Performance Evaluation of Yielding Pipe in Pipe Damper by Using Incremental Dynamic Analysis

Using of passive dampers is one of the common method to improve dynamic characteristics of structures and reduce the earthquake force. The Philosophy of such dampers is using of interchangeable energy absorbing devices to focus damage on them in the hope that reducing structural damage in the other main members. Suitable seismic performance, relatively low price and ease in design and implementation are their benefits, but invariant performance parameters proportional to the type and amount of input energy decreases their efficiency. In this study, at first a new multi stage passive damper with variable stiffness, strength and energy absorption capacity is introduced and its performance in three 5, 10 and 15 floors frames is evaluated by incremental nonlinear dynamic analysis using the SAP2000 software. Results indicate that despite of differences in dynamic parameters of selected seismic records such as duration and frequency content, structural performance has been significantly improved which proved new damper effectiveness on improving the seismic performance of structures. Besides, results show the structural performance levels improvement and increasing its energy absorption capacity. The first mode spectral acceleration of moment frame structures reached to 4.75g, 4.53g and 3.36g respectively for 5, 10 and 15 story frames which confirms the downtrend by increasing the number of stories. Moreover, the related amounts in the structures equipped by new damper, obtained 5.95g, 4.98g and 3.93g respectively. Comparing the median values, revealed significant differences in the behavior of moment frames and frame equipped by proposed damper such that increasing the spectral acceleration and relative displacement causes horizontal part in the moment frame IDA graphs due to the lack of lateral stiffness. But, in all three damper structures, performance enhancement and relative displacement decrement is visible and even at the end of the IDA graphs, there are remarkable capacity to cope with lateral forces. According to the results, the proposed damper despite its simplicity, applicability and relatively low cost, demonstrates good performance in reducing the input energy and seismic vibrations of structures.