Analytical Case Study of Seismic Performance of Retrofit Strategies for Reinforced Concrete Frames : Steel Bracing with Shear Links Versus Column Jacketing

Abstract

The effectiveness of seismic retrofitting applied to enhance seismic performance is assessed for a five-storey reinforced concrete (RC) frame building structure as built in Jordan in mid 80s. The response of the structure is evaluated using nonlinear static and dynamic analysis with synthetic ground motion records for rock base. FEMA 356 criteria are used to evaluate the seismic performance of the case study building. Two approaches are used for seismic evaluation: global-level evaluation (drift values) and member-level evaluation using three performance levels (immediate occupancy, life safety and collapse prevention). Based on the seismic evaluation results, two possible retrofit techniques are applied to improve the seismic performance of the structure, including the addition of RC column jackets and the addition of eccentric steel bracing. SAP 2000 is used to perform linear and nonlinear dynamic analysis, whereas plastic hinge analysis is performed by Response 2000. This study shows that adding new structural elements as steel members to an existing RC building proves to be effective in enhancing performance and reducing cost than adding RC elements. Even more, the eccentric bracing proves to outperform the column jacketing drift limit, plastic hinge limit and cost effectiveness.