Alper Ilki

Istanbul Technical University · Department of Civil Engineering

Two three-story full-scale sub-standard reinforced concrete buildings were tested under self-weight and reversed cyclic lateral displacements to examine their behavior during earthquakes. While one of these buildings was a part of an actual existing building (TB1) built in the beginning of 1990’s in Istanbul, the other was constructed by the author...

Existing seismic design and assessment documents do not contain detailed specific guidance on seismic performance assessment of existing reinforced concrete (RC) structures, which have suffered from corrosion. This may cause unsafe consideration of reinforcement corrosion and, consequently, misleading seismic evaluation of such structures. In this...

Recent destructive earthquakes have shown that many existing buildings, particularly in developing countries, are not safe against seismic actions. Since code-based seismic safety evaluation methods generally require detailed and complex structural analysis, the necessity for simplified, yet sufficiently accurate evaluation methods emerges for redu...

In this study, 68 reinforced concrete columns were tested under uniaxial compression after being jacketed externally with carbon fiber-reinforced polymer (CFRP) sheets. Forty specimens were cast using low strength concrete and inadequate internal transverse reinforcement, while 28 specimens were cast with medium strength concrete and adequate inter...

Two series of tests of exterior beam-column joints were conducted. In the first series of tests, the longitudinal reinforcement of the beam was anchored in the joint with 90-degree hooks. In the second series, hooks of top bars were welded to hooks of bottom bars. Parameters varied from one test to the next and included axial load, amount of joint...

In this study, it was aimed to investigate the dynamic impact and post-impact performances of high-strength reinforced concrete (RC) beams, which have different ductility and load-bearing capacities. The dynamic behavior and impact damages of RC beams were compared after exposure to a constant magnitude of impact energy. The applied impact energy w...

On February 6, 2023, two earthquakes with Mw 7.7 and 7.6 struck South Eastern Anatolian Region of Türkiye. These earthquakes had varying impacts on the buildings in 11 cities around the epicenter. More than 90,000 reinforced concrete buildings were damaged heavily or collapsed in the earthquake-struck region. It was surprising to observe that sever...

Historical minarets, which are among invaluable cultural heritage in Turkey, are prone to a significant loss of functionality due to seismic actions. This study introduces the main planning stages of shaking table testing campaign of a typical historical minaret representing mid-height early Ottoman period architecture, typically built-in 15th cent...

In this study, large-scale settlement tests were carried out on two test building samples consisting of masonry load-bearing walls, which are known to be sensitive to differential settlements. Test buildings were constructed in ½ scale to represent the characteristics of historical row buildings built in Istanbul in the 19th century. Test buildings...

The inclined minaret of Sivas Ulu Cami (Mosque) from the 13th century Danishmend Period is one of the most invaluable architectural heritages in Turkey. The extent of inclination of the minaret towards the North-West direction, the seismicity of the region, and structural damages that occurred in time have emphasized the need for comprehensive stru...

Most of the buildings in Turkey constructed before 1999 Kocaeli and Duzce Earthquakes do not have sufficient seismic resistance due to construction errors and do not satisfy the recent Turkish Building Earthquake Code (2018) or its preceding versions. In Istanbul, the building stock consists of 1,116,300 buildings. Clearly, seismic safety assessmen...

Columns can suffer heavy damage due to dynamic impact effects, which are ignored during their design. The impact effect could be a vehicle crash to columns of streetside buildings, parking garages or bridges. However, the effect of impact loading on the behavior of reinforced concrete columns has not been sufficiently studied. In this study, an exp...

This paper aims to summarize the findings of a comprehensive study on the correlation of displacement and deformation demands estimated using various code-compliant nonlinear modeling approaches commonly used in real-life performance-based seismic design and assessment applications, with experimental results obtained from the full-scale shake table...

Introduction Autoclaved Aerated Concrete (AAC) is a lightweight and energy‐efficient material which makes it one of the most convenient materials to be used in infill walls. Accordingly, AAC walls are becoming more and more favored infill systems in earthquake‐prone regions. Although the infills are not considered primary components in seismic desi...

This study investigates the seismic retrofit of substandard reinforced concrete (RC) columns through external jacketing of potential plastic hinge zones using sprayed glass fiber-reinforced mortar and basalt textile reinforcement. An innovative spraying method was used to apply the matrix material to the concrete surface. A total number of eight fu...

Considering the significant number of substandard buildings in the building stock of Turkey, demolishing, and reconstructing all these vulnerable structures are not feasible due to time and budget constraints. On the other hand, this considerable number of vulnerable buildings also leads to much challenging intervention efforts (i.e., strengthening...

In this study, results of nonlinear response history analysis are presented for an existing RC wall-frame building, which has suffered collapse-level damage during the devastating February 2023 Kahramanmaras earthquakes. Performance analysis results for two building configurations are compared; first for the existing building configuration generate...

Autoclaved Aerated Concrete (AAC) is a lightweight, energy-efficient and easy-to-transport material. As a result, AAC walls are becoming increasingly common as an infill solution in earthquake-prone areas such as Turkey, Italy, and Greece. Although infills are considered as secondary components in seismic design, they are extremely vulnerable to da...

The proposed study combines sprayed glass fiber-reinforced mortar and basalt textile-reinforcement to harness the favorable properties of each component to obtain a composite material that can be used for strengthening of existing structures. This includes crack resistance and a bridging effect of glass fiber-reinforced mortar and the strength prov...

Underground construction activities such as tunnelling and deep excavations in urban areas may impact a significant number of surface structures and cause damage. Tunnelling-induced damage can often be repaired, but at great expense, due to significant repair costs and associated project delays. Within this context, damage caused by excavation-indu...

Turkey has been exposed to catastrophic earthquakes in the last decades. Consequently, seismic design codes and maps have been continuously improved with the experiences gained from these seismic events. These earthquakes have demonstrated that the RC (reinforced concrete) buildings collapsing and causing casualties and financial losses were genera...

Past earthquakes demonstrate that most significant part of losses in buildings are due to the poor seismic performance of substandard reinforced concrete (RC) buildings. It is necessary to retrofit substandard buildings to reduce/prevent casualties and economic losses. Two of the most widely preferred conventional seismic retrofit approaches are th...

The infill walls made of Autoclaved Aerated Concrete (AAC), which is a lightweight, fire resistant and energy efficient material, provide effective insulation solutions for building types of structures and becoming more and more popular in earthquake prone regions. Although the number of experimental tests examining the seismic response of clay bri...

The Reinforced Concrete (RC) buildings in countries within earthquake zones like Turkey are generally damaged more than anticipated during earthquakes. Corrosion of reinforcement and other damages caused by the corrosion are also widely encountered in relatively old structures that have not received adequate engineering services. Although it is not...

The behavior of a reinforced concrete beam under a dynamic load, i.e., an impact load, affects the overall structural system by altering its static and dynamic features. This study investigates the performance of large-scale reinforced concrete (RC) beams under different impact loads and the residual load-bearing and displacement capacities of impa...

Industry procedures to assess the risk of settlement-induced damage to masonry buildings ignore key aspects of the problem, such as the influences of building weight, façade openings, and floor structures. Experimental data are needed to characterise the influence of these aspects on damage. This paper describes tests on three brick masonry half-sc...

This paper discussed the effectiveness of the hybrid use of fiber-reinforced polymer (FRP) reinforcement for the seismic retrofitting of substandard reinforced concrete (RC) columns. Four columns, except for the reference, were retrofitted with externally embedded FRP (EE–FRP) bars in a longitudinal and external FRP jacket in the transverse directi...

Most of the buildings in Turkey constructed before 1999 Kocaeli and Duzce Earthquakes do not have sufficient seismic resistance due to construction errors and do not satisfy the recent Turkish Building Earthquake Code (2018) or its preceding versions. In Istanbul, the ratio of buildings constructed before 2000 is nearly 70% in building stock. Clear...

Deprem olgusu, ülkemiz için göz ardı edilemeyecek bir gerçekliktir. Son yıllarda yazılım, sistem mühendisliği ve yapay zekâ alanlarında gözlemlenen gelişmeler, deprem mühendisliği alanında yürütülen çalışmalarda da etkinliğini arttırmaktadır. Bu amaçla, ülkemizde deprem mühendisliği alanında yurtiçi/yurtdışı birçok bilimsel aktiviteye öncülük eden...

ÖZET Camilerin bir bölümü olan tarihi yığma minareler, ülkemizin tarihi mirası için büyük önem arz etmektedir. Bu yapılar ayrıca yapısal eksiklikler nedeniyle önemli bir işlevsellik kaybına eğilimlidir. Bu çalışma, AFAD-UDAP (Afet ve Acil Durum Yönetimi Başkanlığı) tarafından desteklenen "Bursa Tarihi Minarelerinin Deprem Performanslarının Analitik...

Past destructive earthquakes in highly seismic areas of the world have shown that the failure of earthquake-prone buildings endangers the lives of the inhabitants and may cause enormous financial losses. Management of the seismic risks through effective mitigation efforts requires the identification of risky buildings in our cities. However, this i...

Based on the fact that there are many substandard reinforced concrete buildings in developing countries built with low or extremely low strength concrete (LSC or ELCS) and the urgent need of improving the structural performance of such buildings, this study aims to examine the axial behavior of low and extremely low strength concrete externally con...

On 30.10.2020, a Mw = 6.6 magnitude earthquake occurred at the offshore Aegean Sea, hitting the western coast of Turkey and Samos Island of Greece, causing loss of lives and properties. In the scope of this study, a site investigation was conducted at the earthquake-hit area of İzmir (Turkey), where 17 buildings (7 partially, 10 totally) were colla...

While the lateral confinement provided by an FRP jacket to a concrete column is passive in nature, confinement is activated when the concrete expands due to additional compression stresses or significant shear deformations. This characteristic of FRP jacketing theoretically leads to similar initial stiffness properties of FRP retrofitted buildings...

A considerable amount of existing reinforced concrete (RC) buildings in developing countries possess vital deficiencies such as incorporating poor quality of concrete and insufficient transverse reinforcement, and use of plain reinforcing bars without proper detailing, such as inadequate configurations of lap-splices at critical plastic hinging zon...

İstanbul’da 2000 yılı öncesinde inşa edilmiş yaklaşık 800000 bina bulunmaktadır. Bu binaların önemli bölümü ciddi bir mühendislik hizmeti almamış ve projesine uygun inşa edilmemiş olup genellikle malzeme dayanımları ve konstrüktif detaylar açısından problemli ve tabi oldukları Deprem Yönetmeliklerinin şartlarını dahi sağlamamaktadır. Bu binaların d...

In this study, a novel retrofitting intervention on the Hirka-i Serif Mosque (constructed in 1851), which has a significant importance for Muslims due to its historical relic preservation unit keeping the cloak of the Prophet Muhammad, was illustrated. For this purpose, first the seismic performance of the mosque was investigated through site inves...

Short columns with deficiencies of low-strength concrete and large spacing of transverse reinforcement are quite common in construction practice in many developing countries in seismically active regions. Therefore, it is important to retrofit this type of column to avoid negative consequences in the case of severe damage. External fiber–reinforced...

Material characterization of low strength concrete has significant importance for structural/ seismic performance assessments of existing low-quality structures. The main objectives of this study are to characterize the compressive and tensile behaviors of low strength concrete (LSC). For this purpose, an extensive experimental database is formed b...

There is a myriad amount of substandard reinforced concrete (RC) buildings in developing countries that do not comply with the requirements and instructions of the current building design codes. In particular, columns in these substandard buildings demonstrate unsatisfactory and undesired behavior against lateral loads, mainly due to low concrete c...

Although monotonic bond tests are available in the literature, limited experimental studies exist for cyclic loading conditions. To fill this gap, this work describes results from cyclic pull-out tests of eleven specimens with Carbon Fiber Reinforced Polymer (CFRP) rebars embedded in high strength concrete (fck > 50 MPa). Six of the samples were sa...

In the last decades, lessons learnt from the major earthquakes, that occurred in many countries, brought revisions in prevailing seismic design codes. As a consequence of this phenomenon, the current building stock in Turkey is mainly comprised of reinforced concrete (RC) buildings which were designed according to different seismic design codes. Th...

Within SERA Horizon 2020 INMASPOL project, the paper reports the first results from seismic tests on shake table for a real scale reinforced concrete (RC) frame building with modified orthoblock brick wall infills. The building received innovative protection using polyurethane resin (PU) flexible joints (PUFJ) at the frame-infill interface together...

This volume highlights the latest advances, innovations, and applications in the field of FRP composites and structures, as presented by leading international researchers and engineers at the 10th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering (CICE), held in Istanbul, Turkey on December 8-10, 2021. It co...

Brittle failure of lightly reinforced concrete columns is one of the primary reasons for partial or total collapse of substandard existing buildings subjected to earthquake loading. This study presents collapse performance of a full-scale building that was performed to gain insight into the seismic behavior and the collapse mechanisms of nonductile...

Although monotonic bond tests are available in the literature, limited experimental studies exist for cyclic loading conditions. To fill this gap, this work describes results from cyclic pull-out tests of eleven specimens with Carbon Fiber Reinforced Polymer (CFRP) rebars embedded in high strength concrete (fck> 50 MPa). Six of the samples were san...

It is important to determine the structural behavior of historical buildings under the effects of earthquakes of different content and magnitude, to improve them by intervening beforehand when necessary, and to ensure that these structures can survive in the future. In this study, modal analysis and material value update of the historical Hocaaliza...

Precast structures are increasingly used in modern construction since they offer advantages such as cost-efficiency, better material quality, and fast construction due to their mass production compared to cast-in-situ structures. However, development of monolithic-like precast connections to ensure adequate seismic performance is still a challengin...

Recent earthquakes in Turkey revealed that a remarkable number of existing reinforced concrete (RC) buildings do not have sufficient capacity against seismic actions because of the considerably low compressive strength of concrete and inadequate transverse reinforcement details. The low strength of concrete results in higher axial stress ratios of...

Historical masonry minarets, which are tall and slender structures, are important parts of mosques. Since many of them are located in the earthquake-prone areas, the seismic responses of these minarets should be studied both experimentally and analytically. For this purpose, an experimental program of shake table tests has been planned on a represe...

Masonry structures comprise a significant portion of the historical building stock all over the world. Previous studies have clearly pointed out that unreinforced masonry buildings are vulnerable against extreme loading conditions, such as seismic actions. Therefore, strengthening is inevitable in most cases for historical masonry to withstand seve...

The aim of this study is to define the cyclic axial behavior of hybrid FRP (fiber reinforced polymer)-confined concrete based on the results of an experimental study presented here. Two different types of fiber sheets with different ultimate tensile strain capacities were used together in a suitable epoxy resin matrix to confine concrete. The inner...

The Great Mosque and Hospital of Divrigi is located in the central eastern part of Turkey, in Divrigi, Sivas. The historical facility consists of a monumental mosque and a two-story hospital, which are adjacent to each other. The structure dates back to 13th century Mengujekids period and has been listed by the UNESCO as a World Heritage since 1985...

The October 30, 2020 Earthquake caused unexpectedly significant damage in İzmir 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 Engineeri...

Experience from past earthquakes all around the globe has shown that the lack of seismic resilience due to failure of earthquake-prone buildings lead to vast financial losses and endanger the inhabitant’s lives. In order to prevent such catastrophic results, management of the seismic risks through pinpoint mitigation efforts with effective resource...

In earthquake prone areas, columns of many relatively old RC (reinforced concrete) structures do not comply with the current seismic design codes, particularly in developing countries. Low concrete strength, improper seismic detailing of transverse reinforcement and high axial stress-es on the columns are common problems causing lack of sufficient...

In this study, a novel hybrid thin jacketing method, in which fiber-reinforced polymer (FRP) sheets are used together with conventional steel reinforcing bars and cement-based repair mortar for strengthening of substandard full-scale columns, is proposed. The application of the method is comprised of three parts, i) cover concrete is removed and ad...

Özet Tarihi yapıların deprem etkileri altındaki yapısal davranışının belirlenmesi ve gerektiğinde iyileştirilmesi, bu yapıların gelecekteki varlıklarını sürdürebilmesi açısından önem taşımaktadır. Bu çalışmada, Bursa'da bulunan tarihi Hocaalizade Cami Minaresi'nin modal analizi ve Kocaeli depremi Düzce istasyonu ivme kaydı altında zaman tanım alanı...

Post-Earthquake damage assessment has always been one of the major challenges that both engineers and authorities face after disastrous earthquakes all around the world. Considering the number of buildings in need of inspection and the insufficient number of qualified inspectors, the availability of a thorough, quantitative and rapidly applicable d...

A potential but commonly inconsiderable hazard is the concomitant occurrence of fires and earthquakes. The influence of fire induced structural damage on the seismic performance of reinforced concrete (RC) structures, particularly RC columns, may be critical for the probable future earthquakes. The current modelling attempts on estimation of post-f...

In this study, four full-scale reinforced concrete columns were built replacing 50% of natural coarse aggregates in concrete mix by recycled aggregates. Three of the columns were exposed to standard ISO-834 fire for 30, 60 or 90 minutes, while the reference specimen was not exposed. Sixty days after fire exposure, the columns were tested under cons...

An experimental study was performed to determine the dynamic structural response of high-strength reinforced concrete (RC) beams exposed to impacts of various energies. The residual load-bearing capacities of the impacted beams were measured by static loading tests after their dynamic impact responses had been assessed. Considering the shear behavi...

This study investigates the effects of seismic damages and retrofitting on dynamic characteristics of substandard reinforced concrete buildings. Two identical 3-story buildings were constructed, one of which was retrofitted through application of carbon fiber-reinforced polymer jacketing on its columns. Ambient vibration tests were conducted at und...

Shape Memory Alloys (SMAs) are smart materials that have plenty of distinctive features. Having huge damping capability, combined with good corrosion resistance and ability to recover their original shape up to 8% strain by heating the material or removing the stress, SMAs have been widely investigated for civil engineering applications in last dec...

Underground construction activities, such as tunnelling, cause local ground movements to occur. Nearby surface structures interact with the moving ground, potentially leading to building damage. Although it is understood that the severity of building damage is influenced by the façade opening ratio (OpR) and the stiffness of the floors, experimenta...

Inelastic flexural deformations adversely affect shear resistance of columns, and may cause building damage/collapse during earthquakes. In this paper, shear-flexure interaction on seismic performance of reinforced concrete columns constructed with recycled aggregate concrete is experimentally investigated. For this aim, reinforced concrete columns...

This open access book originates from an international workshop organized by Turkish Natural Catastrophe Insurance Pool (TCIP) in November 2019 that gathered renown researchers from academia, representatives of leading international reinsurance and modeling companies as well as government agencies responsible of insurance pricing in Turkey. The boo...

On 30 October 2020, an M 7.0 earthquake occurred north of Samos Island. The fault rupture caused sudden lowering of the seafloor, which produced a tsunami that mainly impacted nearby Samos Island as well as a series of Anatolian cities along the coast of Seferihisar Bay, with maximum runup and inundation lengths of about 3.8 m and 2500 m, resulting...