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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: 4)
Challenge J. of Structural Mechanics     Open Access   (Followers: 5)
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Challenge Journal of Structural Mechanics
Number of Followers: 5  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2149-8024
Published by TULPAR Academic Publishing Homepage  [2 journals]
  • Cover & Contents Vol.5 No.1

    • Authors: Journal Management CJSMEC
      PubDate: 2019-03-12
      Issue No: Vol. 5, No. 1 (2019)
  • Estimation of capacity of eccentrically loaded single angle struts with
           decision trees

    • Authors: Saha Dauji
      First page: 1
      Abstract: Single angle struts are used as compression members for many structures including roof trusses and transmission towers. The exact analysis and design of such members is challenging due to various uncertainties such as the end fixity or eccentricity of the applied loads. The design standards provide guidelines that have been found inaccurate towards the conservative side. Artificial Neural Networks (ANN) have been observed to perform better than the design standards, when trained with experimental data and this has been reported literature. However, practical implementation of ANN poses problem as the trained network as well as the knowhow regarding the application should be accessible to practitioners. In another data-driven tool, the Decision Trees (DT), the practical application is easier as decision based rules are generated, which are readily comprehended and implemented by designers. Hence, in this paper, DT was explored for the evaluation of capacity of eccentrically loaded single angle struts and was found to be robust and yielded comparable accuracy as ANN, and better than design code (AISC). This has enormous potential for easy and straightforward implementation by practicing engineers through the logic based decision rules, which would be easily programmable on computer. For this application, use of dimensionless ratios as inputs for the development of DT was found to yield better results when compared to the approach of using the original variables as inputs.
      PubDate: 2019-02-09
      DOI: 10.20528/cjsmec.2019.01.001
      Issue No: Vol. 4, No. 4 (2019)
  • Dynamic instability of castellated beams subjected to transverse periodic

    • Authors: Sahar Sahib Elaiwi, Boksun Kim, Long-yuan Li
      First page: 9
      Abstract: In this study, an analytical solution is developed for the investigation of free vibration, static buckling and dynamic instability of castellated beams subjected to transverse periodic loading. Bolotin’s method is used to perform the dynamic instability analysis. By assuming the instability modes, the mass, stiffness, and geometric stiffness matrices are derived using the kinetic energy, strain energy and potential of applied loads. Analytical equations for determining the free vibration frequency, critical buckling moment, and excitation frequency of castellated beams are derived. In addition, the influences of the flange width of the castellated beam and the static part of the applied load on the variation of dynamic instability zones are discussed.
      PubDate: 2019-02-11
      DOI: 10.20528/cjsmec.2019.01.002
      Issue No: Vol. 4, No. 4 (2019)
  • Improving the impact resistance of recycled aggregate concretes with
           different types of fibers

    • Authors: Muhammet Gökhan Altun, Meral Oltulu
      First page: 19
      Abstract: In this study, the aim was to use different types of fibers to improve the impact resistance of recycled aggregate concrete (RAC) that normally shows poor performance against mechanical impacts compared to normal concrete (NC). For this purpose, 18 groups of concrete were cast using different parameters. The study examined different types of concrete mixtures where the proportion of RCA (recycled coarse aggregate) used was 30% and 50% respectively, and where steel fiber-reinforcement was used in proportions of 1% and 2%, and polypropylene fiber-reinforcement was used in proportions of 0.1%. While the material performance of RAC compared to NC is analyzed in existing published literature, there is no evidence on whether the use of RCA and hybrid fibers affect the impact properties of concrete. Drop weight impact testing was conducted on test specimens and the impact resistance of these specimens was studied at 28 days. It was observed that the increasing use of RCA reduced the impact resistance. The use of 30% RCA does not significantly influence the strength of concrete. According to the results, the performance of both the NC and RAC was increased with an increase in the volume fractions of steel fiber used. In addition, hybrid fiber-reinforced concretes showed the best results of all the concrete groups.
      PubDate: 2019-03-05
      DOI: 10.20528/cjcrl.2019.01.003
      Issue No: Vol. 4, No. 4 (2019)
  • Research on effect of the quantity and aspect ratio of steel fibers on
           compressive and flexural strength of SIFCON

    • Authors: Nurullah Soylu, Ahmet Ferhat Bingöl
      First page: 29
      Abstract: SIFCON (Slurry Infiltrated Fiber Reinforced Concrete) is a composite which occur hardening of the matrix phase, consists of cement, water, mineral additives, fine sand, water reducing plasticizer, and reinforced with high volume fiber (5–20%). The main difference from the high strength concrete (HSC) is the ductile behaviour at failure. However, the brittleness increases with the strength increase in HSC, SIFCON has a ductile behaviour because of the high volume fiber content, low permeability, high durability. Despite fiber content is 2-3% in fiber reinforced concrete, fiber content may be ten times more in SIFCON and ductility is gained. This concrete is suggested to be used in military buildings against explosion, industrial grounds, airports, and bridge feet. In this study, in order to investigate the compressive and flexural strengths of SIFCON, the aspect ratio and fiber volume of steel fibers were chosen as variable and the effects of these parameters on compressive and flexural strengths were investigated. In the study, steel fibers with aspect ratio of 40, 55, 65, and 80 were used in 0, 4, 8 and 12% ratios. The water/binder ratio was kept constant at 0.35. Silica fume is used 10% and water-reducing plasticizer is used 1.5% of cement by weight. 7 and 28 days cured samples were subjected to compressive and flexural tests and the results were compared. As a result of the tests carried out, increases in both the compressive and flexural strengths of SIFCON specimens were determined with increasing fiber volume up to 8%. Strength reductions were observed at higher ratios. In cases where the fiber volume is too high, it has been seen that the strengths were decreased. The reason of strength reduction can be explained by the difficulty of passing ability of mortar between the fibers. The highest strengths were obtained from fibers with the aspect ratio of 80. Increase in the aspect ratio as well as increases in compressive and flexural strengths have been found.
      PubDate: 2019-02-12
      DOI: 10.20528/cjsmec.2019.01.004
      Issue No: Vol. 4, No. 4 (2019)
  • Cover & Contents Vol.4 No.4

    • Authors: Journal Management CJSMEC
      PubDate: 2018-12-05
      Issue No: Vol. 4, No. 4 (2018)
  • An insight into design of prefabricated and prestressed concrete monoblock
           railway ties for service loads

    • Authors: Niyazi Özgür Bezgin
      Pages: 126 - 136
      Abstract: Ballasted railway track ties support the wheel forces of a train that are transferred by the rails, maintain the track gauge and provide track stability.  Prestressed concrete ties provide the required track bearing to the applied wheel loads and constitute a major part of the track self-weight. Design of prestressed concrete ties involves an evaluation of their structural interaction with the ballast and an understanding of prestressed concrete design for service loads and ultimate loads. This paper aims to provide an insight for the design of a prestressed concrete ballasted railway tie under service loads and highlight the genuine qualities of tie design in terms geotechnical engineering, materials engineering and structural engineering. Through the analysis of a finite element model, this paper presents estimations for bending moment values under service conditions for a prestressed concrete high-speed railway tie under varying track support conditions. The paper then compares the estimated values with those suggested by the relevant design guidelines for railway ties.
      PubDate: 2018-12-05
      DOI: 10.20528/cjcrl.2018.04.001
      Issue No: Vol. 4, No. 4 (2018)
  • Monitored structural behavior of a long span cable-stayed bridge under
           environmental effects

    • Authors: Alemdar Bayraktar, Ashraf Ashour, Halil Karadeniz, Altok Kurşun, Arif Erdiş
      Pages: 137 - 152
      Abstract: 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 temperature and wind using the monitoring data. Nissibi cable-stayed bridge with total length of 610m constructed in the city of Adıyaman, Turkey, in 2015 is chosen for this purpose. Structural behaviors of the main structural elements including deck, towers (pylons) and cables of the selected long span cable-stayed bridge under environmental effects such as air temperature and wind are investigated by using daily monitoring data. The daily variations of cable forces, cable accelerations, pylon accelerations and deck accelerations with air temperature and wind speed are compared using the hottest summer (July 31, 2015) and the coldest winter (January 1, 2016) days data.
      PubDate: 2018-12-05
      DOI: 10.20528/cjcrl.2018.04.002
      Issue No: Vol. 4, No. 4 (2018)
  • Necessary height of the vertical stiffeners in steel silos on discrete

    • Authors: Lyubomir Zdravkov
      Pages: 153 - 158
      Abstract: The steel silos are interesting complex facilities. In order to ensure unloading of whole amount of stored product by gravity, the steel silos are often placed on supporting frame structure. Values of stresses in the joints between the thin walled shell and supporting frame elements are very high. It can causes local loss of stability in the shell. To prevent its local buckling, many designers put stiffening elements above the supports. Here the question is how high should be the stiffening elements' The right solution is that they should reach that level till which the values of the meridional normal stresses above the supports and in the middle between them are equalized. Under this level the cylindrical shell will be considered as a ring beam, stiffened by elements above the supports. Above it, the cylinder can be calculated as continuously supported shell. But where is this level' A lot of researchers worked on values and way of distribution of normal meridional stresses above the supports of the cylindrical shells. As a result of their efforts are determined critical height Hcr of the shell and the ideal position HI   of intermediate stiffening ring. But these heights are considerably different between each other. To which of them our vertical stiffening elements should achieve'
      PubDate: 2018-12-05
      DOI: 10.20528/cjcrl.2018.04.003
      Issue No: Vol. 4, No. 4 (2018)
  • Earthquake performance of collapsed school building under Van-Tabanli
           (Mw=7.2) earthquake

    • Authors: Cumhur Cosgun, Atakan Mangir
      Pages: 159 - 175
      Abstract: A majority of the present building stock of Turkey is under seismic risk. It is believed that a significant proportion of the existing structures will either collapse or will get heavily damaged during a possible strong earthquake. With this respect, as an initial stage in the betterment of the structurally deficient building stock, assessment of existing buildings is of vital importance. From this viewpoint, in this study, earthquake performance of a collapsed school building was investigated through numerical performance analysis based on codified rules. At the end of 2011, numerous ground motions of various intensities have been registered in city of Van in eastern Turkey starting from 23 October 2011. Two major earthquakes were experienced at the Tabanli and Edremit district of Van. The moment magnitudes of these earthquakes were announced as 7.2 and 5.6, respectively. The investigated school building in this study was located in the city of Van and collapsed after first major earthquake (Mw=7.2). Structural details of the load-bearing members of the investigated building including as-built drawings and specified material properties were obtained. Based on obtained data, a numerical model was created to simulate the behavior of the building under code specified earthquake effects. Earthquake performance assessment of the structure was carried based on the recommendations given in the related chapter of the Turkish Seismic Code. Pushover analyses were performed and expected member by member damage levels and overall structural damage were determined in accordance with Turkish Seismic Code. The results are discussed to enlighten the actual cause of the collapse.
      PubDate: 2018-12-05
      DOI: 10.20528/cjcrl.2018.04.004
      Issue No: Vol. 4, No. 4 (2018)
  • Cover & Contents Vol.4 No.3

    • Authors: Journal Management CJSMEC
      PubDate: 2018-09-04
      Issue No: Vol. 4, No. 3 (2018)
  • Cover & Contents Vol.4 No.2

    • Authors: Journal Management CJSMEC
      PubDate: 2018-06-09
      Issue No: Vol. 4, No. 2 (2018)
  • Re-examination of steel frame office buildings in preventing collapse when
           subject to intense fires

    • Authors: Robert Mathews Korol, Ken S. Sivakumaran, Paul Heerema
      First page: 82
      Abstract: The purpose of the paper is to investigate the extent to which present-day design of steel framed buildings is susceptible to total collapse when subjected to extreme fire events. We select a 50 storey structure in which 2 and 4 adjacent storeys located at different above-ground heights are, in separate scenarios engulfed in raging fires. A total of 8 scenarios are analyzed, employing Newtonian mechanics and realistic energy dissipating properties of H-shaped columns and normal concrete floor slabs possessing secondary (shrinkage and temperature) reinforcement alone. While the present Canadian building code is the basis for our column designs, other standards provide very similar specifications. Although fire proofing is required in virtually all high rise building construction, we are excluding such materials in order to simplify the analyses, but clearly do not advocate its omission – quite the opposite in fact. As well, attributes such as floor beams, partitions and furnishings of every description, all of which would in practice participate in absorbing the kinetic energy of a crush-down upper block are excluded. Despite such a vast array of conservative assumptions, it is shown that partial collapse may occur during crush-down, however, in no case will total collapse be the consequence. These results should provide some comfort to code writers that their requirements should indeed prevent the most catastrophic of failures due to fires.
      PubDate: 2018-06-11
      DOI: 10.20528/cjsmec.2018.03.001
      Issue No: Vol. 4, No. 2 (2018)
  • Optimum design of purlin systems used in steel roofs

    • Authors: İbrahim Aydoğdu, Mukaddes Merve Kubar, Dahi Şen, Osman Tunca, Serdar Çarbaş
      First page: 89
      Abstract: In this study, one existing purlin system which is used in steel roof is optimized by taking into account less cost and bearing maximum load via developed software. This software runs with firefly algorithm which is one of the recent stochastic search techniques. One of the metaheuristic techniques, so-called firefly algorithm imitates behaviors of natural phenomena. Behaviors and communications of firefly are inspired by this algorithm. In optimization algorithm, steel sections, distance between purlins, tensional diagonal braces are determined as design variables. Design loads are taken into account by considering TS498-1997(Turkish Code) in point of place where structure will be built, outside factors and used materials. Profile list in TS910 is used in selection stage of cross sections of profile. Constraints of optimization are identified in accordance with bending stress, deformation and shear stress in TS648. Design variables of optimization are selected as discrete variables so as to obtain applicable results. Developed software is tested on existing real sample so; it is evaluated with regard to design and performance of algorithm.
      PubDate: 2018-06-12
      DOI: 10.20528/cjsmec.2018.03.002
      Issue No: Vol. 4, No. 2 (2018)
  • Analyzing pre-stressed steel arch beams

    • Authors: Erkan Polat, Barlas Özden Çağlayan
      First page: 95
      Abstract: Techniques are being developed day-by-day to make it possible to pass through larger openings using smaller beam-column sections. Parallel to this trend, there is another necessity to produce not only smaller but also more economical and architecturally attractive beams. The aim of this study is to explain the structural behavior of steel arch beams reinforced using post-tension cables. Due to the effect of these, the arch beam load carrying capacity increases and a smaller sized optimized section can be obtained with a better architectural view. Moreover, it also allows better mechanical and applicable solutions for buildings. For a better understanding of the behavior of the reinforced beam, a steel beam and a steel arch beam with post-tensioned cables were modeled and analyzed using the SAP2000 finite element analysis computer program and compared with each other. In addition, full-scale specimens were prepared for testing to determine the structural behavior and compare the results with those from the computer modeling, the outcome of which was very promising. The similarity between the results inferred that no extra engineering knowledge and effort are needed to design such beams. The predicted (and proved by the testing) beam bearing capacity was 35% higher than that of the unreinforced beam. With just three full-scale tests completed, it was evident that the ratio (35%) could be increased by adjusting the cable post-tension force on much smaller sized beams.
      PubDate: 2018-06-11
      DOI: 10.20528/cjsmec.2018.03.003
      Issue No: Vol. 4, No. 2 (2018)
  • An investigation of the behavior of header end-plate connections under
           monotonic loading

    • Authors: Adem Karasu, Cüneyt Vatansever, Haluk Emre Alçiçek
      First page: 108
      Abstract: In seismically active regions such as Turkey, the context of the nonlinearity provided by a building is based on the behaviors of structural components; beams, columns and their connections constituting the seismic force resisting system of the structure. Of these members, beam-to-column connections can play a considerably important role even if they have a capability of limited stiffness and flexural strength. Structural steel connections are mainly classified as a pinned or a moment connection. However, some beam-to-column connections having limited stiffness and flexural strength, which are called semi-rigid connections such as header end-plate connections designed so as to transmit only shear forces, can be characterized by moment-rotation relationship. This paper investigates the behavior of header end-plate connections using finite element (FE) modeling. The FE models include material, geometrical and contact nonlinearities. FE modeling technique was first verified through the test results of the experimental research performed by Aggarwal (1990). Then the effect of header end-plate thickness upon moment-rotation relationship was investigated. According to the analyses results, in addition to shear stresses, axial tensile stresses have been observed to occur in the bolts at the tension side and thickness of the header end-plate and beam web play a governing role in the development of initial rotational stiffness and the flexural strength of header end-plate connections.
      PubDate: 2018-08-03
      DOI: 10.20528/cjsmec.2018.03.004
      Issue No: Vol. 4, No. 2 (2018)
  • Numerical investigation of reinforced concrete frame behavior subjected to
           progressive collapse

    • Authors: Mohammad Bagher Paripour, Ahmet Budak, Oğuz Akın Düzgün
      First page: 117
      Abstract: Progressive collapse is defined as the spread of an initial local failure of a structure. This phenomenon, caused by the removal of one or more load-bearing element, is followed by a chain of failures through the structure and ultimately leads to partial or even full collapse of an entire structure. As a result, an accurate understanding of structural behavior subjected to large displacements, caused by progressive collapse, is essential to ensure a safe structural design. A progressive collapse in buildings often starts with the removal of one or more columns and continues with the collapse of adjoining structural elements. Experimental studies on progressive collapse are generally not recommended because of its cost and safety reasons. Today, as a result of progress in computer technology, more complicated problems can be investigated numerically. In this study, a numerical model is used for nonlinear analysis of a reinforced concrete (RC) frame behavior subjected to progressive collapse. It is obtained that there is a good agreement between the results with those of the experimental study given in the literature. According to the results, it can be predicted numerically the response of an RC frame to progressive collapse at a highly accurate level.
      PubDate: 2018-08-15
      DOI: 10.20528/cjsmec.2018.03.005
      Issue No: Vol. 4, No. 2 (2018)
  • Cover & Contents Vol.4 No.1

    • Authors: Journal Management CJSMEC
      PubDate: 2018-03-03
      Issue No: Vol. 4, No. 1 (2018)
  • Influencing factors on effective width of compressed zone in joint column
           - cylindrical shell of steel silo

    • Authors: Lyubomir Zdravkov
      Pages: 1 - 8
      Abstract: In order to ensure unloading of whole amount of stored product by gravity, steel silos are often placed on supporting structure. The simplest way to design these complicated facilities is to divide cylindrical shell on two parts in our minds - discretely supported ring beam and continuously supported shell above it. Obviously, to ensure continuously support of shell, bending stiffness of ring beam should be high. In European standard EN 1993-4-1, that concept is recognized but it keeps silence about recommended stiffness of ring beam. Another way to design is to know law of distribution of compressive axial stresses due to discrete column reactions R, by height of shell. Knowing it, we could calculate the effective width leff of distribution of compressive stresses on every level. Where effective width is equal to distance between discrete supports, there critical height of shell ends and above it cylindrical body is continuously supported. Unfortunately the above quoted standard EN 1993-4-1 does not give an information how to calculate leff. The questions here are; should we accept linear distribution of compressive forces by height' In addition, could we use directly the results of Whitmore (1952), where angle of distribution α = 30°' Or, even to accept a far more brave opinion that α = 45°, used by many of the elder designers' Moreover, is value of angle α constant or does it depend on various influencing factors'
      PubDate: 2018-03-03
      DOI: 10.20528/cjsmec.2018.01.001
      Issue No: Vol. 4, No. 1 (2018)
  • Mechanical performance comparison of glass and mono fibers added gypsum

    • Authors: Sadık Alper Yıldızel, Serdar Çarbaş
      Pages: 9 - 12
      Abstract: Gypsum and gypsum based composite are widely preferred in construction industry for various purposes. Mechanical performances of gypsum composite have been enhanced by researchers in order to increase its area of usage. In this research, gypsum composites containing expanded glass were reinforced by glass fibers (GF) and mono polypropylene fibers (MPF). GF and MPF were used up to 1.5 %. The flexural strength, compressive strength, and shrinkage behavior of the composites were examined within the scope of this study. 50 x 50 x 50 mm and 40 x 40 x 160 sized specimens were prepared for the mechanical performance tests. It was obtained that flexural and shrinkage behavior of the composite were enhanced with the addition of MPF compared to GF added mixes; however, compressive strength values were not as high as GF reinforced composites.
      PubDate: 2018-03-03
      DOI: 10.20528/cjsmec.2018.01.002
      Issue No: Vol. 4, No. 1 (2018)
  • Seismic assessment of a curved multi-span simply supported truss steel
           railway bridge

    • Authors: Mehmet Fatih Yılmaz, Barlas Özden Çağlayan, Kadir Özakgül
      Pages: 13 - 17
      Abstract: Fragility curve is an effective method to determine the seismic performance of a structural and nonstructural member. Fragility curves are derived for Highway Bridges for many studies. In Turkish railway lines, there are lots of historic bridges, and it is obvious that in order to sustain the safety of the railway lines, earthquake performance of these bridges needs to be determined. In this study, a multi-span steel truss railway bridge with a span length of 25.7m is considered. Main steel truss girders are supported on the abutments and 6 masonry piers. Also, the bridge has a 300m curve radius. Sap 2000 finite element software is used to model the 3D nonlinear modeling of the bridge. Finite element model is updating according to field test recordings. 60 real earthquake data selected from three different soil conditions are considered to determine the seismic performance of the bridge. Nonlinear time history analysis is conducted, and maximum displacements are recorded. Probabilistic seismic demand model (PSDMs) is used to determine the relationship between the Engineering Demand Parameter (EDP) and Intensity Measure (IMs). Fragility curve of the bridge is derived by considering the serviceability limit state, and results are discussed in detail.
      PubDate: 2018-03-03
      DOI: 10.20528/cjsmec.2018.01.003
      Issue No: Vol. 4, No. 1 (2018)
  • Forced vibration analysis of Mindlin plates resting on Winkler foundation

    • Authors: Yaprak Itır Özdemir
      Pages: 18 - 26
      Abstract: The purpose of this paper is to study shear locking-free parametric earthquake analysis of thick and thin plates resting on Winkler foundation using Mindlin’s theory, to determine the effects of the thickness/span ratio, the aspect ratio and the boundary conditions on the linear responses of thick and thin plates subjected to earthquake excitations. In the analysis, finite element method is used for spatial integration and the Newmark-β method is used for the time integration. Finite element formulation of the equations of the thick plate theory is derived by using higher order displacement shape functions. A computer program using finite element method is coded in C++ to analyze the plates clamped or simply supported along all four edges. In the analysis, 8-noded finite element is used. Graphs are presented that should help engineers in the design of thick plates subjected to earthquake excitations. It is concluded that 8-noded finite element can be effectively used in the earthquake analysis of thick plates. It is also concluded that, in general, the changes in the thickness/span ratio are more effective on the maximum responses considered in this study than the changes in the aspect ratio.
      PubDate: 2018-03-03
      DOI: 10.20528/cjsmec.2018.01.004
      Issue No: Vol. 4, No. 1 (2018)
  • Investigating the effect of infill walls on steel frame structures

    • Authors: Osman Fatih Bayrak, Seda Yedek, Muhammet Musab Erdem, Murat Bikce
      Pages: 27 - 32
      Abstract: Infill walls consisting of materials such as hollow concrete, hollow clay and autoclaved aerated concrete bricks are not only preferred in reinforced concrete buildings but also in steel frame structures. It is a well-known fact that infill walls limit the displacement of frames under horizontal loads. However, they may also bring about certain problems due to being placed randomly in horizontal and discontinuously in vertical directions for some architectural reasons. Moreover, cracks in frame-wall joints are observed in steel frame structures in which ductile behaving steel and brittle behaving infill walls are used together. In this study, the effect of infill walls on steel frames has been investigated. In the steel frame structure chosen for the study, four different situations consisting of different combinations of infill walls have been modeled by using ETABS Software. Later, the pushover analyses have been performed for all the models and their results have been compared. As a result of the analyses done by using the equivalent diagonal strut model, it has been found out that infill walls limit the displacement of steel frames and increase the performance of a structure. However, it has been also determined that in the steel frame structure in which the infill walls have been placed discontinuously in vertical and asymmetrically in horizontal, infill walls may lead to torsional and soft story irregularities. As a result, it is possible to observe cracks in the joints of infill walls and steel frame, the deformation properties of which differ, unless necessary precautions are taken.
      PubDate: 2018-03-03
      DOI: 10.20528/cjsmec.2018.01.005
      Issue No: Vol. 4, No. 1 (2018)
  • Effects of structural irregularities on low and mid-rise RC building

    • Authors: Hüseyin Bilgin, Rezarta Uruçi
      First page: 33
      Abstract: During the recent earthquakes, it has been observed that structural irregularities are one of the main reasons of the building damage. Irregularities are weak points in a building which may cause failure of one element or total collapse of the building during an earthquake. Since Albania is a country with moderate seismicity which has been hit by earthquakes of different magnitudes many times establishes the need to study the effect of irregularities is well-founded. The main structural irregularities encountered in Albanian construction practice consist of short column, large and heavy overhangs and soft story. In this study, these types of irregularities are considered in two different types of buildings, low and mid-rise reinforced concrete frame buildings represented by 3- and 6- story respectively. Pushover analyses are deployed to get the effect of structural irregularities on RC buildings response. A building set is chosen to represent the existing construction practice in the region; regular framed building and buildings with irregularities such as soft stories, short columns, heavy overhangs and the presence of soft story with heavy overhangs. The analyses have been conducted by using ETABS and Seismosoft software. Pushover curves of building set are determined by nonlinear static analysis in two orthogonal directions. Comparative performance evaluations are done by considering EC8 and Albanian Seismic codes (KTP-N2-89). From the obtained results, it is observed that low and mid-rise structures with soft story- two sided overhangs and short column are more vulnerable during earthquakes.
      PubDate: 2018-04-19
      DOI: 10.20528/cjsmec.2018.02.001
      Issue No: Vol. 4, No. 1 (2018)
  • Performance based study on the seismic safety of buildings

    • Authors: Zinnur Çelik, Ahmet Budak
      First page: 45
      Abstract: In the scope of this study, information has been provided on the Static Pushover Analysis which is a nonlinear deformation controlled analysis method and the Capacity Spectrum Method used to determine the performance point. In this study, static pushover analysis was made on a six-storey building with reinforcement concrete frame system by changing the materials, steel rebars and soil characteristics. The building’s capacity curves were drawn and decided according to different concrete and reinforcement groups. Furthermore the performance points of different classes of concrete were studied according to three seismic effect levels. In the case of a decrease in the reinforcement strength, a decrease of approximately 30% occurs in the base shear force. If the concrete strength is increased, an increase of 11% occurred in the base shear force. Consequently, in the comparisons made with five different concrete groups and two different reinforcement groups, rather than the increase in the strength of the concrete, an increase in the reinforcement strength was observed to be more effective on the structural capacity. Furthermore, local soil classifications were observed to be the most significant point regarding peak displacement.
      PubDate: 2018-02-23
      DOI: 10.20528/cjsmec.2018.02.002
      Issue No: Vol. 4, No. 1 (2018)
  • Use of geosynthetics to reduce the required right-of-way for roadways and

    • Authors: Niyazi Özgür Bezgin
      First page: 54
      Abstract: Roadway and railway routes require a right-of-way (ROW) to provide the necessary width for the required travelled way, drainage and earthwork. Correct understanding of ROW along a route is necessary in order to establish a correct width for the intended transportation corridor. Availability of land becomes scarce and cost of land increases in urban zones. Therefore, the costs of establishing a ROW in rural areas and in urban areas are not the same. Earthworks are an important component of route establishment. The required excavations and fills necessitate the use of proper side slopes for the stability of the excavation or the fill. These side slopes directly relate to the mechanical properties of the soil and the depth of the earthwork. This study provides a quantitative and a qualitative understanding of the ROW requirements of roadways and railways and the influence of the earthworks on the determined values of the ROW. The study further investigates the benefits of using geogrids to reduce the necessary ROW for a transportation route through finite element analysis.
      PubDate: 2018-05-25
      DOI: 10.20528/cjsmec.2018.02.003
      Issue No: Vol. 4, No. 1 (2018)
  • Eigenvector and eigenvalue analysis of thick plates resting on elastic
           foundation with first order finite element

    • Authors: Yaprak Itır Özdemir
      First page: 61
      Abstract: The purpose of this paper is to study free vibration analysis of thick plates resting on Winkler foundation using Mindlin’s theory with first order finite element, to determine the effects of the thickness/span ratio, the aspect ratio, subgrade reaction modulus and the boundary conditions on the frequency parameters of thick plates subjected to free vibration. In the analysis, finite element method is used for spatial integration. Finite element formulation of the equations of the thick plate theory is derived by using first order displacement shape functions. A computer program using finite element method is coded in C++ to analyze the plates free, clamped or simply supported along all four edges. In the analysis, 4-noded finite element is used. Graphs are presented that should help engineers in the design of thick plates subjected to earthquake excitations. It is concluded that 4-noded finite element can be effectively used in the free vibration analysis of thick plates. It is also concluded that, in general, the changes in the thickness/span ratio are more effective on the maximum responses considered in this study than the changes in the aspect ratio.
      PubDate: 2018-05-25
      DOI: 10.20528/cjsmec.2018.02.004
      Issue No: Vol. 4, No. 1 (2018)
  • Structural features of cold-formed steel profiles

    • Authors: Osman Tunca, Ferhat Erdal, Arif Emre Sağsöz, Serdar Çarbaş
      First page: 77
      Abstract: Using capacity of cold-formed steel sections increases thanks to the opportunities which are offered by the developing technology. Low production cost and variety of profiles that can be produce easy, fast, high quality provide to improve its popularity as a structural material. In production, Sulphur and Phosphorous accumulation region occurs at intersection region of flanges and web of hot rolled steel profile. This causes to decrease strength of profile. Other difference between cold-formed and hot rolled steel sections is that mechanical properties of steel material homogeneously distributes throughout the profile. Both in frame and truss systems, cold-formed steel profiles develop both as main and secondary bearing element. These present variety options to the designers with pure, galvanized, aluminized applications. As with many building materials, mechanical behavior of cold-formed steel profile is quite complex due to the nature of thin walled steel sections. Design and analysis methods of cold-formed steel profile are rapidly shaped day by day. The general theory of beams investigated in past studies make possible analyses of cold-formed steel profile. Moreover, in structural systems, using of cold-formed steel profile provide height strength besides sustainable, environmentalist, green building because it requires less material and cost. Although these profiles have many advantages, use of cold-formed steel profiles in our country structures is rather limited unfortunately. New steel construction regulations in Turkey also do not mention cold-formed thin walled steel structure. Main purpose of this study reviews structural specifications of cold-formed steel profiles which are applied world-wide.
      PubDate: 2018-06-02
      DOI: 10.20528/cjsmec.2018.02.005
      Issue No: Vol. 4, No. 1 (2018)
School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
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