PSI - Issue 64

Massimiliano Ferraioli et al. / Procedia Structural Integrity 64 (2024) 1017–1024 Ferraioli et al./ Structural Integrity Procedia 00 (2019) 000–000

1024

8

step" pushover methodology was developed for seismic retrofitting of plan-asymmetric buildings using buckling restrained braces. The design approach was devised to appropriately dimension HBF dampers for installation at specific spans and levels of the structure. A real case-study school building was examined. Key findings include: - Mitigation of Torsional Effects: The initial insertion of non-dissipative steel braces effectively balanced lateral stiffness, mitigating torsional effects and improving the building’s modal properties. The modal mass ratio around the Z-axis for the first torsional mode shape decreases from 0.278 to 0.007. - Effective Seismic Retrofit: The use of HBF dampers in the retrofit strategy significantly enhanced seismic performance, reducing the maximum inter-story drift to 1.22% in the X-direction and 1.62% in the Y-direction. - Robust Validation: The retrofit design was validated through nonlinear time-history analyses conducted under various earthquake scenarios with strong ground motions, ensuring reliable and robust analysis. Overall, the study presents a practical approach to seismic retrofit for plan-asymmetric buildings, addressing critical challenges. The findings contribute valuable insights into improving the safety and reliability of structures. References ATC 40 Applied Technology Council, 1996. Seismic evaluation and retrofit of concrete buildings. Redwood City, United States. ASCE/SEI 41-13, 2014. Seismic evaluation and retrofit of existing buildings. Federal Emergency Management Agency, Reston, United States. Bhatt, C., Bento, R., 2011. Assessing the seismic response of existing RC buildings using the extended N2 method. Bulletin of Earthquake Engineering 9, 1183–1201. Chopra, A.K., Goel, R.K., Chintanapakdee, C., 2004. Evaluation of a Modified MPA Procedure Assuming Higher Modes as Elastic to Estimate Seismic Demands. Earthquake Spectra 20 (3), 757-778. CSI Computer & Structures Inc. SAP2000, 2023. Linear and nonlinear static and dynamic analysis of three-dimensional structures. Research Ultimate Version 24.0, Analysis Ref. Manual, Computer and Structures, Berkeley, United States. De Stefano, M., Pintucchi, B., 2008. Parametric bounds for application of pushover analysis to plan irregular buildings, 5th European Workshop on the Seismic Behaviour of Irregular and Complex Structures. Catania, Italy. EN 1998-3, 2005. Eurocode 8 - Design of structures for earthquake resistance - Part 3: Assessment and retrofitting of buildings. European Communities for Standardization, Brussels, Belgium. FEMA 273, 1997. Building Seismic Safety Council, NEHRP Guidelines for the Seismic Rehabilitation of Buildings. Federal Emergency Management Agency: Washington D.C., United States. FEMA 356, 2000. Prestandard and Commentary for the Seismic Rehabilitation of Buildings, Federal Emergency Management Agency, Washington D.C., USA. FEMA 440, 2005. Improvement of nonlinear static seismic analysis procedures. Federal Emergency Management Agency, Washington D.C., USA. Ferraioli, M., 2015. Case study of seismic performance assessment of irregular RC buildings: hospital structure of Avezzano (L’Aquila, Italy). Earthquake Engineering and Engineering Vibration 14(1), 141–156. Ferraioli, M., 2017. Multi-mode pushover procedure for deformation demand estimates of steel moment-resisting frames. International Journal of Steel Structures 17(2), 653–676. Ferraioli, M., Lavino, A., Mandara, A., 2016, An adaptive capacity spectrum method for estimating seismic response of steel moment-resisting frames. Ingegneria Sismica 33(1-2), 47–60. Ferraioli, M., Lavino, A., 2018. A displacement-based design method for seismic retrofit of RC buildings using dissipative braces. Mathematical Problems in Engineering 2018, 1-28. Ferraioli, M., Lavino, A., Mandara, A., 2018. Effectiveness of multi-mode pushover analysis procedure for the estimation of seismic demands of steel moment frames. Ingegneria Sismica 35(2), 78–90. Ferraioli, M., Concilio, A., Molitierno, C., 2022. Seismic performance of a reinforced concrete building retrofitted with self-centering shape memory alloy braces. Earthquake Engineering and Engineering Vibration 21(3), 785–809. Ferraioli, M., Lavino, A., 2020. Irregularity Effects of Masonry Infills on Nonlinear Seismic Behaviour of RC Buildings. Mathematical Problems in Engineering 2020, 1-18. Ferraioli, M., Lavino, A., Mandara, A., 2018. Multi-mode pushover procedure to estimate higher modes effects on seismic lnelastic response of steel moment-resisting frames. Key Engineering Materials 763, 82–89. Ferracuti, B., Savoia, M. and Pinho, R., 2009. 3D Pushover Analysis for Evaluating Torsional Effect of RC Structures. L'Ingegneria sismica in Italia, Imready (SMR), Anidis 2009. Mander, J.B., Priestley, M.J.N., Park, R., 1988. Theoretical stress-strain model for confined concrete. J. Structural Engineering 114(8), 1804-1826. Mazza, F., Vulcano, A., 2015. Displacement-based design procedure of damped braces for the seismic retrofitting of r.c. framed buildings. Bulletin of Earthquake Engineering 13(7), 2121-2143. NTC-Guidelines, 2018. Technical Standards for Constructions. Official Journal of the Italian Republic, Rome, Italy. Reyes, J.C, Chopra, A., 2011. Three-dimensional modal pushover analysis of buildings subjected to two components of ground motion, including its evaluation for tall buildings. Earthquake Engineering & Structural Dynamics 40(7), 89–806.