The identification of building structural systems

1976 ◽  
Vol 66 (1) ◽  
pp. 125-151
Author(s):  
Firdaus E. Udwadia ◽  
Panos Z. Marmarelis
Keyword(s):  
Nonlinear Behavior ◽  
Strong Motion ◽  
Ambient Vibration ◽  
Structural Systems ◽  
Reinforced Concrete Structure ◽  
Earthquake Excitation ◽  
Ground Shaking ◽  
Ambient Vibration Testing ◽  
Suitable System ◽  
Strong Ground

abstract This paper investigates the response of structural systems to strong earthquake ground shaking by utilizing some concepts of system identification. After setting up a suitable system model, the Weiner technique of nonparametric identification has been introduced and its experimental applicability studied. The sources of error have been looked into and several new results have been presented on accuracy calculations stemming from the various assumptions in the Wiener technique. The method has been applied in studying the response of a 9-story reinforced concrete structure to earthquake excitation as well as ambient vibration testing. The linear contribution to the total roof response during strong ground shaking has been identified, and it is shown that a marked nonlinear behavior is exhibited by the structure during the strong-motion portion of the excitation.

Nonlinear behavior of soil sediments identified by using borehole records observed at the Ashigra Valley, Japan

1995 ◽  
Vol 85 (6) ◽  
pp. 1821-1834
Author(s):  
Toshimi Satoh ◽  
Toshiaki Sato ◽  
Hiroshi Kawase
Keyword(s):  
Shear Strain ◽  
Main Part ◽  
Nonlinear Behavior ◽  
Strong Motion ◽  
S Wave ◽  
Ground Shaking ◽  
Wave Velocities ◽  
The One ◽  
Soil Sediments ◽  
Strong Ground

Abstract We evaluate the nonlinear behavior of soil sediments during strong ground shaking based on the identification of their S-wave velocities and damping factors for both the weak and strong motions observed on the surface and in a borehole at Kuno in the Ashigara Valley, Japan. First we calculate spectral ratios between the surface station KS2 and the borehole station KD2 at 97.6 m below the surface for the main part of weak and strong motions. The predominant period for the strong motion is apparently longer than those for the weak motions. This fact suggests the nonlinearity of soil during the strong ground shaking. To quantify the nonlinear behavior of soil sediments, we identify their S-wave velocities and damping factors by minimizing the residual between the observed spectral ratio and the theoretical amplification factor calculated from the one-dimensional wave propagation theory. The S-wave velocity and the damping factor h (≈(2Q)−1) of the surface alluvial layer identified from the main part of the strong motion are about 10% smaller and 50% greater, respectively, than those identified from weak motions. The relationships between the effective shear strain (=65% of the maximum shear strain) calculated from the one-dimensional wave propagation theory and the shear modulus reduction ratios or the damping factors estimated by the identification method agree well with the laboratory test results. We also confirm that the soil model identified from a weak motion overestimates the observed strong motion at KS2, while that identified from the strong motion reproduces the observed. Thus, we conclude that the main part of the strong motion, whose maximum acceleration at KS2 is 220 cm/sec2 and whose duration is 3 sec, has the potential of making the surface soil nonlinear at an effective shear strain on the order of 0.1%. The S-wave velocity in the surface alluvial layer identified from the part just after the main part of the strong motion is close to that identified from weak motions. This result suggests that the shear modulus recovers quickly as the shear strain level decreases.

The island of Hawaii earthquakes of November 29, 1975: Strong-motion data and damage reconnaissance report

1977 ◽  
Vol 67 (2) ◽  
pp. 493-515
Author(s):  
Christopher Rojahn ◽  
B. J. Morrill
Keyword(s):  
Local Time ◽  
Structural Damage ◽  
Strong Motion ◽  
Maximum Acceleration ◽  
Epicentral Area ◽  
Ground Shaking ◽  
Motion Data ◽  
Large Sector ◽  
Threshold Duration ◽  
Strong Ground

Abstract Two earthquakes occurred on the island of Hawaii on November 29, 1975, a magnitude (Ms) 5.7 event at 0335 (local time) and a magnitude (Ms) 7.2 event at 0447. During the larger event, a maximum acceleration of 0.22 g was recorded in the southern part of Hilo, 43 km north of the epicenter. A 0.05 g threshold duration of 13.7 sec was measured for the same component. Smaller amplitude accelerograph records were obtained at two other locations on the island along with four seismoscope records. During or subsequent to the larger event, a large sector of the southeastern coastline subsided by as much as 3.5 meters. A tsunami generated by the larger event caused at least one death (one person also missing), injury to 28 persons, and significant structural and nonstructural damage. Only scattered evidence of strong ground shaking was observed in the epicentral area, and most of the several dozen nearby structures sustained little or no structural damage from ground shaking. In Hilo, 45 km north of the Ms = 7.2 epicenter, structural and nonstructural damage was slight to moderate but more extensive than elsewhere on the island.

scholarly journals Near-Source Ground Motion and its Effects on Flexible Buildings

1995 ◽  
Vol 11 (4) ◽  
pp. 569-605 ◽  
Author(s):  
John F. Hall ◽  
Thomas H. Heaton ◽  
Marvin W. Halling ◽  
David J. Wald
Keyword(s):  
Source Region ◽  
Nonlinear Behavior ◽  
Ground Shaking ◽  
Collapse Potential ◽  
Blind Thrust ◽  
Frame Buildings ◽  
Steel Frame Buildings ◽  
Blind Thrust Fault ◽  
Large Earthquakes ◽  
Strong Ground

Occurrence of large earthquakes close to cities in California is inevitable. The resulting ground shaking will subject buildings in the near-source region to large, rapid displacement pulses which are not represented in design codes. The simulated Mw7.0 earthquake on a blind-thrust fault used in this study produces peak ground displacement and velocity of 200 cm and 180 cm/sec, respectively. Over an area of several hundred square kilometers in the near-source region, flexible frame and base-isolated buildings would experience severe nonlinear behavior including the possibility of collapse at some locations. The susceptibility of welded connections to fracture significantly increases the collapse potential of steel-frame buildings under strong ground motions of the type resulting from the Mw7.0 simulation. Because collapse of a building depends on many factors which are poorly understood, the results presented here regarding collapse should be interpreted carefully.

The identification of building structural systems

1976 ◽  
Vol 66 (1) ◽  
pp. 153-171 ◽  
Author(s):  
P. Z. Marmarelis ◽  
F. E. Udwadia
Keyword(s):  
Structural Response ◽  
Feedback System ◽  
System Model ◽  
Reinforced Concrete Structure ◽  
Nonlinear Feedback ◽  
Identification Procedure ◽  
Ground Shaking ◽  
Nonlinear Contribution ◽  
Nonlinear Kernels ◽  
Strong Ground

abstract This paper models a building structure as a nonlinear feedback system and studies the effects of such a system model on the structural response to strong ground shaking. Nonlinear kernels arising in the identification procedure have been investigated and an error analysis presented. Applications of the Weiner method in studying the response of a reinforced concrete structure to strong ground shaking have been illustrated. The nature of the second order kernels has been displayed and the nonlinear contribution to the response at the roof level, during strong ground shaking, has been determined.

scholarly journals Stand-Alone Tsunami Alarm Equipment

2016 ◽  
Author(s):  
Akio Katsumata ◽  
Yutaka Hayashi ◽  
Kazuki Miyaoka ◽  
Hiroaki Tsushima ◽  
Toshitaka Baba ◽  
...  
Keyword(s):  
Ground Motion ◽  
Low Cost ◽  
Strong Motion ◽  
Source Area ◽  
Single Site ◽  
Peak Displacement ◽  
Ground Shaking ◽  
Mems Accelerometer ◽  
Current Location ◽  
Strong Ground

Abstract. One of the quickest means of tsunami evacuation is transfer to higher ground soon after strong and long ground-shaking. Strong ground motion means that the source area of the event is close to the current location, and long ground-shaking or large displacement means that the magnitude is large. We investigated the possibility to apply this to tsunami hazard alarm using single-site ground motion observation. Information from the mass media may not be available sometimes due to power failure. Thus, a device that indicates risk of a tsunami without referring to data elsewhere would be helpful to those should evacuate. Since the sensitivity of a low-cost MEMS accelerometer is sufficient for this purpose, tsunami alarms equipment for home use may be easily realized. Several observation values (e.g., strong-motion duration, peak ground displacement) were investigated as candidates. It was found that a suitable value for a single-site tsunami alarm is long-period peak displacement or the product of strong-motion duration and peak displacement. It was possible to detect an earthquake with a magnitude greater than 7.8 with a 0.8 threat score. Application of this method to recent major earthquakes indicated that such equipment could effectively alert people to the possibility of tsunami.

scholarly journals Earthquake ground shaking hazard assessment for the Lower Hutt and Porirua areas, New Zealand

1992 ◽  
Vol 25 (4) ◽  
pp. 286-302 ◽  
Author(s):  
R. J. Van Dissen ◽  
J. J. Taber ◽  
W. R. Stephenson ◽  
S. Sritheran ◽  
S. A. L. Read ◽  
...  
Keyword(s):  
Ground Motion ◽  
Strong Motion ◽  
Spectral Ratio ◽  
Fine Sand ◽  
Geographic Variations ◽  
Ground Acceleration ◽  
Ground Shaking ◽  
Earthquake Scenarios ◽  
Shear Wave Velocities ◽  
Strong Ground

Geographic variations in strong ground shaking expected during damaging earthquakes impacting on the Lower Hutt and Porirua areas are identified and quantified. Four ground shaking hazard zones have been mapped in the Lower Hutt area, and three in Porirua, based on geological, weak motion, and strong motion inputs. These hazard zones are graded from 1 to 5. In general, Zone 5 areas are subject to the greatest hazard, and Zone 1 areas the least. In Lower Hutt, zones 3 and 4 are not differentiated and are referred to as Zone 3-4. The five-fold classification is used to indicate the range of relative response. Zone 1 areas are underlain by bedrock. Zone 2 areas are typically underlain by compact alluvial and fan gravel. Zone 3-4 is underlain, to a depth of 20 m, by interfingered layers of flexible (soft) sediment (fine sand, silt, clay, peat), and compact gravel and sand. Zone 5 is directly underlain by more than 10 m of flexible sediment with shear wave velocities in the order of 200 m/s or less. The response of each zone is assessed for two earthquake scenarios. Scenario 1 is for a moderate to large, shallow, distant earthquake that results in regional Modified Mercalli intensity V-VI shaking on bedrock. Scenario 2 is for a large, local, but rarer, Wellington fault earthquake. The response characterisation for each zone comprises: expected Modified Mercalli intensity; peak horizontal ground acceleration; duration of strong shaking; and amplification of ground motion with respect to bedrock, expressed as a Fourier spectral ratio, including the frequency range over which the most pronounced amplification occurs. In brief, high to very high ground motion amplifications are expected in Zone 5, relative to Zone 1, during a scenario 1 earthquake. Peak Fourier spectral ratios of 10-20 are expected in Zone 5, relative to Zone 1, and a difference of up to three, possibly four, MM intensity units is expected between the two zones. During a scenario 2 event, it is anticipated that the level of shaking throughout the Lower Hutt and Porirua region will increase markedly, relative to scenario 1, and the average difference in shaking between each zone will decrease.

A State-of-Knowledge Review of the Influence of Strong-Motion Duration on Structural Damage

2006 ◽  
Vol 22 (3) ◽  
pp. 827-845 ◽  
Author(s):  
Jonathan Hancock ◽  
Julian J. Bommer
Keyword(s):  
Structural Damage ◽  
Strong Ground Motion ◽  
Strong Motion ◽  
Strong Correlations ◽  
Review Of The Literature ◽  
Cumulative Energy ◽  
Ground Shaking ◽  
Soil Deposits ◽  
Structural Demand ◽  
Strong Ground

The important role played by the duration of ground shaking in the response of saturated soil deposits is universally acknowledged, but no such consensus exists regarding the degree of influence that duration exerts on structural damage. There are several hundred papers in the literature that link structural damage to parameters related either directly or indirectly to the duration of strong ground motion. The conclusions of these studies differ widely with regard to the influence of strong-motion duration on structural demand. This paper provides a summary and critical review of the literature on this subject. It is found that studies employing damage measures related to cumulative energy usually find a positive correlation between strong-motion duration and structural damage, while studies employing damage measures using maximum response generally do not find strong correlations between duration and damage.

scholarly journals Near-Source Simulation of Strong Ground Motion in Amatrice Downtown Including Site Effects

Geosciences ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 186
Author(s):  
Alessandro Todrani ◽  
Giovanna Cultrera
Keyword(s):  
Ground Motion ◽  
Site Effects ◽  
Central Italy ◽  
Strong Motion ◽  
Seismic Source ◽  
Spectral Ratio ◽  
Intensity Measures ◽  
Standard Spectral Ratio ◽  
Heavy Damage ◽  
Strong Ground

On 24 August 2016, a Mw 6.0 earthquake started a damaging seismic sequence in central Italy. The historical center of Amatrice village reached the XI degree (MCS scale) but the high vulnerability alone could not explain the heavy damage. Unfortunately, at the time of the earthquake only AMT station, 200 m away from the downtown, recorded the mainshock, whereas tens of temporary stations were installed afterwards. We propose a method to simulate the ground motion affecting Amatrice, using the FFT amplitude recorded at AMT, which has been modified by the standard spectral ratio (SSR) computed at 14 seismic stations in downtown. We tested the procedure by comparing simulations and recordings of two later mainshocks (Mw 5.9 and Mw 6.5), underlining advantages and limits of the technique. The strong motion variability of simulations was related to the proximity of the seismic source, accounted for by the ground motion at AMT, and to the peculiar site effects, described by the transfer function at the sites. The largest amplification characterized the stations close to the NE hill edge and produced simulated values of intensity measures clearly above one standard deviation of the GMM expected for Italy, up to 1.6 g for PGA.

Ambient vibration test results of the Imperial County Services Building

1983 ◽  
Vol 73 (6A) ◽  
pp. 1895-1902
Author(s):  
Gerard C. Pardoen
Keyword(s):  
Strong Motion ◽  
Ambient Vibration ◽  
Vibration Test ◽  
Test Results ◽  
Structural Failure ◽  
Imperial Valley ◽  
Ambient Vibration Test ◽  
Significant Interest ◽  
First Time ◽  
County Services

Abstract The ambient vibration test results conducted on the Imperial County Services Building prior to the 15 October 1979 Imperial Valley earthquake are summarized. These results are of significant interest because the Imperial County Services Building has been the source of many postearthquake investigations due to the fact that the 1979 earthquake represented the first time a building instrumented with strong motion recorders suffered and recorded the major structural failure.

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