scholarly journals Damping Reduction Factors for Crustal, Inslab, and Interface Earthquakes Characterizing Seismic Hazard in Southwestern British Columbia, Canada

2016 ◽  
Vol 32 (1) ◽  
pp. 45-74 ◽  
Author(s):  
Poulad Daneshvar ◽  
Najib Bouaanani ◽  
Katsuichiro Goda ◽  
Gail M. Atkinson
Keyword(s):  
British Columbia ◽  
Seismic Hazard ◽  
Seismic Design ◽  
Ground Motions ◽  
Seismic Protection ◽  
Frequency Content ◽  
Displacement Spectra ◽  
Protection Systems ◽  
Displacement Based ◽  
Reduction Factors

High-damping displacement spectra and corresponding damping reduction factors ( η) are important ingredients in seismic design and analysis of structures equipped with seismic protection systems, as well as in displacement-based design methodologies. In this study, we investigated η factors for three types of earthquake characterizing seismic hazard in southwestern British Columbia, Canada: shallow crustal, deep inslab, and interface subduction. We used a large and comprehensive database including records from recent relevant earthquakes, such as the 2011 Tohoku event. Our key observations were as follows: (1) there is negligible dependence of η on soil class; (2) there is significant dependence of η on the frequency content and duration of ground motions that characterize the different record types, and (3) η is dependent on period, particularly for inslab events. Period-dependent equations were proposed to predict η for damping ratios between 5% and 30% corresponding to the three event types.

Inelastic Displacement Spectra and Its Utilization of DDB Design for Seismic Isolated Bridges Subjected to Near-Fault Pulse-Like Ground Motions

2019 ◽  
Vol 35 (3) ◽  
pp. 1109-1140 ◽  
Author(s):  
Yi-feng Wu ◽  
Hao Wang ◽  
Jian Li ◽  
Ben Sha ◽  
Ai-qun Li
Keyword(s):  
Design Method ◽  
Ground Motions ◽  
Single Degree Of Freedom ◽  
Sdof System ◽  
Inelastic Displacement ◽  
Displacement Spectra ◽  
Near Fault ◽  
The Mean ◽  
Displacement Based ◽  
Isolated Bridges

A variety of research has focused on the inelastic displacement demand of a single degree of freedom (SDOF) system when subjected to near-fault pulse-like ground motions, in which the concerned ductility, μ, is typically lower than ten for normal structures. However, for seismic isolated structures that are more prone to large displacement, the corresponding research is limited. The purpose of this paper is to investigate the inelastic displacement spectra of an SDOF system with μ ranging from 5 to 70 and further proposes a direct displacement-based (DDB) design method for seismic isolated bridges. More concretely, a pool of near-fault pulse-like records is assembled, the mean C μ as a function of T/ T p is developed, and the influences of the ductility, μ, and the post-to-pre-yield ratio, α, on C μ are carefully investigated. Then the corresponding inelastic displacement spectra, S d, are obtained, and a comprehensive piecewise expression is proposed to fit S d. After that, the utilization of the spectra for the DDB design of a three-span seismic isolated continuous bridge is performed, and the principal of simplifying the bridge to an SDOF system is carefully explained and verified.

scholarly journals Insights and challenges associated with determining seismic design forces in a loading code

1995 ◽  
Vol 28 (3) ◽  
pp. 224-246 ◽  
Author(s):  
A. C. Heidebrecht
Keyword(s):  
New Zealand ◽  
Seismic Hazard ◽  
Seismic Design ◽  
Ground Motions ◽  
Performance Expectations ◽  
Hazard Parameters ◽  
Seismic Hazard Parameters ◽  
Frequent Reference

This paper presents and discusses a number of important topics which affect the determination of seismic design forces in a loading code. These range broadly from seismic hazard through to design philosophy and include the following aspects: influence of uncertainty in determining seismic hazard, seismic hazard parameters, site effects, probability level of design ground motions, role of deformations in seismic design, performance expectations and level of protection. The discussion makes frequent reference to the seismic provisions of both the National Building Code of Canada (1995) and the New Zealand Loading Standard (1992). Also, comparisons are made of seismic hazard and seismic design forces for several Canadian and New Zealand cities.

scholarly journals Hazard-consistent seismic losses and collapse capacities for light-frame wood buildings in California and Cascadia

2021 ◽  
Author(s):  
Robert E. Chase ◽  
Abbie B. Liel ◽  
Nicolas Luco ◽  
Zach Bullock
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Seismic Risk ◽  
Ground Motions ◽  
Spectral Shape ◽  
Economic Losses ◽  
Frequency Content ◽  
Crustal Earthquakes ◽  
Design Values ◽  
American Society

AbstractWe evaluate the seismic performance of modern seismically designed wood light-frame (WLF) buildings, considering regional seismic hazard characteristics that influence ground motion duration and frequency content and, thus, seismic risk. Results show that WLF building response correlates strongly with ground motion spectral shape but weakly with duration. Due to the flatter spectral shape of ground motions from subduction events, WLF buildings at sites affected by these earthquakes may experience double the economic losses for a given intensity of shaking, and collapse capacities may be reduced by up to 50%, compared to those at sites affected by crustal earthquakes. These differences could motivate significant increases in design values at sites affected by subduction earthquakes to achieve the uniform risk targets of the American Society of Civil Engineers (ASCE) 7 standard.

Preliminary Design of Low-Rise Buildings Stiffened with Buckling-Restrained Braces by a Displacement-Based Approach

2009 ◽  
Vol 25 (1) ◽  
pp. 185-211 ◽  
Author(s):  
Amador Teran-Gilmore ◽  
Neftali Virto-Cambray
Keyword(s):  
Mexico City ◽  
Seismic Design ◽  
Mechanical Characteristics ◽  
Ground Motions ◽  
Flexural Behavior ◽  
Preliminary Design ◽  
Lake Zone ◽  
Buckling Restrained Braces ◽  
Displacement Based ◽  
Story Building

A displacement-based methodology for the preliminary design of a system of buckling-restrained braces is introduced. The methodology applies to the case of low-rise buildings, whose dynamic response is not significantly influenced by global flexural behavior or higher modes. The methodology is applied to the preliminary design of a five-story building located in the Lake Zone of Mexico City. From the evaluation of the global mechanical characteristics of the building and of its seismic performance when subjected to ground motions generated in that zone, it is concluded that the proposed methodology yields an adequate level of seismic design.

Compatible ground-motion time histories for new national seismic hazard maps

1998 ◽  
Vol 25 (2) ◽  
pp. 305-318 ◽  
Author(s):  
Gail M Atkinson ◽  
Igor A Beresnev
Keyword(s):  
British Columbia ◽  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Hazard Maps ◽  
Probability Level ◽  
Seismic Hazard Maps ◽  
Motion Time ◽  
Time Histories ◽  
Canadian Council

Ground-motion time histories which are compatible with the uniform hazard spectra (UHS) provided by the new national seismic hazard maps of the Geological Survey of Canada (GSC) are simulated. Time histories are simulated for the following cities: Halifax, La Malbaie, Québec, Montreal, Ottawa, Toronto, Prince George, Tofino, Vancouver, and Victoria. The target UHS for the time history simulations are the GSC 5% damped horizontal-component spectra for "firm ground" (Class B) sites for an annual probability of 1/500. The Canadian Council on Earthquake Engineering is currently considering the adoption of these maps as the seismological basis for the earthquake design requirements for future editions of the National Building Code of Canada. It is therefore useful to have compatible time histories for these spectra, in order that dynamic analysis methods requiring the use of time histories can be employed. The simulated records provide a realistic representation of ground motion for the earthquake magnitudes and distances that contribute most strongly to hazard at the selected cities and probability level. For each selected city, two horizontal components are generated for a moderate earthquake nearby, and two horizontal components are generated for a larger earthquake farther away. These records match the short- and long-period ends of the target UHS, respectively. These simulations for local and regional crustal earthquakes are based on a point-source stochastic simulation procedure. For cities in British Columbia, records are also simulated for a scenario M8.5 earthquake on the Cascadia subduction zone, using a stochastic finite-fault simulation model. Four different rupture scenarios are considered. The ground motions for this scenario event are not associated with a specific probability level, but current information suggests that their probability of occurrence is comparable to that of the 1/500 UHS (the probabilistic analyses performed for the national hazard maps do not explicitly include the Cascadia subduction event). Thus it would be reasonable to conduct engineering analyses for cities in British Columbia using both the simulated crustal-event motions and the simulated Cascadia-event motions for the Cascadia event. The time histories simulated for this study are available free of charge to all interested parties.Key words: compatible time-histories, seismic hazard, ground motions.

Design for low/moderate seismic risk

2000 ◽  
Vol 33 (3) ◽  
pp. 303-324
Author(s):  
Paolo E. Pinto
Keyword(s):  
Seismic Hazard ◽  
Seismic Design ◽  
Good Practice ◽  
Seismic Intensity ◽  
Economic Progress ◽  
Moderate Seismicity ◽  
Regular Configuration ◽  
Risk Zones ◽  
Displacement Based

The increase of knowledge about seismic hazard worldwide, associated to an increase of awareness of the potential losses due to earthquakes, and economic progress allowing for policies of risk reduction, have led several countries in which seismic hazard was formerly ignored to pay greater attention to seismic design. The paper deals with a number of aspects related to this increased interest. It is first discussed, with reference to the solutions adopted in a few countries, the problem of where to put the lower limit to seismic intensity for which explicit seismic design is worth being carried out. It is shown that the limit varies considerably among countries, depending on economic conditions and on the general quality of the constructions. Based on the results of analytical simulations illustrated in the paper, it is concluded that modern RC buildings can have a substantial capacity to resist earthquake motions, if they have a regular configuration and are correctly designed for gravity loads only. In terms of PGA, this capacity may go up to 0.15 - 0.25g for structural damages still far below the ultimate state. This stresses the greater importance, especially in regions of moderate seismicity, of providing the profession with documents of good practice, rather than with analytically sophisticated codes. Looking at the future, ample space is given in the paper to discuss about which one of the two design methods, the established force- based or the emerging displacement-based is best suited to the needs specific to L/M risk zones. In their present state, they are both less effective for L/M areas than in ones of high seismicity. The DBD approach offers better perspectives for being extended to the L/M case on more rational bases.

scholarly journals Ductility and Strength Reduction Factors for Degrading Structures Considering Cumulative Damage

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Edén Bojórquez ◽  
Sonia E. Ruiz ◽  
Alfredo Reyes-Salazar ◽  
Juan Bojórquez
Keyword(s):  
Structural Properties ◽  
Seismic Design ◽  
Ground Motions ◽  
Strength Reduction ◽  
Cumulative Damage ◽  
Earthquake Resistant ◽  
Earthquake Resistant Structures ◽  
Simple Systems ◽  
Insight Into ◽  
Reduction Factors

The effect of cumulative damage on the strength requirements of degrading structures is assessed through the evaluation of the target ductility and corresponding strength reduction factors of simple degrading structures. While the reduction on ductility is established through the use of Park and Ang index, the suggestions given by Bojórquez and Rivera are used to model the degradation of the structural properties of the simple systems. Target ductilities and their corresponding reduced strength reduction factors are established for five sets of ground motions; most of them are recorded in California. The results given in this paper provide insight into all relevant parameters that should be considered during seismic design of earthquake-resistant structures. Finally, some recommendations to evaluate the effect of cumulative damage on seismic design are suggested.

Inelastic Displacement Spectra for Displacement-Based Seismic Design of High-Speed Railway Bridge Pier

2011 ◽  
Vol 121-126 ◽  
pp. 892-896
Author(s):  
Ling Kun Chen ◽  
Li Zhong Jiang
Keyword(s):  
Cross Section ◽  
Seismic Design ◽  
High Speed ◽  
Reinforcement Ratio ◽  
Railway Bridge ◽  
High Speed Railway ◽  
Inelastic Displacement ◽  
Displacement Spectra ◽  
Displacement Based ◽  
Performance Target

The inelastic displacement spectra is established based on the elastic displacement spectra and the strength reduction factor, the calculation process of Displacement-Based Seismic Design is presented in this paper, the seismic design of high-speed railway bridge piers is conducted to verified the method. The calculation results show that, at the same performance target, the pier height is taller, the cross-section is bigger; at the same pier height, the performance target is higher, the cross-section of pier is bigger; the reinforcement ratio with the different pier height and performance target are the lower limit of calculation value, it mean that the lateral reinforcement ratio of piers can just meet the detailing requirements.

Sign in / Sign up

Export Citation Format

Share Document