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Summary
This project focuses on promoting enhanced seismic building performance. The main idea is to investigate the use of low-damage earthquake-resisting structural systems as a cost-effective solution to minimize earthquake damage and enable timely recovery after major earthquake events. This research task consists of analytical studies, dissemination, and collaboration with industry stakeholders. The analytical component will focus on evaluating the seismic performance of a suite of archetype buildings, designed with conventional and low-damage approaches, to further assess the feasibility of low-damage systems. 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 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 effort is envisioned as an initial attempt 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
The objective of this project is to better understand the seismic performance of buildings designed in areas of medium-to-high seismicity and to identify and evaluate ways to enhance the seismic performance of buildings through advances in design approaches, including conventional and low-damage approaches, improved code provisions, and improved analysis procedures. Specifically, the objective is to provide new information and guidance to the professional design community that enables wider adoption of low-damage earthquake-resting technologies in buildings.
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. 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. Rocking systems have been implemented in a small number of buildings with little additional cost (ECQ 2020). Despite extensive research demonstrating their feasibility, wider implementation of rocking systems has been hindered, presumably due to a lack of knowledge, experience, technical design guidelines, and other factors. To bridge the gap between research and practice, this project will provide new information to the professional community that enables the wider adoption of low-damage rocking technologies in buildings.
Research Plan
RT1: Seismic Performance of Low-Damage Rocking Systems
The project 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 a comprehensive suite of archetype buildings designed using conventional and low-damage rocking seismic force-resisting systems. The archetype space will include varying building heights and locations to assess the parameters that make rocking 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 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 preliminary design guidelines for rocking reinforced concrete shear walls and/or steel braced frames. Currently, design guidelines specific to U.S. practice do not exist for these rocking systems. 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.
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.