Many of the steel buildings available for various reasons, such as design, failure to observe the conditions of plasticity, construction, an operation may be weak and the existing structure will not have safety and favorable conditions for bearing loads, so seismic rehabilitation and upgrading Increasing the bearing capacity of the structure is necessary. Seismic reconstruction of existing buildings is carried out at two levels of structure and elements.
One of the effective methods of increasing the seismic strength and lateral stiffness of these buildings is the use of a variety of steel bracing methods, such as converging bracing, the use of large braces and trusses, which are compared and analyzed in this study. One of the most important advantages of this method is to increase the flexibility and optimum performance of the structure in controlling displacement, speed and ease of operation, simplicity and less costly restoration or replacement of damaged damping system after an earthquake.