**Comparative Seismic Performance of Mega Bracing and X‑Bracing Systems in Tall Steel Structures**

Payam PourSheikh Ali Asghari¹ Mohammad Saberi²

1) DOCTOR
2) DOCTOR

IOI Code : AACZ-ABGDDK
Publication : The 5th International Conference on Seismic Retrofitting(5icst.ir)
Abstract :
    **Abstract** With the increase in the height of structures and the complexity of their behavior under lateral loads, particularly earthquakes, the use of efficient lateral load–resisting systems with appropriate seismic performance has become increasingly important. Among these systems, Mega Bracing has emerged as a modern bracing system for tall structures that can significantly improve seismic performance by providing considerable structural stiffness. In addition to increasing the overall stiffness of the structure, this system distributes forces more effectively along the height of the building, preventing some of the local problems commonly observed in conventional bracing systems while also providing adequate ductility capacity. In this study, in order to investigate and compare the seismic behavior of mega bracing systems and X‑bracing systems in tall steel structures, several structural models were developed and analyzed using SAP2000 software. The models were examined in two conditions: structures equipped with X‑bracing systems and structures utilizing mega bracing systems. To accurately evaluate the dynamic behavior of the structures, time history analysis was performed, and parameters such as story displacement and base shear were investigated. The results of the analyses indicate that the use of mega bracing systems, compared with X‑bracing systems, can significantly reduce story displacements and increase the base shear of the structure, which reflects an increase in structural stiffness and an improvement in seismic performance. The findings of this research suggest that mega bracing systems can be considered an appropriate option for enhancing the seismic behavior of tall structures.

Keywords : mega bracing x‑bracing seismic behavior tall steel structures dynamic analysis