Alemdar Bayraktar

University of British Columbia - Vancouver | UBC · Department of Civil Engineering

This paper presents the earthquake response of the Kömürhan cable-stayed bridge with a single pylon and steel deck which was exposed to the Elazığ-Sivrice earthquake (Mw = 6.8) on January 24, 2020, while it was under construction. The distance from the epicenter to the bridge is approximately 40 km. 82% of the Kömürhan bridge was completed during t...

Cable-stayed bridges are flexible and complex structures. Impact-induced vibrations may play an important role on the behaviors of the structural elements. Many efforts have been devoted to clarifying the experimental static and dynamic responses of cable-stayed bridges. However, experimental dynamic responses of structural elements of cable-stayed...

Historical masonry domes are an important part of the architectural and engineering heritage in the World. They have been extensively used to cover the spaces of temples, mausoleums, palaces, forts, baths, churches, mosques, etc. Damages and collapses of masonry domes occurred as a result of earthquakes or lack of maintenance. Therefore, many effor...

In this study, the response of frames subjected to earthquake is determined considering material properties and section properties and equivalent earthquake forces as random parameters using reliability analysis. For this purpose, two groups of frames are constituted. First group includes 7 frames involving different material properties and second...

Long-term structural health monitoring of bridges is very important to ensure their serviceability and structural integrity. Strain monitoring data is better suited to characterize the local deficiencies and damage in bridges than global responses. Strain behaviors of structural elements of in-service long-span cable-stayed bridges under operationa...

General stability and failure behaviors of masonry domes under static loads have been investigated extensively in literature. However, a few studies have been done on the seismic failure behavior of masonry domes under strong ground shaking. This study aims to investigate the seismic failure behaviors and failure angles of masonry domes with suppor...

General stability and failure behaviours of masonry domes under static loads have been detailly searched in literature. However, researchers have devoted little attention to their seismic failure behaviours under strong ground motions. This study aims a better understanding of seismic failure behaviours of masonry domes with support system includin...

Cable-stayed bridges have been constructed with different type of towers (pylons) in the World, namely H-shaped, A-shaped, inverted Y-shaped, single column, diamond-shaped. More than half of the cable-stayed bridges utilised the towers with inclined legs. The dynamic response of inclined tower legs can be extremely complicated during earthquakes. R...

Historical masonry aqueducts were constructed to convey water over rivers, valleys, etc. Many of them have deteriorated due to different effects and may need to be repaired or strengthened to increase their load carrying capacities. Historical aqueducts are invaluable cultural heritage, and they require particular attention and appropriate seismic...

The high and slender historical masonry minarets are vulnerable to the static and dynamic loads. Performance analyses of minarets are implemented using three-dimensional numerical models in recent years. However, the complex and inhomogeneous nature of historical structures increases the likelihood of incorrect creation of numerical models. For tha...

Many collapses or severe damages in minarets occur due to large structural deformations during earthquakes. Minarets, which are part of the cultural heritage, require particular attention and appropriate methodologies for their strengthening. The present study proposes a cost-effective seismic strengthening technique, which includes minimal interve...

Masonry arch bridges, which were generally built using brick and stone materials, still form a significant part of the highway and railway networks in the World. The subsoil deformability may considerably affect seismic damage mechanics of masonry arch bridges. The paper investigates the effects of nonlinear foundation soil behavior on the seismic...

Earthquake input mechanism model A B S T R A C T Minarets, which are tall and slender structures, are important elements of mosques. Seismic performances of minarets can be strongly affected by the nonlinear dynamic soil-structure interaction and earthquake input mechanism models. The present paper investigates the influences of different earthquak...

Historical masonry stone mosques with timber truss roofs were widely constructed all over the world. Due to the complex structural behaviors of this type of building, it is difficult to determine natural frequencies during the seismic safety evaluations numerically. The article aims to develop simplified natural frequency formulas based on ambient...

Historical stone mosques with masonry dome are complex structures due to their different structural elements, material properties, boundary conditions, connections, etc. It is very difficult to develop the numerical models representing the real behaviour of these structures. Therefore, their numerical models should be checked with ambient vibration...

ABSTRACT The majority of historical masonry bridges were constructed early years and they were not originally designed to carry the extent of loads imposed on them by current vehicular traffic and seismic loads. Therefore, many existing masonry arch bridges can need reassessment and upgrading. In addition to arch elements, the most vulnerable struc...

The main structural elements of historical masonry arch bridges are arches, spandrel walls, piers and foundations. The most vulnerable structural elements of masonry arch bridges under transverse seismic loads, particularly in the case of out of plane actions, are spandrel wall. The vulnerability of spandrel walls under transverse loads increases w...

The aim of this study is to develop a simplified natural fundamental frequency formula for the post-tensioned balanced cantilever bridges using the Operational Modal and Finite Element Analyses results. For this purpose, experimental and numerical studies were carried out on the five post-tensioned balanced cantilever bridges constructed in the cit...

Post-tensioned balanced cantilever reinforced concrete (RC) bridges allow the economic spanning of wide spans using fewer columns than in more traditional bridges. More and more post-tensioned balanced cantilever bridges are constructed every year all round the world. The aim of this study was to investigate numerically the effects of near-fault ve...

The structural assessment of historic timber mosques is a challenging process with many uncertainties such as strength and stiffness of structural members, joints and boundary conditions. The analytical models of timber mosques must be calibrated using experimental dynamic characteristics for reliable structural evaluation and accurate intervention...

The structural performances of long span cable-stayed bridges having different elements such as pylons, stayed cables and decks are very sensitive to earthquake ground motions due to their highly statically indeterminacy. Therefore, responses of pylon, cable and deck components of long span cable-stayed bridges should be continuously monitored to p...

Traditional domes are obtained by double curvature shells, which can be rotationally formed by any curved geometrical plane figure rotating about a central vertical axis. They are self-supported and stabilized by the force of gravity acting on their weight to hold them in compression. However, the behavior of inverted domes is different since the d...

An accurate numerical analysis of the behavior of long-span cable-stayed bridges under environmental effects is a challenge because of complex, uncertain and varying environmental meteorology. This study aims to investigate in-situ experimental structural behavior of long-span steel cable-stayed bridges under environmental effects such as air tempe...

An accurate numerical analysis of the behavior of long-span cable-stayed bridges under environmental effects is a challenge because of complex, uncertain and varying environmental meteorology. This study aims to investigate in-situ experimental structural behavior of long-span steel cable-stayed bridges under environmental effects such as air tempe...

Masonry minarets are sensitive to wind and earthquake forces due to their slenderness and supporting structural system. They are restored in order to safely transfer to future generations. This paper investigates the restoration effects on the dynamic characteristics of masonry stone minarets using ambient vibrations tests. Three historical masonry...

In this study, effects of the impulse waves caused by the reviving of the Havuzlu paleo-landslide, which is located 8 km to the upstream of Artvin Dam, were investigated using 3D simulation-based numerical analyses. 3D solid model of the corresponding area was created using raster data. The topography was modelled in 1/10000 scale and the landslide...

Structural walls of old historical structures are either blind or have openings for functional requirements. It is well known that in and out of plane responses of structural walls are affected by the size, locations, and arrangements of such openings. The purpose of this investigation is to study the window opening effects on static and seismic be...

Structural health monitoring (SHM) offers the potential to evaluate the safety and integrity of the civil infrastructure. By obtaining accurate information about the condition of the structure, appropriate preventive measures can be taken to prolong the service life and prevent the catastrophic failure of the structure. Application of effective dam...

The dynamic behavior of buildings can change during construction stages. The brick walls cause a considerable effect on the modal behavior depending on the wall configuration. In this paper, it is aimed to present the effects of construction stages (bare frame, brick-walled and coated cases) on the modal parameters of reinforced concrete (RC) build...

Finite element model updating is very effective procedure to determine the uncertainty parameters in structural model and minimize the differences between experimentally and numerically identified dynamic characteristics. This procedure can be practiced with manual and automatic model updating procedures. The manual model updating involves manual c...

Gecmisin birikimlerinin gelecege aktarimi konusunda belge ozelligi tasiyan han, hamam, cami, kilise, cesme, kopru gibi tarihi eserler zaman icinde dogal afetler veya canlilarin tahribatlari neticesinde cesitli hasarlara maruz kalmaktadirlar. Genellikle en sik rastlanilan bilincsiz mudahale sekillerinden biri, ahsap catili tarihi yigma camilerin ahs...

With the recent advances in computer technology and digital simulation software, it is now possible to rapidly and accurately build computer models for complex linear and nonlinear dynamic systems. MATLAB is a unique system that can be used for structural and earthquake engineering problems. This study presents MATLAB tools developed for numerical...

Natural stone masonry mosques with wooden roof are the most widespread historical building of Eastern Black Sea Region in Turkey. The main walls of buildings are made with the combination of natural stone, lime, soil or horosan mortar and their roofs are constituted with wooden elements. Within the scope of this study, it is aimed to determine the...

Historical masonry structures have an important value for cultures and it is essential for every society to strengthen them and confidently transfer to the future. For this reason, determination of the seismic earthquake response, which is the most affecting factor to cause the damage at these structures, gain more importance. In this paper, the se...

In this paper, it is aimed to determine the stochastic response of a suspension bridge subjected to spatially varying ground motions considering the geometric nonlinearity. Bosphorus Suspension Bridge built in Turkey and connects Europe to Asia in Istanbul is selected as a numerical example. The spatial variability of the ground motion is considere...

Dynamic characteristics, named as natural frequencies, damping ratios and mode shapes, affect the dynamic behavior of buildings and they vary depending on the construction stages. It is aimed to present the effects of construction stages on the dynamic characteristics of reinforced concrete (RC) buildings considering theoretical and experimental in...

This paper addresses the ambient vibration-based finite element model updating of long span reinforced concrete highway bridges. The procedure includes ambient vibration tests under operational conditions, finite element modeling using special software and finite element model updating using some uncertain parameters such as section properties, dam...

Continuous health monitoring and regular condition assessment is of vital importance for engineering structures in general and especially for arch dams. These structures can be exposed to many different loads such as earthquake, blast, wind, ice, and water pressure, which may cause deterioration and loss of structural integrity. Such development ma...

This technical note presents an investigation about the changing of dynamic characteristics of an arch dam model before and after strengthening considering reservoir water. To this end, an arch dam-reservoir-foundation model has been constructed in the laboratory. Ambient vibration tests have been performed on the damaged and strengthened arch dam...

This paper presents a study about the spatial variability effects of ground motions on the dynamic behavior of a suspension bridge by a random vibration based spectral analysis approach and two response spectrum methods. Bosphorus Suspension Bridge built in Turkey and connects Europe to Asia in Istanbul is selected as a numerical example. The spati...

This paper describes an arch type long span highway bridge, its finite element modeling, experimental measurements, finite element model updating using some uncertain parameters, and structural performance evaluation before and after model updating. For this purpose, Birecik Highway Bridge located on the 81st km of Şanlıurfa-Gaziantep state highway...

The paper investigates the structural performance of a seven-story reinforced concrete (RC) building that collapsed during the Van (Turkey) earthquake on October 23, 2011, using nonlinear static and dynamic methods. The selected RC building has two blocks and was designed according to the Turkish Earthquake Code (TEC) in 1975. The site investigatio...

Geçmişten günümüze tarihi miras değerinde olan taş köprüler, inşa edildiği dönemde aktif ulaşım güzergâhları üzerinde bulunmalarına karşın günümüzde daha çok tarihi değerleriyle ön plana çıkmaktadır. Bu köprülerin mevcut halleriyle korunabilmesi ve geleceğe güvenle aktarılabilmesi için gerekli bakım ve onarım işlemlerinin yapılması gereklidir. Fark...

In this paper, the finite element model calibration of precast structures was investigated by considering ambient vibration test results. Two precast structures, an overpass and a precast production facility, were selected for investigation. The initial finite element models of these structures were developed by using SAP2000 software and the initi...

This study investigates the effects of near and far fault ground motion on the seismic behavior of historical arch bridges through a combined numerical and experimental evaluation. The approach undertaken begins with finite element modeling of the arch bridge and identification of the most significant vibration modes of the bridge through ambient v...

In this study, stability of the paleo-landslide material, whose toe area will remain within the lake area due to impoundment of Artvin dam (Yusufeli-Artvin) retaining water, was investigated. During the study, 22 boreholes, the depths of which vary between 40-120 meters, were drilled and electric-resistivity and multi-electrode studies were perform...

The purpose of this study is to investigate the effect of retrofitting dynamic characteristics of a damaged laboratory arch dam model, subsequently repaired with high-strength structural mortar and strengthened with composite carbon fiber reinforced polymer. This study constructed in laboratory conditions is a prototype arch dam–reservoir–foundatio...

In this paper, it is aimed to investigate the restoration effect on the structural behavior of masonry arch bridges. Dandalaz masonry arch bridge located on the 4km east of Karacasu town of Aydin, Turkey is selected as a numerical example. The construction year of the bridge is not fully known, but the bridge is dated back to 15th century. Consider...

This paper investigates the time dependent changing of dynamic characteristics of laboratory arch dam models using ambient vibration test. For this aim, a prototype arch dam-reservoir-foundation model is constructed in laboratory conditions. The first experimental measurement tests are performed after the poured concrete aged for 10 months for some...

Stochastic seismic finite element analyses of the Kömürhan Bridge, the material properties of which are described by random fields, are presented in this paper. The stochastic perturbation technique and Monte Carlo simulation (MCS) method are used in the analyses. A summary of MCS and perturbation-based stochastic finite element dynamic analysis fo...

This study investigates the non-linear response of the rockfill in a concrete-faced rockfill dam under seismic excitation for various concrete slab thicknesses from 30 to 100 cm thick. The effect of the friction in the concrete slab rockfill interface on the non-linear response of the rockfill is also considered in the numerical solutions. The fric...

In this paper, it is aimed to determine the finite element model updating effects on the structural behavior of long span concrete highway bridges. Birecik Highway Bridge located on the 81stkm of Sanliurfa-Gaziantep state highway over Firat River in Turkey is selected as a case study. The bridge consist of fourteen spans, each of span has a nearly...

The structural safety evaluation of a bowstring type reinforced concrete (RC) arch bridge was investigated by ambient vibration testing and finite element model calibration in this study. The bridge named as Ali Çetinkaya Bridge in Samsun, Turkey, was selected for this investigation. The bridge constructed in 1937 consists of the seven discrete arc...

Historical masonry arch bridges composed of foundation, arch, walls, slab and infill are very complex structures. The dynamic characteristics of the masonry arch bridges using analytical or numerical methods cannot be determined accurately. The aim of this study is to determine the frequency and damping ratios of historical masonry arch bridges exp...

This paper presents the effects of the construction stages using time dependent material properties on the structural behaviour of concrete arch dams. For this purpose, a double curvature Type-5 arch dam suggested in "Arch Dams" symposium in England in 1968 is selected as a numerical example. Finite element models of Type-5 arch dam are modelled us...

Z Deprem bölgelerindeki yer hareketinin silindirle sıkıĢtırılmıĢ beton (SSB) barajlar üzerindeki etkilerinin dikkate alınması gerekmektedir. Bu çalıĢmada SSB barajların üç boyutlu deprem davranıĢı geometri bakımından doğrusal olmayan davranıĢ dikkate alınarak incelenmektedir. Ayrıca, malzeme ve birleĢim bakımından doğrusal olmayan davranıĢ da zaman...

Z Bu çalıĢmada, depreme etkisi altında kaldığı kabul edilen Torul ön yüzü beton kaplı kaya dolgu barajının güvenilirlik analizi yapılmıĢtır. Sayısal çözümlerde güvenilirlik analizi-sonlu elemanlar analizi birleĢimi dikkate alınmıĢtır. Deprem yer hareketi kaya tabanına indirgenmek suretiyle kullanılmıĢtır. 1992 Erzincan depremi kullanılarak yapılan...

This paper investigates environmental effects on dynamic characteristics of isolated highway bridges constructed with the balanced cantilever method using ambient vibration test. The Gülburnu Highway Bridge located on the Giresun-Espiye state highway is selected as an application. Measurement time, frequency span and effective mode number are selec...

This paper illustrates the damages of reinforced concrete and masonry minarets during October 23 (Erciş) and November 9 (Edremit), 2011 Van earthquakes in Turkey. Erciş and Edremit are townships located 90km and 18km from Van city center in Turkey, respectively. Ground accelerations and response spectrums for these earthquakes are given in this pap...

The nonlinear seismic behavior of a collapsed reinforced concrete (RC) residential building in the city of Van in Turkey is investigated by the static pushover and nonlinear time history analyses. The selected RC structure was designed according to the 1975 version of Turkish Earthquake Code (TEC-1975). The building had experienced heavy damage, an...

In this study, the dynamic characteristics of the masonry vault of Küçük Fatih Mosque have been identified by using Ambient Vibration Test. The vault was damaged and then restored. The mosque is located in the Bahçecik Quarter of Trabzon in Turkey, and it was registered as immovable cultural property. The mosque was restored by the local Regional D...

In this paper, the development of a new optimization software for finite element model updating of engineering structures titled as FemUP is described. The program is used for computational FEM model updating of structures depending on modal testing results. This paper deals with the FE model updating procedure carried out in FemUP. The theoretical...

The traditional destructive tests in damage detection require high cost, long consuming time, repairing of damaged members, etc. In addition to these, powerful equipments with advanced technology have motivated development of global vibration based damage detection methods. These methods base on observation of the changes in the structural dynamic...

This paper aims to determine the dynamic characteristics, such as natural frequencies, mode shapes and damping ratios, of two different domed structures, namely Hamza Pasa Mausoleum and Kavak Meydan Fountain, built in the sixteenth century by experimental methods. The experimental dynamic characteristics are used to develop initial analytical model...

Dynamic characteristic identification provides an important insight about structural behavior of steel structures. The experimental modal analysis is used to detect dynamic characteristics and consists of several phases. First, forced-vibration tests are carried out, spectral functions are produced, dynamic characteristics are determined by analyzi...

In this study, the dynamic behavior of a model building for different damage cases is studied based on the changes in the natural frequencies and mode shapes. The damage is assumed to occur on the walls and at the column-ends of the first story, because they are generally affected by earthquakes, explosions, etc. A 1/2-scale three-story reinforced-...

Vibration based damage detection is very popular in the civil engineering area. Especially, special structures like dams, long-span bridges and high-rise buildings, need continues monitoring in terms of mechanical properties of material, static and dynamic behavior. It has been stated in the International Commission on Large Dams that more than hal...

This paper provides an overview on some of the latest advances in the applications of fiber reinforced polymeric (FRP) composites in construction. The paper focuses on three main inter related review areas, namely; (i) Repair and rehabilitation of concrete, steel, masonry and wood structures using composites, and (ii) All-composite structural appli...

The aim of this study is to determine the dynamic characteristics of long reinforced concrete highway bridges with post-tension tendons using analytical and experimental methods. It is known that the deck length and height of bridges are affected the dynamic characteristics considerably. For this purpose, Berta Bridge constructed in deep valley, in...

In this study, analytical and experimental modal analyses of a scaled bridge model are carried out to extract the dynamic characteristics such as natural frequency, mode shapes and damping ratios. For this purpose, a scaled bridge model is constructed in laboratory conditions. Three dimensional finite element model of the bridge is constituted and...

This paper focuses on both the monitoring of the dynamic response of steel buildings with and without brace elements and the importance of model calibration on the steel buildings. The study involves the application of modal testing techniques to collect data from a three-story steel frame building model tested at the Civil Engineering Department o...

The structural performance evaluation is presented of 90 reinforced concrete (RC) buildings that collapsed during the October 23 (Erci) and November 9 (Edremit), 2011, earthquakes in Van, Turkey. A total of 35,000 buildings are damaged or collapsed in the city center and surrounding villages after the Erci and Edremit earthquakes. Almost all the RC...

In this paper, it aimed to investigate the performance and damages of reinforced concrete buildings during October 23 (Erciş) and November 9 (Edremit), 2011 Van earthquakes in Turkey. A total of 28,000 buildings are damaged or collapsed in the city center and surrounding villages after the Erciş earthquake. This number increased to 35,000 after the...