Evaluation of the seismic response factor introduced in the 1985 edition of the National Building Code of Canada

1988 ◽  
Vol 15 (3) ◽  
pp. 382-388 ◽  
Author(s):  
A. C. Heidebrecht ◽  
Chee Yuen Lu
Keyword(s):  
Seismic Response ◽  
Strong Motion ◽  
Building Code ◽  
Response Factor ◽  
Seismic Zone ◽  
Response Factors ◽  
Dynamic Factors ◽  
Wall Structures ◽  
Time Histories ◽  
Velocity Spectra

The seismic loading provisions included in the 1985 edition of the National Building Code of Canada simulate the dynamic response of structures using a seismic response factor, which has three branches depending upon the relationship between the velocity-related seismic zone Zv and the acceleration-related zone Za. This paper utilizes three ensembles of actual seismic strong motion records to evaluate the seismic response factor; each ensemble has acceleration/velocity ratios corresponding to one of the three branches of the seismic response factor. These strong motion time histories are used as input to relatively simple elastic models of frame and wall structures in order to obtain dynamic seismic response factors. The comparison of these dynamic factors with those specified in the NBCC 1985 indicates that the code factors are generally quite satisfactory, with the exception of the case of frame structures with low fundamental periods located such that Za is two zones higher than Zv. The paper references several other investigations that produce similar results. In that instance, it is recommended that the seismic response factor should be increased, particularly if the structure is located on stiff soil rather than on rock. Key words: structures, loading, seismic, code, earthquake, dynamic, elastic, acceleration, velocity, spectra.

On the dynamic foundation factor for the National Building Code of Canada: low to medium rise buildings

1994 ◽  
Vol 21 (2) ◽  
pp. 353-356
Author(s):  
A. C. Heidebrecht ◽  
A. Rutenberg
Keyword(s):  
Engineering Design ◽  
Seismic Response ◽  
Earthquake Engineering ◽  
Building Codes ◽  
Building Code ◽  
Building Structures ◽  
Response Factors ◽  
Vibration Period ◽  
Site Specific ◽  
Site Investigations

Site-specific seismic response factors for low-period building structures are presented as an alternative to the recently proposed foundation factor F* for inclusion in the seismic provision of the National Building Code of Canada. These factors are not explicit functions of the site vibration period, and, therefore, are more suitable for the design of small to medium rise buildings for which only limited site investigations are routinely carried out. Key words: earthquake engineering, design spectra, site-specific, building codes.

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.

The June 13, 1975 earthquake and its relationship to the New Madrid seismic zone

1977 ◽  
Vol 67 (1) ◽  
pp. 209-218
Author(s):  
R. B. Herrmann ◽  
G. W. Fischer ◽  
J. E. Zollweg
Keyword(s):  
Parameter Estimation ◽  
Seismic Moment ◽  
Strong Motion ◽  
P Wave ◽  
Eastern North America ◽  
New Madrid Seismic Zone ◽  
Seismic Zone ◽  
Long Period ◽  
Consistent Solution ◽  
New Madrid

abstract The June 13, 1975 earthquake in the New Madrid seismic zone produced the first recorded strong-motion accelerograms for an event in the region, as well as the largest recorded accelerations to date for any event in eastern North America. The peak strong-motion values obtained from an analysis of the accelerograms are the following: amax = 43 cm/sec2, vmax = 1 cm/sec and dmax = 0.05 cm for the longitudinal S88°W component; amax = 31 cm/sec2, vmax = 0.6 cm/sec and dmax = 0.01 cm for the DOWN component; amax = 64 cm/sec2, vmax = 1.6 cm/sec2, and dmax = 0.09 cm for the tangential S02°E component. Source parameter estimation using long-period surface waves, Lg spectra, P-wave first motions and the integrated accelerograms leads to a consistent solution. The seismic moment is estimated to be 4E21 dyne-cm and the corner period 0.6 sec. The corner period-seismic moment pair for this event agrees with the regional scaling of these parameters observed by Street et al. (1975).

Spectral matching RotD100 target spectra: Effect on records characteristics and seismic response

2021 ◽  
pp. 875529302110492
Author(s):  
Alan Rivera-Figueroa ◽  
Luis A Montejo
Keyword(s):  
Seismic Response ◽  
Strong Motion ◽  
Bridge Piers ◽  
Spectral Variability ◽  
Reinforced Concrete Bridge ◽  
Energy Demands ◽  
Target Spectrum ◽  
Single Column ◽  
Scaling Down ◽  
Motion Characteristics

This article investigates three different approaches to generate seismic input compatible with RotD100 design spectra: (1) separately matching each horizontal component to the target spectrum, (2) separately matching and then scaling-down the records to improve the match and (3) directly pursuing the match of RotD100 by simultaneously modifying both horizontal components. We examine the strong motion characteristics of the resulting records individually and their variability as suites of input records. The records generated, along with a set of amplitude-scaled records, are used as input for bi-directional non-linear response history analyses of idealized single column reinforced concrete bridge piers with different geometric and reinforcement characteristics. It is shown that the records generated pursuing a direct match of the target spectrum attain the closest match, retain better the strong motion characteristics of the seed records and their horizontal components exhibit a spectral variability comparable to suites of amplitude-scaled records. Regarding the effect on seismic response, the suites constructed separately matching each component consistently imposed larger peak inelastic and total energy demands than all other suites. Directly pursuing the match of RotD100 generated responses close but consistently below the expected from amplitude-scaled suites. The best results were obtained using the direct match methodology but using as target 110% the RotD100 spectrum as required in ASCE 7-16.

scholarly journals A hybrid model for mapping simplified seismic response via a GIS-metamodel approach

2014 ◽  
Vol 14 (7) ◽  
pp. 1703-1718 ◽  
Author(s):  
G. Grelle ◽  
L. Bonito ◽  
P. Revellino ◽  
L. Guerriero ◽  
F. M. Guadagno
Keyword(s):  
Seismic Hazard ◽  
Seismic Response ◽  
Hybrid Model ◽  
Computational Models ◽  
Site Response ◽  
Seismic Hazard Assessment ◽  
Physical Parameters ◽  
Seismic Zone ◽  
Acceleration Response ◽  
Good Correspondence

Abstract. In earthquake-prone areas, site seismic response due to lithostratigraphic sequence plays a key role in seismic hazard assessment. A hybrid model, consisting of GIS and metamodel (model of model) procedures, was introduced aimed at estimating the 1-D spatial seismic site response in accordance with spatial variability of sediment parameters. Inputs and outputs are provided and processed by means of an appropriate GIS model, named GIS Cubic Model (GCM). This consists of a block-layered parametric structure aimed at resolving a predicted metamodel by means of pixel to pixel vertical computing. The metamodel, opportunely calibrated, is able to emulate the classic shape of the spectral acceleration response in relation to the main physical parameters that characterize the spectrum itself. Therefore, via the GCM structure and the metamodel, the hybrid model provides maps of normalized acceleration response spectra. The hybrid model was applied and tested on the built-up area of the San Giorgio del Sannio village, located in a high-risk seismic zone of southern Italy. Efficiency tests showed a good correspondence between the spectral values resulting from the proposed approach and the 1-D physical computational models. Supported by lithology and geophysical data and corresponding accurate interpretation regarding modelling, the hybrid model can be an efficient tool in assessing urban planning seismic hazard/risk.

Seismic response and retrofit of industrial brick masonry chimneys

1992 ◽  
Vol 19 (1) ◽  
pp. 117-128 ◽  
Author(s):  
A. Ghobarah ◽  
T. Baumber
Keyword(s):  
Seismic Response ◽  
Ground Motion ◽  
Strong Motion ◽  
Brick Masonry ◽  
Wind Loading ◽  
Earthquake Ground Motion ◽  
Lumped Mass ◽  
Mass System ◽  
Higher Modes ◽  
Recent Earthquakes

During recent earthquakes, the documented cases of collapsed unreinforced brick masonry industrial chimneys are numerous. Observed modes of structural failure are either total collapse or sometimes collapse or damage of the top third of the structure. The objective of this study is to analyze and explain the modes of observed failure of masonry chimneys during earthquake events, and to evaluate two retrofit systems for existing chimneys in areas of high seismicity. The behaviour of the masonry chimney, when subjected to earthquake ground motion, was modelled using a lumped mass system. Several actual strong motion records were used as input to the model. The shear, moment, and displacement responses to the earthquake ground motion were evaluated for various chimney configurations. It was found that the failure of the chimney at its base is the result of the fundamental mode of vibration. Failure at the top third of the structure due to the higher modes of vibration is possible when the chimney is subjected to high frequency content earthquakes. Higher modes, which are normally not of concern under wind loading, were shown to be critical in seismic design. Post-tensioning and the reinforcing steel cage were found to be effective retrofit systems. Key words: masonry, chimneys, behaviour, analysis, design, retrofit, dynamic, earthquakes, seismic response.

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