The investigation of seismic performance of existing RC buildings with and without infill walls

Hakan Dilmac,Hakan Ulutas,Hamide Tekeli,Fuat Demir 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.22 No.5

One of the important factors is the infill walls in the change of the structural rigidity, ductility, dynamic and static characteristics of the structures. The infill walls are not generally included in numerical analysis of reinforced concrete (RC) structural system due to lack of suitable theory and the difficulty of calculating the recommended models. In seismic regions worldwide, the residential structures are generally RC buildings with infill wall. Therefore, understanding the contribution of the infill walls to seismic performance of buildings may have a vital importance. This paper investigates the effects of infill walls on seismic performance of the existing RC residential buildings by considering requirements of the Turkish Earthquake Code (TEC). Seismic performance levels of residential RC buildings with and without walls in high-hazard zones were determined according to the nonlinear procedure given in the code. Pushover curves were obtained by considering the effect of masonry infill walls on seismic performance of RC buildings. The analysis results showed that the infill walls beneficially effected to the rigidity, roof displacements and seismic performance of the building.

Investigation of the effects of geometrical parameters on heat transfer from buried finned pipes

Hakan Demir,Ahmet Koyun,S. Özgür Atayılmaz,Özden Ağra,Ahmet Selim Dalkılıç 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.8

Heat transfer from finned pipes buried in the soil has been investigated using experimental, analytical and numerical techniques. The experimental setup consists of a ground source heat pump system and two separate ground heat exchangers. Constant surface temperature approach based on Carslaw and Jaeger’s theory study was used for calculating the heat transfer from the pipes analytically. The problem was modeled and solved using a CFD program numerically. Effects of the fin number, fin length and simulation time on the heat transfer rate have been investigated and compared with bare tube. A modified analytical formula was also proposed for finned pipes in this study.

Experimental and numerical investigation of walls strengthened with fiber plaster

Hakan Basaran,Ali Demir,Muhiddin Bagcı,Sefa Ergun 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.56 No.2

The topic of this study is to investigate behaviors of masonry walls strengthened with reinforced fiber plaster under diagonal tensile loads. Full blend brick 100×50×30 mm in dimensions were used to make masonry walls with dimensions of 400×400×100 mm. Three different samples were manufactured by plastering masonry walls with traditional style, with 3% polypropylene or with 5% steel fiber. All the samples were tested using ASTM 1391- 81 standards. The propagation of damage on samples caused by diagonal tensile load was observed and load-displacement graphs were plotted for each sample. A finite element software (ABAQUS) was used to obtain numerical values for all samples and crack patterns and load-displacement responses were obtained. Experimental and numerical results were compared.

Atrial Septal Defect Closure: Comparison of Vertical Axillary Minithoracotomy and Median Sternotomy

Huseyin Hakan Poyrazoglu,Mustafa Kemal Avsar,Şerafettin Demir,Zeynep Karakaya,Tayfun Güler,Funda Tor 대한흉부외과학회 2013 Journal of Chest Surgery (J Chest Surg) Vol.46 No.5

Background: This study aims to evaluate whether or not the method of right vertical axillary minithoracotomy (RVAM) is preferable to and as reliable as conventional sternotomy surgery, and also assesses its cosmetic results. Methods: Thirty-three patients (7 males, 26 females) with atrial septal defect were admitted to the Cardiovascular Surgery Clinic of Cukurova University from December 2005 until January 2010. The patients’ ages ranged from 3 to 22. Patients who underwent vertical axillary minithracotomy were assigned to group I, and those undergoing conventional sternotomy, to group II. Group I and group II were compared with regard to the preoperative, perioperative and postoperative variables. Group I included 12 females and 4 males with an average age of 16.5±9.7. Group II comprised 14 female and 3 male patients with an average age of 18.5±9.8 showing similar features and pathologies. The cases were in Class I–II according to the New York Heart Association (NYHA) Classification, and patients with other cardiac and systemic problems were not included in the study. The ratio of the systemic blood flow to the pulmonary blood flow (Qp/Qs) was 1.8±0.2. The average pulmonary artery pressure was 35±10 mmHg. Following the diagnosis, performing elective surgery was planned. Results: No significant difference was detected in the average time of the patients’ extraportal circulation, cross-clamp and surgery (p>0.05). In the early postoperative period of the cases, the duration of mechanical ventilator support, the drainage volume in the first 24 hours, and the hospitalization time in the intensive care unit were similar (p>0.05). Postoperative pains were evaluated together with narcotic analgesics taken intravenously or orally. While 7 cases (43.7%) in group I needed postoperative analgesics, 12 cases (70.6%) in group II needed them. No mortality or major morbidity has occurred in the patients. The incision style and sizes in all of the patients undergoing RVAM were preserved as they were at the beginning. Furthermore, the patients of group I were mobilized more quickly than the patients of group II. The patients of group I were quite pleased with the psychological and cosmetic results. No residual defects have been found in the early postoperative period and after the end of the follow-up periods. All of the patients achieved functional capacity per NYHA. No deformation of breast growth has been detected during 18 months of follow-up for the group I patients, who underwent RVAM. Conclusion: To conclude, the repair of atrial septal defect by RVAM, apart from the limited working zone for the surgeon in these pathologies as compared to sternotomymay be considered in terms of the outcomes, and early and late complications. And this has accounted for less need of analgesics and better cosmetic results in recent years.

Shear stress indicator to predict seismic performance of residential RC buildings

Hamide Tekeli,Hakan Dilmac,Fuat Demir,Mustafa Gencoglu,Kadir Guler 사단법인 한국계산역학회 2017 Computers and Concrete, An International Journal Vol.19 No.3

A large number of residential buildings in regions subjected to severe earthquakes do not have enough load carrying capacity. The most of them have been constructed without receiving any structural engineering attention. It is practically almost impossible to perform detailed experimental evaluation and analytical analysis for each building to determine their seismic vulnerability, because of time and cost constraints. This fact points to a need for a simple evaluation method that focuses on selection of buildings which do not have the life safety performance level by adopting the main requirements given in the seismic codes. This paper deals with seismic assessment of existing reinforced concrete residential buildings and contains an alternative simplified procedure for seismic evaluation of buildings. Accuracy of the proposed procedure is examined by taking into account existing 250 buildings. When the results of the proposed procedure are compared with those of the detailed analyses, it can be seen that the results are quite compatible. It is seen that the accuracy of the proposed procedure is about 80% according to the detailed analysis results of existing buildings. This accuracy percentage indicates that the proposed procedure in this paper can be easily applied to existing buildings to predict their seismic performance level as a first approach before implementing the detailed and complex analyses.

A new approach to determine the moment-curvature relationship of circular reinforced concrete columns

Naci Caglar,Aydin Demir,Hakan Ozturk,Abdulhalim Akkaya 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.15 No.3

To be able to understand the behavior of reinforced concrete (RC) members, cross sectional behavior should be known well. Cross sectional behavior can be best evaluated by moment-curvature relationship. On a reinforced concrete cross section moment-curvature relationship can be best determined by both experimentally or numerically with some complicated iteration methods. Making these experiments or iterations manually is very difficult and not practical. The aim of this study is to research the efficiency of Neural Networks (NN) as a more secure and robust method to obtain the moment-curvature relationship of circular RC columns. It is demonstrated that the NN based model is highly successful to determine the moment-curvature relationship of circular reinforced concrete columns.

Author's reply

Sencan, Savas,Edipoglu, Ipek Saadet,Demir, Fatma Gul Ulku,Yolcu, Gunay,Gunduz, Osman Hakan The Korean Pain Society 2020 The Korean Journal of Pain Vol.33 No.4

Are steroids required in the treatment of ganglion impar blockade in chronic coccydynia? a prospective double-blinded clinical trial

Sencan, Savas,Edipoglu, Ipek Saadet,Demir, Fatma Gul Ulku,Yolcu, Gunay,Gunduz, Osman Hakan The Korean Pain Society 2019 The Korean Journal of Pain Vol.32 No.4

Background: Ganglion impar blockade is a reliable and effective treatment option used in patients with coccydynia. Our primary objective was to specify the role of corticosteroids in impar blockade. We compared applications of local anesthetic with the local anesthetic + corticosteroid combination in terms of treatment efficiency in patients with chronic coccydynia. Methods: Our study was a prospective randomize double-blind study. The patients were divided into 2 groups after randomization. The first group (group SL) was made up of patients where a corticosteroid + local anesthetic were used during ganglion impar blockade. In the second group (group L) we used only local anesthetic. We evaluated numeric rating scale (NRS) and Beck depression scale, which were employed before the procedure and in 1st and 3rd months after the procedure. Results: Seventy-three patients were included in the final analysis. We detected a significantly greater decrease in NRS values in the 1st month in group SL than in group L (P = 0.001). In the same way, NRS values in the 3rd month were significantly lower in the group with steroids (P = 0.0001). During the evaluation of the Beck test, we detected significantly greater decreases in the 1st month (P = 0.017) and 3rd month (P = 0.021) in the SL group than in the L group. Conclusions: Ganglion impar blockade decreases pain in the treatment of chronic coccydynia and improve depression. Addition of steroids in a ganglion impar blockade is required for treatment response that should accumulate over a long period of time.

TEMPO-treated CNF Composites: Pulp and Matrix Effect

Bayram Poyraz,Ayhan Tozluoğlu,Zeki Candan,Ahmet Demir,Mustafa Yavuz,Ümit Büyuksarı,H. İbrahim Ünal,Hakan Fidan,Rasim Cem Saka 한국섬유공학회 2018 Fibers and polymers Vol.19 No.1

This study examined the effects of matrix (PVA and Si) on the properties of TEMPO-treated nanocomposites preparing from different pulp sources (Kraft and NaBH4 treated Kraft). Chemical characterization and crystallization were determined via FT-IR, thermal stability via TGA and morphological alterations via SEM. UTM and DTMA were used to measure the Young’s and storage moduli. The real and imaginary parts of permittivity and electric modulus were evaluatedusing an impedance analyzer. After interaction, prominent vibrations and alteration of crystallinity were seen. Storage and Young’s moduli decreased after Si and PVA interaction. The Si-TOCN films showed higher permittivity properties and all of the films followed a similar trend of significantly dropping ε' and ε'' values at high frequency. The PVA-TOCN films had mechanical advantages at room temperature compared to the Si-TOCN films. However, the Si-TOCN films had better thermomechanical properties at high temperatures. NaBH4 revealed favorable effects on mechanical properties of the films.

Novel Directions in Adjuvant Chemotherapy for Early Stage Epithelial Ovarian Cancer

Sakarya, Derya Kilic,Yetimalar, M Hakan,Ozbasar, Demir Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.10

Treatment of early stage ovarian cancer remains controversial despite advances in chemotherapeutic options. Over the past 30 years, molecular and clinicopathologic studies accelerated and treatment of ovarian cancer has undoubtedly improved although there is a debate as to whether this impacts outcome or not. More recently, the introduction of targeted therapy started a new era. Probably it is because early stage disease comprises a small portion of the epithelial ovarian cancer, studies have mostly ignored this group and still there is no clear consensus regarding systemic treatment of early-stage lesions. However this group of patients has the best chance of cure. In this review, we focus on current developments in the treatment of early stage ovarian cancer and query the options.