Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2025Scopus SJRQ2/r/munzur/2163
  Assessment of seismic fragility of reinforced concrete buildings retrofitted with steel bracing elements: A numerical study

  Tam, Gürkan; Yön, Burak

  In this study, the effectiveness of reinforcement with steel diagonal elements in a reinforced concrete building was investigated. A typical reinforced concrete building with ground floor+4 floors was designed for the numerical study. All column dimensions were 400×400 mm, all beam dimensions were 250×500 mm, transverse reinforcement spacing in column and beam elements was 100 mm and floor heights were 3 meters. The existing building was strengthened with X steel diagonal elements and two models were obtained. Nonlinear static pushover and incremental dynamic analyses of the buildings were performed. 11 earthquake records were used for incremental dynamic analyses. The acceleration amplitudes of these records were increased from 0.1 g to 1.0 g by 0.1 g and the analyses were performed. In order to model the nonlinear behaviour, lumped plastic hinges were assumed at the ends of the structural elements. As a result of nonlinear static pushover and incremental dynamic analyses of the buildings, capacity curves, maximum responses, inter-storey drifts, hysteretic curves at the ends of selected columns and damage patterns were obtained. Fragility curves were created by considering the damage levels in the buildings. According to the results, the average inter-storey drifts of the building strengthened using X steel diagonal elements decreased by approximately 90% compared to its current condition for 1.0 g PGA, while the damage probability and vibration period were also significantly reduced. In addition, the base shear force encountered by the strengthened building increased more than 4 times compared to its current condition.

  AtıfScopus11·WoS8

  İncele
• MakaleYalnız künye2021Scopus SJRQ2/r/munzur/3051
  Examination of contact problem between functionally graded punch and functionally graded layer resting on elastic plane

  Polat, Alper

  In this study, continuous contact problem in the functionally graded (FG) layer loaded with a FG flat punch resting on the elastic semi-infinite plane was analyzed by the finite element method (FEM). It was assumed that the shear modulus and density of the layer and punch varied according to exponentially throughout their depth. FG layer's weight was included to the problem and additionally all surfaces were considered as frictionless. Analysis of FG materials was performed with a special macro which was added to the ANSYS program. Firstly, the shear modulus of the punch was considered to be very rigid and the results of initial separation load (λcr) and distance (xcr) were compared with the analytical solution. Afterwards, results obtained from the contact analysis made according to the inhomogeneity parameters (β, γ) between FG punch-FG layer which had been unprecedented in the literature were discussed. As a result, FG punch's stress values at the punch edges where stress accumulations occurred were found to be smaller than the rigid punch. The security of the structure, longer life of the material and ease of production are directly related to the reduction of the stress values. The results obtained in this study are important in this respect. Also this work is the first study that investigates the effect of FG punch on the FG layer.

  AtıfScopus8·WoS10·OpenAlex2

  İncele
• MakaleYalnız künye2019Scopus SJRQ1/r/munzur/4796
  Fundamental vibration frequency prediction of historical masonry bridges

  Onat, Onur

  It is very common to find an empirical formulation in an earthquake design code to calculate fundamental vibration period of a structural system. Fundamental vibration period or frequency is a key parameter to provide adequate information pertinent to dynamic characteristics and performance assessment of a structure. This parameter enables to assess seismic demand of a structure. It is possible to find an empirical formulation related to reinforced concrete structures, masonry towers and slender masonry structures. Calculated natural vibration frequencies suggested by empirical formulation in the literatures has not suits in a high accuracy to the case of rest of the historical masonry bridges due to different construction techniques and wide variety of material properties. For the listed reasons, estimation of fundamental frequency gets harder. This paper aims to present an empirical formulation through Mean Square Error study to find ambient vibration frequency of historical masonry bridges by using a non-linear regression model. For this purpose, a series of data collected from literature especially focused on the finite element models of historical masonry bridges modelled in a full scale to get first global natural frequency, unit weight and elasticity modulus of used dominant material based on homogenization approach, length, height and width of the masonry bridge and main span length were considered to predict natural vibration frequency. An empirical formulation is proposed with 81% accuracy. Also, this study draw attention that this accuracy decreases to 35%, if the modulus of elasticity and unit weight are ignored.

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  AtıfWoS14·OpenAlex6

  İncele
• MakaleYalnız künye2015Scopus SJRQ2/r/munzur/4237
  Experimental and numerical analysis of RC structure with two leaf cavity wall subjected to shake table

  Onat, Onur; Lourenço, Paulo B.; Koçak, Ali

  This paper presents finite element (FE) based pushover analysis of a reinforced concrete structure with a two-leaf cavity wall (TLCW) to estimate the performance level of this structure. In addition to this, an unreinforced masonry (URM) model was selected for comparison. Simulations and analyses of these structures were performed using the DIANA FE program. The mentioned structures were selected as two storeys and two bays. The dimensions of the structures were scaled 1: 1.5 according to the Cauchy Froude similitude law. A shake table experiment was implemented on the reinforced concrete structure with the two-leaf cavity wall (TLCW) at the National Civil Engineering Laboratory (LNEC) in Lisbon, Portugal. The model that simulates URM was not experimentally studied. This structure was modelled in the same manner as the TLCW. The purpose of this virtual model is to compare the respective performances. Two nonlinear analyses were performed and compared with the experimental test results. These analyses were carried out in two phases. The research addresses first the analysis of a structure with only reinforced concrete elements, and secondly the analysis of the same structure with reinforced concrete elements and infill walls. Both researches consider static loading and pushover analysis. The experimental pushover curve was plotted by the envelope of the experimental curve obtained on the basis of the shake table records. Crack patterns, failure modes and performance curves were plotted for both models. Finally, results were evaluated on the basis of the current regulation ASCE/SEI 41-06.

  AtıfWoS15

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