scholarly journals Improvements to the simplified analysis method for the design of seismically isolated bridges in CSA-S6-14

2016 ◽  
Vol 43 (10) ◽  
pp. 897-907
Author(s):  
Viacheslav Koval ◽  
Constantin Christopoulos ◽  
Robert Tremblay
Keyword(s):  
North America ◽  
Seismic Isolation ◽  
Time History ◽  
Equivalent Damping ◽  
Damping Coefficients ◽  
Simplified Method ◽  
Simplified Analysis ◽  
Seismically Isolated ◽  
Nonlinear Time History ◽  
Isolated Bridges

The design provisions for seismically isolated bridges in the CAN/CSA-S6 Canadian Highway Bridge Design Code and the AASHTO Guide Specifications for Seismic Isolation Design ( AASHTO 2010 , 2014 ) have been developed primarily based on ground motions recorded along the west coast of North America. Both codes include a simplified analysis procedure that relies on an equivalent effective linearization of the nonlinear isolated structure together with damping coefficients to account for the effect of energy dissipation on the response of the isolated system. The appropriateness and range of application of code-specified simplified methods were investigated through nonlinear time-history analyses to propose improvements to this procedure for the new edition of the CSA-S6-2014 code. Based on these analyses, new damping coefficients are proposed for Eastern North America (ENA) and new limits for the application of the simplified method are defined. For ENA, the method with newly proposed damping coefficients can give good bridge displacement estimates for equivalent damping ratios of up to 40%, which broadens the possible designs that can be achieved using the simplified method. This study also showed that applicability limits could be defined more accurately as a function of the system properties.

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 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.

Friction-Type Seismic Isolation Device of Steel Pile Foundation in Shaking Table Tests and its Numerical Simulations

2016 ◽  
Vol 845 ◽  
pp. 233-239
Author(s):  
Buntara Sthenly Gan ◽  
Susumu Nakamura ◽  
Noriaki Sento ◽  
Kosuke Ito
Keyword(s):  
Numerical Simulations ◽  
Pile Foundation ◽  
Seismic Isolation ◽  
Low Cost ◽  
Time History ◽  
Shaking Table ◽  
Steel Sphere ◽  
Pile Cap ◽  
Isolation Device ◽  
Nonlinear Time History

Pile foundation equipped with a low-cost frictional type seismic isolation device is investigated. The frictional mechanism results from a contact between two surfaces of a half steel sphere mounted on the pile cap and the corresponding inner steel sphere embedded in the footing of upper structure. To verify the mechanical behaviors of the pile with frictional type seismic isolation device, tests, and its numerical simulations have been performed. The rotational friction device is found to be very effective in releasing the internal energy transferred from the pile foundation to the upper structure. The behavior of the friction-type device was studied by modeling using the nonlinear time history dynamic analysis. It was observed that the responses of the structures with devices can be approximated by using springs and dampers model.

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.

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.

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.

Evaluation of Simplified Methods for the Design of Bridges with Seismic Isolation Systems

2009 ◽  
Vol 25 (2) ◽  
pp. 221-238 ◽  
Author(s):  
Donatello Cardone ◽  
Mauro Dolce ◽  
Giuseppe Palermo
Keyword(s):  
Seismic Isolation ◽  
Time History ◽  
Single Mode ◽  
Analysis And Design ◽  
Strongly Nonlinear ◽  
Mode Method ◽  
Proper Design ◽  
Isolation Systems ◽  
Nonlinear Time History ◽  
Seismic Isolation Systems

In this paper, simplified methods for the design of bridges equipped with strongly nonlinear isolation systems (IS) are examined. Reference is made to the single mode method (SMM), adopted in many seismic codes and guidelines for the analysis and design of bridges with flexible substructure. Two different design approaches are considered, one aimed at controlling the maximum force transmitted by the IS to the pier, while the other the maximum pier-deck displacement. The background of the SMM and the implementation of the two design approaches are presented first. This is followed by a series of examples of application and validation studies through nonlinear time-history analyses (NTHA). The variability of the mechanical behavior of the IS with air temperature is taken into account in both design procedures and NTHA. The NTHA results point out that simplified methods of analysis can be reliably used for bridges with IS, to satisfy the design performance objectives over the whole operation range of temperature, once a proper design temperature is selected.

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.

Sign in / Sign up

Export Citation Format

Share Document