NEHRP Extramural Research

Summary

Research performed by the EL Earthquake Engineering Group (2EG) consists of a combination of in-house and extramural research. Policy related work is awarded to the Science Technology Policy Institute. Traditional technical extramural research is performed by an outside contractor via a series of annually awarded Indefinite Delivery Indefinite Quantity (IDIQ) task orders. The extramural research provides a breadth and depth of multi-disciplinary research capabilities that strongly supplements the in-house work force. 

One task order (Project 1) will be issued to a policy contractor to assist in updating the NEHRP Strategic Plan. Two perhaps three task orders will be awarded to a new support contractor to be identified. The existing IDIQ contract expired earlier in FY2019 and a new contract will be competed in FY2020. Once that is in place the task orders will be issued against this new IDIQ contract. These technical task orders will (Project 2) assist NIST in updating RP-8, Standards of Seismic Safety for Existing Federally Owned and Leased Buildings, (Project 3) evaluation of the design rules in ASCE/SEI 7 and the NEHRP Provisions concerning how vertical accelerations are handled, and (Project 4) Development of a research plan to study mitigation approaches to improve the performance of pre-1980 non-ductile steel column splices and weak panel zones. 

Projects 1 & 2 are priorities for funding; Projects 3 & 4 are subject to availability of funds. 

Description

Objective -  A task order to assist NIST and the NEHRP agencies in updating the NEHRP Strategic Plan will be awarded to a policy contractor. In addition, other planned FY 2020 extramural research will be assigned by task order to the new IDIQ contractor once that award is made. It is anticipated that two or three technical task orders will be awarded, subject to availability of funds. These task orders concern specific efforts to support the Earthquake Engineering Group (2EG) research portfolio in support of the NEHRP mission; all will be managed by the PI, supported by co-PI Sattar (with Jay Harris of 2EG as the COR). The task orders include: 

1.  A task order will be issued to the Science and Technology Policy Institute (STPI) to assist NIST and the NEHRP agencies in updating the 2008 NEHRP Strategic Plan. The Plan was published in 2008 and needs to be updated to reflect progress in earthquake hazard mitigation over the past decade. Moreover, earthquake engineering has evolved to be more than mitigation to now aimed at providing resilient communities. The role of buildings and their interconnecting lifelines are part of the community system that must be sufficiently robust to perform under strong shaking. Moreover, the traditional life safety design approach is being replaced with a goal of functional recovery with a faster return to service. The Strategic Plan needs to reflect this new thinking and to identify  issues that the Plan must address over the next decade of NEHRP operation, and the removal of items that are completed or no longer need study. https://www.nehrp.gov/pdf/strategic_plan_2008.pdf
2. A task order will be issued to the new IDIQ Contractor to assist NIST in completing the updating of RP-8, Standards of Seismic Safety for Existing Federally Owned and Leased Buildings. RP-8 is published by the Interagency Committee on Seismic Safety in Construction (ICSSC) and provides the consensus approaches to determine if seismic strengthening is required in existing Federally owned or leased buildings. A draft update of RP-8 was completed by the Applied Technology Council in 2016. Now that the 2017 edition of ASCE/SEI 41 has been published, the update can be completed. 
3. A task order will be issued to the new IDIQ contractor to assess the current approaches in ASCE/SEI 7 and the NEHRP Provisions to address vertical accelerations in design. Current provisions date back to the original NEHRP Provisions (ATC-3) that were published in 1979. The efficacy of these provisions has not been studied. The Building Seismic Safety Council Provisions Update Committee has requested that NIST conduct a study of this question to determine if modifications to the provisions are required and to suggest what the language should be. 
4. A fourth task order will be considered, depending on available funds, to develop a research plan to address two specific issues found in pre-1980, non-ductile structural steel buildings. These issues include (1) the performance of weak panel zones, the areas formed by the intersection of beams and columns and (2) the performance of column splices utilizing partial penetration welds, as was typical in these older buildings. These two issues are related and are a function of design and detailing decisions made prior to 1980 that can result in poor performance in these steel buildings. The development of the research plan also will identify the resources that are available concerning panel zones and non-ductile column splices. The goal will be to determine the problem statement, the approach to be utilized to determine solutions and the available information published in the literature. 

What is the technical idea?  A total of four task orders are proposed to be completed by outside contractors. The following task orders are part of this overall extramural research project:
 

1. Assist NIST and the NEHRP agencies in developing an updated Strategic Plan. The existing plan dates from 2008 and needs to be updated and revised to reflect current Program needs and anticipated issues going forward. Priority task order. 
2. Assist NIST in updating the RP-8 Standards of Seismic Safety for Existing Federally Owned and Leased Buildings which is required to be used by Federal agencies in examining their buildings to determine which buildings must be assessed in detail. Priority task order.
3. Assist NIST in evaluating the current provisions found in ASCE/SEI 7 and the NEHRP Provisions concerning how to incorporated the effects of vertical accelerations in design. The goal will be to determine what changes are needed and to propose revised language for consideration by the BSSC PUC. Depending on funds availability. 
4. Assist NIST in examining the question of non-ductile partial penetration welds found in pre-1980 structural steel panel zones, the intersection of columns and beams, as well as column splices. Modern design requirements and materials produce ductile welds that perform significantly better than these older connections. The question is how widespread is this problem and what information is needed to provide solutions? Depending on funds availability.
    

What is the research plan?

NIST will award three task orders, depending on funds to the new IDIQ Contractor once the award is made in FY2020, and one task order to the Science and Technology Policy Institute (STPI).  

1. The NEHRP Strategic Plan was published in 2008 reflecting the then Program priorities. There is an urgent need to review the Plan, to identify topics that have been addressed, to identify topics that remain to be addressed as well as new issues to add to the Plan. Earthquake engineering has evolved since 2008 and has become oriented towards providing a resilient nation as opposed to a concentration on mitigation. Additional considerations concerning lifelines and faster return to service of shaken buildings also need to be addressed. The updating process will involve all four NEHRP agencies and will be supported by a task order planned to be awarded to STPI, a contractor that specializes in policy-related studies. The updating will require a number of community workshops to reach out to specific stakeholder groups and other forms of contact with communities, building owners, building residents, local building departments, engineers, urban planners and social scientists. A key theme is that of moving from classic mitigation-focused work to that of resilience. 
   
   The task order is anticipated to require 30 months of effort to complete the study. 
2. A task order will be awarded to the new IDIQ contractor to assist NIST in completing the updating of RP-8, Standards of Seismic Safety for Existing Federally Owned and Leased Buildings, published by the ICSSC, which is chaired by NIST. RP-8 is required to be used by Federal agencies who own or lease buildings. The document provides the approach to determine if a building’s seismic performance has to be evaluated. A draft update of RP-8 was completed by the Applied Technology Council in 2016; the 2017 edition of ASCE/SEI 41 has been published and the final update document can be completed and published. The International Existing Building Code also will be included in this updating.   It must be noted that Executive Order 13717 that established the requirements for Federal building seismic safety requires that NIST update the RP series periodically. 
   
   It is anticipated that this will require a modest effect of approximately 18 months. The work will include holding of at least one workshop in the DC area to get review input from ICSSC agencies concerning the proposed changes in the RP document. 
3. A task order will be awarded to the new IDIQ contractor to assist NIST in evaluating the existing provisions found in ASCE/SEI 7 and the NEHRP Provisions concerning vertical accelerations. The present provisions date back to 1979 and the first NEHRP Provisions document; no changes in the provisions have been made. The effectiveness of the existing language needs to be assessed in light of the knowledge gained over the past 40 years from research and from observations from actual earthquakes. 
   
   This study is anticipated to require 18 months to complete. 
4. Pre-1980 structural steel moment frames favored panel zones that would yield before the adjacent beams and columns. Panel zones as well as column splices used partial joint penetration (PJP) welds that are less expensive than full penetration welds that are now required. The welding requirements used during this era were not as stringent as modern requirements. Weld fracture in structural components can result in undesirable behavior of the moment frame during a seismic event. A weak panel zone mechanism may result in excessive shear deformations within the panel zone and significant column flange bending at the corners of the panel zone resulting in fracture of the welds connecting the bottom beam flange to the column flange.  Similar issues with welds in beam-to-column connections identified during the Northridge earthquake also put welded column splices at risk of fracture. 
   
   In this era column splices also were accomplished by welding splice plates to the column flanges using partial penetration welds. The resulting splices are not as ductile as modern splices produced using full penetration welds and improved welding methods and materials. Work being conducted on the west coast has indicated that perhaps many buildings were constructed using this approach, resulting in non-ductile columns splices and building performance that will not meet modern requirements. 
   
   A task order will be awarded to the new IDIQ contractor to determine the scope of the problem and what approaches should be taken to research potential solutions to this issue. A combination of analytical and testing work will no doubt be required to do the actual research. It is estimated that this task order will require 18 months to complete. The award will be made to the new IDIQ contractor subject to availability of funds in FY2020.

Major Accomplishments

Results:

These new TechBriefs will be the tenth and eleventh in a series of documents that have addressed the following seismic analysis and design issues:

• TechBrief No. 1: Seismic Design of Reinforced Concrete Special Moment Frames: A Guide for Practicing Engineers. NIST GCR 8-917-1,
• TechBrief No. 2: Seismic Design of Steel Special Moment Frames: A Guide for Practicing Engineers, NIST GCR 9-917-3
• TechBrief No. 3: Seismic Design of Cast-in-Place Concrete Diaphragms, Chords, and Collectors: A Guide for Practicing Engineers, NIST GCR 10-917-4
• TechBrief No. 4 Nonlinear Structural Analysis For Seismic Design: A Guide for Practicing Engineers, NIST GCR 10-917-5
• TechBrief No. 5: Seismic Design of Composite Steel Deck and Concrete-filled Diaphragms: A Guide for Practicing Engineers, NIST GCR 11-917-10
• TechBrief No. 6: Seismic Design of Cast-in-Place Concrete Special Structural Walls and Coupling Beams: A Guide for Practicing Engineers, NIST GCR 11-917-11REV-1
• TechBrief No. 7: Seismic Design of Reinforced Concrete Mat Foundations: A Guide for Practicing Engineers, GCR 12-917-22
• TechBrief No. 8: Seismic Design of Steel Special Concentric Braced Frame Systems: A Guide for Practicing Engineers, in process
• TechBrief No. 9: Seismic Design of Structural Wood Diaphragm Systems: A Guide for Practicing Engineers, in process

The TechBrief series has had significant impact on the structural engineering community. The National Council of Structural Engineers Associations (NCSEA) provided webinars on TechBriefs 1 through 4 in 2011. In addition, TechBrief No. 2 was the subject of a presentation at the 2009 SEAOC Annual Conference, the subject of an article in Structure Magazine and won the SEAONC Award of Merit in 2010 for Excellence in Structural Engineering. TechBrief 4 was also cited in FEMA P-58. The TechBrief series has received high praise from practicing engineers and the university community as a source of concise information from subject matter experts on important structural engineering topics related to seismic design.

Standards and Codes:

Each TechBrief will be a concise synthesis of recent research results, model building code provisions and recommended design practices as developed by recognized experts in structural steel and reinforced masonry, as appropriate. The document will be completely compatible with existing and developing model building code provisions. The braced frame TechBrief will assist designers in their application of AISC 341 (see endnote i) and ASCE 7. The masonry TechBrief will assist designers in their application of MSJC and ASCE 7.