CODE-369.1-22: Seismic Evaluation and Retrofit of Existing Concrete Buildings—Code and Commentary (SI Units)

Abstract:

This code provides retrofit and rehabilitation criteria for reinforced concrete buildings based on results from the most recent research on the seismic performance of existing concrete buildings. The intent of this code is to provide provisions related to concrete material and concrete members, including material testing criteria, modeling parameters, and acceptance criteria for use within the ASCE 41 framework, similar to how the National Earthquake Hazards Reduction Program (NEHRP) Recommended Seismic Provisions produced by the Federal Emergency Management Agency (FEMA) (FEMA 450) have served as source documents for the International Building Code (IBC) and its predecessor building codes. Starting in the 2023 edition, ASCE 41 references ACI 369.1 directly for concrete-related provisions. Chapter and section numbers of ASCE 41 cited in ACI 369.1 correspond to ASCE 41-17 unless otherwise noted. This code should be used in conjunction with Chapters 1 through 8 of ASCE 41-17 and applicable sections of the ACI 318-19 Building Code. Chapter 1 of ASCE 41 provides general requirements for evaluation and retrofit, including the selection of performance objectives and retrofit strategies. Chapter 2 of ASCE 41 defines performance objectives and seismic hazards. Chapter 3 of ASCE 41 provides requirements for evaluation and retrofit, including treating as-built information and selecting appropriate screening procedures. Chapter 4 of ASCE 41 summarizes Tier 1 screening procedures, while Chapters 5 and 6 summarize Tier 2 deficiency-based procedures and Tier 3 systematic procedures for evaluation and retrofit, respectively. Chapter 7 of ASCE 41 details analysis procedures referenced in ACI 369.1, including linear and nonlinear analysis procedures, acceptance criteria, and alternative methods for determining modeling parameters and acceptance criteria. Chapter 8 of ASCE 41 provides geotechnical engineering provisions for building foundations and assessment of seismic-geologic site hazards. References to these chapters can be found throughout the standard. The design professional is referred to FEMA 547 for detailed information on seismic rehabilitation measures for concrete buildings. Repair techniques for earthquake-damaged concrete components are not included in ACI 369.1. The licensed design professional is referred to ACI 562, FEMA 306, FEMA 307, and FEMA 308 for information on evaluation and repair of damaged concrete wall components. This code does not provide modeling procedures, acceptance criteria, or rehabilitation measures for concrete-encased steel composite components. Keywords: acceptance criteria; building; deformation-controlled; dynamic analysis; earthquake; force-controlled; modeling parameters; nonlinear analysis; retrofit; seismic evaluation, seismic assessment; structural evaluation.



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