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

Modeling the Observed Site Response from Istanbul Strong Motion Network

An extensive site investigation study was carried out in the European side of Istanbul as part of the large-scale microzonation project for the Istanbul Metropolitan Municipality. 2912 borings mostly down to 30m depth with approximately 250m spacing were conducted within an area of 182 sqkm to investigate local site conditions. 55 stations of the Istanbul Rapid Response Network and Ataköy vertical array are located in this area. There have been few small earthquakes in the recent years with local magnitude slightly over M=4. One of these earthquakes took place on 12/3/2008 in Yalova with local magnitude of M=4.8. Vertical array stations at 4 levels (ground surface, at depths of 50m, 75m and 140m) and 23 of the 55 Istanbul Rapid Response Network stations recorded this earthquake. Based on the recorded acceleration time histories on the engineering bedrock at Ataköy vertical array, the remaining recorded acceleration time histories are modeled based on empirical site amplification relationships proposed by Borcherdt (1994) and based on a modified version of Shake91 (Idriss and Sun, 1992). An attempt is also made to model the recorded acceleration time histories during the Mw=7.4, 1999 Kocaeli Earthquake recorded at Ataköy, Fatih and Zeytinburnu stations located in the same area

Site response from Istanbul vertical arrays and strong motion network

In the framework of Istanbul Microzonation Project for the European side, the investigated region was divided by a grid system of 250m×250m and site investigations were performed for each cell based on borings and in-situ seismic wave velocity measurements for defining representative soil profiles with shear wave velocity values extending down to the engineering bedrock. Geological and geotechnical laboratory and field testing data with measured seismicwave velocities enabled to determine the engineering properties of the soil and rock layers encountered in all the cells. There have been limited number of earthquakes within 100km range of Istanbul with local magnitude in the range of ML=4-5 and few more distant and more stronger earthquakes that were recorded by the existing three vertical arrays as well as by the Istanbul Rapid Response Network (IRRN) strong motion stations. Even though the maximum PGA were similar, the observed spectral response were different indicating the importance of the distance and source magnitude concerning the frequency content and predominant soil period ranges. Even though the level of ground shaking intensity is relatively low, efforts were made to evaluate the variation of the recorded accelerations with depth in vertical arrays located at Ataköy, Zeytinburnu and Fatih. Attempts were also made to model the recorded acceleration time histories at the triggered IRRN stations using the acceleration records obtained at the bedrock level from the vertical array stations in the case of the recent 19.5.2011 Mw=5.7 Kütahya earthquake that took place approximately 185km away

A simplified approach for site-specific design spectrum

Gökçe Tönük (MEF Author)##nofulltext##The design acceleration spectrum requires site investigations and site-response analyses in accordance with the local seismic hazard. The variability in earthquake source and path effects may be considered using a large number of acceleration records compatible with the earthquake hazard. An important step is the selection and scaling of input acceleration records. Likewise, a large number of soil profiles need to be considered to account for the variability of site conditions. One option is to use Monte Carlo simulations with respect to layer thickness and shear wave velocity profiles to account for the variability of the site factors. The local seismic hazard analysis yields a uniform hazard acceleration spectrum on the bedrock outcrop. Site-specific response analyses also need to produce a uniform hazard acceleration spectrum on the ground surface. A simplified approach is proposed to define acceleration design spectrum on the ground surface that may be considered a uniform hazard spectrum.WOS:000451220500003Scopus - Affiliation ID: 60105072Conference Proceedings Citation Index- ScienceProceedings PaperOcak2018YÖK - 2017-1

Microzonation with respect to ground shaking intensity

Seismic microzonation is conducted to assess the seismic hazard on the ground surface with respect to ground shaking intensity. A probabilistic seismic hazard study is conducted to define earthquake characteristics on the rock outcrop. A grid system is generated to divide the investigation area into cells according to geological and geotechnical data. Site characterizations are based on available information to define soil profiles for each cell with soil stratifications and shear wave velocities extending down to the engineering bedrock. Site-specific 1D site response analyses are carried out for all soil profiles, based on the engineering properties of encountered soil layers, selection and scaling of the sufficient number of input acceleration time histories compatible with the regional seismicity and earthquake source characteristics. The microzonation study carried out for Zeytinburnu town on the European side of Istanbul with respect to ground shaking intensity is presented. The importance of the selection of the microzonation parameters for assessing ground shaking intensity is discussed. © 2019 Associazione Geotecnica Italiana, Rome, Italy.WOS:000623514300025Scopus - Affiliation ID: 60105072Conference Proceedings Citation Index – ScienceProceedings PaperUluslararası işbirliği ile yapılmayan - HAYIRHaziran2019YÖK - 2020-2

Implications of site specific response analysis

Definition of design earthquake characteristics, more specifically uniform hazard acceleration response spectrum, on the ground surface is the primary component for performance based design of structures and assessment of seismic vulnerabilities in urban environments. The adopted approach for this purpose requires a probabilistic local seismic hazard assessment, definition of representative site profiles down to the engineering bedrock, and 1D or 2D quivalent or nonlinear, total or effective stress site response analyses depending on the complexity and importance of the structures to be built. Thus, a site-specific response analysis starts with the probabilistic estimation of regional seismicity and earthquake source characteristics, soil stratification, engineering properties of encountered soil layers in the soil profile. The local seismic hazard analysis would yield probabilistic uniform hazard acceleration response spectrum on the bedrock outcrop. Thus, site specific response analyses also need to produce a probabilistic uniform hazard acceleration response spectrum on the ground surface. A general review will be presented based on the previous studies conducted by the author and his co-workers in comparison to major observations and methodologies to demonstrate the implications of site-specific response analysis.WOS:000546471200002Scopus - Affiliation ID: 60105072Conference Proceedings Citation Index- ScienceProceedings PaperHaziran2018YÖK - 2017-1

Implications of site specific response analysis

Due to copyright restrictions, the access to the full text of this article is only available via subscription.Definition of design earthquake characteristics, more specifically uniform hazard acceleration response spectrum, on the ground surface is the primary component for performance based design of structures and assessment of seismic vulnerabilities in urban environments. The adopted approach for this purpose requires a probabilistic local seismic hazard assessment, definition of representative site profiles down to the engineering bedrock, and 1D or 2D equivalent or nonlinear, total or effective stress site response analyses depending on the complexity and importance of the structures to be built. Thus, a site-specific response analysis starts with the probabilistic estimation of regional seismicity and earthquake source characteristics, soil stratification, engineering properties of encountered soil layers in the soil profile. The local seismic hazard analysis would yield probabilistic uniform hazard acceleration response spectrum on the bedrock outcrop. Thus, site specific response analyses also need to produce a probabilistic uniform hazard acceleration response spectrum on the ground surface. A general review will be presented based on the previous studies conducted by the author and his co-workers in comparison to major observations and methodologies to demonstrate the implications of site-specific response analysis

A simplified approach for site-specific design spectrum

Due to copyright restrictions, the access to the full text of this article is only available via subscription.The design acceleration spectrum requires site investigations and site-response analyses in accordance with the local seismic hazard. The variability in earthquake source and path effects may be considered using a large number of acceleration records compatible with the earthquake hazard. An important step is the selection and scaling of input acceleration records. Likewise, a large number of soil profiles need to be considered to account for the variability of site conditions. One option is to use Monte Carlo simulations with respect to layer thickness and shear wave velocity profiles to account for the variability of the site factors. The local seismic hazard analysis yields a uniform hazard acceleration spectrum on the bedrock outcrop. Site-specific response analyses also need to produce a uniform hazard acceleration spectrum on the ground surface. A simplified approach is proposed to define acceleration design spectrum on the ground surface that may be considered a uniform hazard spectrum

Observations from geotechnical arrays in Istanbul

Due to copyright restrictions, the access to the full text of this article is only available via subscription.Few small earthquakes with local magnitude slightly larger than ML = 4 were recorded by geotechnical downhole arrays that have been recently deployed in the west side of Istanbul. Same events were also recorded by Istanbul Rapid Response Network (IRRN) which comprises of 55 surface strong motion stations in the European side of Istanbul. The strongest one of these earthquakes took place on 12/3/2008 in Çınarcık with local magnitude of ML = 4.8. Even though the observed PGAs were not exceeding 0.01 g, an effort is made to model the recorded response at the downhole array sites as well as the at the IRRN stations using the acceleration records obtained by the deepest sensors, i.e. on the engineering bedrock, at the downhole array sites as input bedrock motions. 1D equivalent linear site response analysis that is generally adopted for site-specific response analysis is used for modelling. Observations from the recorded response and results from 1D modelling of ground response have yielded in general good agreement between the observed and recorded soil response at the station sites

Site specific response analysis for performance based design earthquake characteristics

Due to copyright restrictions, the access to the full text of this article is only available via subscription.During strong earthquakes, seismic waves travelling towards the ground surface alter the engineering characteristics of the soil layers and consequently the characteristics of travelling seismic waves also change with respect to their frequency and amplitude contents. In assessing the site-specific design earthquake characteristics in seismically active zones for performance levels of Collapse Prevention, Life Safety, and Immediate Occupancy that may correspond to 72, 475 and 2475 year return period earthquakes, detailed site characterization and site response analyses may be required. This process may be conducted in two consecutive statistically independent stages. The first stage involves the seismic hazard study to assess the design earthquake characteristics on rock outcrop for selected exceedance levels and the second stage involves detailed site characterization and site response analyses to estimate design earthquake characteristics on the ground surface. The uncertainties arising from the source characteristics need to be taken into account by using a representative number of strong motion acceleration records for site response analyses recorded in locations that are compatible with the seismic hazard with respect to fault mechanism, earthquake magnitude, and source distance. In addition, the strong motion acceleration records should be compatible with respect to peak acceleration and acceleration response spectra levels estimated by the probabilistic or deterministic seismic hazard study. One approach is to use the uniform acceleration hazard spectra and another option is to adopt conditional mean spectrum on rock outcrop estimated in the first stage from the earthquake hazard study for scaling input motions for site response analysis. It was observed that the scaling methodology adopted may play an important role in the calculated earthquake characteristics on the ground surface. A semi empirical procedure was proposed to determine the site specific design earthquake characteristics on the ground surface. A parametric study was conducted to demonstrate the applicability of the proposed methodology based on one dimensional site response analyses using Shake91 and DeepSoil site response codes to evaluate design earthquake characteristics on the ground surface