Erratum: Evaluation of base shear provisions in the 1985 edition of the National Building Code of Canada

1989 ◽  
Vol 16 (6) ◽  
pp. 966-966
Author(s):  
T. J. Zhu ◽  
W. K. Tso ◽  
A. C. Heidebrecht
Keyword(s):  
Building Code ◽  
Base Shear

Combined seismic base shear and torsional loading provisions in the 1990 edition of the National Building Code of Canada

1991 ◽  
Vol 18 (6) ◽  
pp. 945-953
Author(s):  
A. M. Chandler
Keyword(s):  
Ground Motions ◽  
Building Code ◽  
Soil Conditions ◽  
Building Structures ◽  
Base Shear ◽  
Ground Acceleration ◽  
Period Range ◽  
Natural Period ◽  
Short Period ◽  
Edge Response

This paper evaluates the earthquake-resistant design provisions of the 1990 edition of the National Building Code of Canada (NBCC 1990) for asymmetric building structures subjected to combined lateral shear and torsional dynamic loadings arising from earthquake base excitation. A detailed parametric study is presented, evaluating the dynamic edge displacement response in the elastic range, for the side of the building which is adversely affected by lateral–torsional coupling. A series of buildings is studied, with realistic ranges of the fundamental natural period, structural eccentricity, and uncoupled frequency ratio. These buildings are evaluated under base loadings arising from a total of 45 strong motion records taken from earthquakes in North America, Mexico, Europe, the Middle East, and Southern Pacific, categorized according to site soil conditions and the ratio a/v of peak ground acceleration to velocity. The latter parameter together with the uncoupled lateral period are found to influence strongly the combined dynamic edge response, with the greatest forces on edge members arising from earthquakes with high a/v ratio in structures with natural periods below 0.8 s. In this case the NBCC 1990 loading provisions significantly underestimate the elastic dynamic response. For buildings with periods longer than 0.8 s, the conservatism of the base shear provisions leads to overestimation of combined dynamic edge response in asymmetric systems, and this is also true in the short-period range for buildings subjected to ground motions with low a/v ratio. The NBCC 1990 provisions are reasonably conservative for short-period systems subjected to ground motions with intermediate a/v ratio. Key words: earthquakes, seismic, design, response, spectra, base, shear, torsional, provisions.

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.

scholarly journals Engineering applications of new probabilistic seismic ground-motion maps of Canada

1983 ◽  
Vol 10 (4) ◽  
pp. 670-680 ◽  
Author(s):  
A. C. Heidebrecht ◽  
P. W. Basham ◽  
J. H. Rainer ◽  
M. J. Berry
Keyword(s):  
Ground Motion ◽  
Seismic Risk ◽  
Velocity Ratio ◽  
Large Population ◽  
Building Code ◽  
Base Shear ◽  
Probability Of Exceedance ◽  
Seismic Ground Motion ◽  
Short Period ◽  
Current Code

New peak horizontal acceleration and velocity zoning maps with a probability of exceedance of 10% in 50 years and seven seismic zones are developed from new probabilistic strong seismic ground-motion estimates for replacement of the 1970 seismic zoning map in the National Building Code of Canada. The adoption of a probability of exceedance of 10% in 50 years produces reference seismic ground motion appropriate to the level of protection afforded by provisions of the current code; the use of two ground-motion parameters, the relative levels of which vary considerably throughout the country, provides independent reference levels for structures having short and long fundamental periods.For calculating seismic base shear, a new seismic response factor is derived in which seismic forces for long-period structures are directly proportional to zonal velocities, and for short-period structures proportional to zonal accelerations, with an upper limit on the acceleration/velocity ratio applicable for any location. To maintain the same design standard as provided by the current code, the base shear is calibrated to remain the same, on average, in large population centres in regions of moderate to high seismic risk. The resulting changes in the base shear applicable at various locations reflect the improved estimates of seismic risk, in particular the introduction of additional zones in the higher risk regions of the country and the higher levels of short-period ground motion estimated for some regions of eastern Canada.These and associated changes in seismic design provisions have been recommended for adoption in the 1985 edition of the National Building Code of Canada.

Seismic loading provision changes in National Building Code of Canada 1985

1985 ◽  
Vol 12 (3) ◽  
pp. 653-660 ◽  
Author(s):  
A. C. Heidebrecht ◽  
W. K. Tso
Keyword(s):  
Seismic Response ◽  
Seismic Risk ◽  
Seismic Loading ◽  
Building Code ◽  
Seismic Zoning ◽  
Probability Level ◽  
Base Shear ◽  
Response Parameter ◽  
Most Significant Change ◽  
Risk Methodology

This paper describes the process by which Canadian seismic loading provisions are developed and then details the primary changes being introduced in the 1985 edition of the National Building Code of Canada. The most significant change is the inclusion of new seismic zoning maps, based on a new seismic risk methodology, a new probability level, and additional seismic zones, and incorporating both horizontal ground velocity and acceleration as zoning parameters. The format of base shear calculation is revised to incorporate these changes, including the specification of a new seismic response parameter. The base shear formula is calibrated to ensure that, on a cumulative basis throughout the country, the level of seismic loading remains unchanged. Additional changes discussed in the paper include the removal of dynamic analysis as a specific option in the base shear calculation and some significant changes in the calculation of torsional effects.

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.

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.

A proposal for the compatibility of static and dynamic seismic base shear provisions of the National Building Code

1982 ◽  
Vol 9 (2) ◽  
pp. 308-312 ◽  
Author(s):  
W. K. Tso
Keyword(s):  
Reinforced Concrete ◽  
Shear Wall ◽  
Masonry Wall ◽  
Building Code ◽  
Frame Structures ◽  
Base Shear ◽  
Significant Discrepancy ◽  
Moment Resisting Frame ◽  
Wall Structures ◽  
Moment Resisting

A comparison is made, based on static and dynamic base shear calculations according to the National Building Code of Canada of 1980, for four types of simple structures, namely, uniform moment resisting frame structures, uniform ductile flexural wall structures, uniform reinforced concrete shear wall structures, and unreinforced masonry wall structures. It is shown that a significant discrepancy exists between the static and dynamic base shear values, depending on the type and the fundamental period of the structure. The causes for the discrepancy and the necessity to make static and dynamic base shears compatible are discussed.

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.

Overview of seismic provision changes in National Building Code of Canada 1990

1992 ◽  
Vol 19 (3) ◽  
pp. 383-388 ◽  
Author(s):  
W. K. Tso
Keyword(s):  
Building Code ◽  
Load Factor ◽  
Base Shear ◽  
Concentrated Force ◽  
Drift Estimation ◽  
Seismic Design Code ◽  
Story Drift ◽  
Importance Factor ◽  
Modification Factor ◽  
Earthquake Load

This paper highlights the changes of the seismic provisions in the 1990 edition of the National Building Code of Canada (NBCC) and provides the reasons and interpretations for these changes. The major changes include load factor for earthquake load, base shear formula, force modification factor in place of structural coefficient, story drift estimation, design and anchorage force for parts of portions of building, importance factor, foundation factor, and top concentrated force on structure. A comparison of the base shear calculated according to NBCC-1985 and NBCC-1990 is given to show that the base shears for most structural systems are similar. The major exceptions are the ductile flex-ural wall systems and the unreinforced masonry system. The base shear is reduced for the former system and increased for the latter system in NBCC-1990. Key words: earthquake, seismic design, code, lateral loading, overstrength.

Evaluation of base shear provisions in the 1985 edition of the National Building Code of Canada

1989 ◽  
Vol 16 (1) ◽  
pp. 22-35 ◽  
Author(s):  
T. J. Zhu ◽  
W. K. Tso ◽  
A. C. Heidebrecht
Keyword(s):  
Yield Strength ◽  
Seismic Response ◽  
Structural Damage ◽  
Ground Motions ◽  
Response Spectra ◽  
Building Code ◽  
Base Shear ◽  
Response Factors ◽  
Period Range ◽  
Short Period

A statistical analysis is performed to evaluate the base shear provisions in the 1985 edition of the National Building Code of Canada (NBCC 1985). Three sets of real earthquake records are selected to represent seismic ground motions with low, normal, and high peak acceleration to velocity (a/v) ratios. Single degree of freedom stiffness degrading systems are used as structural models; three damage indicators are employed to measure structural damage. The yield strength of the systems is specified in two different ways: (a) a single seismic response factor is used, irrespective of the a/v ratios of the input ground motions; (b) three different seismic response factors are used in the short-period range, depending upon the a/v ratios of the input ground motions, as suggested in NBCC 1985. A comparison of the statistical results of the three damage parameters for the systems designed with these two methods of strength specification indicates that the NBCC 1985 base shear provisions provide consistent control over structural damage when the structural systems are subjected to ground motions with different a/v ratios. Key words: earthquakes, ground motions, response spectra, stiffness degrading systems, seismic design, base shear, yield strength, inelastic response, damage parameters.

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