بهسازي لرزه يي ساختمان هاي موجود با استفاده از سيستم ستون هاي پيونديافته

SEISMIC REHABILITATION OF EXISTING BUILDINGS BY LINKED COLUMN SYSTEM

در اين تحقيق به ارزيابي عملكرد لرزه يي سيستم ستون هاي پيونديافته به عنوان يك سيستم باربر جانبي ثانويه پرداخته شده است. ستون هاي پيونديافته ايده يي جديد از يك سيستم باربر جانبي است كه مي تواند در بهسازي ساختمان هاي موجود مورد استفاده قرار گيرد و باعث افزايش ظرفيت باربري ساختمان در برابر بارهاي ناشي از زلزله شود. در اين تحقيق براي بهسازي ساختمان هاي موجودي كه از ظرفيت باربري جانبي كافي برخوردار نيستند، از سيستم ستون هاي پيونديافته استفاده شده است. سپس ظرفيت غيرارتجاعي، قابليت حفظ پايداري و سازوكار خرابي مدل هاي بهسازي شده با استفاده از روش هاي غيرخطي مورد بررسي قرارگرفته است. نتايج حاصل از اين تحقيق نشان مي دهد كه سيستم ستون هاي پيونديافته از قابليت تامين مقاومت جانبي لازم براي ساختمان هاي فاقد مقاومت جانبي كافي برخوردار است. اين سيستم در يك طرح بهينه با قابليت جذب و استهلاك انرژي بالا و اشغال فضايي كم، بدون نياز به ايجاد تغيير يا مقاوم سازي در اعضاي سازه يي، كمبود مقاومت جانبي ساختمان را جبران مي كند.

In this research, the seismic performance of a linked column system is evaluated as a secondary lateral resisting system. The linked column is a new idea of the lateral resisting system that can be used in seismic rehabilitation of existing buildings and increases the lateral load-carrying capacity of buildings against the earthquake load. Moreover, this research used the linked column system for the seismic rehabilitation of existing buildings, which do not have adequate lateral load resisting capacity. For this purpose, several models are designed in 3, 6 and 9 stories with 40, 60, and 80 percents of the required lateral load resisting capacity in a special concentrically braced frame and special moment-resisting frame systems. Then, the linked column as a secondary lateral resisting system was added to the first models for supplying the required lateral load-carrying capacity. After the evaluation of rehabilitated models with nonlinear static pushover analysis, the results show that the increased capacity of models using the linked column system is possible, and rehabilitated models have adequate capacity for lateral loads. In the next part, the capacity of structural stability and collapse mechanism of rehabilitated models have been evaluated by using nonlinear dynamic time history analysis under the 14 ground motion records that scaled to the base design earthquake. The coming results are indicated based on the maximum inter-story drift of models. Based on these results, the mean value of maximum inter-story drift for all models is below 2 percent, and rehabilitated models have the capability of structural stability against the earthquake records. The plastic hinges spreading and beginning (collapse mechanism) in nonlinear analysis show that the secondary linked column system has a good interaction with the first system of models. Based on these results, linked column system has the capability to provide an increase in the lateral load-carrying capacity of buildings in an optimum design with high energy absorption and dissipation, while low space occupancy is considered and also without requirement of changing or retrofitting structural members. Thus, the linked column system is presented as a convenient choice for the existing buildings seismic rehabilitation.