Overview of seismic provisions of the proposed 2005 edition of the National Building Code of Canada

2003 ◽  
Vol 30 (2) ◽  
pp. 241-254 ◽  
Author(s):  
Arthur C Heidebrecht
Keyword(s):  
Seismic Design ◽  
Urban Areas ◽  
Building Code ◽  
Structural Systems ◽  
Base Shear ◽  
Site Factors ◽  
Higher Mode Effects ◽  
Explicit Recognition ◽  
History Of ◽  
The Impact

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.

scholarly journals Seismic design implications of revisions to the National Building Code of Canada

2003 ◽  
Vol 36 (2) ◽  
pp. 108-116
Author(s):  
A.C. Heidebrecht
Keyword(s):  
Seismic Hazard ◽  
Seismic Design ◽  
Site Effects ◽  
Major Change ◽  
Building Code ◽  
Structural Systems ◽  
Seismic Code ◽  
History Of ◽  
Force Reduction ◽  
Code Development

This paper begins with a brief introduction to Canadian seismicity and the history of seismic code development in Canada; a summary of major changes planned for the 2005 edition of the National Building Code of Canada follows. Areas of major change include seismic hazard, site effects, irregularities, force reduction factors and methods of analysis (dynamic analysis now being preferred). The implications of the proposed changes are presented in terms of impact on seismic design force for several structural systems located in regions of high, moderate and low seismicity; implications for seismic level of protection and the seismic design process are also discussed. The paper concludes with a discussion of ongoing seismic code development issues.

Determination of seismic design forces by equivalent static load method

2003 ◽  
Vol 30 (2) ◽  
pp. 287-307 ◽  
Author(s):  
JagMohan Humar ◽  
Mohamed A Mahgoub
Keyword(s):  
Seismic Design ◽  
Static Load ◽  
Base Shear ◽  
Uniform Hazard Spectra ◽  
Uniform Hazard Spectrum ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Equivalent Static Load ◽  
Adjustment Factors ◽  
Mode Vibration

In the proposed 2005 edition of the National Building Code of Canada (NBCC), the seismic hazard will be represented by uniform hazard spectra corresponding to a 2% probability of being exceeded in 50 years. The seismic design base shear for use in an equivalent static load method of design will be obtained from the uniform hazard spectrum for the site corresponding to the first mode period of the building. Because this procedure ignores the effect of higher modes, the base shear so derived must be suitably adjusted. A procedure for deriving the base shear adjustment factors for different types of structural systems is described and the adjustment factor values proposed for the 2005 NBCC are presented. The adjusted base shear will be distributed across the height of the building in accordance with the provisions in the current version of the code. Since the code-specified distribution is primarily based on the first mode vibration shape, it leads to an overestimation of the overturning moments, which should therefore be suitably adjusted. Adjustment factors that must be applied to the overturning moments at the base and across the height are derived for different structural shapes, and the empirical values for use in the 2005 NBCC are presented.Key words: uniform hazard spectrum, seismic design base shear, equivalent static load procedure, higher mode effects, base shear adjustment factors, distribution of base shear, overturning moment adjustment factors.

scholarly journals Map of Impact of Natural Hazards

2016 ◽  
pp. 69-77
Author(s):  
Maria BOSTENARU DAN ◽  
◽  
Cristina Olga Gociman ◽  
Keyword(s):  
Natural Disasters ◽  
Natural Hazards ◽  
19Th Century ◽  
Urban Areas ◽  
General Assembly ◽  
German Research ◽  
History Of ◽  
Historical Photographs ◽  
The 19Th Century ◽  
The Impact

This paper investigates the mapping of the impact of natural hazards as included in several databases reviewed or created by the author. These are: - The database of the contribution of the session series “Natural hazards’ impact on urban areas and infrastructure”, convened and co-convened by the first author over 15 years at the European Geosciences General Assembly. - A database created from reviews of students supervised by the authors in frame of the course “Protection of settlements against risks” at the home university. - A collection of historical photographs from the 19th century on different natural and man-made hazards from the Canadian Centre for Architecture, the archive review of which has been performed by the first author and which will be subject of a book to be published about the time of the conference. -Two reviewed collections, one from the exhibition and book on “Images of disasters” (German research) and one on the book “Illustrated history of natural disasters” which include major disasters from the beginning of the mankind. In frame of the paper maps of the spread of data will be presented, created using both arcGIS online and GoogleMaps (see https://www.google.com/maps/d/edit?mid=zpbbz3WgVMBs.k-3vhGj- -l1M&usp=sharing), comparing the source and the type of hazard, to see eventual overlappings between the databases.

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

2021 ◽  
Author(s):  
Kasra Habibi ◽  
S. Saeid Hosseini Varzandeh ◽  
Mojtaba Mahsuli
Keyword(s):  
Seismic Design ◽  
The United States ◽  
Construction Cost ◽  
Building Code ◽  
Steel Buildings ◽  
Base Shear ◽  
Risk Models ◽  
Concentrically Braced Frame ◽  
Optimal Target

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.

Inelastic analysis of a reinforced concrete shear wall building according to the National Building Code of Canada 2005

2006 ◽  
Vol 33 (7) ◽  
pp. 854-871 ◽  
Author(s):  
M Panneton ◽  
P Léger ◽  
R Tremblay
Keyword(s):  
Reinforced Concrete ◽  
Three Dimensional ◽  
Time History ◽  
Shear Walls ◽  
Shear Wall ◽  
Fundamental Period ◽  
Building Code ◽  
Base Shear ◽  
Inelastic Analysis ◽  
The Impact

An eight-storey reinforced concrete shear wall building located in Montréal and designed according to the 1995 National Building Code of Canada (NBCC) and the Canadian Standards Association standard CSA-A23.3-94 is studied to evaluate the impact of new requirements for inclusion in new editions of the NBCC and CSA-A23.3. Static and modal analyses were conducted according to the 2005 NBCC (draft 2003) and CSA-A23.3-04 (draft 4) procedures, and three-dimensional dynamic inelastic time history analysis was performed using three earthquake records. The building is braced by four flat shear walls and three cores. Various estimates of the fundamental period of vibration based on empirical expressions presented in the literature or structural models with different stiffness assumptions were examined. The analysis also permitted the study of the displacement and force demand on the lateral load resisting system. It was found that the base shear from the 2005 NBCC is 29% higher than the 1995 NBCC value when code empirical formulae are used for the fundamental period of vibration.Key words: building, shear wall, inelastic seismic response, NBCC, CSA-A23.3 design of concrete structures.

Report Analysis: The Impact of Head Start

1970 ◽  
Vol 40 (1) ◽  
pp. 51-104 ◽  
Author(s):  
Marshall Smith ◽  
Joan Bissell
Keyword(s):  
Head Start ◽  
Urban Areas ◽  
Black Children ◽  
Policy Implications ◽  
Social Scientists ◽  
History Of ◽  
Report Analysis ◽  
Sampling Procedures ◽  
The Impact ◽  
The Relationship

The Westinghouse-Ohio national evaluation of Head Start evoked criticism from both social scientists and statisticians when it was issued last Spring. The authors present a history of Head Start and of the national evaluation. They raise serious questions about the sampling procedures used in the study, and they present the results of a re-analysis which suggest that some full-year Head Start centers were effective, particularly those with black children in urban areas. Policy implications discussed by the authors focus on the relationship between program evaluation and public policy.

Application of uniform hazard spectra in seismic design of multistorey buildings

2000 ◽  
Vol 27 (3) ◽  
pp. 563-580 ◽  
Author(s):  
J L Humar ◽  
M A Rahgozar
Keyword(s):  
Seismic Design ◽  
Reduction Factor ◽  
Degree Of Freedom ◽  
Base Shear ◽  
Uniform Hazard Spectra ◽  
Single Degree Of Freedom ◽  
Building Frames ◽  
Higher Mode Effects ◽  
Mode Effects ◽  
Adjustment Factors

The use of uniform hazard spectra for obtaining the seismic design forces is being considered for the next version of the National Building Code of Canada. Such spectra provide the spectral accelerations of a single-degree-of-freedom system for a range of periods but for a uniform level of hazard. One of the issues that need to be resolved before uniform hazard spectra are used in the design of multistorey buildings is the adjustment required in the base shear to account for the higher mode effects present in a multi-degree-of-freedom system. This issue is examined through analytical studies of the response of idealised elastic and inelastic multistorey building frames to ground motions representative of the seismic hazard in the eastern and western regions of Canada. Representative values are obtained for the adjustment factors that must be applied to the design base shear and to the base overturning moment.Key words: seismic design base shear, uniform hazard spectra, higher mode effects, base shear adjustment factor, base overturning moment reduction factor.

Site response effects for structures located on sand sites

1990 ◽  
Vol 27 (3) ◽  
pp. 342-354 ◽  
Author(s):  
P. Henderson ◽  
A. C. Heidebrecht ◽  
N. Naumoski ◽  
J. W. Pappin
Keyword(s):  
Key Words ◽  
Seismic Design ◽  
Site Response ◽  
Response Spectra ◽  
Building Code ◽  
Base Shear ◽  
Sand Soil ◽  
Low Intensity ◽  
Soil Site ◽  
A Site

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.

Evolution of seismic design provisions in the National building code of Canada

2010 ◽  
Vol 37 (9) ◽  
pp. 1157-1170 ◽  
Author(s):  
Denis Mitchell ◽  
Patrick Paultre ◽  
René Tinawi ◽  
Murat Saatcioglu ◽  
Robert Tremblay ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Seismic Design ◽  
Seismic Hazards ◽  
Building Code ◽  
Hazard Maps ◽  
Base Shear ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Wall Structures ◽  
Energy Dissipation Capacity

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.

scholarly journals Impact of Air Pollutants on Agricultural Crops

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Alok Singh Jayara
Keyword(s):  
Urban Areas ◽  
Air Pollutants ◽  
Canopy Temperature ◽  
Crop Plants ◽  
Health It ◽  
The Past ◽  
History Of ◽  
The Impact ◽  
Motorized Transport ◽  
Particulate Matter Pollution

History of mankind has witnessed transformation in form of industrialization, urbanization and motorized transport in the past. These all had made the life easier for human but these also led to increase in level of pollutants in the atmosphere. These pollutants have cascading impact on agriculture. The impact of some of the major pollutants such as SO2, NOx and ozone is in the form of production of ROS, reduced photosynthesis and energy metabolism. The aerosol and particulate matter pollution also leads to reduced transpiration which raises the canopy temperature and also disturbs the water and nutrient uptake by the crop plants. To date most of the pollution related studies, especially in developing countries, are restricted to its impact on urban areas and human health. It is needed to extend these studies to impact of air pollution on agriculture. In this paper we have discussed the various mechanisms through which the pollutants act on the crop plants and their impact on yield.

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