شقايق پاك نيت

Structures located in seismically active areas are often exposed to earthquakes containing the phenomenon of seismic sequence. This phenomenon generally refers to a situation where several earthquakes occur consecutively in the same area in a short period of time (several days or weeks). In fact, this phenomenon is described by a main earthquake with medium-high intensity, which after a short time is accompanied by earthquakes with comparable intensity to the main earthquake. In this thesis, the effect of successive critical earthquakes on the displacement amplification factor of reinforced concrete frames has been investigated. In this regard, firstly, the phenomenon of seismic sequence has been introduced and the need to consider it in the design process of structures has been mentioned. Studies show that aftershocks that occur after the main earthquake increase the rate of damage and death of residents. On the other hand, due to the preva‎lence of concrete structures due to the very quick and easy use of these structures, the background of the research investigated in this thesis is to investigate the seismic performance of these structures under successive earthquakes in the form of ductility, damage index, growth and development of plastic joint and displacement in It is exposed to successive earthquakes that have been mentioned earlier in the technical literature. After the selection of consecutive earthquakes, the steps of extracting and calculating the displacement amplification factor have been introduced and this factor has been calculated for all concrete frames after performing dynamic analysis in two states of linear and non-linear behavior under single and successive earthquakes. During the calculations, it was observed that the phenomenon of the seismic sequence has led to an increase in the displacement amplification factor of the studied frames. The average total Cd is equal to 3.5 in single mode and 3.7 in sequential mode. Therefore, it can be concluded that the value of Cd suggested in standard 2800 is suitable for medium concrete bending frames (equal to 4.5) to face successive earthquakes.

پديده توالي لرزه‌اي , ضريب بزرگ‌نمايي تغييرمكان , پس لرزه هاي بحراني , تحليل ديناميكي غيرخطي

Successive Earthquakes , Displacement Amplification Factor , Critical Aftershocks , Nonlinear Dynamic Analysis

Shaghayegh Pakniat

Gholam Reza Ghodrati Amiri