This paper investigates the seismic behavior of steel moment-resisting frames equipped with a newly developed brace-type damper system, comprising replaceable energy-dissipating pipe elements and supporting cruciform and box elements, and proposes appropriate seismic design factors for implementing such systems within code-based design frameworks. For this purpose, structural models with and without the damper system are developed in OpenSees. The study also evaluates two distinct patterns for allocating pipe elements within the braces in order to estimate the required quantity and to examine their impact on structural performance. An iterative design method, integrated with incremental dynamic analysis (IDA), is employed to quantify the seismic design factors of the system, such as reduction factor due to ductility, overstrength, response modification, and displacement amplification. Fragility curves are subsequently developed to evaluate the likelihood of damage in the analyzed models. The findings indicate the excellent performance of the dual systems, with the first-mode-based distribution of pipe dampers increasing the response modification factor by about 87% compared to the moment-resisting frame. For intermediate steel moment-resisting frames equipped with dampers arranged according to the first mode shape, the overstrength, response modification, and displacement amplification factors are approximately 2.28, 8.57, and 5.42, respectively. The analysis also shows that the first-mode-based distribution performs more effectively than a uniform allocation, achieving comparable structural performance while reducing the total required length of pipe elements.
Taiyari et al. (Wed,) studied this question.