Perspectives on European Earthquake Engineering and Seismology: Volume 1

Civil Engineering; Natural Hazards; Geotechnical Engineering & Applied Earth Sciences Industry Sec; 2ECEES; Earthquake Engineering; Performance Based Design and Earthquake Engineering; Irregular Buildings and Earthquakes; Historical Structures and Earthquakes; Precast Buildings and Earthquakes; Bridge Design and Earthquake

Perspectives on European Earthquake Engineering and Seismology: Volume 2

Geotechnical Engineering & Applied Earth Science

Evaluation of Liquefaction Susceptibility for Microzonation and Urban Planning

Various procedures were developed to evaluate liquefaction susceptibility of soil layers for implementing engineering remediation measures. The approach that has gained wide acceptance within the framework of urban planning is to establish microzonation maps with respect to liquefaction susceptibility to mitigate possible earthquake damage related to liquefaction. In this context, microzonation maps were produced recently for six municipalities in Turkey as a part of a major Pilot Project. Two variables are required for the assessment of liquefaction resistance of sandy soil layers; the seismic demand expressed in terms of cyclic stress ratio, CSR; and the capacity of the soil layers to resist liquefaction, expressed in terms of cyclic resistance ratio, CRR. The approach adopted to perform microzonation maps for liquefaction susceptibility was based on the procedure proposed by Youd et al., 2001 and Iwasaki et al., 1982. The variation of the safety factors with depth were determined for each representative borehole where CSR is calculated using stress reduction factor and CRR based on SPT blow counts. In addition CSR was calculated based on site response analyses. The results are compared and the source of uncertainties and the effects of the two approaches are discussed in terms of the final microzonation maps

Probabilistic seismic microzonation for ground shaking intensity, a case study in Türkiye

The purpose of seismic microzonation is to estimate earthquake characteristics on the ground surface based on a probabilistic approach to mitigate earthquake damage in the foreseeable future for the new buildings, as well as for the existing building stock. The probabilistic analysis and related results are very important from an engineering perspective since the nature of the problem can only be dealt with in a probabilistic manner. The uncertainties associated with these analyses may be large due to the uncertainties in source characteristics, soil profile, soil properties, and building inventory. At this stage, the probability distribution of the related earthquake parameters on the ground surface may be determined based on hazard-compatible input acceleration-time histories, site profiles, and dynamic soil properties. One option, the variability in earthquake source and path effects may be considered using a large number of acceleration records compatible with the site-dependent earthquake hazard. Likewise, large numbers of soil profiles may be used to account for the site-condition variability. The seismic microzonation methodology is proposed based on the probabilistic assessment of these factors involved in site response analysis. The second important issue in seismic microzonation procedure is the selection of microzonation parameters. The purpose being mitigation of structural damage, it is possible to adopt earthquake parameters like cumulative average velocity (CAV) or Housner intensity (HI) that was observed to have better correlation with building damage after earthquakes. A seismic microzonation procedure will be developed with respect to ground shaking intensity considering probabilistic values of the cumulative average velocity (CAV) or Housner intensity (HI).WOS:001087844900003ArticleUluslararası işbirliği ile yapılmayan - HAYIRNovember2023YÖK - 2022-23Kası

Factors affecting site-specific response analysis

The engineering purpose of a site-specific response analysis is to estimate the uniform hazard acceleration spectrum on the ground surface for a selected hazard level. One of the mandatory components for site response analyses is one or more representative acceleration time histories that need to be scaled with respect to the calculated seismic hazard level for the selected site. The selection and scaling procedures of earthquake acceleration records play an important role in this approach. The effects and differences in using two different scaling approaches are studied: scaling with respect to ground motion parameters and response spectrum scaling. A set of homogeneous ground motion prediction relationships are developed for peak ground acceleration, peak ground velocity, root-mean-square acceleration, Arias intensity, cumulative absolute velocity, maximum spectral acceleration, response spectrum intensity, and acceleration spectrum intensity based on a uniform set of acceleration records for ground motion parameter scaling. The uncertainties associated with site response analysis are considered as epistemic and aleatory uncertainties in source characteristics, soil profile, and soil properties. Aleatory variability is due to the intrinsic randomness of natural systems; it cannot be reduced with additional data (Passeri et al. 2020), however; its variability may be modeled by probability distribution functions. Thus, one possibility is to determine the probability distribution of the acceleration spectrum calculated on the ground surface for all possible input acceleration records, site profiles, and dynamic soil properties. The variability in the earthquake source and path effects are considered using a large number of acceleration records compatible with the site-dependent earthquake hazard in terms of fault mechanism, magnitude, and distance range recorded on stiff site conditions. Likewise, a large number of soil profiles may be considered to account for the site condition variability. The uncertainties related to dynamic soil properties may be considered as possible variability of maximum dynamic shear modulus in site response analyses. A methodology is proposed to estimate a uniform hazard acceleration spectrum on the ground surface based on the probabilistic assessment of the factors involved in site response analysis. The uniform hazard acceleration spectra obtained from a case study are compared with the spectra calculated by probabilistic models proposed in the literature.WOS:000743801200001Scopus - Affiliation ID: 60105072Science Citation Index ExpandedQ1-Q2Article; Early AccessUluslararası işbirliği ile yapılmayan - HAYIROcak2022YÖK - 2021-22Oca

The Consolidation Behavior of the Clay-Core in a Rock Fill Dam — Atatürk Dam Case Study

Unexpectedly large settlements occurred in the 165 meter high clay core of Atatürk Dam during the reservoir filling stage. An investigation was conducted based on laboratory experiments and numerical analysis. Consolidation tests were performed on compacted samples under stress levels expected to take place in the field by considering the possible factors affecting the consolidation behavior. The experimental findings were used to model the observed settlements based on a parametric study and by back-calculation. The total expected settlements were determined to be in the order of 16.0 m. While a good fit was captured between the observed and modeled settlements prior to the reservoir filling, it was not possible to model the significantly large settlements observed within the clay core located approximately 120 meter below the crest following the reservoir filling. Evaluating other observations and findings, it was concluded that this phenomenon could be attributed to the lateral displacement of the core material into the filter and shell zones that were prone to instabilities due to disintegration under water

Damage to Water and Sewage Pipelines in Adapazari During 1999 Kocaeli, Turkey Earthquake

Vulnerability of pipeline systems were studied for the city of Adapazari based on available information on the performance of the water and sewage pipeline systems during 1999 Kocaeli, Turkey Earthquake. The water supply pipeline system in Adapazari experienced extensive damage. The main damage was observed in transmission and distribution systems primarily due to brittle asbestos cement (AC) pipes used in the system combined with the fracturing effect of ground deformations associated with liquefaction and softening of alluvial sediments. Recently, pipeline damage inventory was compiled based on repair reports and interviews with water works technicians. Since the entire system was replaced after the earthquake only limited number of repair reports was available. The geotechnical and geological site conditions were evaluated based on available borings, and in-situ tests. Vulnerability of water pipelines due to ground shaking and liquefaction was evaluated separately. Variation of earthquake characteristics on the ground surface was estimated based on 1D site response analyses using the outcrop motion recorded in Adapazari during the 1999 Earthquake as input motion. Liquefaction susceptibility was estimated based on a simplified liquefaction analysis and SPT blow counts obtained during the site investigations. Distribution of damage predicted by means of empirical vulnerability functions proposed in literature was compared to the pipeline damages observed during the 1999 Earthquake

Micromechanism-based endochronic modeling of sand behavior

Mikroskobik değişkenlerin ve bunların şekil değişimi ile birlikte değişimlerinin belirlenmesi ve tanecikli ortama ait bu değişkenlerle sürekli ortam arasındaki bağlantının sade ve basit bir şekilde kurulması oldukça önemli ve büyük bir sorundur. Bu çalışmada, mikroskobik sürece ait içsel durum değişkenlerine dayalı olması ve sürekli ortamda tanımlanabilen bünye ifadelerine olanak vermesinden dolayı, endokronik teorinin olanakları geliştirilmeye çalışılmıştır. Zemin davranışının mikro ölçekte gerçekleşen sürecinin anlaşılması amacıyla, ilkin, hangi mikro ölçek değişkenlerinin zemin davranışını izah edebileceği tartışılmıştır. Daha sonra, zeminlerin şekil değiştirmesinin mikromekanizması bir seri sava bağlı olarak izah edilerek, endokronik bünye ifadeleri elde edilmiştir ve önerilen modelin öngörü kapasitesi drenajlı üç eksenli basınç koşulları için irdelenmiştir. Anahtar Kelimeler: Zemin modelleri, kum, mikromekanizma, endokronik model.The observed macroscopic properties of soil behaviour is mainly the manifestation of microscopic mechanism during deformation. Consequently, modeling of soil behaviour should ideally be based on the microscopic process determining the behaviour. But, observation and determination of the related microscopic properties and parameters is a difficult and time consuming process. Besides this problem, the link between the microscopic particulate medium and continuum medium is an another problem and usually very complex relations have been proposed. One of the main advantage of endochronic theory is its fundamental philosophy which bases the phenomenology of the soil behaviour on the internal state variables that need not to be observed. The first part of this study focuses on the arguments related with micro variables that are supposed to be controlling macroscopic soil behaviour. It is aimed to determine the important micro variables and consequently to propose a general hypothesis about the micromechanism of deformation process in sands. Regarding to the perspective gained by the proposed hypothesis for the micromechanism of soil deformation, constitutive relations are obtained and the predictive capacity of the proposed model is investigated by modeling of drained triaxial tests conducted on sands. It has been seen that stress-strain behaviour can well be modelled while observed softening phenomena still needs to be more clearly formulated in the model.  Keywords: Soil Models, sand, micromechanism, endochronic model.