Muharrem Aktas

Nonlinear finite element analysis of damaged and strengthened reinforced concrete beams

AbstractBending test of seven reinforced concrete beams are modeled in finite element program to validate the modeling strategies by comparing the structural response of the beams. Three beams in the set are pre-damaged and strengthened with fiber reinforced composites before the bending tests. Cracks are implemented into the model by inserting geometrical discontinuities to represent the pre-damaged beams. Parametric variables such as crack width, length and interval are chosen to simulate different pre-damage levels. Once the proposed modeling strategies are validated by real experimental tests then 196 finite element models are created to study the effects of pre-damage levels on the moment capacity of reinforced concrete beams repaired with CFRP. Results indicate that inclusion of pre-damage levels by means of cracks into the cross sections have significant effect on beams moment capacity.

YAPAY ANAKAYA KULLANILARAK YÜKSEK HIZLI TRENLERİN ALÜVYON ZEMİNLERDEKİ ÇEVRE YAPILARDA OLUŞTURDUĞU TİTREŞİM ETKİLERİNİN AZALTILMASI

Hizli demiryolu hattina yakin yapilari yumusak zemin kosullarinda tasinan kuvvetli titresimlerden korumak icin dalga bariyeri olarak yapay anakaya modeli insaat muhendisliginin pratik uygulamalarinda kullanilmaktadir. Bu calismada, yuksek hizli tren trafiginin meydana getirdigi titresimlerin demiryolu aginin cevresindeki binalarda olusturdugu etkilerin azaltilmasi icin dalga engelleyici bariyerlerin yerlestirilmesi arastirilmistir. Yapay anakayanin aktif ve pasif yalitim durumlarina gore performansini degerlendirebilmek icin ayrintili parametrik calismalar gerceklestirilmistir.

Transportation Risk Analysis (TRA) of Bosphorus Suspended Bridge, Using Probabilistic Approach

The expected destructive earthquake of Istanbul in the near future urges the researches to determine the proper and effective measures in order to make sure that the Bosphorus related traffic is affected at the possible lowest level. By considering the fact that the traffic on this bridge corresponds to the busiest in Turkey, especially in the peak hours, the amount of lives to be lost when the earthquake hits the bridge must be kept at the minimum levels according to the different scenarios. In this research a probabilistic approach is employed to develop a risk analysis model by manipulating the speeds of the vehicles and the length of the danger.

INFLUENCE OF THE GEOMETRIC IMPERFECTIONS ON THE BUCKLING OF THIN PLATES

Slender structural elements are subjected to both local buckling and global buckling under impact loading and earthquake loading. Thus, elements under neutral equilibrium must be checked for the safety of the structural system. More over it is obvious that structural elements with imperfections can never achieve the Euler Buckling load levels and all the structural members come with their own geometric imperfections. Buckling is affected by several factors such as: elastic modulus of the material, slenderness ratio of the element and existing geometrical imperfections in the element. In this study; influence of geometrical imperfections on the buckling of slender steel plates is investigated.

Energy Production and Economic Growth: A Causality Analaysis for Turkey Based on Computer

High levels of energy prices and the promise of international initiatives on decreasing the greenhouse gas emissions have regenerated the argument about the execution of energy conservation policies. This paper investigates the causal relationship between aggregated and disaggregated levels of energy production, energy demand, energy import and economic growth for Turkey for the period of 1975–2007. The relationship between the energy production, energy demand, energy import and Gross Domestic Product is examined. To this end, Engle-Granger cointegration, Error Correction Model and Granger causality tests are applied in order to determine the aforementioned relation. It is found that the energy production has direct relationship with the GDP and it has causality effects.