International Journal of Earthquake and Impact Engineering (4 papers in press)

Regular Issues

• Bayesian model updating-based and simulation-based system identification of shear-bending model for high-rise building  
  by Kohei Fujita, Yuha Hoshi, Izuru Takewaki 
  Abstract: A new system identification method is proposed for high-rise buildings based on the original simulation-assisted Bayesian model updating using a shear-bending model (SB model). The shear and bending stiffnesses of the SB model can be obtained by applying the inverse-eigenmode method based on the fundamental natural mode of the target building. A probabilistic SB model is investigated where the mean values of bending stiffnesses are controlled by the stiffness ratio of the bending stiffness to the shear stiffness. In this paper, a simulation-assisted Bayesian model-updating approach is proposed to identify the fundamental natural mode shape of rotation angles based on the limited-point floor rotation angle responses. The Bayes formula is applied to additionally observed floor rotation angles for evaluating the posterior probability distribution of the fundamental natural mode shape. To investigate the applicability of the proposed method, numerical examples of a 20-story building frame subjected to micro-tremor are shown.
  Keywords: system identification; shear-bending model; Bayesian model updating; subspace method; inverse-eigenmode method.
  DOI: 10.1504/IJEIE.2021.10044435
   
  
• Dynamics of free standing flexible structures subjected to base excitations  
  by Anupam Saraswat 
  Abstract: Dynamics of a flexible structure, freely standing on a rigid base and subjected to base excitation is a complex problem. This paper presents experimental investigation of dynamics of a free standing flexible structure subjected to base excitation. Two different steel structures viz. mechanical containment structure of a nuclear facility and a test specimen were tested on a shake table. Systematic study unveiled that free rocking frequencies of a flexible structure effect initiation of rocking motion from the rest state Amplitude of base excitation required for initiation of rocking motion was observed to be much lower for base frequencies matching with free rocking frequencies whereas it was higher for all other frequencies Further, overturning instability was evaluated and represented by way of overturning curves Contrary to the present understanding of the subject, it was demonstrated that fundamental modal frequency hadnt effected rocking initiation whereas free rocking frequencies had.
  Keywords: flexible body dynamics; free rocking frequencies; freestanding structure; seismic response; glove box; base excitation; rocking initiation.
  DOI: 10.1504/IJEIE.2022.10051000
   
  
• Reduced micropolar half-space subjected to earthquake sources  
  by Mohammad Atif, S.T.G. Raghukanth, S.R. Manam 
  Abstract: The paper makes a novel attempt to present a mathematical model for a buried source in the homogeneous reduced micropolar half-space and to study the propagation of waves when half-space is subjected to an arbitrary harmonic load. Specific solutions are also discussed in the case when the force field is distributed uniformly in vertical directions over a circular region. The obtained solutions are numerically evaluated to compare displacements and rotations between classical elastic half-space (EHS) and reduced micropolar half-space (RMHS). As an application of the proposed model, the Wutai 2012 and Central Italy 2016 earthquakes are simulated, assuming the source as a point moment tensor. A finite-fault rupture simulation is also presented for the Pocito, Argentina earthquake of 6.4 Mw, which occurred on 19 January 2021. The application of the proposed model is also shown in the field of impact with a brief discussion of source function.
  Keywords: reduced micropolar theory; half-space; dispersion curve; translations; rotations; moment tensor; Wutai earthquake; Central Italy earthquake; finite-fault; impact.
  DOI: 10.1504/IJEIE.2022.10051178
   
  
• Random number generation and other approaches for development of geotechnical correlations: Limitations, uncertainties and future scope  
  by Saha Dauji 
  Abstract: Correlation expressions are extensively employed to estimate unknown static or dynamic soil/rock parameters from known or easily measured variables and these derived properties are used as inputs for numerical analysis of founding media or foundation design. Such expressions are usually generated using data from subsurface exploration, laboratory or surface tests. Synthetic data has been used to develop correlation expressions for soil or rock in certain cases. Whereas engineers have to work around the aleatory uncertainty of founding media, the epistemic uncertainty arising due to procedures adopted for generation of data, and development or validation of correlation models should definitely be reduced. This study would sensitize the foundation designers about the strengths and limitations of correlation equations of soil properties available in literature and this would enable them to take informed and judicious decisions for safe foundation design. Further, this article attempts to sensitize researchers regarding limitations of approaches of synthetic data generation and model evaluation through simulations and calculations.
  Keywords: Soil investigation; Synthetic data; Random number generation; Rock properties; Soil properties; Correlation expression; Linear interpolation; Uncertainty.