Deprem Güvenliği Tarama Yöntemi Ve Bir Uygulama

Abstract

Ülkemizin jeolojik konumu incelendiğinde sismik aktivite bakımından yoğun bir bölgede olduğu görülmektedir. Tam bir deprem ülkesi olarak görülen ülkemizde, olası bir sismik etkiye maruz kalan yapıların bu etkiyi karşılayıp karşılayamayacağı sorusu önemlidir. Deprem mühendisliği açısından mevcut yapıların depreme karşı performansı önem teşkil etmektedir. Olası bir depremden sonra mevcut bina stoğunun sayısını göz önünde bulundurduğumuzda klasik yöntemler ile performans değerlendirmesinin yapılmasının uzun süreceği görülmektedir. Süreyi kısaltmak adına kurulacak olan bir ekibinde ekonomik olarak pratik olmayacağı aşikardır. Hızlı tarama yöntemleri ile kısa sürede çok sayıda bina stoğunun incelemesi yapılarak binaların deprem performansları hakkında yorum yapılabilir. Risk unsuru taşıyan binalar hızlıca taranarak, oldukça fazla olan mevcut yapı stoğundan diğerlerine oranla dayanıklı olan binalar ayıklanır. Göçme risk unsuru bulunan binalara detaylı analizde öncelik verilmesi sağlanır. Sunulan bu tez çalışmasında, hızlı tarama yöntemi olarak dünyaca kabul görmüş hızlı değerlendirme yöntemlerinden biri olan Japon Sismik İndeks Yöntemi’nin ülkemiz koşullarına uyarlanması ile geliştirilmiş Deprem Güvenliği Tarama Yöntemi (DGTY) kullanılmıştır. Beş bölümden oluşan yüksek lisans tezinin birinci bölümü, konunun açıklanmasına ayrılmış, çalışmanın amacı ve kapsamı hakkında bilgi verilmiştir. İkinci bölümde, uygulamada ve literatürde kullanılan ATC 21, FEMA 310 ve P25 yöntemleri de Japon Sismik İndeks Yöntemi ile birlikte genel olarak incelenmiştir. Üçüncü bölümde, Deprem Güvenliği Tarama Yöntemi detaylı bir şekilde açıklanmıştır. Dördüncü bölümde, incelenen binanın özelliklerinden genel olarak bahsedilmiştir. Bina Deprem Güvenliği Tarama Yöntemi ve Doğrusal Elastik Yöntemler ile çözülmüştür. Elde edilen sonuçlar kıyaslanmıştır. Beşinci bölümde ise, yapılan çalışmalardan elde edilen bulgular değerlendirilip karşılaştırılmıştır. Sonuç olarak tezde çalışması yapılan bina, DBYBHY-07 Bölüm 7’de verilen kurallar uygulanarak uzun ve ayrıntılı analiz gerektiren hesaplamalarla çözüldüğünde performans seviyesinin yeterli olduğu görülmektedir. Aynı zamanda RBTE ile yapılan çalışmada bina “Risksiz” bulunmuştur. Binanın RBTE ile çözümü her ne kadar DBYBHY-07’ye göre daha pratik olsada, iki yöntem ile de yapılan çalışmalar uzun zaman ve emek almaktadır. Deprem Güvenliği Tarama Yöntemi ile yapılan hesaplamalarda elde edilen bulgular, bahsi geçen iki yönteme nazaran daha ekonomik ve kısa sürede benzer analiz sonuçlarını vermektedir.

Considering seismic activity in our country, many casualties and constructional damage due to the earthquake seems to occur. Thus emerged the importance of the seismic performance of existing buildings. As a result of the earthquakes heavy damages and collapsing were occurred in our country.This shows that existing constructions do not have sufficiently seismic safety. After the examinations of the recent earthquakes, many shortcomings have been identified in the damaged buildings.These determinations shows us that the safety of existing buildings are not sufficent. Considering the number of the existing buildings after a pottential earthquake, it takes long time to make performance assessment with the current methods. A team that will be established in order to shorten the time it is obvious that economically impractical. It is possible to make comments for seismic performance of numerous buildings with the investigation rapid screening methods in a little while. With this method risk factors bearing buildings quickly scanned into numerous existing buildings and the durable buildings can be divided than others. In this way it is given priority to a detailed analysis on the buildings which have collapsing factor. In this study, a rapid screening method is presented Seismic Safety Screening Method, is an adaptation of the Japanese Seismic Index Method. An application has been made with use this method. An the results have been compared with linear elastic method results. In the first chapter of this thesis, which consists of five chapters, explanation of the subject, purpose and scope are given. In the second chapter, some other seismic performance evaluation methods are also mentioned such as ATC 21, FEMA 310 and Japanese Seismic Index Method explained. In the third chapter, Seismic Safety Screening Method has been studied. In the four chapter, the building which is investigated in this study is examined. A two story reinforced concrete building is evaluated for seismic performance by using Seismic Safety Screening Method. The results compared with linear elastic method results. In the five chapter, results obtained by Seismic Safety Screening Method and Linear Methods from the previous chapter are given and discussed in detail. ATC 21 is easy to apply and less costly method. It is not necessary any of static analysis and allows establishing the buildings which will be able to damaged during an earthquake quickly. The screener collects building informations with visual observation of the building. The collected data are documented in the form of data collection (processed). The Data Collection Form includes space for documenting building identification information. Firstly before starting to quick scan, the proper data form is selected for the earthquake zone. General information and soil conditions which are obtained with the research to record on the form. The Basic Structural Risk Point is determined for each building according to structural system of building , the structure of the material and depending on the earthquake zone. The observed performance characteristics points are determined such as irregularities , soil type and number of stories. These identified points are added to basic structural risk points or removed from the basic structural risk points according to the earthquake effects. Thus, the recent structural points (S) of the characterized the seismic behavior are obtained. It needs a limit point for the interpretation of this identified point. In this method , this limit point is given as 2. The expected seismic performance in despite of earthquake loads is the acceptable level if the building has more than 2 of S score. Buildings having an S score of 2 or less should be investigated by a design professional experienced in seismic design. FEMA 310 is intended for the purpose of the seismic performance of existing buildings by ASCE for FEMA. All structural seismic performance of buildings are determined by the basic soil and non-structural features. This method consists of three levels of review process for each earthquake zone. This investigation stages, the building can be evaluated according to any of life safety or immediate use performance levels. Japanese Seismic Index Method is rapid assessment methods used in order to improve the seismic safety of existing buildings and determining capacity. It is based on investigate the buildings in place and making structural analysis. This method can be applied for structures having a story number 6 or less with reinforced concrete frame, shear wall or dual frame-shear wall structural systems. Results obtained using this method allows for the observation of possible seismic performance of the building during earthquake. The method has three different stages which gives more realistic results and requires further investigation and accountability. Seismic Safety Screening Method has been developed considering the building damages in recent earthquakes such as 1992 Erzincan, 1998 Adana-Ceyhan, and 1999 Kocaeli and Düzce Earthquakes and Turkish Seismic Design Code. Seismic Safety Screening Method is rapid screening method which is developed by considering the first two stages of the the Japanese Seismic Index Method. In this method , the performance of the building’s structural-load-resisting factors expressed by coefficients defined according to certain criteria. These coefficients are determined by from the static calculations and data obtained of the observed building. Representing seismic structural performance I-index is calculated. The calculated I-index and comparison ID-index are compared separately for all the critical floor and two prime earthquake direction and the earthquake resistance of building is determained. The seismic performance of the building is an acceptable level if I-index is greater than the ID-index. Otherwise, seismic safety of building is critical and more detailed research should be done. Seismic Index Screening Method and Japan Seismic Screening Method give seismic capacity index of buildings. Both methods are checked against demand index. At Seismic Index Screening method, the seismic capacity index gives effective information to quantitative understanding, not a subjective assesment data. This index is modified by lots of coefficients that reflect the quality of materials and workmanship, and the faeture of Turkey’s buildings. The calibration of coefficients proposed method have been done by considering the studiescarried out Zeytinburnu. Dynamic or non linear analyses results of several existing buildings are used to calibrate coefficients. The data gathered after recent earthquakes indicated the average concrete compressive strength is as low as 10 MPa and the amount of longitudinal reinforcement bar is %1 of gross cross sectional area of columns with the tensile strength of 220 MPa on the large number of the buildings. Due to these facts some assumptions were made to simplify the quick assessment procedure. If the investigation building construction material information are avaible actual values also could be used in this screening method.