Building-Level Seismic Performance Assessment

Summary

This project focuses on demonstrating the feasibility and promoting wider implementation of low-damage earthquake-resisting structural systems that can minimize earthquake damage and enable timely recovery of building functions after major earthquake events. The analytical component will evaluate the seismic performance of a suite of archetype buildings, designed with conventional and low-damage approaches, to quantify the benefits of low-damage systems considering earthquake damage levels, post-earthquake functionality, and repair time to recover building functions. The project team will collaborate and coordinate with researchers, practicing structural engineers, and standards development organizations to inform recommendations on how to increase the use of low-damage earthquake-resisting systems for new and existing buildings. Project findings, including analytical studies, will be disseminated through reports, journal publications, and presentations to industry stakeholders. Additionally, the team will coordinate with industry stakeholders to develop technical design guidelines that will provide essential tools for practicing engineers to implement low-damage systems more readily. This overall vision is to promote wider use of low-damage technologies, synergistically supporting the goals of immediate occupancy, functional recovery and other general resilience-based goals widely circulating in the current public and technical discourse.

Description

Objective
This research effort will identify and evaluate methods to enhance the seismic performance of buildings in areas prone to moderate-to-high earthquake shaking through the utilization of new conventional and low-damage seismic design approaches, improved seismic code provisions and design guidelines, and improved analysis procedures.

Technical Idea

RT1: Seismic Performance of Low-Damage Rocking Systems
The present surge of interest in designing structures with consideration of post-earthquake functionality has created the opportunity for innovative approaches to be brought into the mainstream of structural design. Low-damage post-tensioned “rocking” structural systems can be implemented to limit damage and preserve building functionality, while also ensuring occupant safety, offering a potentially inexpensive solution for earthquake-resistant construction that better aligns with societal expectations. The structural components in rocking systems are designed to uplift once the resistance provided by post-tensioning and/or their self-weight is exceeded. The ingenuity of the system is that the uplifting behavior protects the rocking elements from damage while utilizing gravity to re-center and prevent permanent deformation. Despite research demonstrating their feasibility as an alternative to conventional construction, rocking systems have only been implemented in a small number of buildings and with little additional cost (ECQ 2020).

To bridge the gap between research and practice, this research task will provide new information to the professional community that enables wider adoption of low-damage rocking technologies in buildings. A research report will be published that quantifies and compares the seismic performance, repairability, and post-earthquake recovery cost and timeframe for a set of conventional and low-damage archetype buildings representing typical construction practices in areas of the United States prone to moderate-to-high earthquake shaking. The expected earthquake damage and repair costs for the archetype buildings will be compared, thus enabling recommendations to be made for the structural design space best suited for conventional and low-damage design approaches. The research findings will be used to develop new and/or improved design guidelines for structural engineers interested in designing low-damage, post-tensioned concrete walls to maximize seismic performance benefits, improve post-earthquake functional recovery of concrete buildings and the communities they serve, and minimize additional costs.

NIST is uniquely positioned to bridge the gap between research and practice and to provide practical solutions for achieving higher building performance in cost-effective ways. As the lead agency of the National Earthquake Hazards Reduction Program and as a part of the Department of Commerce, conducting research to advance U.S. competitiveness and financial well-being is readily within the mission and expertise of NIST.

Research Plan

RT1: Seismic Performance of Low-Damage Rocking Systems 
The research task is focused around two major components: (1) an analytical investigation to evaluate and demonstrate benefits for a broad set of archetype buildings; and (2) design guidelines to support industry uptake. The analytical investigation will focus on developing and evaluating the seismic response for a comprehensive suite of archetype buildings designed using conventional reinforced concrete structural walls and low-damage, post-tensioned rocking walls as the seismic force-resisting systems. The archetype space will include varying building heights and locations to assess the parameters for which rocking wall structures are most advantageous. This includes exploring the sensitivity of rocking behavior to various ground motion characteristics. Nonlinear computer models will be developed to enable performance comparisons. Findings will be documented in a research report that includes a comprehensive assessment of the cost-benefit of rocking systems and helps identify the design space best suited for implementation of rocking. There are potential benefits of designing for rocking in both the superstructure and foundation. The initial project efforts will focus on rocking of the superstructure. A plan will also be developed to incorporate foundation rocking. The second component of this project will be to develop new and improved design guidelines for rocking concrete walls. These guidelines will be developed in collaboration with a group of external experts. The guidelines will ultimately help promote practical implementation of low-damage rocking systems. The guidelines will also help pave the way for development of a pre-standard.

New computational data will be generated as part of this research effort that will be useful for continued and future NIST research on conventional and low-damage structural behavior, including efforts to better understand and improve post-earthquake recovery. The designs of the archetype buildings will be published for use in future research.

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References:

AISC (2016). Seismic Provisions for Structural Steel Buildings – ANSI/AISC 341-16. American Institute of Steel Construction, Chicago, IL.

ASCE (2016). Minimum Design Loads for Buildings and Other Structures. ASCE/SEI 7-16. American Society of Civil Engineers, Reston, VA.

ASCE (2017). Seismic Evaluation and Retrofit of Existing Buildings. ASCE/SEI 41-17. American Society of Civil Engineers, Reston, VA.

Dassault Systemes (2014). ABAQUS Unified Finite Element Analysis 6.14 [Software]. Waltham, MA.

ECQ (2020). “US Engineer Designs Resilient Building with a Little Help from his Kiwi Friends,”  The Earthquake Commission, https://www.eqc.govt.nz/news/us-engineer-designs-resilient-building-with-a-little-help-from-his-kiwi-friends

FEMA (2009). Quantification of Building Seismic Performance Factors. FEMA P695. Federal Emergency Management Agency, Washington, D.C.

FEMA-NIST (2021). “Recommended Options for Improving the Built Environment for Post-Earthquake Reoccupancy and Functional Recovery Time,” FEMA-NIST Special Publication FEMA P-2090/NIST SP-1254, 135 pp.

ICC (2008). “Strategic Plan for the National Earthquake Hazards Reduction Program,” Prepared by the Interagency Coordinating Committee (ICC) of NEHRP, www.nehrp.gov/pdf/strategic_plan_2008.pdf

Harris, J.L. and M.S. Speicher (2015a). Assessment of First Generation Performance-Based Seismic Design Methods for New Steel Buildings Volume 1: Special Moment Frames. NIST TN 1863-1. National Institute of Standards and Technology. Gaithersburg, MD.

Harris, J.L and M.S. Speicher (2015b). Assessment of First Generation Performance-Based Seismic Design Methods for New Steel Buildings Volume 2: Special Concentrically Braced Frames. NIST TN 1863 2. National Institute of Standards and Technology. Gaithersburg, MD.

Harris, J.L and M.S. Speicher (2015c). Assessment of First Generation Performance-Based Seismic Design Methods for New Steel Buildings Volume 3: Eccentrically Braced Frames. NIST TN 1863 3. National Institute of Standards and Technology. Gaithersburg, MD.

LSTC (2015). LS-DYNA R8.0 [Computer Software]. Livermore Software Technology Corp., Livermore, CA.

NIST (2018). “Research Needs to Support Immediate Occupancy Building Performance Objective Following Natural Hazard Events,” NIST Special Publication NIST SP-1224, 95 pp.

NIST (2021). “NIST-FEMA Post-Earthquake Functional Recovery Workshop Report,” NIST Special Publication NIST SP-1269, 52 pp.

NRC (2011). “National Earthquake Resilience: Research, Implementation, and Outreach,” Prepared by the Committee on National Earthquake Resilience and Committee on Seismology and Geodynamics for the National Research Council (NRC), National Academies Press, Washington, D.C.

Pampanin, S. (2015). “Towards the Ultimate Earthquake-Proof Building: Development of an Integrated Low-Damage System,” Geotechnical, Geological and Earthquake Engineering, Vol 39, pp. 321-358.

Speicher, M.S. and J.L. Harris (2020). Assessment of First Generation Performance-Based Seismic Design Methods for New Steel Buildings Volume 4: Buckling Restrained Braced Frames. NIST TN 1863 4. National Institute of Standards and Technology. Gaithersburg, MD.