scholarly journals Quantification of Optimal Target Reliability for Seismic Design: Methodology and Application to Midrise Steel Buildings

Author(s):  
Kasra Habibi ◽  
S. Saeid Hosseini Varzandeh ◽  
Mojtaba Mahsuli

Abstract Quantification of the optimal target reliability based on the minimum lifecycle cost is the goal standard for calibration of seismic design provisions, which is yet to be fully-materialized even in the leading codes. Deviation from the optimally-calibrated design standards is significantly more pronounced in countries whose regulations are adopted from the few leading codes with no recalibration. A major challenge in the quantification of optimal target reliability for such countries is the lack of risk models that are suited for the local construction industry and design practices. This paper addresses this challenge by presenting an optimal target reliability quantification framework that tailors the available risk models for the countries from which the codes are adopted to the local conditions of the countries adopting the codes. The proposed framework is showcased through the national building code of Iran, which is adopted from the codes of the United States, using a case study of three midrise residential steel building archetypes. The archetypes have various structural systems including intermediate moment-resisting frame (IMF) and special concentrically braced frame (SCBF). Each of these archetypes are designed to different levels of the base shear coefficient, each of which corresponds to a level of reliability. To compute the lifecycle cost, the initial construction cost of buildings is estimated. Next, robust nonlinear models of these structures are generated, using which the probability distribution of structural responses and the collapse fragility are assessed through incremental dynamic analyses. Thereafter, the buildings are subjected to a detailed seismic risk analysis. Subsequently, the lifecycle cost of the buildings is computed as the sum of the initial construction cost and the seismic losses. Finally, the optimal strength and the corresponding target reliability to be prescribed are quantified based on the notion of minimum lifecycle cost. The results reveal a 50-year optimal reliability index of 2.0 and 2.1 for IMF and SCBF buildings, respectively and an optimal collapse probability given the maximum considered earthquake of 16% for both systems. In the context on the case study of the national building code of Iran, the optimal design base shear for IMF buildings is 40% higher than the current prescribed value by the code, whereas that of SCBF buildings is currently at the optimal level.

1999 ◽  
Vol 15 (2) ◽  
pp. 331-360 ◽  
Author(s):  
Arturo Tena-Colunga

The Uniform Building Code (UBC) is perhaps one of the most advanced seismic codes worldwide. The 1997 version of the Uniform Building Code (UBC-97) has important modifications with respect to previous versions, among other changes, the introduction of structural overstrength, redundancy and reliability factors for the design of structural elements. In addition, the UBC-97 code revises seismic zoning for areas outside the United States under Division III, Section 1653. In fact, practically the entire world is zoned by the UBC-97 under this section, and many practicing engineers worldwide may feel confident to use the UBC code for the design of civil structures in countries other than the United States, particularly because it is written in this section that “Note: This division has been revised in its entirety”. This paper discusses whether or not Section 1653 of the UBC-97 code has any justification for Mexico, by comparing the UBC design criteria with the criteria established by ruling Mexican codes. According to Mexican authorities, only the referenced Mexican building codes should be used for the design of civil structures in Mexico, so the UBC-97 cannot be used for the seismic design of civil structures in Mexico legally.


2017 ◽  
Vol 8 (1) ◽  
pp. 152
Author(s):  
Zoya Susan Benyaminov ◽  
Merins Sadiku ◽  
Mishka Stueber

This paper addresses the need for reassessment and revision of the New York City Seismic Design Building Code to include reinforcing existing structures that were built before 1995. Although earthquakes in New York City are rare, the combination of its geology and pedology allow for little damping and the lack of adequate reinforcement in existing structures have the potential to amplify the consequences of otherwise small events. The NYC Building Code of 1995 requires new structures to be designed against seismic activity, but does not require the addition of seismic reinforcement for existing buildings.  In an effort to fill this gap, a case study of Brooklyn Brownstones is presented, illustrating the concern for unreinforced masonry (URM) buildings and describing the cultural and economic implications of reassessment. This case study, in combination with a literature review and commentary, supports the need for an updated seismic building code. Reassessment will not only preserve culturally significant structures like the Brooklyn Brownstone, but also provide standards for a more resilient infrastructure that will keep New York City operating through greater magnitude events.


1990 ◽  
Vol 27 (3) ◽  
pp. 342-354 ◽  
Author(s):  
P. Henderson ◽  
A. C. Heidebrecht ◽  
N. Naumoski ◽  
J. W. Pappin

Results are presented for 4 sand sites forming part of a site response study of 11 soil sites. The results are in the form of spectral accelerations and ratios, base shear coefficients, and foundation factors. They indicate that significant amplifications can be expected at sand sites, especially for low-intensity excitation. Comparisons are made with the provisions of the proposed National Building Code of Canada (NBCC) 1990. They show that, depending on the site and the nature and level of the excitation, the expected base shears can be well in excess of the values specified by the NBCC. Key words: seismic, design, sand, soil, site, response, spectra, amplification, base, shear.


2010 ◽  
Vol 37 (9) ◽  
pp. 1157-1170 ◽  
Author(s):  
Denis Mitchell ◽  
Patrick Paultre ◽  
René Tinawi ◽  
Murat Saatcioglu ◽  
Robert Tremblay ◽  
...  

The purpose of this paper is to provide a summary of the evolution of seismic design in Canada. This paper presents the significant changes to the approach taken in determining seismic hazards and seismic hazard maps, and describes the evolution of the seismic design provisions of the National building code of Canada. The introduction of important parameters in determining the seismic base shear such as the period of vibration of the structure, the influence of type of soil, and the concepts of ductility and energy dissipation capacity of elements and structures are presented. The levels of seismic design base shears, determined from different versions of the National Building Code of Canada, are compared for reinforced concrete frame and wall structures to illustrate the changes.


Author(s):  
Charles A. Kircher

The United States contains regions of greatly varying seismicity ranging from a relatively narrow strip of very high seismicity along coastal California in the West to broad areas of low or moderate seismicity typical of the Central and Eastern United States. The United States currently has three major regional model building codes. While all three codes have traditionally used the concept of seismic zones to identify and distinguish between regions of different seismicity, they have not had a consistent basis for their seismic criteria. Beginning in the year 2000, the three model building codes will merge and become the new International Building Code (IBC) applicable to the whole United States. New seismic design criteria have been developed for the 2000 IBC that now define ground shaking for building design by spectral acceleration contours. This paper describes the background and basis for the new seismic design criteria of the 2000 IBC, and how these criteria address the large variation in seismic hazard across the United States.


2003 ◽  
Vol 30 (2) ◽  
pp. 241-254 ◽  
Author(s):  
Arthur C Heidebrecht

The proposed 2005 edition of the National Building Code of Canada (NBCC) will contain very significant changes in the provisions for seismic loading and design. A brief history of the NBCC seismic provisions is presented followed by a discussion of the reasons for introducing such major changes in the next edition of the code. The major changes to the seismic provisions are summarized; this includes updated hazard in spectral format, change in return period (probability of exceedance), period-dependent site factors, delineation of effects of overstrength and ductility, modified period calculation formulae, explicit recognition of higher mode effects, rational treatment of irregularities, triggers for special provisions incorporated directly in classification of structural systems, and placing dynamic analysis as the normal "default" method of analysis for use in seismic design. The impact of these changes on the seismic level of protection is considered by comparing the 2005 NBCC and 1995 NBCC base shear coefficients for a selection of common structural systems located on a range of site conditions in three urban areas having low to high levels of seismic hazard, i.e., Toronto, Montréal, and Vancouver.Key words: seismic, design, loading, code, hazard, buildings, structures, foundations, period, analysis.


2014 ◽  
Vol 7 (1) ◽  
pp. 33-41 ◽  
Author(s):  
Elisabeth Scheibelhofer

This paper focuses on gendered mobilities of highly skilled researchers working abroad. It is based on an empirical qualitative study that explored the mobility aspirations of Austrian scientists who were working in the United States at the time they were interviewed. Supported by a case study, the paper demonstrates how a qualitative research strategy including graphic drawings sketched by the interviewed persons can help us gain a better understanding of the gendered importance of social relations for the future mobility aspirations of scientists working abroad.


2015 ◽  
Vol 36-37 (1) ◽  
pp. 163-183
Author(s):  
Paul Taylor

John Rae, a Scottish antiquarian collector and spirit merchant, played a highly prominent role in the local natural history societies and exhibitions of nineteenth-century Aberdeen. While he modestly described his collection of archaeological lithics and other artefacts, principally drawn from Aberdeenshire but including some items from as far afield as the United States, as a mere ‘routh o’ auld nick-nackets' (abundance of old knick-knacks), a contemporary singled it out as ‘the best known in private hands' (Daily Free Press 4/5/91). After Rae's death, Glasgow Museums, National Museums Scotland, the University of Aberdeen Museum and the Pitt Rivers Museum in Oxford, as well as numerous individual private collectors, purchased items from the collection. Making use of historical and archive materials to explore the individual biography of Rae and his collection, this article examines how Rae's collecting and other antiquarian activities represent and mirror wider developments in both the ‘amateur’ antiquarianism carried out by Rae and his fellow collectors for reasons of self-improvement and moral education, and the ‘professional’ antiquarianism of the museums which purchased his artefacts. Considered in its wider nineteenth-century context, this is a representative case study of the early development of archaeology in the wider intellectual, scientific and social context of the era.


2019 ◽  
Vol 3 (1) ◽  
pp. 1-8
Author(s):  
Sarmistha R. Majumdar

Fracking has helped to usher in an era of energy abundance in the United States. This advanced drilling procedure has helped the nation to attain the status of the largest producer of crude oil and natural gas in the world, but some of its negative externalities, such as human-induced seismicity, can no longer be ignored. The occurrence of earthquakes in communities located at proximity to disposal wells with no prior history of seismicity has shocked residents and have caused damages to properties. It has evoked individuals’ resentment against the practice of injection of fracking’s wastewater under pressure into underground disposal wells. Though the oil and gas companies have denied the existence of a link between such a practice and earthquakes and the local and state governments have delayed their responses to the unforeseen seismic events, the issue has gained in prominence among researchers, affected community residents, and the media. This case study has offered a glimpse into the varied responses of stakeholders to human-induced seismicity in a small city in the state of Texas. It is evident from this case study that although individuals’ complaints and protests from a small community may not be successful in bringing about statewide changes in regulatory policies on disposal of fracking’s wastewater, they can add to the public pressure on the state government to do something to address the problem in a state that supports fracking.


2020 ◽  
Vol 4 (1) ◽  
pp. 1-13
Author(s):  
Miriam R. Aczel ◽  
Karen E. Makuch

This case study analyzes the potential impacts of weakening the National Park Service’s (NPS) “9B Regulations” enacted in 1978, which established a federal regulatory framework governing hydrocarbon rights and extraction to protect natural resources within the parks. We focus on potential risks to national parklands resulting from Executive Orders 13771—Reducing Regulation and Controlling Regulatory Costs [1]—and 13783—Promoting Energy Independence and Economic Growth [2]—and subsequent recent revisions and further deregulation. To establish context, we briefly overview the history of the United States NPS and other relevant federal agencies’ roles and responsibilities in protecting federal lands that have been set aside due to their value as areas of natural beauty or historical or cultural significance [3]. We present a case study of Theodore Roosevelt National Park (TRNP) situated within the Bakken Shale Formation—a lucrative region of oil and gas deposits—to examine potential impacts if areas of TRNP, particularly areas designated as “wilderness,” are opened to resource extraction, or if the development in other areas of the Bakken near or adjacent to the park’s boundaries expands [4]. We have chosen TRNP because of its biodiversity and rich environmental resources and location in the hydrocarbon-rich Bakken Shale. We discuss where federal agencies’ responsibility for the protection of these lands for future generations and their responsibility for oversight of mineral and petroleum resources development by private contractors have the potential for conflict.


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