İnşaat Mühendisliği / Civil Engineering

Application of k-means and Gaussian mixture model for classification of seismic activities in Istanbul

2020-03-06T08:08:20Z

Application of k-means and Gaussian mixture model for classification of seismic activities in Istanbul Küyük, Hüseyin Serdar; Yıldırım, Eray; Doğan, Emrah; Horasan, Gündüz Two unsupervised pattern recognition algorithms, k-means, and Gaussian mixture model (GMM) analyses have been applied to classify seismic events in the vicinity of Istanbul. Earthquakes, which are occurring at different seismicity rates and extensions of the Thrace-Eskisehir Fault Zone and the North Anatolian Fault (NAF), Turkey, are being contaminated by quarries operated around Istanbul. We have used two time variant parameters, complexity, the ratio of integrated powers of the velocity seismogram, and S/P amplitude ratio as classifiers by using waveforms of 179 events (1.8 < M < 3.0). We have compared two algorithms with classical multivariate linear/quadratic discriminant analyses. The total accuracies of the models for GMM, k-means, linear discriminant function (LDF), and quadratic discriminant function (QDF) are 96.1 %, 95.0 %, 96.1 %, 96.6 %, respectively. The performances of models are discussed for earthquakes and quarry blasts separately. All methods clustered the seismic events acceptably where QDF slightly gave better improvements compared to others. We have found that unsupervised clustering algorithms, for which no a-prior target information is available, display a similar discriminatory power as supervised methods of discriminant analysis.

Geotechnical properties of Adapazari silt

2020-03-06T08:08:20Z

Geotechnical properties of Adapazari silt Arel, Ersin The geotechnical properties of silts have not been investigated extensively, because they are not found in every soil environment. It is even more difficult to understand the behaviour of silts when they are encountered in appreciable volumes. It has recently been claimed that such fine-grained soils have a potential for liquefaction, similar to sands a fact that was confirmed during the 1999 Marmara earthquake in Turkey. This paper provides a basis for explaining the unique behaviour of silts in seismic conditions by investigating their physical and mechanical features. The results are ultimately expected to provide a satisfactory answer to the as yet unexplained issue of how silts behave during earthquakes.

Non-linear finite element analysis for prediction of seismic response of buildings considering soil-structure interaction

2020-03-06T08:08:20Z

Non-linear finite element analysis for prediction of seismic response of buildings considering soil-structure interaction Çelebi, Erkan; Göktepe, Fatih The objective of this paper focuses primarily on the numerical approach based on two-dimensional (2-D) finite element method for analysis of the seismic response of infinite soil-structure interaction (SSI) system. This study is performed by a series of different scenarios that involved comprehensive parametric analyses including the effects of realistic material properties of the underlying soil on the structural response quantities. Viscous artificial boundaries, simulating the process of wave transmission along the truncated interface of the semi-infinite space, are adopted in the non-linear finite element formulation in the time domain along with Newmark's integration. The slenderness ratio of the superstructure and the local soil conditions as well as the characteristics of input excitations are important parameters for the numerical simulation in this research. The mechanical behavior of the underlying soil medium considered in this prediction model is simulated by an undrained elasto-plastic Mohr-Coulomb model under plane-strain conditions. To emphasize the important findings of this type of problems to civil engineers, systematic calculations with different controlling parameters are accomplished to evaluate directly the structural response of the vibrating soil-structure system. When the underlying soil becomes stiffer, the frequency content of the seismic motion has a major role in altering the seismic response. The sudden increase of the dynamic response is more pronounced for resonance case, when the frequency content of the seismic ground motion is close to that of the SSI system. The SSI effects under different seismic inputs are different for all considered soil conditions and structural types.

The İmpact of the HM-CFRP ratio on the Strengthening of steel Composite I-Beams

2020-03-06T08:08:18Z

The İmpact of the HM-CFRP ratio on the Strengthening of steel Composite I-Beams Ağcakoca, Elif; Aktaş, Muharrem