Publisher: TULPAR Academic Publishing   (Total: 2 journals)   [Sort by number of followers]

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Challenge J. of Concrete Research Letters     Open Access   (Followers: 7)
Challenge J. of Structural Mechanics     Open Access   (Followers: 8)
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Challenge Journal of Structural Mechanics
Number of Followers: 8  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2149-8024
Published by TULPAR Academic Publishing Homepage  [2 journals]
  • Cover & Contents Vol.7 No.3

    • Authors: Journal Management CJSMEC
      PubDate: 2021-09-15
      Issue No: Vol. 7, No. 3 (2021)
       
  • Evaluation of the period and soft story conditions of reinforced concrete
           buildings with and without infill walls

    • Authors: Başak Zengin
      Pages: 151 - 161
      Abstract: Since the ground floor of most of the buildings in our country is designed as a shop or ground floor (in the buildings created as a workplace), there is very little infill wall ratio on the ground floors due to architectural and functional reasons, and some of them do not even exist at all. However, infill walls significantly increase the horizontal rigidity and strength of the structure, thus causing a decrease in the period value that determines the earthquake loads that will affect the structure. However, the infill wall meets the first destructive forces of the earthquake, and during this time, it cracks and absorbs some of the earthquake energy. The structural system elements of the building (columns and shear walls) start to meet the earthquake forces only when the infill walls are damaged and fail. In this direction, the aim of this study is to investigate to what extent the amount of infill wall on the ground floor affects the period of the building, and whether there are soft storey irregularities in the building according to the change in the amount of infill wall on the ground floor. In this study, while there are infill walls on all floors and all axes of buildings of various heights (3, 6, 9 and 11 floors), the amount of infill walls in the x and y directions on the ground floors is reduced to a certain extent, and many models are created until the ground floor is completely without infill walls. All these models created were analyzed with the support of the SAP2000 program, and the period values were determined and examined according to the soft storey problems and compared with the case of the entire building with and without infill walls. In addition, it was examined whether the period formulas determined as a result of the studies and taking into account the infill wall give realistic results for the situation examined in this study.
      PubDate: 2021-09-15
      DOI: 10.20528/cjsmec.2021.03.004
      Issue No: Vol. 7, No. 3 (2021)
       
  • Cover & Contents Vol.7 No.2

    • Authors: Journal Management CJSMEC
      PubDate: 2021-06-23
      Issue No: Vol. 7, No. 2 (2021)
       
  • Evaluating the effects of different slab types on static and dynamic
           characteristics of structures

    • Authors: Yılmaz Keleş, Hüseyin Kasap, Zeynep Yaman
      Pages: 71 - 83
      Abstract: In this study, the effect of different types of slabs on dynamic characteristics of structures under the lateral loading was investigated. For this purpose, four different types of slabs namely, beamed slab, flat slab, one way ribbed (hollow core) slab and waffle slab have been modeled in buildings having 3, 4 and 5 storeys with the same geometric dimensions, in accordance to design and construction requirements (TS 500) and Turkish building seismic codes (TBDY, 2018). Seismic analysis calculations of the modeled buildings were done using the equivalent seismic load method. The assumed local soil class was taken from the geotechnical report as ZD. As a result of the analysis, natural periods, base shear forces, maximum horizontal displacements and relative storey drifts of the buildings were compared. Seismic analysis and calculations of the buildings were completed using SAP2000 finite element software.
      PubDate: 2021-06-23
      DOI: 10.20528/cjsmec.2021.02.003
      Issue No: Vol. 7, No. 2 (2021)
       
  • Rapid power outage estimation for typical electric power systems in Turkey

    • Authors: Ali Yeşilyurt, Seyhan Okuyan Akcan, Abdullah Can Zülfikar
      Pages: 84 - 92
      Abstract: Electric power systems have critical importance in the sustainability of social life and economy. The past and recent earthquakes showed clearly that these systems have high vulnerability due to earthquakes. In this study, the typical electric power systems which are commonly preferred and located at five different sites in high seismic zone of Turkey, Marmara region, have been examined. In the first part of the study, the earthquake hazard for Marmara region has been accomplished. The earthquake hazard curves at five different sites for two different earthquake levels, and two different site conditions as soft and stiff site classes according to the Turkish Building Seismic Design Code 2018 have been obtained. The seismic vulnerability assessment of substation and distribution circuits for two different design states, namely anchored and unanchored, achieved by the fragility functions. The probability of power outage durations have been evaluated based on the restoration curves. It has been observed that the results obtained within the scope of the study are highly consistent with post-earthquake studies in the literature. The proposed methodology through the power outage graphics enable a quick preliminary evaluation of the power outage based on the current design status and location for any electric power systems in the Marmara region.
      PubDate: 2021-06-23
      DOI: 10.20528/cjsmec.2021.02.004
      Issue No: Vol. 7, No. 2 (2021)
       
  • A comparative study on yield line mechanisms for four bolted extended
           end-plated connection

    • Authors: Yasin Onuralp Özkılıç
      Pages: 93 - 106
      Abstract: Extended end-plated connections are preferred in moment resisting frames due to their advantages such as no required in-situ welding, accurate fabrication and economic feasibility compared to flange welded moment connections. The capacity of the extended end-plated connections depends on bolt configurations, end-plate thickness, bolt diameter and their material properties excluding column part. The thickness of end-plate can be computed using yield line mechanisms. Different yield line patterns are available in the literature and some of these are adopted in seismic codes to estimate the thickness of end-plate. In this study, the accuracy of different yield line patterns is compared using collected experimental data and numerical analysis. A parametric numerical analysis was conducted utilizing the finite element tool, ABAQUS. The results of experimental data and parametric study were evaluated for both unstiffened and stiffened four bolted extended end-plated connections. The results revealed that the capacity of the end-plate connections significantly depends on the yield line mechanism. Therefore, selecting an accurate yield line mechanism is essential in order not to overestimate the thickness of the end-plate. More importantly is that these yield line mechanisms can be directly implemented to AISC 358 and Turkish Building Earthquake Code 2018 (TBEC-2018).
      PubDate: 2021-06-23
      DOI: 10.20528/cjsmec.2021.02.005
      Issue No: Vol. 7, No. 2 (2021)
       
  • Assessment of an old roadway bridge under static and seismic loading
           conditions

    • Authors: Abdulkadir Cüneyt Aydın, Mehmet Fatih Yılmaz
      Pages: 107 - 116
      Abstract: A large proportion of road and railway bridges, present in Turkey served for many years, have been completed their service life or will soon. Continuing safety and sustainability of these bridges under traffic loads have been of great increasing importance to roadway and railway transportation line to be continuous servicing. In addition, the demolition and reconstruction of bridges that have reached the end of their service life or are nearing completion will have a negative impact on the country's economy. All of these requirements' detailed examination of bridges in order to provide economical and safe service, considering current vehicle loads and earthquake loads. The Mahmutçavuş Bridge is investigated as a simply supported continuous composite roadway bridge at this work. The finite-element model of the bridge is constituted by site investigation and measurement. Different truckloads using for the design of the bridge are determined, and static analysis of the bridge is conducted. Seven earthquake records are scaled for two different earthquake design spectrums. The nonlinear time-history analyses are conducted, considering Δ-δ effects. The performance of the bridge for varying truckloads and earthquake loads is investigated, and results are discussed in detail.
      PubDate: 2021-06-23
      DOI: 10.20528/cjsmec.2021.02.006
      Issue No: Vol. 7, No. 2 (2021)
       
  • A numerical study on influence of strain gradients on lattice rotation in
           micro-machining of a single crystal

    • Authors: Murat Demiral, Anish Roy, Vadim V. Silberschmidt
      First page: 117
      Abstract: In latest years small scale machining has been widely used in advanced engineering applications such as medical and optical devices, micro- and nano-electro-mechanical systems. In micromachining of metals, a depth of cut becomes usually smaller than an average crystal size of a polycrystalline structure; thus, the cutting process zone can be localized fully indoors of a single grain. Due to the crystallographic anisotropy, development of small scale machining models accounting for crystal plasticity are essential for a precise calculation of material removal under such circumstances. For this purpose, a 3D finite-element model of micro-cutting of a single grain was developed. A crystal-plasticity theory accounting for gradients of strain, implemented in ABAQUS/Explicit via a user-defined material subroutine VUMAT, was used in the computations. The deformation-induced lattice rotations in micro-cutting of a single crystal were analyzed extensively.
      PubDate: 2021-08-25
      DOI: 10.20528/cjsmec.2021.03.001
      Issue No: Vol. 7, No. 2 (2021)
       
  • A comparative study on the structural performance of an RC building based
           on updated seismic design codes: case of Turkey

    • Authors: Ercan Işık
      First page: 123
      Abstract: The destructive earthquakes and structural damages reveal the importance of the rules of earthquake-resistant structural design. The need of update and renewal of these rules periodically become inevitable as a result of scientific developments, innovations in construction technologies and building materials. Turkey which is an extremely region in terms of seismicity was adapted to these changes through time. The last five seismic design codes (1968, 1975, 1998, 2007 and 2018) were taken into account within the scope of this study. The differences in dimension and material grades of structural elements such as columns as beams have been compared in detail for each code. Three different analysis types have been performed for a 4-story reinforced-concrete model such as eigenvalue, pushover and dynamic time-history via the minimum conditions for these elements in each code. The natural vibration period of the building was obtained with empirical formulas stipulated in different codes for the sample RC building, additionally. The size and the type of the materials used in beams and columns within the last five codes have been changed. We see that the changes in these two important parameters which affect the behavior of buildings during an earthquake, enhance the performance of the building. It has been revealed that changes and renewals in seismic design codes are a necessity and gain. It has been clearly revealed that each amended code increases the stiffness and enhance the seismic capacity of a structure. Each updated seismic design code is aimed to complete the deficiency of the previous one. The results revealed that there are changes to be made to increase the seismic capacity of the structure at the point of reducing earthquake damage.
      PubDate: 2021-08-31
      DOI: 10.20528/cjsmec.2021.03.002
      Issue No: Vol. 7, No. 2 (2021)
       
  • Investigation of moment-curvature and effective section stiffness of
           reinforced concrete columns

    • Authors: Saeid Foroughi, Süleyman Bahadır Yüksel
      First page: 135
      Abstract: In determining the seismic performance of reinforced concrete (RC) structures in national and international seismic code, it is desired to use effective section stiffness of the cracked section in RC structural elements during the design phase. Although the effective stiffness of the cracked section is not constant, it depends on parameters such as the dimension of the cross-section, concrete strength and axial force acting on the section. In this study, RC column models with different axial load levels, concrete strength, longitudinal and transverse reinforcement ratios were designed to investigate effective stiffness. Analytically investigated parameters were calculated from TBEC (2018), ACI318 (2014), ASCE/SEI41 (2017), Eurocode 2 (2004) and Eurocode8 (2004, 2005) regulations and moment-curvature relationships. From the numerical analysis results, it is obtained that the axial load level, concrete strength, longitudinal and transverse reinforcement ratios have an influence on the effective stiffness factor of RC column sections. The calculated effective stiffness for RC columns increases with increasing transverse reinforcement ratio, longitudinal reinforcement ratio and concrete strength. Due to the increase of axial force, effective stiffness values of concrete have increased.
      PubDate: 2021-09-06
      DOI: 10.20528/cjsmec.2021.03.003
      Issue No: Vol. 7, No. 2 (2021)
       
  • Cover & Contents Vol.7 No.1

    • Authors: Journal Management CJSMEC
      PubDate: 2021-03-12
      Issue No: Vol. 7, No. 1 (2021)
       
  • Strengthening and performance assessing historical cinema hall balcony
           according to new Turkish Earthquake Code

    • Authors: Memduh Karalar, Murat Çavuşli
      First page: 27
      Abstract: Strengthening historical buildings and evaluating their performances make great contributions to both the history of the country and the tourism of the country. In this study, performance analysis and evaluations of the historical cinema hall balcony, which was built in 1933 by a French company and served to Zonguldak province for a long time, are presented in detail. This cinema hall was frequently used by local people between 1933 and 1999 and hosted many Yeşilçam movies. Firstly, examinations were performed in the historical cinema hall and the areas (columns, beams and floors) that were damaged in time were identified. According to the obtained information, it was determined that there were significant damages in the carrier system of the building and there were visible cracks and damages in the columns of the cinema hall. It was also observed that explosions occurred in one of the main carrier columns of the balcony. After the core samples taken from the balcony were tested in the laboratory, the current status of the carrier elements and reinforcements were determined with the help of an x-ray rebar scanner. After all these processes, the structure was modeled as three dimensional (3D) using a special computer program and performance evaluations were performed regarding the current state of the structure. As a result of the performance evaluation, it was determined that the balcony of the historical cinema hall could not survive anymore and would collapse over time. It was concluded that there were great damages especially on the balcony columns and a reinforcement should be made on a total of 6 columns. Strengthening was made to 4 different main columns and a performance analysis was performed again in strengthened structure. After strengthening, it was understood that the columns of the balcony of the cinema hall could survive for a long time.
      PubDate: 2021-01-01
      DOI: 10.20528/cjsmec.2021.01.004
      Issue No: Vol. 6, No. 4 (2021)
       
  • Buckling analysis of natural fiber reinforced composites

    • Authors: Celal Çakıroğlu, Gebrail Bekdaş
      First page: 58
      Abstract: In the recent years natural fiber reinforced composites are increasingly receiving attention from the researchers and engineers due to their mechanical properties comparable to the conventional synthetic fibers and due to their ease of preparation, low cost and density, eco-friendliness and bio-degradability. Natural fibers such as kenaf or flux are being considered as a viable replacement for glass, aramid or carbon. Extensive experimental studies have been carried out to determine the mechanical behavior of different natural fiber types such as the elastic modulus, tensile strength, flexural strength and the Poisson’s ratio. This paper presents a review of the various experimental studies in the field of fiber reinforced composites while summarizing the research outcome about the elastic properties of the major types of natural fiber reinforced composites. Furthermore, the performance of a kenaf reinforced composite plate is demonstrated using finite element analysis and results are compared to a glass fiber reinforced laminated composite plate.
      PubDate: 2021-01-02
      DOI: 10.20528/cjsmec.2021.02.001
      Issue No: Vol. 6, No. 4 (2021)
       
  • Determination of the exact mode frequencies of multi-storey structures by
           state-space method and a comparison with mode superposition method

    • Authors: Ahmad Yamin Rasa, Mehmet Hamit Özyazıcıoğlu
      First page: 1
      Abstract: A comparative research has been carried out for obtaining the time-consuming exact solution (state-space) and approximate solution (mode superposition) of transient and steady-state vibrations of linearly damped linear frame buildings. In the mode superposition method, the proportional damping matrix has been constructed by different approaches such as modal combination of mass and stiffness matrixes (Rayleigh) and disregarding the off-diagonal elements of the non-classical damping matrix, while in the state-space method the non-proportional damping matrix is constructed in exact situation. These observations are individually investigated, which the most suitable parameter to render the approximate results as close as possible to the exact results. Harmonic forces are applied on the different storeys of three and five storey frame buildings, and the responses are displayed in comparative tables and figures. The maximum responses are calculated by square root of sum of the squares (SRSS) method. A MATLAB code is generated and the equations of exact and approximate methods are solved.
      PubDate: 2020-12-21
      DOI: 10.20528/cjsmec.2021.01.001
      Issue No: Vol. 6, No. 4 (2020)
       
  • The effect of dome properties on design of the axial symmetric cylindrical
           wall

    • Authors: Aylin Ece Kayabekir
      First page: 11
      Abstract: The usage of computer software in civil engineering has expanded in last decades. Many general-purpose and special-purpose commercial programs perform a very important function, especially at the design stage. In this study, a computer program is introduced for the analysis and design of the axial symmetric cylindrical wall considering the dome effects. Analysis processes are carried out according to Flexibility theory with long wall assumption and during the reinforced concrete (RC) design of the wall, ACI 318-Building code requirements for structural concrete are considered. In numerical investigation, the effects of the dome properties (thickness and height) on the analysis and design of the wall are investigated by performing a totally 72 case analyzes. These cases include different support condition at bottom of the wall, wall heights, dome thicknesses and heights. According to analysis results, it is concluded that effects of dome thickness and heights on the wall on the wall are very limited.
      PubDate: 2020-12-26
      DOI: 10.20528/cjsmec.2021.01.002
      Issue No: Vol. 6, No. 4 (2020)
       
  • Evaluation of artificial neural network-based formulations for tuned mass
           dampers

    • Authors: Melda Yucel, Sinan Melih Nigdeli, Gebrail Bekdaş
      First page: 17
      Abstract: Tuned mass dampers (TMDs) are used to damp vibration of mechanical systems. TMDs are also used on structures to reduce the effects of strong forces such as winds and earthquakes. For the efficiency of TMD, optimization of TMD parameters is needed. Several classical formulations were proposed, but metaheuristic methods are generally used to find the best result. In addition, the metaheuristic based optimum results are used in machine learning of artificial intelligence-based models like artificial neural networks (ANN). These ANN models are also used in development of tuning equation via curve fitting. The classical and ANN-based formulations were found according to frequency domain responses. In the present study, the classical and ANN-based formulations were evaluated by comparing on time-history responses of seismic structure. In comparison, near-fault ground motion records including directivity pulses are used. The ANN based methods have advantages by providing smaller stroke requirement and damping for TMDs.
      PubDate: 2020-12-22
      DOI: 10.20528/cjsmec.2021.01.003
      Issue No: Vol. 6, No. 4 (2020)
       
  • Effect of high temperature on the mechanical behavior of cement-bonded
           wood composite produced with wood waste

    • Authors: Mehmet Canbaz, İlkay Kara, İlker Bekir Topçu
      First page: 42
      Abstract: The increase in the population day by day and urbanization has led to a rapid increase in the construction sector. With the increase in demand in construction, the product types of building materials are increasing. It is seen that wastes are formed during and after the production of the materials used in the building. This highlights studies on waste management and recycling of waste.  After construction activities, wastes are recycled or converted to secondary products. One of these is wood waste, a traditional building material. In addition to the production of wood furniture, it is used in various areas from the beginning of construction to the end of the building. In this study, sawdust, which is the waste of a woodworking company, was used. Utilizing the advantages of wood, recyclable and sustainable cement bonded wood composite production practices have been explored. It is aimed to produce nature and environment friendly, ecological and economic and durable composite materials. In this research, it is aimed to determine the optimum ratio by using different ratios of sawdust-cement while keeping the water-cement ratio constant in production. The specimens taken from the production were exposed to high temperature after gaining strength. The strength results, unit weights and ultrasonic pulse velocity results of cement bonded wood composite samples exposed to high temperature were examined. Although cement bonded wood composites are exposed to high temperatures such as 400°C, it has been observed that strength is achieved. With this study, an alternative area was proposed for the evaluation of these wastes.
      PubDate: 2020-12-26
      DOI: 10.20528/cjsmec.2021.01.005
      Issue No: Vol. 6, No. 4 (2020)
       
  • Study on slope stability of frame prestressed anchor sheet pile wall with
           finite element strength reduction method

    • Authors: Amna Saeed Al-Banaa, Zhou Yong
      First page: 49
      Abstract: Slope stability analysis is performed in practical geotechnical engineering using the finite element method, which is an advanced method and is widely used by engineers. With the development of computer technology, it has become easy to study the slope's stability supported by frame prestressed anchor and sheet pile wall through the displacement-based finite element numerical analysis method, to calculate the safety factors. However, the expansion angle ψʹ is not widely covered. In this study, PLAXIS two-dimensional finite element method is using to establish the slope model supported by frame prestressed anchor and sheet pile wall, and the influence of expansion angle on slope deformation is studied. The results show that the expansion angle has a different effect on the convergence of the two-dimensional slope model. In the model slope, a prestressed frame anchor and sheet pile wall reinforce the slope. The failure mechanisms were unclear when ϕʹ= ψʹ (flow base). Besides, when the slope has high soil strength parameters (c' or φʹ), the expansion angle will affect the calculation results and convergence. In general, the expansion angle significantly influences the slope's stability and is not affected. Therefore, it was necessary to note the effect of the angle of expansion on stability.
      PubDate: 2020-12-30
      DOI: 10.20528/cjsmec.2021.01.006
      Issue No: Vol. 6, No. 4 (2020)
       
  • Jaya algorithm based optimum design of reinforced concrete retaining walls
           under dynamic loads

    • Authors: Nur Eroğlu, Sena Aral, Sinan Melih Nigdeli, Gebrail Bekdaş
      First page: 64
      Abstract: In this study, the optimum dimensioning of a reinforced concrete retaining wall that meets the safety conditions under static and dynamic loads in terms of cost has been performed using Jaya algorithm, which is one of the metaheuristic algorithms. In the optimization process, reinforced concrete design rules and ground stress, sliding and overturn tests have been determined as design constraints for the safe design of the retaining wall. While 5 cross-section dimensions of the retaining wall are defined as the design variable, the objective function is targeted as the total cost per unit length of the retaining wall. In the study, optimum results are also presented by examining the changes of the toe projection length of the retaining wall, which is one of the design variables, narrowing between 0.2-10 m. The design variables minimizing the objective function were found via Jaya algorithm that have single-phase. In addition to achieving optimum dimensioning results in terms of safety and cost with the optimization method used as a result of the reinforced concrete design made by applying the rules of the regulation on buildings to be constructed in earthquake zones, the change in cost in seismic and static conditions was examined.
      PubDate: 2020-12-31
      DOI: 10.20528/cjsmec.2021.02.002
      Issue No: Vol. 6, No. 4 (2020)
       
 
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