scholarly journals Evaluation of seismic performance measures for MDOF RC structures subjected to simulated and real ground motions

2020 ◽  
Vol 323 ◽  
pp. 02003
Author(s):  
Shaghayegh Karimzadeh ◽  
Aysegul Askan ◽  
Ahmet Yakut
Keyword(s):  
Ground Motion ◽  
Seismic Performance ◽  
Performance Measures ◽  
Ground Motions ◽  
Time History ◽  
Motion Simulation ◽  
Ground Motion Simulation ◽  
Nonlinear Time History Analyses ◽  
Nonlinear Time History ◽  
Simulated Ground Motions

Nonlinear time history analyses of structures require full time series of ground motion records. For regions with sparse seismic networks or potential large earthquakes, ground motion simulation has gained more attention in recent years. Simulated records are required to be generated using regional input dataset and then verified against existing recorded ground motions of past events. To use simulated ground motions in engineering applications, estimation of reliable seismic demand parameters is essential. In this study, the real and simulated records of the 2009 L’Aquila, Italy earthquake with (Mw=6.3) are investigated for their use in engineering practice. In the first step, misfits are evaluated for alternative seismological measures (peak values, duration and frequency as well as energy content of the time histories). Next, varying multi-degree-of-freedom reinforced concrete structures with different number of stories are selected. Numerical models of the structures are performed in the OpenSees platform. Seismic performance measures in terms of inter-story drift ratio for the selected structures are assessed through nonlinear time history analyses for both the real and simulated ground motions. Then, the misfits are estimated in terms of structural demand parameters. Results reveal a good fit between the seismological and engineering demand misfits for the selected ground motion simulation approaches.

Regional Ground-Motion Simulation Using Recorded Ground Motions

2021 ◽  
Author(s):  
Xinzheng Lu ◽  
Qingle Cheng ◽  
Yuan Tian ◽  
Yuli Huang
Keyword(s):  
Ground Motion ◽  
Damage Assessment ◽  
Target Location ◽  
Response Spectrum ◽  
Ground Motions ◽  
Time History ◽  
Seismic Damage ◽  
Motion Simulation ◽  
Ground Motion Simulation ◽  
Seismic Damage Assessment

ABSTRACT Regional ground-motion simulation is important for postearthquake seismic damage assessment. Herein, a ground-motion simulation method using recorded ground motions is proposed. Inverse-distance-weighted interpolation of the response spectra is performed to obtain the response spectrum at the target location. Then the ground-motion time history for the target location is obtained by correcting the nearest-station records using the continuous wavelet transform. An evaluation measure for the accuracy of the predicted ground motion, that is, the response-spectrum error, is introduced, and its relationship with the seismic damage of regional buildings is determined via a city-scale nonlinear time-history analysis. The response-spectrum errors under different site conditions, distances, and elevation differences are analyzed. The application conditions for the proposed method are subsequently outlined. The Tsinghua campus is examined as a case study to validate the method. Finally, downtown San Francisco under an Mw 7.0 simulated earthquake on the Hayward fault is selected as an example to demonstrate the proposed method. The proposed method overcomes the difficulties in determining the intrastation ground motions and provides valuable input to postearthquake seismic damage assessment.

Influence of Earthquake Attack Angle on Seismic Demands for Structures under Bi-Directional Ground Motions

2011 ◽  
Vol 255-260 ◽  
pp. 2330-2334 ◽  
Author(s):  
Yu Zhang ◽  
Quan Wang Li ◽  
Jian Sheng Fan
Keyword(s):  
Seismic Design ◽  
Ground Motions ◽  
Time History ◽  
Earthquake Excitation ◽  
Seismic Demands ◽  
3 Dimensional ◽  
Nonlinear Time History Analyses ◽  
Modification Factor ◽  
Structural Responses ◽  
Nonlinear Time History

The earthquake may attack the structural building from any angle, but in current seismic design codes, this type of uncertainty is seldom accounted. The uncertainty associated with the direction of earthquake excitation was considered in this paper, and its effect on structural responses was investigated. For this purpose, a simple 3-dimensional model with symmetric plan was established, which had fundamental periods ranged from 0.1s to 5.0s, and was subjected to a set of 30 ground motion pairs for which both linear and nonlinear time history analyses were performed. Analyzing results showed that, on average, the elastic roof acceleration is 32% underestimated, and the inelastic roof displacement is 18% underestimated if the variation of earthquake excitation direction is not consider. Recognizing this, a modification factor for the seismic demand was proposed thorough a statistical analysis, which guarantees a probability of 95% design safety

scholarly journals A Wavelet-based Approach for Truncating Pulse-like Records

2021 ◽  
Author(s):  
Vicky Dimakopoulou ◽  
Michalis Fragiadakis ◽  
Ioannis Taflampas
Keyword(s):  
Ground Motion ◽  
Near Field ◽  
Time History ◽  
Response Spectra ◽  
Degree Of Freedom ◽  
Seismic Performance Assessment ◽  
Analysis And Design ◽  
Nonlinear Time History Analyses ◽  
Ground Motion Records ◽  
Nonlinear Time History

Abstract The seismic performance assessment of structures using truncated pulse-like ground motion records is discussed. It is shown that it is possible to truncate pulse-like signals using a novel wavelet-based definition that identifies the duration of the predominant velocity pulse. The truncated time history can efficiently reproduce the increased seismic demand that near-field records typically produce. Substituting the original ground motion with the truncated signal, significantly accelerates structural analysis and design. The truncated signal is the part of the original accelerogram that coincides with the duration of the predominant pulse, which is identified using a wavelet-based procedure, previously proposed by the authors. Elastic and inelastic response spectra and nonlinear time history analyses for SDOF (single-degree-of-freedom) systems are first studied. Subsequently a nine-storey steel frame is examined in order to demonstrate the performance of the proposed approach on a multiple-degree-of-freedom system. The proposed approach is found very efficient for pulse-like ground motions, while it is also sufficient for many records that are not characterized as such.

The Anti-Seismic Analysis of the Lock-up Device on the Arch Bridge

2011 ◽  
Vol 368-373 ◽  
pp. 1047-1050
Author(s):  
Ling Jun Kong ◽  
Yan Bei Chen ◽  
Peng Li ◽  
Qi Bin Jiang
Keyword(s):  
Seismic Performance ◽  
Computational Models ◽  
Seismic Analysis ◽  
Time History ◽  
Bending Moments ◽  
Shear Forces ◽  
Arch Bridge ◽  
Nonlinear Time History Analyses ◽  
Nonlinear Time History

To study the anti-seismic performance of Lock-up device, the two computational models which are respectively uninstalled Lock-up device and installed Lock-up device on the arch bridge are established. Nonlinear time-history analyses are carried out by the Midas/Civil software in this paper. The interaction between pile and soil is considered in the analyses. The results show that the maximum shear forces of the tops and the maximum bending moments of the bottoms of all piers are quite uniform after the LUD are installed and that the displacements of the top of the fixed pier has been decreased.

scholarly journals Assessment of the Seismic Performance for a Low-Code RC Shear Walls Structure in Bucharest (Romania)

2020 ◽  
Vol 14 (1) ◽  
pp. 111-123
Author(s):  
Florin Pavel ◽  
Radu Vacareanu
Keyword(s):  
Seismic Performance ◽  
Significant Proportion ◽  
Time History ◽  
Shear Walls ◽  
Seismic Rehabilitation ◽  
Nonlinear Time History Analyses ◽  
Principal Directions ◽  
Section Type ◽  
Nonlinear Time History ◽  
Sectional Analysis

Background: Low-code RC shear walls structures house a significant proportion (over 20%) of the inhabitants of Bucharest. Objective: In this research, the seismic performance of a low-code reinforced concrete shear walls structure located in various sites in Bucharest (Romania) is assessed. Methods: The seismic performance is assessed using both static and dynamic nonlinear time-history analyses, as well as detailed sectional analysis of the RC shear walls. Results: The results show that the structure has significant capacity differences in the two principal directions. Moreover, it has been observed that the maximum top displacements obtained from nonlinear time history analyses are larger in the transversal direction. Conclusion: Considering the behaviour of such structures during the 1977 Vrancea earthquake, the fact that these structures are already 40 – 50 years old and given the results of some of the analyses shown in this study, it can be concluded that immediate seismic rehabilitation measures are needed in order to correct, at least partially the structural issues of this section type.

scholarly journals Sensitivity Analysis of the Interfrequency Correlation of Synthetic Ground Motions to Pseudodynamic Source Models

2020 ◽  
Vol 92 (1) ◽  
pp. 301-313
Author(s):  
Seok Goo Song ◽  
Mathieu Causse ◽  
Jeff Bayless
Keyword(s):  
Seismic Hazard ◽  
Ground Motion ◽  
Ground Motions ◽  
Source Parameters ◽  
Simulation Methods ◽  
Motion Simulation ◽  
Ground Motion Simulation ◽  
Earthquake Source Parameters ◽  
Source Models ◽  
Earthquake Rupture Processes

Abstract Given the deficiency of recorded strong ground-motion data, it is important to understand the effects of earthquake rupture processes on near-source ground-motion characteristics and to develop physics-based ground-motion simulation methods for advanced seismic hazard assessments. Recently, the interfrequency correlation of ground motions has become an important element of ground-motion predictions. We investigate the effect of pseudodynamic source models on the interfrequency correlation of ground motions by simulating a number of ground-motion waveforms for the 1994 Northridge, California, earthquake, using the Southern California Earthquake Center Broadband Platform. We find that the cross correlation between earthquake source parameters in pseudodynamic source models significantly affects the interfrequency correlation of ground motions in the frequency around 0.5 Hz, whereas its effect is not visible in the other frequency ranges. Our understanding of the effects of earthquake sources on the characteristics of near-source ground motions, particularly the interfrequency correlation, may help develop advanced physics-based ground-motion simulation methods for advanced seismic hazard and risk assessments.

Assessment on the deflection amplification factor of steel buckling-restrained bracing frames

2021 ◽  
pp. 136943322110439
Author(s):  
Mussa Mahmoudi ◽  
Mohammad Jalili Sadr Abad
Keyword(s):  
Earthquake Engineering ◽  
Amplification Factor ◽  
Time History ◽  
Braced Frames ◽  
Ground Motion Simulation ◽  
Nonlinear Time History Analyses ◽  
Deflection Amplification Factor ◽  
Ductility Capacity ◽  
Nonlinear Time History ◽  
Factor C

Researchers in the field of earthquake engineering are always looking for new ways to improve the seismic behavior of structures. The buckling-restrained brace (BRB) is one of these exciting innovations that are employed to increase the ductility capacity of traditional steel braced frames. Understanding the nonlinear response of these novel systems in estimating maximum displacements due to an earthquake has been of significant importance for structural designers. Accordingly, this research is carried out to study of deflection amplification factor ( C d) in BRBs, which have recently been presented in seismic design provisions as one of the seismic lateral-resisting systems. To this end, five 3-, 5-, 7-, 10-, and 15-story BRBs are modeled in the software framework of OpenSees. Ground motion simulation is performed by selecting several scaled earthquake records, and the values of elastic and ultimate displacements of structural systems are computed through pushover and nonlinear time-history analyses. The results showed that the deflection amplification factor suggested within famous building codes (such as ASCE-7-16) compared to the obtained values is, in some cases, for certainty; conversely, it is underestimated under some conditions. In fact, the findings indicate that the magnitude of C d in these systems is strongly related to the height of the building.

scholarly journals Study on Quasi-Static Loading Protocols considering the Action Characteristics of Long-Period Ground Motions

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Ke Yang ◽  
Bo Wang ◽  
Jiawei Zhang ◽  
Zhe Li ◽  
Boquan Liu
Keyword(s):  
Seismic Performance ◽  
Static Loading ◽  
Ground Motions ◽  
Low Frequency ◽  
Time History ◽  
Experimental Investigations ◽  
Structural Components ◽  
Cycle Number ◽  
Long Period ◽  
Nonlinear Time History

Due to abundant low-frequency components of long-period ground motions (LPGMs), long-period structures are susceptible to severe damage. The corresponding time-history displacement responses have significant “large-displacement” and “long-duration” characteristics. These action characteristics essentially reflect the different loading paths imposed on structures of LPGMs from ordinary ground motions (OGMs). Hence, revealing the influence mechanism of the action characteristics on the seismic performance of structural components is the key to investigating the influence of LPGMs on the whole structure. This paper presents a kind of quasi-static loading protocol considering the action characteristics of LPGMs. Firstly, nonlinear time-history analyses on structural systems subjected to 50 selected representative LPGMs were conducted. Inelastic cycles and corresponding amplitudes of time-history displacement responses under LPGMs were statistically analyzed through the rainflow method. Then, considering two of the most significant factors, structural period and target ductility, a prediction model of cycle number and cycle amplitude was obtained by regression. On this basis, the quasi-static loading protocol considering the action characteristics of LPGMs was developed. Proposed protocols can be directly applied to experimental investigations on the seismic performance for structural components under LPGMs.

Sign in / Sign up

Export Citation Format

Share Document