Seismic analysis of short-period structures subjected to the 1988 Saguenay earthquake

1992 ◽  
Vol 19 (3) ◽  
pp. 510-520 ◽  
Author(s):  
Pierre Léger ◽  
Angelo Romano
Keyword(s):  
Seismic Design ◽  
Seismic Analysis ◽  
Strong Motion ◽  
Response Spectra ◽  
Base Shear ◽  
Ductility Demand ◽  
Short Period ◽  
Modification Factor ◽  
Energy Dissipation Capacity ◽  
Design Earthquake

This paper presents elastic and inelastic response spectra of strong motion accelerograms recorded during the 1988 Saguenay earthquake. Comparisons are made with the National Building Code of Canada (NBC) 1990 lateral forces requirements for the seismic resistant design of short-period structures. The use of a period-dependent force modification factor is proposed to take advantage of the energy dissipation capacity of short-period structures on a more rational basis. The seismic response of a typical low-rise steel building designed according to the NBC 1990 and CAN3-S16.1-M89 is then investigated. It is shown that to obtain a realistic picture of the ductility demand of low-rise buildings, the structural overstrength, that is, the supplied strength in excess of the seismic design base shear, should be explicitly considered in the design process. Key words: seismic design, earthquake, low-rise structures, code.

Response Modification Factor for Y-Eccentric-Braced Steel Frame Structures

2011 ◽  
Vol 250-253 ◽  
pp. 2285-2290
Author(s):  
Wen Xia Yang ◽  
Qiang Gu ◽  
Zhen Sen Song
Keyword(s):  
Seismic Design ◽  
Pushover Analysis ◽  
Steel Frames ◽  
Design Procedure ◽  
Response Spectra ◽  
Elastic Response ◽  
Base Shear ◽  
Response Modification Factor ◽  
Elastic Response Spectra ◽  
Modification Factor

In current seismic design procedure, structural base shear is calculated according to the linear elastic response spectra divided by response modification factorR. The response modification factor is important to the reliability and economy of building seismic design. In this paper, the response modification factors of Twelve Y-eccentric braced steel frames with various stories and spans lengths were evaluated by capacity spectrum method based on the global capacity envelops obtained from an improved pushover analysis and incremental dynamic analysis. According to the results, an appropriate formula of the response modification factor for the Y-eccentric braced steel frames was suggested.

Analysis of Strong Motion Records from Uttarkashi Earthquake for Assessment of Code Provisions for Different Seismic Zones

1993 ◽  
Vol 9 (4) ◽  
pp. 739-754 ◽  
Author(s):  
Sudhir K. Jain ◽  
Satrajit Das
Keyword(s):  
Seismic Design ◽  
Strong Motion ◽  
Response Spectra ◽  
Average Response ◽  
Period Range ◽  
Strong Motion Records ◽  
Seismic Zones ◽  
Time Histories ◽  
Present Design ◽  
Codal Provisions

Strong motion records have been obtained at 13 stations during the Uttarkashi earthquake of October 20, 1991 (magnitude 6.6). A study has been conducted on these time histories to assess the codal provisions in India. Emphasis of the study is on evaluating relative consistency of design provisions for different seismic zones in India. The average response spectra from this earthquake show concentration of significantly more energy in low period range and less energy in high period range. The magnitude of seismic design force for zones I, II, and III is consistent while it is too low for zone IV; no records were obtained in area with shaking intensity corresponding to zone V. It is seen that for buildings in zones I, II, and III, the present design provisions may be lowered either by relaxing the requirement of special ductile detailing, or by reducing the design force. On the other hand, design provisions for zone IV need to be revised upwards.

Response Modification Factor for Y-Eccentric-Braced Steel Frame Structures Designed Based on Chinese Code

2014 ◽  
Vol 580-583 ◽  
pp. 1449-1457
Author(s):  
Wen Xia Yang ◽  
Qiang Gu ◽  
Ping Zhou Cao ◽  
Rong Jin Shi
Keyword(s):  
Pushover Analysis ◽  
Design Procedure ◽  
Response Spectra ◽  
Elastic Response ◽  
Base Shear ◽  
Response Modification Factor ◽  
Linear Elastic ◽  
Elastic Response Spectra ◽  
Modification Factor ◽  
Steel Frame Structures

In current seismic design procedure, structure base shear is calculated according to the linear elastic response spectra divided by the response modification factor, which accounts for ductility and overstrength of a structural system. In this paper, the response modification factors of Y-eccentric braced steel frames (YECBF) designed based on Chinese Code were evaluated by an improved pushover analysis on 12 examples with various stories and spans lengths. According to the analysis results, the effects of fundamental periods, storey numbers, and spans of frames on the behavior factor were studied. In the end, an appropriate response modification factor was proposed for YECBF designed base on Chinese Code.

Strong motion accelerograph records from the 1993 Napierville earthquake

1995 ◽  
Vol 22 (1) ◽  
pp. 190-196
Author(s):  
René Tinawi ◽  
André Filiatrault ◽  
Pierre Léger
Keyword(s):  
Ground Motion ◽  
Energy Content ◽  
Strong Motion ◽  
Response Spectra ◽  
High Energy ◽  
Period Range ◽  
Attenuation Relationships ◽  
Acceleration Time Histories ◽  
Short Period ◽  
Time Histories

An earthquake of magnitude ML = 4.3 occurred near Napierville, Quebec, on November 16, 1993. An accelerograph at the liquefaction, storage, and regasification plant of Gaz Metropolitain in Montreal, about 55 km from the epicentre, recorded the ground motion. Although the maximum accelerations and velocities from this event are small, the acceleration time histories do confirm the high energy content in the very short period range. The recorded ground motion and corresponding absolute acceleration response spectra are presented and various attenuation relationships, proposed for eastern North America, are utilized to compare the measured and predicted ground motion parameters. Key words: Napierville earthquake, attenuation relationships, acceleration spectra, strong motion records.

Period-dependent seismic force reduction factors for short-period structures

1991 ◽  
Vol 18 (4) ◽  
pp. 568-574 ◽  
Author(s):  
W. K. Tso ◽  
N. Naumoski
Keyword(s):  
Reduction Factor ◽  
Structural Systems ◽  
High Ductility ◽  
Base Shear ◽  
Ductility Demand ◽  
Seismic Design Code ◽  
Short Period ◽  
Seismic Force ◽  
Force Reduction ◽  
Reduction Factors

The seismic force reduction factors proposed in the seismic provisions of the National Building Code of Canada 1990 (NBCC 1990) are examined using ground motion records from two recent Canadian earthquakes. The displacement ductility demands are analyzed for structural systems with different ductility capacity. It is found that the NBCC 1990 force reduction factors, which are period independent, lead to a very high ductility demand for short-period structural systems. To avoid this, two types of period-dependent force reduction factors for short-period structures are investigated. The results show that the linearly varying period-dependent reduction factor represents a viable means to resolve the high ductility problems associated with short-period structural systems. Key words: earthquake, seismic, design, code, response, spectra, ductility, reduction factor, base shear.

Displacement-based seismic design of regular reinforced concrete shear wall buildings

2011 ◽  
Vol 38 (6) ◽  
pp. 616-626 ◽  
Author(s):  
JagMohan Humar ◽  
Farrokh Fazileh ◽  
Mohammad Ghorbanie-Asl ◽  
Freddy E. Pina
Keyword(s):  
Reinforced Concrete ◽  
Seismic Design ◽  
Pushover Analysis ◽  
Shear Wall ◽  
Base Shear ◽  
Ductility Demand ◽  
Inelastic Demand ◽  
Displacement Based ◽  
Ductility Capacity ◽  
Shear Demand

A displacement based method for the seismic design of reinforced concrete shear wall buildings of regular shape is presented. For preliminary design, approximate estimates of the yield and ultimate displacements are obtained, the former from simple empirical relations, and the latter to keep the ductility demand within ductility capacity and to limit the maximum storey drift to that specified by the codes. For a multi-storey building, the structure is converted to an equivalent single-degree-of-freedom system using an assumed deformation shape that is representative of the first mode. The required base shear strength of the system is determined from the inelastic demand spectrum corresponding to the ductility demand. In subsequent iterations a pushover analysis for the force distribution based on the first mode is used to obtain better estimates of yield and ultimate displacements taking into account stability under P–Δ effect. A multi-mode pushover analysis is carried out to find more accurate estimates of the shear demand.

Bi-Directional Pseudo-Acceleration Response Spectra

2016 ◽  
Vol 10 (04) ◽  
pp. 1650007
Author(s):  
Anat Ruangrassamee ◽  
Chitti Palasri ◽  
Panitan Lukkunaprasit
Keyword(s):  
Seismic Design ◽  
Response Spectrum ◽  
Ground Motions ◽  
Strong Motion ◽  
Response Spectra ◽  
Acceleration Response ◽  
Acceleration Response Spectra ◽  
Acceleration Response Spectrum ◽  
Two Degree Of Freedom ◽  
Ratio Response

In seismic design, excitations are usually considered separately in two perpendicular directions of structures. In fact, the two components of ground motions occur simultaneously. This paper clarifies the effects of bi-directional excitations on structures and proposes the response spectra called “bi-directional pseudo-acceleration response spectra”. A simplified analytical model of a two-degree-of-freedom system was employed. The effect of directivity of ground motions was taken into account by applying strong motion records in all directions. The analytical results were presented in the form of the acceleration ratio response spectrum defined as the bi-directional pseudo-acceleration response spectrum normalized by a pseudo-acceleration response spectrum.

scholarly journals Horizontal UHS Amplitudes for Regions with Deep Soil Atop Deep Geological Sediments—An Example of Osijek, Croatia

2021 ◽  
Vol 11 (14) ◽  
pp. 6296
Author(s):  
Borko Đ. Bulajić ◽  
Marijana Hadzima-Nyarko ◽  
Gordana Pavić
Keyword(s):  
Pannonian Basin ◽  
Strong Motion ◽  
Response Spectra ◽  
Eurocode 8 ◽  
Deep Soil ◽  
Regional Seismicity ◽  
South Central ◽  
Local Soil ◽  
Short Period ◽  
Deep Soils

In this paper, we demonstrate how UHS-based seismic microzonation can be applied in low-to-medium seismicity areas with deep local soil and deep geological deposits under the local soil. The case study area surrounds the city of Osijek, Croatia, which is in the south–central region of the Pannonian Basin. New frequency-dependent scaling equations are derived, and the empirical response spectra are compared to the spectra of real strong motions in the surrounding region. Empirical calculations for deep soil atop deep geological strata show a 37% reduction in short-period spectral amplitudes when compared to rock locations. This demonstrates that local soil amplification is mitigated by energy dissipation in deep soils. For vibration periods longer than 0.3 s, spectral amplitudes are being amplified. This amplification goes up to 2.37 times for vibration periods around 0.5 s. UHS spectra for Osijek are computed using regional seismicity estimates, data on local soil and deeper geological surroundings, and newly created regional empirical equations for scaling various spectral amplitudes. UHS amplitudes for Osijek are also compared to the Eurocode 8 spectra for ground type C. The results show that ratios of the maximum UHS amplitudes to PGA values are up to 46% larger than the corresponding 2.5 factor that is recommended by Eurocode 8 for horizontal spectra. The UHS results might be viewed as preliminary for Osijek and regions with similar seismicity and local soil and deep geology conditions. When the number of regional strong-motion records grows many times beyond what it is currently, it will be feasible to properly calibrate the scaling equations, resulting in more reliable and long-term UHS estimations for the area under consideration.

Seismic performance of reinforced concrete ductile moment-resisting frame buildings located in different seismic regions

1992 ◽  
Vol 19 (4) ◽  
pp. 688-710 ◽  
Author(s):  
T. J. Zhu ◽  
W. K. Tso ◽  
A. C. Heidebrecht
Keyword(s):  
Reinforced Concrete ◽  
Seismic Design ◽  
Ground Motions ◽  
Base Shear ◽  
High Rise ◽  
Moment Resisting Frame ◽  
Short Period ◽  
Frame Buildings ◽  
Moment Resisting ◽  
Seismic Regions

Seismic areas in Canada are classified into three categories for three different combinations of acceleration and velocity seismic zones (Za < Zv, Za = Zv, and Za > Zv), and ground motions in different zonal combination areas are expected to have different frequency characteristics. The National Building Code of Canada specifies different levels of seismic design base shear for short-period buildings located in areas with different zonal combinations. The specification of seismic design base shear for long-period buildings is directly tied to zonal velocity, irrespective of seismic zonal combination. This paper evaluates the seismic performance of both high-rise long-period and low rise short-period reinforced concrete ductile moment-resisting frame buildings located in seismic regions having Za < Zv, Za = Zv, and Za > Zv. Two frame buildings have 10 and 18 storeys were used as structural models for high-rise buildings, while a set of four-storey buildings were used to represent low-rise buildings. All buildings were designed to the current Canadian seismic provisions and concrete material code. Three groups of earthquake records were selected as representative ground motions in the three zonal combination regions. The inelastic responses of the designed buildings to the three groups of ground motions were analyzed statistically. The results indicate that the distribution of inelastic deformations is significantly different for high-rise frame buildings situated in seismic regions with Za < Zv, Za = Zv, and Za > Zv. Inelastic deformation is concentrated in the lower storeys for high-rise buildings located in Za < Zv areas, whereas significant inelastic deformation can develop in the upper storeys for high-rise buildings situated in Za > Zv regions. The use of three different levels of seismic design base shear for short-period structures improves the consistency of ductility demands on low-rise buildings situated in the three different zonal combination regions. Despite the use of appropriate design base shears for different seismic regions, the ductility demands for these low-rise buildings are relatively high. To avoid excessive ductility demands, it is suggested that the seismic strengths for low-rise short-period buildings should not be significantly reduced from their elastic design base shears. Key words: earthquake, ground motion, seismic, design, reinforced concrete, frame buildings, beams, columns, ductility.

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.

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