Evaluation of Methods of Design for Strongback Braced Frames
Publication: Journal of Structural Engineering
Volume 150, Issue 11
Abstract
Strongback braced frames (SBFs) are a relatively new structural system intended to reduce structural damage during seismic events and improve resilience. SBFs combine buckling-restrained braces, which provide the primary lateral resistance and energy dissipation, with a stiff elastic spine to distribute demands across the height of the structure and prevent the formation of weak- and soft-story mechanisms. Designing the spine is challenging, as higher mode effects and partial nonlinear mechanisms have been shown to be significant. These effects, and their interaction, are not fully accounted for by standardized design methods. It is also unclear how stiff and strong the spine must be in order to achieve the desired behaviors. There are proposed procedures for designing SBFs; however, they have not been broadly evaluated, and they have not been compared. This work evaluates two proposed design procedures, the simplified modal pushover analysis (SMPA) and generalized modified modal superposition (GMMS), with a “control” procedure based on current standardized capacity design procedures. A total of nine frames were designed for three buildings using the three procedures. Nonlinear response history analyses were performed to evaluate the differences in behavior resulting from the different design methods. To determine the effect of the strength and stiffness of the strongback, the yield strength and elastic modulus of the strongback members were varied and the analyses repeated. The results of this work show that the GMMS and SMPA design procedures are generally well-calibrated and provide benefits over current standardized procedures in several ways: collapse performance is improved, and yielding in the strongback and residual drifts is reduced. The GMMS procedure results in larger members, but provides similar outcomes to the more-complicated-to-implement SMPA. The insights from this work will assist engineers when implementing these design methods and support the codification of strongback braced frames in design standards.
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Data Availability Statement
All data, models, and code generated or used during the study are available in a repository online at Talley et al. (2024) in accordance with funder data retention policies.
Acknowledgments
This material is based upon work supported by the National Science Foundation under Grant No. 1940197. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. The computation for this work was performed on the University of Tennessee Infrastructure for Scientific Applications and Advanced Computing (ISAAC) computational resources.
References
Abolghasemi, S., N. E. Wierschem, and M. D. Denavit. 2024. “Impact of strongback on structure with varying damper and stiffness irregularity arrangements.” J. Constr. Steel Res. 213 (Feb): 108333. https://doi.org/10.1016/j.jcsr.2023.108333.
AISC. 2016a. Seismic provisions for structural steel buildings. Chicago: AISC.
AISC. 2016b. Specification for structural steel buildings. Chicago: AISC.
ASCE. 2017. Seismic evaluation and retrofit of existing buildings. Reston, VA: ASCE.
ASCE. 2022. Minimum design loads and associated criteria for buildings and other structures. Reston, VA: ASCE.
Bosco, M., E. M. Marino, and P. P. Rossi. 2018. “A design procedure for pin-supported rocking buckling-restrained braced frames.” Earthquake Eng. Struct. Dyn. 47 (14): 2840–2863. https://doi.org/10.1002/eqe.3112.
Broujerdian, V., and E. Mohammadi Dehcheshmeh. 2022. “Locating the rocking section in self-centering bi-rocking walls to achieve the best seismic performance.” Bull. Earthquake Eng. 20 (5): 2441–2468. https://doi.org/10.1007/s10518-022-01325-y.
Bruneau, M., and A. Reinhorn. 2006. “Overview of the resilience concept.” In Proc., 8th U.S. National Conf. on Earthquake Engineering. Oakland, CA: Earthquake Engineering Research Institute.
Charney, F. A., T. F. Heausler, and J. D. Marshall. 2020. Seismic loads: Guide to the seismic load provisions of ASCE 7-16. Reston, VA: ASCE.
Chopra, A. K., and R. K. Goel. 2002. “A modal pushover analysis procedure for estimating seismic demands for buildings.” Earthquake Eng. Struct. Dyn. 31 (3): 561–582. https://doi.org/10.1002/eqe.144.
Eatherton, M. R., X. Ma, H. Krawinkler, G. G. Deierlein, and J. F. Hajjar. 2014. “Quasi-static cyclic behavior of controlled rocking steel frames.” J. Struct. Eng. 140 (11): 04014083. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001005.
FEMA (Federal Emergency Management Agency). 2009. Quantification of building seismic performance factors. Washington, DC: FEMA.
Galambos, T. V., and R. L. Ketter. 1959. “Columns under combined bending and thrust.” J. Eng. Mech. Div. 85 (2): 1–30. https://doi.org/10.1061/JMCEA3.0000084.
Gioiella, L., E. Tubaldi, F. Gara, L. Dezi, and A. Dall’Asta. 2018. “Modal properties and seismic behaviour of buildings equipped with external dissipative pinned rocking braced frames.” Eng. Struct. 172 (Oct): 807–819. https://doi.org/10.1016/j.engstruct.2018.06.043.
Korlapati, S. C. R., R. Raman, and M. Bruneau. 2021. “Modeling and test data uncertainty factors used in prior FEMA P695 studies.” J. Struct. Eng. 147 (2): 06020009. https://doi.org/10.1061/(ASCE)ST.1943-541X.0002906.
Kurama, Y., S. Pessiki, R. Sause, and L.-W. Lu. 1999. “Seismic behavior and design of unbonded post-tensioned precast concrete walls.” PCI J. 44 (3): 72–89. https://doi.org/10.15554/pcij.05011999.72.89.
Lai, J.-W., and S. A. Mahin. 2014. “Strongback system: A way to reduce damage concentration in steel-braced frames.” J. Struct. Eng. 141 (9): 04014223. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001198.
Martin, A., and G. G. Deierlein. 2021. “Generalized modified modal superposition procedure for seismic design of rocking and pivoting steel spine systems.” J. Constr. Steel Res. 183 (Aug): 106745. https://doi.org/10.1016/j.jcsr.2021.106745.
Martin, A., G. G. Deierlein, and X. Ma. 2019. “Capacity design procedure for rocking braced frames using modified modal superposition method.” J. Struct. Eng. 145 (6): 04019041. https://doi.org/10.1061/(ASCE)ST.1943-541X.0002329.
McKenna, F., M. H. Scott, and G. L. Fenves. 2010. “Nonlinear finite-element analysis software architecture using object composition.” J. Comput. Civ. Eng. 24 (1): 95–107. https://doi.org/10.1061/(ASCE)CP.1943-5487.0000002.
Newell, J., and C.-M. Uang. 2006. Cyclic behavior of steel columns with combined high axial load and drift demand. San Diego: Univ. of California, San Diego.
Palermo, M., V. Laghi, G. Gasparini, S. Silvestri, and T. Trombetti. 2021. “Seismic design and performances of frame structures connected to a strongback system and equipped with different configurations of supplemental viscous dampers.” Front. Built Environ. 7 (Aug): 748087. https://doi.org/10.3389/fbuil.2021.748087.
Priestley, M. J. N., and A. Amaris. 2003. “Dynamic amplification of seismic moments and shear forces in cantilever walls.” In Proc., FIB Symp., 196–197. Lausanne, Switzerland: fib International.
Priestley, M. J. N., R. J. Evison, and A. J. Carr. 1978. “Seismic response of structures free to rock on their foundations.” BNZSEE 11 (3): 141–150. https://doi.org/10.5459/bnzsee.11.3.141-150.
Priestley, M. J. N., S. Sritharan, J. R. Conley, and S. Stefano Pampanin. 1999. “Preliminary results and conclusions from the PRESSS five-story precast concrete test building.” PCI J. 44 (6): 42–67. https://doi.org/10.15554/pcij.11011999.42.67.
Roke, D., R. Sause, J. M. Ricles, and N. Gonner. 2009. “Design concepts for damage-free seismic-resistant self-centering steel concentrically braced frames.” In Proc., Structures Congress 2009: Don’t Mess with Structural Engineers: Expanding Our Role. Reston, VA: ASCE.
Roke, D. A. 2010. “Damage-free seismic-resistant self-centering concentrically-braced frames.” Ph.D. dissertation, Dept. of Civil and Environmental Engineering, Lehigh Univ.
Simpson, B. G. 2018. “Design development for steel strongback braced frames to mitigate concentrations of damage.” Ph.D. dissertation, Dept. of Civil and Environmental Engineering, Univ. of California, Berkeley.
Simpson, B. G. 2020. “Higher-mode force response in multi-story strongback-braced frames.” Earthquake Eng. Struct. Dyn. 49 (14): 1406–1427. https://doi.org/10.1002/eqe.3310.
Simpson, B. G., and S. A. Mahin. 2018. “Experimental and numerical investigation of strongback braced frame system to mitigate weak story behavior.” J. Struct. Eng. 144 (2): 04017211. https://doi.org/10.1061/(ASCE)ST.1943-541X.0001960.
Simpson, B. G., and D. Rivera Torres. 2021. “Simplified modal pushover analysis to estimate first- and higher-mode force demands for design of strongback-braced frames.” J. Struct. Eng. 147 (12): 04021196. https://doi.org/10.1061/(ASCE)ST.1943-541X.0003163.
Steele, T. C., and L. D. A. Wiebe. 2016. “Dynamic and equivalent static procedures for capacity design of controlled rocking steel braced frames.” Earthquake Eng. Struct. Dyn. 45 (14): 2349–2369. https://doi.org/10.1002/eqe.2765.
Talley, P. C., M. D. Denavit, and N. E. Wierschem. 2024. “Nonlinear analysis of strongback braced frames for evaluation of design methods.” In Evaluation of methods of design for strongback braced frames. Austin, TX: DesignSafe-CI. https://doi.org/10.17603/ds2-jrcm-2c58.
Tremblay, R. 2003. “Achieving a stable inelastic seismic response for multi-story concentrically braced steel frames.” Eng. J. 40 (2): 111–129. https://doi.org/10.62913/engj.v40i2.802.
Uriz, P., and S. A. Mahin. 2008. Toward earthquake-resistant design of concentrically braced steel-frame structures. Berkeley, CA: Pacific Earthquake Engineering Research Center, Univ. of California, Berkeley.
Wiebe, L., and C. Christopoulos. 2009. “Mitigation of higher mode effects in base-rocking systems by using multiple rocking sections.” J. Earthquake Eng. 13 (S1): 83–108. https://doi.org/10.1080/13632460902813315.
Wiebe, L., and C. Christopoulos. 2015. “A cantilever beam analogy for quantifying higher mode effects in multistorey buildings.” Earthquake Eng. Struct. Dyn. 44 (11): 1697–1716. https://doi.org/10.1002/eqe.2549.
Ziemian, R. D., and W. McGuire. 1992. “A method for incorporating live load reduction provisions in frame analysis.” Eng. J. 29 (1): 1–3. https://doi.org/10.62913/engj.v29i1.586.
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© 2024 American Society of Civil Engineers.
History
Received: Oct 31, 2023
Accepted: May 17, 2024
Published online: Aug 24, 2024
Published in print: Nov 1, 2024
Discussion open until: Jan 24, 2025
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