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Consistency limits are essential and simple design parameters that are utilized as standard entries of all kinds of soil investigation programs conducted for geotechnical projects which are constructed in/on fine grained soils. These limits also represent mineralogical and physical properties of clayey soils directly and used to estimate their strength and rigidity properties indirectly. However, the consistency tests are assumed as the simple and basic tests of geotechnical engineering investigations, but the effects of operator, calibration of the device and environmental aspects at the tests damage the reliability and correctness of results. In this paper, it is aimed to overcome these challenges by evaluating the consistency characteristics of clayey soils considering only the values of liquid limit of specific clays with the use of simple regression analysis. A database is prepared by using 500 soil investigation reports that are involving the site characterization information, laboratory and field tests of Istanbul Province European side clayey soils, including Avcılar, Esenyurt, Küçükçekmece, Büyükçekmece, Çatalca, Zeytinburnu, Bahçelievler, Bakırköy districts. 1523 liquid limit tests are obtained from the mentioned database for high and very high plastic clays. The regression analyses have been applied to query the parameter effect ratio on the consistent characteristics and relationships have been tried to be developed to evaluate the values of plastic limit and plasticity index directly from only liquid limit test applications. The effects of fine material content, depth and natural water content is also investigated. Verifications of the suggested equations have been done for different cases and comparisons are made with the well-known sources of literature. Consequently, strong equations are acquired to determine the plasticity index value in terms of liquid limit, liquid limit-depth, liquid limit-fine content, natural water content-fine content respectively based on the actual experimental tests conducted in Istanbul.

The aim of this paper is to investigate the effects of soil properties associated with the project requirements and environmental conditions, on the prediction of the design dimensions of L-Shaped restricted reinforced concrete retaining walls by the use of optimization algorithms. Numerous parametric analysis was conducted with Flower Pollination Algorithm to examine the influence of soil geotechnical properties such as internal friction angle and unit weight. The backfill soil, surrounding earth and foundation soil was modelled same and assumed to be comprised of granular soils for modelling. Additionally, dual effects of external surcharge load application and excavation depth change was also analyzed against the change of soil properties. As a result, the change of the retaining wall height and the foundation base width has been discussed and the achievement of the cost-effective optimized sizing of the system has been obtained. Finally, the design differences caused by the changes in soil properties have been revealed and the practicalness of the use of the optimization algorithms for the design of restricted type of retaining walls are shown.

This paper has been prepared to detail the main theme of the paper titled “A Comparative study on the application of artificial intelligence networks versus regression analysis for the prediction of clay plasticity” and to improve the content integrity in addition to being a reply to the discussion paper of O’Kelly and Soltani (2021).

Plasticity is the significant integrated property of clay-water relationship that can be initially associated with the consistency which is an outstanding term used especially in cohesive soils to describe the geotechnical behavior characteristics depending upon the change of water content. In the context of this study, the consistency characteristics of plastic clays are investigated based on the analyses conducted with both applications of regression and artificial intelligence methods. In order to acquire an actual input mesh, a domain-specific dataset has been created with the evaluation of 350 soil investigation reports containing a huge number of consistency tests, including the districts located on the European side of Istanbul, Turkey. The results of the conducted laboratory tests are recorded for very high and high plastic clays which are dominantly situated in the southwest regions of Istanbul. Regression analyses and artificial intelligence techniques have been performed with a frequently used software to query the attainment of the values of plastic limit and plasticity index directly from only liquid limit test results. The main aim to acquire a direct relationship between the liquid limit versus plasticity index value is to reduce the dependency of the consistency limit tests to the operators’ experience and also the physical condition of the experimental application environment. As a result of the analyses carried out for this purpose, equations with sufficient reliability, which are applied to obtain the direct plasticity index, were acquired. This condition enables to eliminate the application of the tests of the plastic limit. At the same time, the concurrency of the technique used in obtaining the related equations was questioned comparatively by using regression analysis and artificial intelligence applications. Consequently, discussions are made with well-known studies of literature to validate the applicability of the obtained relationships.

In this paper, the effects of the soil properties on the geotechnical design of reinforced concrete retaining walls are investigated depending on the conducted parametrical analysis based on the Turkish Building Earthquake Code 2018- Part 16. In this connection, the effects of the change of the unit weight of the backfill soil, the shear strength of the backfill soil, the excavation depth and the external surcharge load on the dynamic design of retaining walls is examined with the assumption of the formation of the backfill soil as pure frictional and the foundation as soil pure cohesive. The rules that are defined for sliding, overturning and soil bearing capacity adequateness of the wall system based on “TS 7994 Soil Retaining Structures: Classification, Properties and Projecting Principles” are used to size the wall system. The dimensions which are obtained as the result of the dynamic analysis were compared with the retaining wall preliminary design limits accepted in the literature., Bu makale kapsamında, 2018 Türkiye Bina Deprem Yönetmeliği’nin 16. Bölüm esaslarına dayanarak, betonarme istinat duvarlarının geoteknik tasarımında zemin özelliklerinin etkileri, yapılan parametrik analizler ile incelenmiştir. Bu bağlamda, duvar geri dolgusunun tamamen granüler zeminlerden oluştuğu ve duvar temelinin kohezyonlu zemine oturduğu varsayılarak, istinat duvarının dinamik tasarımında zemin birim hacim ağırlığının, kayma mukavemeti açısının, kazı derinliğinin ve sürşarj yükünün istinat duvarının boyutlarına etkisi irdelenmiştir. İstinat duvarının boyutlandırılmasında “TS 7994 Zemin Dayanma Yapıları: Sınıflandırma, Özellikleri ve Projelendirme Esasları” standardında yer alan kayma, devrilme ve zeminin taşıma gücü için tanımlanmış kurallar uygulanmıştır. Yapılan dinamik analizler sonucunda elde edilen boyutlar, literatürde kabul gören istinat duvarı ön tasarım boyutlandırma sınırları ile de karşılaştırılmıştır.

In addition to conventional retrofitting of constructions, new technologies are rapidly being developed to withstand the external effects while sustaining an acceptable level of damage. Reinforced concrete structures strengthened with fiber reinforced polymer composite materials are becoming more and more widespread in structural applications due to their better mechanical properties, resistance to environmental influences, ease of application and light weight, as well as conventional methods of strengthening. In this study, strengthening technique as a methodology for externally bonded with carbon fiber reinforced polymer (CFRP) sheets to increase the flexural resistance of reinforced concrete beams has been investigated. For this purpose, eight reinforced concrete beams were produced considering different types of CFRP configuration and tested under four-point bending loading. The dimensions of the beams are 150×250×2600 mm and concrete cover of the first and second group of test beam are 20 mm and 40 mm, respectively. Finally, load-deflection behavior with the failure mechanism of the tested beams have been discussed and the effect of different schemes of strengthening on the flexural behavior has been evaluated.

In this paper, the design process of reinforced concrete retaining walls is investigated under the issue of “project location change effect” which becomes a significant requirement to assess the earthquake resistant design depending on the new Turkish Building Earthquake Code-2018 (TBEC-2018). Within this context, in the light of the related code, fourteen different districts which are located in the Anatolian Side of Istanbul Province (Turkey) have been taken into consideration, to search for also the effects of the supported earth fill depth, the unit weight and the shear strength angle of surrounding soil and the external loading conditions. In this way, it has been aimed to focus on the application details of the design code and reflect the outcomes of the analysis in terms of the changes that happened in wall dimensions depending on the locations of project. Besides, with this study, it is aimed to reveal that the definition of type sectional wall will not be possible with the new code. As the result, the influence rates of the investigated project variants have been explained considering site-specific retaining wall design in terms of integrated relations of the design parameters.

In recentyears, in order to determine the structural performance of existing buildingsunder earthquake effect, instead of force-based methods, non-linear methodsbased on the change of deformation and displacement have been started. TurkishBuilding Earthquake Code (TBDY-2018) and Specification for Buildings to beBuilt in Seismic Zones (DBYBHY-2007), both proposes linear and non-linearcalculation methods in order to determine performances of existing buildings.Non-linear analysis methods proposed by TBDY-2018 are; Single Mode Pushover,Multi-mode Pushover and Time History analysis. Non-linear analysis methodsproposed by DBYBHY-2007 are; Incremental Equivalent Earthquake Load Method,Incremental Modal Superposition Method and Non-linear Time History analysis. Themajor difference between TBDY-2018 and DBYBHY-2007 is the description of theeffective cross section stiffness and damage limits of reinforced concretesections. In this study, the performanceanalysis of the structural system under earthquake loads by using non-linearincremental pushover analysis according to DBYBHY-2007 and TBDY-2018 have been performed forexisting five storey reinforced concrete residential structure and results havecomparatively been discussed., Son yıllarda, mevcut binaların depremetkisi altındaki taşıyıcı sistem performanslarının belirlenmesi için kuvvetesaslı yöntemlerin yerine, şekildeğiştirme ve yerdeğiştirme esaslı doğrusalolmayan yöntemler kullanılmaya başlanmıştır. Türkiye Bina Deprem Yönetmeliği(TBDY-2018) ve Deprem Bölgelerinde Yapılacak Binalar Hakkında Yönetmelik’te(DBYBHY-2007) mevcut binaların performanslarının belirlenmesi için doğrusal vedoğrusal olmayan hesap yöntemlerine yer verilmiştir. TBDY-2018’de doğrusalolmayan hesap için önerilen yöntemler, TekModlu İtme Yöntemi, Çok Modluİtme Yöntemi ve Zaman TanımAlanında hesap yöntemidir. DBYBHY-2007’de doğrusal olmayan hesapiçin önerilen yöntemler, ArtımsalEşdeğer Deprem Yükü Yöntemi, Artımsal Mod Birleştirme Yöntemi ve Zaman Tanım Alanında hesap yöntemidir. TBDY-2018 veDBYBHY-2007 arasındaki en büyük fark, betonarme kesitlerin etkin kesitrijitlikleri ve hasar sınırı tarifleridir. Bu çalışmada, mevcut 5 katlıbetonarme konut yapısının DBYBHY-2007 ve TBDY-2018’e göre Doğrusal OlmayanArtımsal İtme Analizi yöntemiyle deprem yükleri altında bina taşıyıcısisteminin performans analizi yapılmış ve sonuçlar karşılaştırılarakirdelenmiştir.

In the context of this study, the design of L-shaped reinforced concrete retaining walls have been scrutinized parametrically depending on the simultaneous analysis of cost and sizing with the use of a recent optimization algorithm. The differences and restrictions of L-shaped reinforced concrete retaining wall design than classical T-shaped walls have been also discussed. The foundation width and the thickness of the wall required for a safe design has been also investigated according to the change of excavation depth, the type of soil dominating field and the external loading conditions. The observed results from optimization analyses shows that the variation of the shear strength angle is the most significant soil geotechnical parameter for supplying an envisaged safe design against sliding, overturning and adequate bearing capacity. Concurrently, the excavation depth is the most important factor that is forming the necessity of the construction of the retaining structure and optimal dimension evaluation. It is also proved that the wall foundation width is the most effected dimension of the retaining structures by the change of design parameters and the cost difference is directly influenced by the change of sizing. A cost-effective wall design can be performed with the use of proposed optimization analysis is capable in a shorter time than the traditional methods. Eventually, it has shown that such optimization methods may be useful to find the optimal design requirements for geotechnical engineering structures.