ارزيابي كيفي آسيب پذيري لرزه اي ساختمانهاي شهر بندرعباس

Qualitative Seismic Vulnerability Evaluation of Buildings in Bandar Abbas

در اين تحقيق، با انجام برداشتهاي ميداني براي حدود 550 ساختمان مختلف در شهر بندر‌عباس، مقايسه‌اي اجمالي ميان تعدادي از روشهاي ارزيابي آسيب‌پذيري موجود صورت گرفته و با بررسي و مقايسه‌ نتايج ارزيابي آسيب‌پذيري توسط چهار روش منتخب بر روي داده‌هاي مربوط به 30 ساختمان نمونه، روش ارزيابي آسيب‌پذيري آريا به همراه اصلاحاتي در جدول مربوط به آن، به عنوان روش نهايي انتخاب شده است. در ادامه، شاخص خسارت مربوط به تمامي ساختمانهاي برداشت‌شده با روش نهايي محاسبه شده و ميانگين اين شاخصها در شدت‌ 7 تا 9 در مقياس MSK ، براي انواع مختلف ساختمانها، به صورت نمودارهايي بر حسب شدت و PGA ترسيم شده است. سپس ساختمانهاي برداشت‌شده به نحو مناسبي بر روي نقشه شهر پياده شده و نقشه آسيب‌پذيري لرزه‌اي به دست آمده است. به موجب اين تحقيق، بيش از 98 درصد ساختمانهاي بنايي فاقد كلافبندي در برابر يك زلزله با شدت 8 تخريب مي‌شوند. عملكرد ساختمانهاي بتن‌مسلح با قاب خمشي مشابه ساختمانهاي فلزي با مهاربند مي‌باشد. حدود 60 درصد اين ساختمانها در زلزله‌هاي با شدت 8، خسارت متوسط و 75 درصد آنها در زلزله‌هاي با شدت 7، خسارت كمي مي‌بينند.

In order to approach general guidelines to improve existing conditions of buildings, it is necessary to predict and evaluate the seismic vulnerability of existing buildings due to future earthquakes. Most constructed buildings in cities like Bandar Abbas/ Iran are seismically vulnerable because of shortcomings of previous codes, changing application, adding new stories, using weak materials, insufficient supervision, lacking expertise and experience of technicians and so on. Due to aggressive corrosion environment in Persian Gulf, existing steel and reinforced concrete structures have more critical conditions in terms of seismic vulnerability. In this study after reviewing the various typical methods for qualitative seismic vulnerability evaluation of existing buildings, four selected methods are compared to investigate seismic vulnerability of 30 sample buildings. Then, the Arya method has been selected as the proper qualitative evaluation method due to most typical building systems in the area, large volume of data and the need for fast and easy evaluation. Considering masonry buildings as the majority of existing structures in Bandar Abbas and compatibility of the Arya method with these buildings and its success in other provinces of Iran, using this method with some relevant modifications based on past experiences was considered the best alternative. Finally, about 550 different buildings in Bandar Abbas have been seismically evaluated by this method and the average damage index values for each kind of structures were illustrated in charts. Also the results were shown graphically on the city map for different building structures subjected to earthquakes with MSK7 intensity. Based on the obtained conclusions, over 98% unreinforced masonry buildings without required bands will be destroyed due to MSK8 intensity. The result for 60% of concrete moment frame structures is moderate damage in MSK8 and for 75% of them is low damage in MSK7. Steel braced structures do almost the same as concrete frames. The concrete moment frame structures with concrete shear walls show the best result which is low damage in MSK8 intensity.