to Severe Ground Motions: Use of Viscous Dampers and Buckling Restrained Braces to Dissipate Earthquake Induced Energy

2021 ◽  
Author(s):  
Osman Hansu ◽  
Esra Mete Guneyisi
Keyword(s):  
Steel Frames ◽  
Structural Response ◽  
Time History ◽  
Base Shear ◽  
Viscous Dampers ◽  
Finite Element Program ◽  
Buckling Restrained Braces ◽  
Interstorey Drift ◽  
Element Program ◽  
Nonlinear Time History

This study addresses an alternative use of viscous dampers (VDs) associated with buckling restrained braces (BRBs) as the innovative seismic protection devices. For this, 4, 8 and 12 storey steel frames were designed with 6.5 m equal span length and 4 m storey height. Thereafter, the VDs and BRBs were placed over the height of each frame considering three different configurations. The structures were modeled using SAP2000 finite element program and evaluated by the nonlinear time history analyses subjected to the six natural accelerograms (1976 Gazlı, 1978 Tabas, 1987 Superstition Hills, 1992 Cape Mendocino, 1994 Northridge and 1999 Chi-Chi). The structural response of the structures with and without VDs and BRBs were studied in terms of variation in the displacement, interstorey drift, absolute acceleration, maximum base shear, time history of roof displacement. The results clearly indicated that the application of VDs and BRBs had remarkable improvement in the earthquake performance of the case study frames by reducing the local/global deformations in the main structural systems and satisfied the serviceability.

The Influence Analysis of Mechanical Behavior between Pile and Soil on End Bearing Pile Foundation’s Dynamic Characteristic

2014 ◽  
Vol 580-583 ◽  
pp. 1481-1485
Author(s):  
Wei Hu ◽  
Ya Hui Zhang ◽  
Ying Zhang
Keyword(s):  
Mechanical Behavior ◽  
Structural Model ◽  
Ground Surface ◽  
Time History ◽  
Horizontal Displacement ◽  
Shearing Stress ◽  
Maximum Acceleration ◽  
Finite Element Program ◽  
Element Program ◽  
End Bearing Pile

Dynamic structural model of saturated soil was introduced, and combining with the finite element program, the finite-infinite element models of end bearing pile foundations was established. Four models of interface between pile and soil including absolutely jointed, slippage, crack, both slippage and crack were considered to study the interface’s effect on pile foundation’s dynamic characteristics. The results were as follows: the interface’s mechanical behavior has a little influence on the distributions of pile section’s shearing stress and horizontal displacement. Pile section’s shearing stress reaches the maximum near the ground surface when interface is slippage or crack, and reaches the minimum ones when interface is absolutely jointed. Horizontal displacement could be divided into two phases and the ground surface is the dividing line. The interface’s behavior greatly changes the distribution of acceleration time-history curve. To different models, the maximum acceleration all appears at the ground surface. On the whole, the interface’s behavior has significant influence on end bearing pile, which should be pay attention in the design from now on.

A Study on the Properties, Friction, Wear and Adhesion of HVOF Thermal Spray Coating of Micron Size Co-Alloy Powder

2009 ◽  
Vol 75 ◽  
pp. 19-24 ◽  
Author(s):  
Tong Yul Cho ◽  
Jae Hong Yoon ◽  
Ki Oh Song ◽  
Yun Kon Joo ◽  
Jae Young Cho ◽  
...  
Keyword(s):  
Friction Coefficient ◽  
Surface Temperature ◽  
Surface Properties ◽  
High Speed ◽  
Wear Behavior ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
Sliding Surface ◽  
Hvof Thermal Spray ◽  
Micron Size

High velocity oxygen fuel (HVOF) thermal spray coating of micron size (μ) T800 powder has been studied for the durability improvement of sliding machine components. The optimal coating process (OCP), surface properties, friction, wear behavior and adhesion of HVOF T800 coating have been investigated. The temperature dependence of friction coefficient and wear behavior have been studied at 25°C and at an elevated temperature 538°C (1,000°F) for the study of the temperature effects on FC and wear behaviors of the coating and for the application on high speed air bearing spindle which operates with no lubricants. The OCP was determined from the best surface properties of the 16 OCP searching coatings designed by the Taguchi experimental program of four spray parameters with three levels: a hydrogen flow rate (FR) of 38-42 FMR (1 FMR=12scfh=9.44×10-5 m/s), oxygen FR of 65-70 FMR and feed rate of 30 g/min, and a spray distance of 5 inch. Hardness, roughness and porosity observed from the 16 coatings were 560-640 Hv (5488-6272 MPa), 2.2-3.0 μm and 0.01-0.04% respectively. Friction coefficient (FC) decreased from 5.5-7.0 to 4.8-6.0 with increasing the sliding surface temperature from 25°C to 538°C because of the higher lubrication effect of Co oxide debris at the higher temperature. Wear trace of the coating and counter sliding SUS 304 surface decreased to more than a half with increasing the sliding surface temperature from 25°C to 538°C. Tensile bond strength (TBS) and tensile fracture location (TFL) of Ti64 / T800 were 8,770 psi (60.5 MPa) and near the middle of the coating respectively. Bond coat NiCr did not influence on the TBS of the coating. The adhesion between Ti64 substrate and T800 coating (Ti64/T800) was stronger than the cohesion strength 8,770 psi (60.5 MPa) of T800 coating. These showed that Ti64/T800 coating was recommendable for durability improvement coating on high speed spindle of Ti64.

Time-History Analysis of the High-Rise Building Structure Based on ANSYS

2011 ◽  
Vol 71-78 ◽  
pp. 2836-2839
Author(s):  
Hui Xia Xiong ◽  
Chang Yong Wang
Keyword(s):  
Structural Design ◽  
Time History ◽  
Time History Analysis ◽  
Building Structure ◽  
Finite Element Program ◽  
High Rise ◽  
High Rise Building ◽  
History Analysis ◽  
Earthquake Load ◽  
Element Program

The dynamic property of a high-rise building structure and time-history analysis under earthquake were analyzed by using the finite element program ANSYS. A modal analysis of the tower was conducted and the first 20 frequencies and modal shapes were obtained. The displacements and inner force under the earthquake were calculated. The result showed that the structural stiffness was enough to sustain earthquake load; and the stiffness distributed equally. These results can provide reliable basis for structural design.

Spatial Analysis of Continuous Rigid Frame High Pier under Completed Bridge State

2011 ◽  
Vol 280 ◽  
pp. 183-185 ◽  
Author(s):  
Ya Xun Yang ◽  
Lei Sun
Keyword(s):  
Deformation Analysis ◽  
Radius Of Curvature ◽  
Finite Element Program ◽  
Horizontal Alignment ◽  
Continuous Rigid Frame Bridge ◽  
Rigid Frame ◽  
Element Program ◽  
Stress And Deformation ◽  
High Pier ◽  
Rigid Frame Bridge

The continuous rigid frame bridge was taken as a typical background, considering the horizontal alignment curvature of the continuous rigid frame bridge space by the force, by selecting a different radius of curvature and height of piers, using the finite element program to the completed bridge state into the curve of the high continuous rigid frame bridge pier stress and deformation analysis, focused on the effects of curvature and height of piers. Analysis of it, provided the design suggestions for the curve corresponding rigid frame bridge.

Comparative Studies of Base Isolation Systems Featured with Lead Rubber Bearings and Friction Pendulum Bearings

2016 ◽  
Vol 846 ◽  
pp. 114-119
Author(s):  
Arati Pokhrel ◽  
Jian Chun Li ◽  
Yan Cheng Li ◽  
Nicos Maksis ◽  
Yang Yu
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Time History ◽  
Elastic Base ◽  
Base Shear ◽  
Isolation Technique ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Isolation Systems ◽  
Friction Pendulum

Due to the fact that safety is the major concern for civil structures in a seismic active zone, it has always been a challenge for structural engineers to protect structures from earthquake. During past several decades base isolation technique has become more and more popular in the field of seismic protection which can be adopted for new structures as well as the retrofit of existing structures. The objective of this study is to evaluate the behaviours of the building with different seismic isolation systems in terms of roof acceleration, elastic base shear and inter-storey drift under four benchmark earthquakes, namely, El Centro, Northridge, Hachinohe and Kobe earthquakes. Firstly, the design of base isolation systems, i.e. lead rubber bearing (LRB) and friction pendulum bearing (FPB) for five storey RC building was introduced in detail. The non-linear time history analysis was performed in order to determine the structural responses whereas Bouc-Wen Model of hysteresis was adopted for modelling the bilinear behaviour of the bearings. Both isolation systems increase the fundamental period of structures and reduces the spectral acceleration, and hence reduces the lateral force cause by earthquake in the structures, resulting in significant improvement in building performance; however the Lead Rubber Bearing provided the best reduction in elastic base shear and inter-storey drift (at first floor) for most of the benchmark earthquakes. For the adopted bearing characteristics, FPB provided the low isolator displacement.

Analysis for the 3-Dimensional Time History Response of a Base-Isolated Building Structure

2011 ◽  
Vol 368-373 ◽  
pp. 1961-1964
Author(s):  
Jin Xia Kang
Keyword(s):  
Composite Structures ◽  
Seismic Waves ◽  
Three Dimensional ◽  
Time History ◽  
Economic Benefits ◽  
Seismic Structure ◽  
Finite Element Program ◽  
Concrete Frame ◽  
Element Program ◽  
Lateral Displacements

In this paper, the models of traditional anti-seismic and base-isolated masonry and concrete frame composite structures were created by the three-dimensional finite element program and their time history responses were analyzed under the actions of different seismic waves. The results show that whether they were under the action of frequently occurred earthquake or rarely occurred earthquake, the story shears of base-isolated structure are far less than those of traditional anti-seismic structure; the lateral displacements of the former are nearly translational, while those of the latter are approximately parabolic; and the fundamental period of the former is much longer than the counterpart. In conclusion, the seismic fortification intensity of base-isolated structure is one or two degree less than that of traditional anti-seismic structure, and adopting the base-isolated structure will protect the life-safety and property of people and achieve good economic benefits as well.

Study on the Effects of Train Live Loads on Isolated and Non-Isolated Simply Supported Railway Bridges

2011 ◽  
Vol 50-51 ◽  
pp. 100-104
Author(s):  
Chang Yong Zhang ◽  
Tie Yi Zhong ◽  
Ke Jian Chen ◽  
Yun Kang Gong
Keyword(s):  
Time History ◽  
Railway Bridge ◽  
Finite Element Program ◽  
Railway Bridges ◽  
Simply Supported ◽  
Rubber Bearing ◽  
Lead Rubber Bearing ◽  
Element Program ◽  
Live Loads ◽  
High Level

In this paper, based on the finite element program ANSYS, the model of a simply supported railway bridge with and without isolation using lead rubber bearing is established. Seismic response time-history analyses of the bridge subjected to high-level earthquakes are carried out considering and not considering train live loads. Through the comparison and analyses of the results, the effects of train live loads on seismic calculation of non-isolated railway bridges and isolated railway bridges are obtained. The results of the research will support the further study on seismic design and isolation design of simply supported railway bridges.

scholarly journals A constant friction coefficient model for concave friction bearings

2020 ◽  
Vol 14 (1) ◽  
pp. 112-126
Author(s):  
Dao Dinh Nhan ◽  
Chung Bac Ai
Keyword(s):  
Friction Coefficient ◽  
Numerical Models ◽  
Structural Response ◽  
Time History ◽  
Friction Model ◽  
System Response ◽  
Isolation System ◽  
Constant Friction ◽  
Friction Pendulum ◽  
Friction Bearings

This paper develops a constant friction coefficient model that best represents a velocity-dependent friction model for predicting structural response of buildings isolated with concave friction bearings. To achieve this goal, the effect of friction model on structural response of three hypothetical isolated buildings with different number of stories subjected to different earthquake scenarios was numerically investigated. The structural numerical models of the isolated buildings were developed in OpenSees with superstructure is represented by a shear frame model and isolation system using single friction pendulum bearings is modeled by a 3-D friction pendulum bearing element which accepts different friction models. The numerical models were subjected to 30 pairs of ground motions, representing service earthquake level, design basic earthquake level and maximum considered earthquake level at a strong seismic activity area in the world. The investigation reveals that friction coefficient models significantly affect the structural response and there is no constant friction coefficient model that simultaneously best predicts isolation system response and superstructure response. The constant friction coefficient that best predicts isolation system response produces a large error on prediction of superstructure response and vice versa. Based on the numerical results, a constant friction coefficient model for different criteria was developed. Keywords: friction coefficient model; friction bearing; isolation system; earthquake response; time-history analysis.

scholarly journals Modeling and design of tuned mass dampers using sliding variable friction pendulum bearings

2020 ◽  
Vol 231 (12) ◽  
pp. 5021-5046
Author(s):  
Emiliano Matta ◽  
Rita Greco
Keyword(s):  
Friction Coefficient ◽  
Pressure Distribution ◽  
Analytical Model ◽  
Seismic Isolation ◽  
Outer Region ◽  
Design Parameters ◽  
Sliding Surface ◽  
Restoring Force ◽  
Variable Friction ◽  
Friction Pendulum

Abstract An effective vibration control device, the pendulum tuned mass damper (P-TMD), can be easily realized as a mass supported on rolling or sliding pendulum bearings. While the bearings’ concavity provides the desired gravitational restoring force, the necessary dissipative force can be obtained either from additional dampers installed in parallel with the bearings or from the same friction resistance developing within each bearing between the roller/slider and the rolling/sliding surface. The latter solution may prove cheaper and more compact but implies that the P-TMD effectiveness will be amplitude dependent if the friction coefficient is kept uniform along the rolling/sliding surface, as in conventional friction bearings. In this case, the friction P-TMD will be as efficient as a viscous P-TMD only at a given vibration level, with large performance reductions at other levels. To avoid this inconvenience, this paper proposes a new type of sliding variable friction pendulum (VFP) TMD, called the VFP-TMD, in which the sliding surface is divided into two concentric regions: a circular inner region, having the lowest possible friction coefficient and the same dimensions of the slider, and an annular outer region, having a friction coefficient set to an optimal value. A similar arrangement has been recently proposed to realize adaptive seismic isolation devices, but no specific application to TMDs is reported. To assess the VFP-TMD performance, first its analytical model is derived, rigorously accounting for geometric nonlinearities as well as for the variable (in time and space) pressure distribution along the contact area, and then, an optimal design methodology is presented. Finally, numerical simulations show the influence of the main design parameters on the device behavior and demonstrate that the VFP-TMD can achieve nearly the same effectiveness of viscous P-TMDs, while considerably outperforming conventional uniform-friction P-TMDs. The proposed analytical model can be used to enhance or validate existing models of VFP isolators that assume a constant and uniform contact pressure distribution.

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