Numerical implementation of variable friction sliding base isolators and preliminary experimental results

2020 ◽  
Vol 36 (2) ◽  
pp. 767-787
Author(s):  
Tianye Yang ◽  
Paolo M Calvi ◽  
Richard Wiebe
Keyword(s):  
Base Isolation ◽  
Numerical Study ◽  
Three Dimensional ◽  
Structural Response ◽  
Time History ◽  
Experimental Results ◽  
Vertical Coupling ◽  
Moment Resisting ◽  
Variable Friction ◽  
Nonlinear Time History

The development of variable friction base isolation systems (VFSs) is the object of an ongoing international research project that involves extensive numerical and experimental activities. This article presents some of the recent numerical developments carried out as part of this project. More specifically, a three-dimensional (3D) variable friction (VF) element is formulated and implemented into OpenSees, providing the foundation for studying structural response in the context of nonlinear time history (NLTH) analysis. The element implementation captures the bearing bidirectional horizontal response along with horizontal–vertical coupling effects. Response predictions obtained using this newly implemented element are compared with the experimental results obtained from testing a full-scale VFS prototype, showing promising results. Finally, a demonstrative numerical study is carried out in which a steel moment resisting frame (MRF) structure, isolated using VFSs, is analyzed via NLTH analyses.

Seismic Isolation Devices Based on Sliding between Surfaces with Variable Friction Coefficient

2016 ◽  
Vol 32 (4) ◽  
pp. 2291-2315 ◽  
Author(s):  
Paolo M. Calvi ◽  
Matteo Moratti ◽  
Gian Michele Calvi
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Time History ◽  
Absorption Capacity ◽  
Sliding Isolation ◽  
Variable Friction ◽  
Displacement Based ◽  
Nonlinear Time History ◽  
High Level ◽  
Base Isolators

Base isolators are effective tools to favor a high level of building performance under lateral load, providing protection to both structural and nonstructural elements. In this context, this paper discusses the possibility of employing materials with different frictional properties to enhance the response of flat and curved-surface base isolators. Two innovative devices, referred to as “BowTie” and “BowC,” are introduced and discussed in some detail. A series of nonlinear time history analyses are then conducted using a customized computer program and considering a number of case study structures, designed applying a displacement-based approach. The results of the analyses are used to discuss the key differences between variable friction and constant friction sliding isolation devices. It is shown that the newly proposed isolators may represent an improvement on classic base-isolation solutions, in light of their higher energy absorption capacity, which contributes to significantly enhance their performance.

scholarly journals Seismic Upgrading of Steel Moment-Resisting Frames by Means of Friction Devices

2014 ◽  
Vol 8 (1) ◽  
pp. 289-299 ◽  
Author(s):  
Esra Mete Güneyisi ◽  
Mario D'Aniello ◽  
Raffaele Landolfo
Keyword(s):  
Structural Response ◽  
Time History ◽  
Seismic Behaviour ◽  
Steel Moment Resisting Frames ◽  
Residual Drift ◽  
Moment Resisting Frames ◽  
Drift Ratio ◽  
Nonlinear Time History Analyses ◽  
Moment Resisting ◽  
Nonlinear Time History

In recent decades, several passive energy dissipation systems have been conceived in order to minimize the damage in structural and non-structural components of either new or existing buildings. In this study, the use of friction damped tension-compression diagonal braces for seismic upgrading of a steel moment resisting frames is investigated. To this aim, nonlinear time history analyses have been carried out on a set of representative frames with and without friction damped braces. In the nonlinear time history analyses, two sets of natural accelerograms compatible with seismic hazard levels of 10% and 2% probability of exceedance in 50 years have been considered. Under these records, the structural response has been comparatively investigated in terms of the maximum inter-storey drift ratio, maximum storey acceleration, residual drift ratio and displacement demand for the friction device. The results clearly highlighted that the application of friction damped braces allows reducing the damages to the main structural elements, thus significantly improving the seismic behaviour of the frame.

Dynamic Nonlinear Analysis of an Hybrid Base Isolation System with Viscous Dampers and Friction Sliders in Parallel

2012 ◽  
Vol 234 ◽  
pp. 96-101 ◽  
Author(s):  
Donato Cancellara ◽  
Fabio de Angelis
Keyword(s):  
Nonlinear Analysis ◽  
Base Isolation ◽  
Three Dimensional ◽  
Time History ◽  
Seismic Action ◽  
Viscous Dampers ◽  
Isolation System ◽  
Fixed Base ◽  
Base Isolation System ◽  
Dynamic Nonlinear Analysis

In the present work we have analyzed a particular base isolation system for the seismic protection of a multi-storey reinforced concrete (RC) building. The viscous dampers and friction sliders are the devices adopted in parallel for realizing the base isolation system. The base isolation structure has been designed and verified according to European seismic code EC8 and by considering for the friction sliders the influence of the sliding velocity on the value of the friction coefficient. A dynamic nonlinear analysis for a three-dimensional base isolated structure has been performed. Recorded accelerograms for bi-directional ground motions have been used which comply with the requirements imposed by EC8 for the representation of a seismic action in a time history analysis. In this paper a comparative analysis is presented between the base isolated structure with the described hybrid base isolation system and the traditional fixed base structure.

scholarly journals The effect of seismic base isolation on structural response of a 12-story hotel building in Padang, Indonesia

2020 ◽  
Vol 156 ◽  
pp. 05026
Author(s):  
Fauzan ◽  
Afdhalul Ihsan ◽  
Mutia Putri Monika ◽  
Zev Al Jauhari
Keyword(s):  
Base Isolation ◽  
Response Spectrum ◽  
Soft Soil ◽  
Structural Response ◽  
Time History ◽  
Seismic Zone ◽  
Isolation System ◽  
Rubber Bearing ◽  
Seismic Base Isolation ◽  
The City

The amount of potential investment in Padang City, Indonesia since 2017 attracted many investors to contribute to the city. One of the investments is a 12-story hotel that will be constructed in By Pass Street of the city. The hotel is located in a high seismic zone area, so the seismic base isolation has been proposed to be used in the hotel building. The main aim of using a seismic base isolation device is to reduce the inertia forces introduced in the structure due to earthquakes by shifting the fundamental period of the structure out of dangerous resonance range and concentration of the deformation demand at the isolation system. An analytical study on the Reinforced Concrete (RC) hotel building with and without rubber bearing (RB) base isolation is carried out using the response spectrum and time history analysis methods. The results show that internal forces and inter-story drift of the building with high damping rubber bearing (HDRB) are lower than that of the fixed base with a remarkable margin. From this study, it is recommended to use the HDRB base isolation for medium and high rise buildings with soft soil in Padang City, Indonesia.

scholarly journals Numerical assessment of vertical ground motion effects on highway bridges

2020 ◽  
Vol 47 (7) ◽  
pp. 790-800 ◽  
Author(s):  
Hadi Aryan ◽  
Mehdi Ghassemieh
Keyword(s):  
Ground Motion ◽  
Numerical Study ◽  
Three Dimensional ◽  
Vertical Component ◽  
Time History ◽  
Highway Bridges ◽  
Vertical Excitation ◽  
Vertical Ground Motion ◽  
Field Evidence ◽  
Vertical Ground

Field evidence of recent earthquakes shows serious bridge damages due to the direct compression or tension in the columns and some flexural and shear failures caused by the variation in axial force of the columns. These damages could not be produced solely by the horizontal seismic excitations; the vertical component of the earthquake is involved. This paper presents a numerical study highlighting the presence of vertical seismic excitation. Nonlinear time history analyses are conducted on detailed three-dimensional models of multi-span simply supported and multi-span continuous bridges using a suite of representative ground motions. The results showed the significant influence of vertical excitation on the bridge responses. Therefore, it is imperative to include more efficient criteria to upgrade the design codes and extend practical techniques that consider and cope with the structural effects of vertical ground motion along with the horizontal excitations.

scholarly journals An Experimental and Computational Investigation of Flow in a Radial Inlet of an Industrial Pipeline Centrifugal Compressor

1994 ◽  
Author(s):  
M. B. Flathers ◽  
G. E. Bache ◽  
R. Rainsberger
Keyword(s):  
Centrifugal Compressor ◽  
Numerical Study ◽  
Three Dimensional ◽  
Experimental Results ◽  
Scale Model ◽  
Navier Stokes ◽  
Angle Distribution ◽  
Computational Results ◽  
Industrial Pipeline ◽  
Design Schedule

The flowfield of a complex three dimensional radial inlet for an industrial pipeline centrifugal compressor has been experimentally determined on a half scale model. Based on the experimental results, inlet guide vanes have been designed to correct pressure and swirl angle distribution deficiencies. The unvaned and vaned inlets are analyzed with a commercially available fully 3D viscous Navier-Stokes code. Since experimental results were available prior to the numerical study, the unvaned analysis is considered a postdiction while the vaned analysis is considered a prediction. The computational results of the unvaned inlet have been compared to the previously obtained experimental results. The experimental method utilized for the unvaned inlet is repeated for the vaned inlet and the data has been used to verify the computational results. The paper will discuss experimental, design and computational procedures, grid generation, boundary conditions, and experimental versus computational methods. Agreement between experimental and computational results is very good, both in prediction and postdiction modes. The results of this investigation indicate that CFD offers a measurable advantage in design, schedule and cost and can be applied to complex, three dimensional radial inlets.

A superelastic protective technique for mitigating the effects of vertical and horizontal seismic excitations on highway bridges

2016 ◽  
Vol 28 (12) ◽  
pp. 1533-1552 ◽  
Author(s):  
Hadi Aryan ◽  
Mehdi Ghassemieh
Keyword(s):  
Three Dimensional ◽  
Vertical Component ◽  
Time History ◽  
Highway Bridges ◽  
Three Dimensional Model ◽  
Seismic Excitations ◽  
Innovative System ◽  
Bridge Responses ◽  
Nonlinear Time History ◽  
New System

Vertical component of seismic excitations tremendously affects the performance of bridges during the earthquakes. Several conducted studies identified the lack of engineering attention to the vertical seismic excitation as the main reason of various considerable bridge damages during the past earthquakes. Thus, in this article, an innovative system with superelastic properties is proposed for retrofitting and also new design of the bridges which can simultaneously mitigate the effects of vertical and horizontal seismic excitations. In order to investigate the efficiency of the new system, an evaluation is performed through many nonlinear time history analyses on a three-dimensional model of a detailed multi-span simply supported bridge using a suite of representative ground motions of the bridge region. The analyses are conducted separately on the pertinent issues that affect the performance of the new proposed system. As a part of the study, to identify the sensitivity of the new system and evaluate the overall seismic performance, several assessment parameters are utilized. The results show that the proposed system is efficient for reducing bridge responses as well as improving nonlinear performance of the columns during vertical and horizontal seismic excitations.

scholarly journals Numerical Study of the Fatigue Crack in Welded Beam-To-Column Connection Using Cohesive Zone Model

2006 ◽  
Vol 324-325 ◽  
pp. 847-850 ◽  
Author(s):  
Cedric Lequesne ◽  
A. Plumier ◽  
H. Degee ◽  
Anne Marie Habraken
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Numerical Study ◽  
Damage Model ◽  
Three Dimensional ◽  
Fatigue Behaviour ◽  
Bending Test ◽  
Zone Model ◽  
Moment Resisting Frame ◽  
Moment Resisting

The fatigue behaviour of the welded beam-to-column connections of steel moment resisting frame in seismic area must be evaluated. The cohesive zone model is an efficient solution to study such connections by finite elements. It respects the energetic conservation and avoids numerical issues. A three-dimensional cohesive zone model element has been implemented in the home made finite element code Lagamine [1]. It is coupled with the fatigue continuum damage model of Lemaître and Chaboche [2]. The cohesive parameters are identified by the inverse method applied on a three points bending test modelling.

INFLUENCE OF HIGH INITIAL ISOLATOR STIFFNESS ON THE SEISMIC RESPONSE OF A BASE-ISOLATED BENCHMARK BUILDING

2011 ◽  
Vol 11 (06) ◽  
pp. 1201-1228 ◽  
Author(s):  
AJAY SHARMA ◽  
R. S. JANGID
Keyword(s):  
Degrees Of Freedom ◽  
Base Isolation ◽  
Near Field ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Time History ◽  
Base Shear ◽  
Isolation System ◽  
Base Displacement ◽  
Floor Acceleration

The influence of high initial isolator stiffness on the response of a base-isolated benchmark building is investigated. The base-isolated building is modeled as a three-dimensional linear-elastic structure having three degrees-of-freedom at each floor level. The time-history analysis of this building is carried out by solving the governing equations of motion using Newmark-beta method along with an iterative predictor–corrector approach. The force–deformation behavior of the isolation system is modeled by a bilinear law, which can be effectively used to model all isolation systems in practice. Three near-field earthquakes with bidirectional ground motions are considered. Structural response parameters such as absolute top floor acceleration, base shear, and base displacement are chosen for investigating the effects of high initial isolator stiffness. It was observed that the high initial isolator stiffness of the isolation system excites the higher modes in the base-isolated building and increases the top floor acceleration. Such a phenomenon can be detrimental to the sensitive instruments placed in the isolated structure. On the other hand, both the base displacement and base shear reduce marginally due to increase in the initial isolator stiffness. Further, the influences of high initial isolator stiffness are found to dependent on the period and characteristic strengths of the base isolation system.

Response of Transmission Lines under Three-Dimensional Seismic Excitations

2012 ◽  
Vol 166-169 ◽  
pp. 2259-2264
Author(s):  
Li Tian ◽  
Hong Nan Li ◽  
Wen Ming Wang
Keyword(s):  
Transmission Line ◽  
Ground Motion ◽  
Transmission Lines ◽  
Three Dimensional ◽  
Time History ◽  
Maximum Response ◽  
Nonlinear Time History Analysis ◽  
Seismic Excitations ◽  
Practical Engineering ◽  
Nonlinear Time History

The behavior of transmission line under three-dimensional seismic excitations is studied by numerical simulation. According to a practical engineering, the transmission towers are modeled by frame elements and the transmission lines are modeled by cable element account for the nonlinearity of the cable. The effects of single-dimensional, two-dimensional and three-dimensional ground motions on the responses of transmission line are investigated using nonlinear time history analysis method, respectively. The results indicate that the longitudinal maximum response of transmission lines can be obtained considering longitudinal ground motion excitation only. The transverse maximum response of transmission lines can be obtained considering transverse ground motion excitation only. Neglecting multiple nature of ground motion in analysis will significantly underestimate the vertical responses of the transmission lines. To obtain an accurate seismic response of transmission lines, three-dimensional ground motion inputs are required.

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