Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Article Citation - WoS: 9Citation - Scopus: 8Effect of Drainage Conditions on Cpt Resistance of Silty Sand: Physical Model and Field Tests(Springer, 2023) Ecemis, Nurhan; Arık, Mustafa Sezer; Taneri, HazalThe influence of drainage conditions on cone penetration test (CPT) resistance and the excess pore pressure during cone penetration in sand and silty sand are examined using field and physical model tests. Drainage can generally occur in saturated clean sand and silty sand under certain conditions. This work aims to understand and explain the effect of sand and silty sand drainage conditions on CPT resistance and pore pressure through the coefficient of consolidation (c h) and penetration rate (v). The physical model test results indicate the significant effect of excess pore pressures and their dissipation rates, depending on the coefficient of consolidation (silt content) and the penetration rate on cone resistance. For the same relative density, normalized CPT resistance decreases as there is a reduction in c h (or an increase in silt content) or an increase in penetration rate. The difference in CPT resistance in silty sand is attributed to drainage conditions. Finally, the results revealed in this study and the field test data reported in the literature were combined to develop an equation for the effect of drainage conditions on excess pore water pressure and CPT resistance. © 2023, The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.Correction Cpt-Based Liquefaction Resistance of Clean and Silty Sands: a Drainage Conditions Based Approach Nurhan Ecemis (aug, 10.1007/S10518-022-01501-0, 2022)(Springer, 2022) Arık, Mustafa Sezer; Ecemiş, Nurhan; Monkul, Mehmet Murat; Tütüncü, Yunus EmreArticle Citation - WoS: 7Citation - Scopus: 8Cpt-Based Liquefaction Resistance of Clean and Silty Sands: a Drainage Conditions Based Approach(Springer, 2022) Ecemis, Nurhan; Monkul, Mehmet Murat; Tütüncü, Yunus Emre; Arik, Mustafa SezerThe cone penetration test-based simplified liquefaction triggering evaluations are largely based on linking liquefaction manifestations in the field to cone penetration resistance. These relationships are interpreted in such a way that for given penetration resistance, the liquefaction resistance increases as non-plastic fines content (FC) increases. However, several studies have indicated discrepancies in this relationship. Hence, there is a lag in rational scientific understanding of this observation. In this study, an experimental research program was undertaken to investigate the CPT-based liquefaction assessment by considering the effects of drainage conditions on the relationship between CPT resistance and liquefaction resistance. First, clean sand and silty sands having 5, 15, and 35% FC were tested at different relative densities by stress-controlled cyclic direct simple shear (CDSS) tests to investigate cyclic resistance of silty sand with varying amounts of non-plastic fines. Then, a set of tests involving piezocone penetration (CPTu), seismic CPTu (SCPTu), and direct push permeability (DPPT) were undertaken in a large-scale box filled with the same soils used in the CDSS tests. The large-scale test results quantified the effect of drainage conditions (coefficient of consolidation) on cone penetration resistance. Finally, by combining the CDSS and CPTu test results, an alternative CPT-based liquefaction resistance relationship was proposed by considering the effects of drainage conditions.Article Citation - WoS: 13Citation - Scopus: 12Geotechnical Reconnaissance Findings of the October 30 2020, Mw7.0 Samos Island (aegean Sea) Earthquake(Springer, 2022) Ziotopoulou, Katerinaa; Pelekis, Panagiotis; Klimis, Nikolaos; Çetin, Kemal Önder; Altun, Selim; Sezer, Alper; Ecemiş, NurhanOn October 30, 2020 14:51 (UTC), a moment magnitude (Mw) of 7.0 (USGS, EMSC) earthquake occurred in the Aegean Sea north of the island of Samos, Greece. Turkish and Hellenic geotechnical reconnaissance teams were deployed immediately after the event and their findings are documented herein. The predominantly observed failure mechanism was that of earthquake-induced liquefaction and its associated impacts. Such failures are presented and discussed together with a preliminary assessment of the performance of building foundations, slopes and deep excavations, retaining structures and quay walls. On the Anatolian side (Turkey), and with the exception of the Izmir-Bayrakli region where significant site effects were observed, no major geotechnical effects were observed in the form of foundation failures, surface manifestation of liquefaction and lateral soil spreading, rock falls/landslides, failures of deep excavations, retaining structures, quay walls, and subway tunnels. In Samos (Greece), evidence of liquefaction, lateral spreading and damage to quay walls in ports were observed on the northern side of the island. Despite the proximity to the fault (about 10 km), the amplitude and the duration of shaking, the associated liquefaction phenomena were not pervasive. It is further unclear whether the damage to quay walls was due to liquefaction of the underlying soil, or merely due to the inertia of those structures, in conjunction with the presence of soft (yet not necessarily liquefied) foundation soil. A number of rockfalls/landslides were observed but the relevant phenomena were not particularly severe. Similar to the Anatolian side, no failures of engineered retaining structures and major infrastructure such as dams, bridges, viaducts, tunnels were observed in the island of Samos which can be mostly attributed to the lack of such infrastructure.Article Citation - WoS: 6Citation - Scopus: 6Kinematic Reverse Flood Routing in Natural Rivers Using Stage Data(Springer, 2022) Tayfur, Gökmen; Moramarco, TommasoIn many developing countries, due to economic constraints, a single station on a river reach is often equipped to record flow variables. On the other hand, hydrographs at the upstream sections may also be needed for especially assessing flooded areas. The upstream flow hydrograph prediction is called the reverse flood routing. There are some reverse flood routing pocedures requiring sophisticated methods together with substantial data requirements. This study proposes a new reverse flood routing procedure, based upon the simple kinematic wave (KW) equation, requiring only easily measurable downstream stage data. The KW equation is first averaged along a channel length at a fixed time, t, assuming that channel width is spatially constant, and then the spatially averaged equation is averaged in time, Δt. The temporally averaged terms are approximated as the arithmetical mean of the corresponding terms evaluated at time t and t + Δt. The Chezy roughness equation is employed for flow velocity, and the upstream flow stage hydrograph is assumed be described by a two parameter gamma distribution (Pearson Type III). The spatially averaged mean flow depth and lateral flow are related to the downstream flow stage. The resulting routing equation is thus obtained as a function of only downstream flow stage, meaning that the method mainly requires measurements of downstream flow stage data besides the mean values of channel length, channel width, roughness coefficient and bed slope. The optimal values of the parameters of reverse flood routing are obtained using the genetic algorithm. The calibration of the model is accomplished by using the measured downstream hydrographs. The validation is performed by comparing the model-generated upstream hydrographs against the measured upstream hydrographs. The proposed model is applied to generate upstream hydrographs at four different river reaches of Tiber River, located in central Italy. The length of river reaches varied from 20 to 65 km. Several upstream hydrographs at different stations on this river are generated using the developed method and compared with the observed hydrographs. The method predicts the time to peak with less than 5% error and peak rates with less than 10% error in the short river reaches of 20 km and 31 km. It also predicts the time to peak and peak rate in other two brances of 45 km and 65 km with less than 15% error. The method satisfactorily generates upstream hydrographs, with an overall mean absolute error (MAE) of 42 m3/s.Article Citation - WoS: 10Citation - Scopus: 10Usage of Tyre Derived Aggregates as Backfill Around Buried Pipelines Crossing Strike-Slip Faults; Model Tests(Springer, 2022) Karaman, Mustafa; Demirci, Hasan Emre; Ecemiş, Nurhan; Bhattacharya, SubhamoyBuried pipelines crossing active faults are exposed to excessive soil forces under fault movements due to large relative movement between pipes and the soil surrounding them. As a result, extreme longitudinal strains develop within pipelines under large fault movements and this leads to pipeline failures. Several seismic mitigation techniques were proposed to improve the performance of buried pipelines crossing active faults. In this study, the potential of using Tyre Derived Aggregates (TDA) as a backfill material for mitigating the effects of strike-slip faulting are investigated through physical model tests. First, the details of the physical model test setup and model configuration are presented. Then a comparative study is carried out to study the effect of TDA content in the backfill and trench configurations on TDA mitigation. Model tests revealed that using a sloped trench with 100% TDA content in the backfill can decrease peak axial pipe strains up to 62% and peak bending strains up to 19%. It is observed that enlarging the trench and using an inclined trench improve the performance of the TDA mitigation technique.Article Citation - WoS: 13Citation - Scopus: 15A Survey of Damage Observed in Izmir Due To 2020 Samos-Izmir Earthquake(Springer, 2021) Demirci, Hasan Emre; Karaman, Mustafa; Bhattacharya, SubhamoyAn earthquake of magnitude 6.9 hit the city of Izmir (Turkey) on 30 October 2020, resulting in 117 deaths (in Turkey) and considerable economic losses. The earthquake also triggered a tsunami. Following the earthquake, field surveys are being conducted in a Covid-secure way to study and document the damages caused. The earthquake caused significant damages to residential buildings mainly located in the district of Bayrakli and Bornova. However, no damages were observed in railway and roadway bridges or tunnels and that helped the rescue operations. The damages were mainly structural which included the so-called pancake collapse (where the entire building collapsed) and soft storey type collapse (weak storey characterised with weak columns collapsed), and in some cases, only the ground floor completely collapsed. Due to the proximity of the epicentre and the geology of the area, it seemed that the ground motions were amplified. This technical note provides a summary of the seismological and recorded ground characteristics of the earthquake together with the lessons learnt.Article Citation - WoS: 61Citation - Scopus: 60Performance of Structures in Izmir After the Samos Island Earthquake(Springer, 2021) Yakut, Ahmet; Sucuoğlu, Haluk; Binici, Barış; Canbay, Erdem; Dönmez, Cemalettin; İlki, Alper; Caner, AlpThe October 30, 2020 Earthquake caused unexpectedly significant damage in Izmir considering its distance to the city. This paper evaluates the recorded ground motions, summarizes the performance of structures affected from the earthquake with emphasis on the reasons of damage. A detailed damage assessment was carried out by the Earthquake Engineering Research Center of Middle East Technical University to compile data on the damage of RC and masonry buildings. It was observed that majority of the damage was concentrated in the Bayrakli district due to its peculiar soil properties where many 7-10 story mid-rise RC buildings suffered heavy damage and collapse. The level of amplified ground motions combined with deficiencies of apparently non-code compliant buildings exacerbated the damage. The main reasons of damage were mainly attributed to the presence of soft stories, lack of proper detailing, poor construction quality, presence of heavy overhangs, and hence significant lack of code-compliance in essence. The influence of infill walls on seismic performance of deficient and inadequate buildings was clearly seen in this earthquake. This paper also discusses seismic code requirements in effect and their influence on the observed building performance. The recorded ground motions were compared with the code spectra to evaluate the performance of the buildings. The code response spectra were found to be well above the recorded ground motion spectra at the sites where significant damage was observed.Article Citation - WoS: 12Citation - Scopus: 16Misorientation and Grain Boundary Orientation Dependent Grain Boundary Response in Polycrystalline Plasticity(Springer, 2021) Yalçınkaya, Tuncay; Özdemir, İzzet; Tandoğan, İzzet TarıkThis paper studies the evolution of intergranular localization and stress concentration in three dimensional micron sized specimens through the Gurtin grain boundary model (J Mech Phys Solids 56:640-662, 2008) incorporated into a three dimensional higher-order strain gradient crystal plasticity framework (Yalcinkaya et al. in Int J Solids Struct 49:2625-2636, 2012). The study addresses continuum scale dislocation-grain boundary interactions where the effect of crystal orientation mismatch and grain boundary orientation are taken into account through the grain boundary model in polycrystalline metallic specimens. Due to the higher-order nature of the model, a mixed finite element formulation is used to discretize the problem in which both displacements and plastic slips are considered as primary variables. For the treatment of grain boundaries within the solution algorithm, an interface element is formulated and implemented together with the bulk plasticity model. The capabilities of the framework is demonstrated through 3D polycrystalline examples considering grain boundary conditions, grain boundary strength, the orientation distribution and the specimen size. A detailed grain boundary condition and stress concentration analysis is presented. The advantages and the disadvantages of the model is discussed in detail through numerical examples.Article Citation - WoS: 36Citation - Scopus: 39Sand-Granulated Rubber Mixture To Prevent Liquefaction-Induced Uplift of Buried Pipes: a Shaking Table Study(Springer, 2021) Ecemiş, Nurhan; Valizadeh, Hadi; Karaman, MustafaBuried pipelines in liquefiable soils are vulnerable and can float during earthquake excitation. The uplift forces due to pore-water-pressure generation relocate the pipelines in the soil. Therefore, it is essential to measure the liquefaction effects of the backfill materials on buried pipes and make an intelligent choice for the surrounding soil to reduce the applied forces on pipelines during liquefaction. Recently, scrap tire-soil mixtures have been used as a new geomaterial to decrease the adverse effects of liquefaction. This paper investigates the flotation of the buried pipe and the sand-granulated rubber mixture's effectiveness around the pipe by a series of shaking table tests. Dynamic tests were performed under 1 g conditions on a fully saturated sand-granulated rubber mixture with small-diameter buried pipes. Three different granulated-rubber dimensions of 2.5-5, 5-10, and 10-15 mm and granulated rubber ratios of 10, 20, and 30 percent were examined in the tests. The outcomes of excess pore water pressure, settlement, pipe uplift, and upward pressure during and after shaking were compared. The test results demonstrated that the sand-granulated rubber mixture reduces excess pore water pressure accumulation and prevents liquefaction. Moreover, the effect of pipe diameter, burial depth, consolidation coefficient of the mixture, and uplift initiation time on pore water pressure and load increment below the pipe were combined to predict the buried pipe's uplift probability.