Ali Koçak

Estimation of the Fundamental Vibration Period of Existing RC Buildings in Turkey Utilizing Ambient Vibration Records

Earthquake design codes generally provide empirical formulae or various approximations for determining fundamental periods of buildings for the evaluation of statically equivalent seismic forces. It is thus important to use realistic periods for the design and performance assessment of existing buildings. This study deals with the evaluation of fundamental vibration periods of reinforced concrete (RC) buildings having a frame-type structural system, and considers the effects of infill walls. The problem is evaluated by utilizing experimental and analytical approaches. A height-dependent relationship to estimate the fundamental period of vibration of Turkish RC moment-resisting frames is derived for a fully elastic condition. Furthermore, a constant parameter is defined to magnify the empirical relationship in order to attain code-specified periods obtained by considering moderate-intensity earthquakes.

Effects of Infill Wall Ratio on the Period of Reinforced Concrete Framed Buildings

Realistic estimates of the earthquake induced natural period of reinforced concrete buildings lead to enhanced reliability in design. Several national building codes and researchers have suggested various empirical formulas and approximations to predict the fundamental natural period of buildings with or without infill walls. In this paper, the effect of infill walls on the natural vibration period of framed reinforced concrete buildings is investigated. Reinforced concrete framed buildings of various storey heights and different infill wall ratios are modeled to examine the effect of the infill walls on the general behavior of the structures. Linear solutions for the structures are performed and their basic vibration periods are determined. As a result of there analyses, a new relationship for the changes in the building periods according to the infill wall ratio is developed for reinforced concrete framed buildings. The predictions of the proposed relation and other correlations found in the codes of various countries are compared.

Investigation of Earthquake Behavior of the Church of St. Sergius and Bacchus in Istanbul/Turkey

In this study The Church of St. Sergius and Bacchus was modeled by Finite Element Method and was put through various tests to determine its structural system, earthquake behavior and structural performance. The geometry of the structure, its material resistance and ground conditions isn’t enough to model a historical structure. Additionally, you need to calculate the dynamic charac-teristics of the structure with an experimental approach to come up with a more realistic and reliable model of the structure. Therefore, a measured drawing of the structure was acquired after detailed studies, material test-ing were made both at summer and winter to examine the seasonal changes and soil conditions were determined by bore holes and exploratory wells dug around the structure. On the other hand, vibra-tion tests were made at The Church of St. Sergius and Bacchus to analyze the structural characteris-tics and earthquake behavior of the building. Structural modeling of the building, modeled by the Finite Element Method, was outlined by determining its free vibration analysis in compliance with experimental periods. Vertical and earthquake loads of the structure were determined by this model. Keywords: Finite element method, earthquake behavior, church

Structural model calibration of RC structure with two-leaf cavity brick infill wall by deterministic approach

An adaptive solution for updating structural model of a RC structure with two-leaf cavity brick infill wall under flexible boundary problem is presented in this paper. The structure was simulated with Diana 9.4.4 finite element software. Next, an elastic foundation with interface elements was used to overcome this stiffness problem of the foundation. The validation of the structure was made with the optimization based modal updating using MATLAB. Five calibration types were performed and compared with experimental data.

Effect of infill wall and wall openings on the fundamental period of RC buildings

The effect of infill walls to stiffness of the structures has been known for a long time and this effect has taken many of the earthquake regulations with empirical relationships and equations into account. However, in strength-based calculations, buildings are taken as bare frames and infill walls are effected as vertical load to system, whereas infill walls contribute to stiffness at the beginning of the earthquake and help meet seismic loads by incurring damage during an earthquake. In this study, contribution of infill walls to stiffness of the structure was analyzed in reinforced concrete framed and load-bearing buildings. Also, the effect of openings in the infill walls to stiffness was examined.

Restoration and Strengthening of a Historical Structure in Antalya - Turkey

Protection and restoration of historical structure has a big importance to transfer past from future. It is necessary to protect all materials and documents that includes past culture, life style and life art in purpose of human history. Structures that used in past, is most important of these materials. Protection of historical structures that reflect to history of period and is historical artifact is also important because of emphasized reason. There are many historical structures in different region of Turkey. Some structuring especially show all cultural structure of that period and stand erect as grand monument. But in the length of time these type structures abrade and lose their nature, because of natural or other reason. After ever earthquake, almost each historical structures have permanent damages in Turkey which is earthquake area. For this reason, It is necessary to transfer future these historical structures by strength and repairing to discover local earth conditions and equipments that used in structure against to earthquake and other affects, determining damaged condition, determining system of architecture and conveyer to these historical structures On the other side, protection of structure can be provided with help of increasing functionality. Unused and closed historical structure will abrade and because of natural and other affects, it will damages and becomes unused. So, basic protection is to use and repair periodically to these historical structures. In near future, protection and restoration of historical structures get importance in Turkey. Many historical structures start to handle for this propose, works pick up speed for restorations. Mustafa Kemal primary school which used as school long time, and completed construction in 1910 Antalya-Turkey, is other important cultural heritage. Accumulation school building has basement, ground floor, and 1.floor. Because of floor height, basement has not been used. Other two floors have been used for common room, laboratory and toilet. In this work, after building survey of historical building used for school had been taken, equipment used in building had been confirmed and local earth condition had been determined, according to exist Turkish Regulations building analyze had been done. According to lacks of structure, it had been invigorated. For propose of implementation of architecture style to period, all added parts had been restored and renewed to damaged parts. Keywords: Restoration, strengthening, historical structure

Disasters and earthquake preparedness of children and schools in Istanbul, Turkey

Unless decision makers urgently exhibit a proactive approach to earthquake preparedness, Istanbul will be the most vulnerable city for the expected great Marmara Earthquake and Tsunami. Because Istanbul has the highest population density (larger than some European countries) and is the commercial/industrial centre of Turkey, the high seismic potential of the North Anatolian Fault (NAF) in the Sea of Marmara is a great risk for Istanbul. The Kocaeli and the Düzce earthquakes, which were the last two seismic events to occur in the eastern part of Marmara in 1999, dramatically demonstrated the vulnerability and lack of awareness and preparedness of Istanbul and the Marmara region for natural disasters. Although Istanbul is 90 km from the epicentre of the earthquake that occurred in 1999, it caused severe damage to many buildings and great loss of life. An earthquake of even greater magnitude is now expected to occur within the submarine fault system that extends west of the 1999 ruptured segments under the Sea of Marmara which is near Istanbul. Although Istanbul is susceptible to seismic hazards and a destructive earthquake and tsunami are anticipated to occur in the Marmara Sea, necessary seismic risk mitigations have not been taken. Disaster preparedness studies, which are conducted by the government and the municipality of Istanbul, are not sufficient or rapid enough. School students, especially, in their unsafe school buildings, are the most vulnerable to earthquakes. The disaster-related issues are so serious because of the students >23 million in Turkey or ∼4 million students in Istanbul, and frequently repeated disaster events.

A study of the earthquake-resistance of masonry buildings constructed with local materials

Masonry buildings constitute most of the buildings in our country. Although they are used both in rural areas and city centres, supplying the material around the building area is an important factor. Thus, especially in the countryside these types of buildings are more preferable but there may be problems under dynamic loads such as horizontal loads and earthquake when some rules in architecture are not obeyed. During this study, many different masonry buildings in many different regions of Turkey were discussed, the materials using in those buildings were examined, and their earthquake resistances were evaluated by using the finite elements technique in terms of seismicity and building models. As a result of the study, the earthquake resistance of buildings which were constructed with different materials in different regions of Turkey were determined, and the reinforcements of buildings having a lack of earthquake resistance and their situations after reinforcement were determined.