scholarly journals Study on Column-Top Seismic Isolation of Single-Layer Latticed Domes

2019 ◽  
Vol 11 (3) ◽  
pp. 936 ◽  
Author(s):  
Yongmei Zhai ◽  
Xuxia Fu ◽  
Yihui Chen ◽  
Wei Hu
Keyword(s):  
Seismic Isolation ◽  
Time History ◽  
Single Layer ◽  
Nonlinear Time History Analysis ◽  
Hysteresis Curve ◽  
Plastic State ◽  
Original Structure ◽  
Engineering Practice ◽  
Support Design ◽  
Support Reaction

In this paper, a single-layer lamella reticulated dome with reinforced concrete bearings was studied, and a method of column-top isolation was proposed to improve the seismic performance of the whole structure, thereby avoiding too large support stiffness in engineering practice. A nonlinear time-history analysis showed that lead rubber bearings (LRB) can reduce the support reaction to a certain extent and make it distribute uniformly, reducing the support design requirements under frequent earthquakes. During rare earthquakes, the LRB was basically in the plastic state and the support reaction remained near the yield force, which was reduced greatly compared with that of the original structure. The bearing hysteresis curve was full, while the plasticity development degree of the upper reticulated dome was greatly reduced and the elasticity was basically maintained, thus achieving a good damping effect.

Seismic Isolation Retrofit of an Office Building Using Friction Pendulum System

2014 ◽  
Vol 578-579 ◽  
pp. 1361-1365
Author(s):  
Lin Liu ◽  
Xuan Min Li ◽  
Wei Tian
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Time History ◽  
Nonlinear Behavior ◽  
Office Building ◽  
Nonlinear Time History Analysis ◽  
Isolation System ◽  
Pendulum System ◽  
Nonlinear Time History ◽  
Friction Pendulum

Friction Pendulum Systems have been used as base isolation systems for both new construction and retrofit around the world. This paper presented its implementation in an office building located in Shanghai. To evaluate its impact on seismic performance of the retrofitted structure, models are needed to capture the intricate nonlinear behavior of both structural components and isolator elements. Nonlinear time history analysis of the building for the original and retrofitted cases was conducted to assess the efficiency of the isolation system at the high earthquake level. The numerical results indicate that the retrofitted structure experiences significantly less damage and less deformation due to the shake isolation and energy dissipation through the isolators.

scholarly journals Seismic Design of Bridges against Near-Fault Ground Motions Using Combined Seismic Isolation and Restraining Systems of LRBs and CDRs

2019 ◽  
Vol 2019 ◽  
pp. 1-11
Author(s):  
Xiaoli Li ◽  
Yan Shi
Keyword(s):  
Control System ◽  
Seismic Design ◽  
High Intensity ◽  
Seismic Isolation ◽  
Ground Motions ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Near Fault ◽  
Combined Control ◽  
Quantitative Design

This paper focuses on the seismic isolation design of near-fault bridges under the seismic excitations of near-fault ground motions in high-intensity earthquake zones and proposes a combined control system using lead rubber bearings (LRBs) and cable displacement restrainers (CDRs) along with ductility seismic resistance for the reinforced concrete piers. As part of the performance-based seismic design framework, this study provides the quantitative design criteria for multilevel performance-based objectives of a combined control system under conditions of frequent earthquake (E1), design earthquake (medium earthquake), and rare earthquake (E2). Moreover, in this study, a preliminary performance-based seismic isolation design for a near-fault actual highway bridge in high-intensity earthquake zones (basic peak of ground acceleration 0.4 g) was developed. Using nonlinear time-history analysis of the actual bridge under near-fault ground motions, the feasibility of a performance-based design method was validated. Furthermore, to ensure the predicted performance of the isolated bridges during a strong earthquake, a relatively quantitative design in structural details derived from the stirrup ratio of piers, expansion joints gap, supported length of capping beams, and limited vertical displacement response was obtained.

scholarly journals Seismic fragility analysis for tall pier bridges with rocking foundations

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Xu Chen ◽  
Jianzhong Li
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Fragility Curves ◽  
Dynamic Performance ◽  
Time History ◽  
Element Model ◽  
Nonlinear Time History Analysis ◽  
Promising Alternative ◽  
Demand Models ◽  
Rocking Foundations

AbstractCostal bridge systems usually contain tall piers with heights over 40 m, due to the engineering site exposed to deep water circumstances. Note that the conventional seismic isolation devices (e.g., isolation bearings) are not that effective for tall piers, since their dynamic performance is significantly affected by the distributed mass and vibration modes of columns; therefore, base isolation design philosophy could be a promising alternative for mitigating seismic demands of this type of bridges. This paper mainly investigates the efficiency of rocking foundations in improving seismic performance of tall pier bridges, with the results presented in the format of fragility curves. Finite element model of the prototype tall pier bridge is developed, and the responses subjected to near-fault motions are obtained using nonlinear time history analysis. Probability seismic demand models and fragility curves are then developed accordingly, based on which the performance of tall pier bridges are assessed. The results show that employment of rocking foundations could significantly reduce the demands of tall piers and the probability of being damaged. Before the initiation of uplifting at pier base, the behavior of rocking piers resembles that of conventional ones with integrated foundation. While rocking initiates under strong excitations, the demands of rocking piers reduce drastically compared with integrated ones and tend to be similar under different motions, which benefits the post-earthquake performance assessment of these bridges.

scholarly journals Inelastic demand spectra for bi-linear seismic isolation systems based on nonlinear time history analyses and the response of lead-rubber bearing isolation systems subjected to near-source ground motions

2007 ◽  
Vol 40 (1) ◽  
pp. 7-17 ◽  
Author(s):  
John X. Zhao ◽  
Jian Zhang
Keyword(s):  
Seismic Isolation ◽  
Ground Motions ◽  
Time History ◽  
Design Tool ◽  
Nonlinear Time History Analysis ◽  
Inelastic Demand ◽  
Isolated Structures ◽  
Seismically Isolated ◽  
Isolation Systems ◽  
Nonlinear Time History

In this study, we present an inelastic demand spectrum for the design of seismically-isolated structures using lead-rubber bearings or other types of isolators with bi-linear hysteresis loops and the inelastic spectrum can be used in the design of seismically-isolated structures in a very similar manner to capacity spectrum method. The inelastic demand spectrum is a very useful design tool for visual selection of optimal isolation parameters, and eliminates the use of equivalent linear-elastic substitute structures as the displacement demand is obtained from nonlinear time history analysis. The responses of seismically-isolated structures subjected to near-source ground motions with either large forward-directivity pulses or fault-fling pulses are presented. Our analyses suggest that seismic isolation can be used to protect structures subjected to recorded ground motions currently available to us, with acceptable levels of base shear coefficient and isolator displacement, except for one component of the TCU068 record from the 1999 Chichi, Taiwan, earthquake (which contained a large permanent displacement of nearly 10 m).

Seismic Isolation Design of Multistory Building

2012 ◽  
Vol 204-208 ◽  
pp. 3592-3595
Author(s):  
Xiao Song ◽  
Peng Li ◽  
Guang Sheng Xu
Keyword(s):  
Seismic Isolation ◽  
Base Isolation ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Seismic Capacity ◽  
Isolation System ◽  
Multistory Building ◽  
History Analysis ◽  
Base Isolation System ◽  
Nonlinear Time History

Design process and the nonlinear time history analysis for base isolation system is performed in this paper. The results show that the earthquake acceleration and displacement response of isolated structure can be significantly reduced. Application of the isolation system to improve the seismic capacity of the structure,can effectively reduce the response of upper structure of in earthquake.

Building Passive Control in Japan

2009 ◽  
Vol 4 (3) ◽  
pp. 261-269 ◽  
Author(s):  
Kazuhiko Kasai ◽  
◽  
Masayoshi Nakai ◽  
Yutaka Nakamura ◽  
Hidekatsu Asai ◽  
...  
Keyword(s):  
Seismic Isolation ◽  
Passive Control ◽  
Design Method ◽  
Time History ◽  
High Strength ◽  
Government Support ◽  
Shaking Table ◽  
Nonlinear Time History Analysis ◽  
Design Rule ◽  
Structure Damage

This paper discusses the following three key issues on passive control using dampers for seismic protection of buildings:1 Major experimental research on passive control of buildings: Tests using the world’s largest shaking table “E-Defense” from March to April 2009 evaluated a full-scale 5-story steel building with and without dampers. 2 Codes and specifications: The Japanese building code requires that the nonlinear time history analysis be performed for buildings with dampers or that energy-based analysis be conducted when steel dampers are used. Unlike code rules leading to iterative design, the specifications of the Japan Society of Seismic Isolation (JSSI) give direct design method (DDM) for target performance set by designers. 3 Damage-free structure and its design: Backed by government support, a large team of researchers and designers has developed a structure damage-free against a catastrophic earthquake, using dampers and super-high-strength steel frames. The structure and its design rule using DDM are being studied for inclusion in projected code.

scholarly journals Comparison and analysis of seismic isolation, energy dissipation structure and traditional seismic structure

2021 ◽  
Vol 248 ◽  
pp. 01001
Author(s):  
Shu-jiang Jiang ◽  
Shun-zhong Yao ◽  
De-wen Liu
Keyword(s):  
Seismic Isolation ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Seismic Structure ◽  
Base Shear ◽  
Finite Element Software ◽  
History Analysis ◽  
Rare Earthquake ◽  
Nonlinear Time History ◽  
The Impact

This paper uses SAP2000 finite element software to perform nonlinear time history analysis of nine structural systems, and compares the period, total floor displacement, base shear force, vertex displacement, and top acceleration of the structure under the action of an 8-degree rare earthquake. The research results show that seismic isolation and damping technology can effectively reduce the impact of earthquakes on structures.

scholarly journals Effect of a Near Fault on the Seismic Response of a Base-Isolated Structure with a Soft Storey

2017 ◽  
Vol 25 (4) ◽  
pp. 34-46
Author(s):  
B. Athamnia ◽  
A. Ounis ◽  
M. Abdeddaim
Keyword(s):  
Seismic Isolation ◽  
Seismic Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Base Shear ◽  
Rc Structures ◽  
Soft Storey ◽  
Near Fault ◽  
Nonlinear Time History ◽  
Far Fault

AbstractThis study focuses on the soft-storey behavior of RC structures with lead core rubber bearing (LRB) isolation systems under near and far-fault motions. Under near-fault ground motions, seismic isolation devices might perform poorly because of large isolator displacements caused by large velocity and displacement pulses associated with such strong motions. In this study, four different structural models have been designed to study the effect of soft-storey behavior under near-fault and far-fault motions. The seismic analysis for isolated reinforced concrete buildings is carried out using a nonlinear time history analysis method. Inter-story drifts, absolute acceleration, displacement, base shear forces, hysteretic loops and the distribution of plastic hinges are examined as a result of the analysis. These results show that the performance of a base isolated RC structure is more affected by increasing the height of a story under nearfault motion than under far-fault motion.

Development of Fragility Curves for Multi-Span RC Bridges using Generalized Pushover Analysis

2019 ◽  
Author(s):  
Camilo Perdomo ◽  
Ricardo Monteiro ◽  
Halûk Sucuoğlu
Keyword(s):  
Seismic Vulnerability ◽  
Fragility Curves ◽  
Pushover Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Engineering Practice ◽  
Nonlinear Analyses ◽  
History Analysis ◽  
Nonlinear Time History ◽  
Existing Bridges

<p>Over the past few decades, fragility curves became a powerful tool for the seismic vulnerability assessment of structures. There are several available analytical procedures for calculating fragility curves, using both static and dynamic nonlinear analyses. In this study, a nonlinear static method, based on Generalized Pushover Analysis (GPA), is implemented for the development of analytical fragility curves of reinforced concrete (RC) bridges. The relative accuracy of the GPA algorithm, when applied to a large number of existing bridges, is evaluated through the comparison with the results from Nonlinear Time History Analysis (NTHA). Results indicate that GPA provides a good estimation of the fragility curves with respect to NTHA. The added computational demand of the GPA algorithm in terms of the number of analyses pays off in terms of accuracy while keeping the simplicity of a non-adaptive conventional pushover algorithm, which is desirable in engineering practice.</p>

Study on Corrugated Steel Web Bridge Seismic Isolation Technology in High Intensity Seismic Region

2014 ◽  
Vol 919-921 ◽  
pp. 965-968
Author(s):  
Hong Xue Li ◽  
Yong Ming Zhao
Keyword(s):  
Seismic Isolation ◽  
Rapid Development ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Seismic Action ◽  
Bridge Structure ◽  
Seismic Region ◽  
Composite Bridge ◽  
Corrugated Steel Web ◽  
Nonlinear Time History

The rapid development of modern seismic isolation technology has opened up new avenues of bridge seismic. For the bridge structure in highly seismic region,seismic isolation devices reduce the effects of the earthquake damage to bridges, but also reduce the ability of the bridge structure to resist other loads along with the increase of the displacement under seismic action. Nowadays, there are few engineering examples of the composite bridge with corrugated steel webs using seismic isolation technology. In this paper, we use Bridge Xiaoshagou as an example to study isolation technology with nonlinear time history analysis.

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