جستجوی مقالات مرتبط با کلیدواژه « سیستم دوگانه فولادی » در نشریات گروه « عمران »

From experimental researches and analytical studies, it has been fully proven that the resistance and stiffness parameters of elements and structures decline during cyclic loading due to the dynamic nature of seismic excitations. The simultaneous effect of the magnitude of the system response and the number of loading cycles is expressed by cumulative damage laws; In other words, the current deformation of an element or structure depends on the accumulation of damage in all past oscillations that remain in the system's memory. The analysis and design of structures based on performance and the branch of health monitoring of structures has led to having a clear picture of the amount of possible damage at different levels of risk, and in the last few decades, it has drawn the attention of many researchers to this field by developing different evaluation methods. In this research, the evaluation of the cumulative damage of steel structures under far and near field earthquakes has been investigated using Park-Ang and Kratzig damage indices. Two structural systems of special steel moment frame and dual structural system (special steel moment frame and special concentric braced frame) with the number of floors 8, 15 and 23 were studied and investigated. The results of this research show that the Kratzig damage index shows more damage values than the Park-Ang damage index for the same structure under the same earthquake record, and the damage values are reduced by changing the moment frame system to a dual structural system.

Steel moment frame and bracing panels compound structures are suitable systems for medium-height resistant skeletons due to their desirable ductility along with high rigidity when facing large dynamic forces caused by earthquakes. In this research, the seismic behavior of two 10-story buildings with compound systems of moment frame/eccentrically braced frames as well as moment frame/eccentrically braced frame with zipper elements are evaluated. The evaluation and changes of the seismic response parameters of the studied models are based on performing nonlinear time history analyses. The studied models are designed according to the fourth edition of seismic design provisions in Code 2800, plus the 6th and 10th issues of the Iranian National Building Regulations. Following the results of this research, it has been recognized that the existence of large coherent pulses in the time history of powerful earthquakes affects the response parameters of the building to a great extent. The results of this research includes the analytical process in the graphs related to maximum push of the drift, floors acceleration and velocity of the studied structural models and also the time history of story’s drift and axial force of the columns. The results show that seismic responses and demands under near-field records have a bigger appearance than the corresponding effects obtained exposed to far-field records.