Room 254 - Sutardja Dai Hall, (CITRIS: Center for Information Technology Research in the Interest of Society), University of California, Berkeley, CA

Agenda

Speakers:

C. Scawthorn (PI - GEM O&T), S. Brzev (Co-PI, Taxonomy), R. Langenbach (GEM Taxonomy)

Participants:

S. Mahin (PEER), B. Stojadonovic (PEER), C. Huyck (GEM IDCT and GED4GEM), K. Porter (PI, GEM GVC), M. Greene (EERI/World Housing Encyclopedia), J. Rogers (GHI; GEM end-user needs assessment), A. Hortacgu (ATC), E. Seymour (EERI intern)

Discussion: Key Points

Day 1: Thursday, March 3, 2011

An overview of the GEM Risk Components and O&T (C. Scawthorn)
· Objectives for GEM taxonomy:

• global in coverage, geographically as well as being comprehensive of building types
• flexible: this has several aspects, (a) extensible / telescopable, (b) adaptable to future needs, including other hazards
• compatible with other taxonomies, such as in insurance, e.g., ACORD, and design / construction BIMs

Global building construction practices and typologies (R. Langenbach)

• Extremely wide variety of buildings in the world
• Engineered (classes defined by ASCE 7) versus vernacular construction (10 vs. 90 % ratio in terms of global occupancy)
• Discussed frame-dominant versus wall-dominant seismic response of buildings and a need to reflect this in the GEM taxonomy
• Features that matter to asset definition, structural analysis, damage analysis, loss analysis
• The features included must be observable, and it should be possible to make inferences (inferability)

An overview of the existing building taxonomies (S. Brzev)

• Taxonomy review table (slide 11)

· need to change “Extensible to non-buildings” to “Currently treats non-buildings”
· change HAZUS review ranking for "other hazards" to true

GEM Building Taxonomy: vision and goals (C. Scawthorn)

• The presentation included an example of a mixed-use building with "Starbucks" cafe at the first floor level and office spaces above. An EXCEL spreadsheet was used to demonstrate the attributes and possible classes.
• The presented taxonomy has 34 attributes.
• Attributes to be presented in a conditional sequence (main/secondary facets), e.g. masonry first, then ask kind of masonry, then ask type of mortar
• Clarity test needed for facets (in terms of terminology)
• A number of attributes to be offered in alternative forms (for example, building height as number of stories or actual height in meters)
• It is important to prioritize attributes
• Should the taxonomy be organized floor-by-floor, considering possible variations in building characteristics?
• The taxonomy should be able to capture trends (for future buildings)

Additional attributes that emerged in the workshop and to be considered for the GEM taxonomy:

• Need to include a separate set of attributes for ground floor and upper floors
• First-floor (ground floor) specific attributes include height, interior walls, occupancy
• Sloping sites
• Building location
• Contiguity
• Foundation needs perimeter grade beam
• Vertical changes in the structural system need to be addressed (for example, RC podium and a steel structure above)
• Need to capture structural flexibility, redundancy, and energy dissipation characteristics (ductility)
• Design strength (for materials)
• Mass per unit area
• Wall density
• Resilience
• Stiffness at various levels of deformation
• Types of connections, e.g. riveted, bolted, welded …
• Relative quantity of various dominant structural and nonstructural components
• Cost
• Previous use of the building (e.g. warehouse turned into residential building, or residential building turned into an office)
• Performance in past earthquakes
• Quantities/properties
• Characteristics for floor and roof horizontal systems; it is required to identify slab thickness (vulnerability-related)
• Compatibility with AUTOCAD/NIBS building information models
• Participants proposed to use ATC-58 taxonomy for nonstructural elements (or NISTIR 6389)
• Occupancy classification: NAICS (http://www.naics.com/referencefiles.htm)? UNICEDE? Something to capture density of occupant load?

GEM Building Taxonomy: the structure and key attributes (S. Brzev)

• Material facet (slide 13): the “concrete” term refers to reinforced concrete
• Discussed a need for the taxonomy to include glossary; synonyms should be included in the glossary
• It is believed that labels used to identify the attributes are not useful without attached quantities - very few users will be able to use the taxonomy without a database (slides 27-30).

General Discussion and Comments
1. The participants agreed with the general approach (faceted taxonomy)
2. It is important for the GEM taxonomy to avoid collecting unnecessary information.
3. Taxonomy needs related to the GEM Vulnerability component (K. Porter):

• Replacement costs: need to estimate area, unit replacement cost, total replacement cost, number of occupants, income
• Structural modeling: need to estimate macroscopic force-deformation relationship, e.g., mass (not just RC slab but also thickness), stiffness at various levels of deformation, strength, backbone and hysteresis; mesoscopic e.g., soft story, and perhaps microscopic, e.g., stress concentrations such as those that caused the damage in Concepcion (2010 Chile earthquake) and the ledgers that killed tilt-up structures in the 1971 San Fernando earthquake
• Damage modeling: need to identify which fragility functions to use (predominant cladding system and interior partition code via UNIFORMAT II or ATC-58 categories)
• Loss modeling: need to estimate repair costs and functionality.

4. A question for the participants: What is the best way to receive feedback related to the taxonomy (after the workshop)?

Day 2: Friday, March 4, 2011

1. Review yesterday's discussion
· Overview of built environment; diversity of buildings; wall/frame dichotomy (R. Langenbach presented a summary slide)
· Taxonomy integrating with BIM (a future trend)
· GEM: faceted versus hierarchical taxonomy: “Next-generation”

2. Discuss attributes for the GEM Building Taxonomy
· Details
· Priority
· Constraints
It has been acknowledged that the taxonomy will need to meet the needs of different groups of users. Users could be overwhelmed considering number and diversity of attributes. A possible way to avoid this is to present subsets of the taxonomy depending on the user (who could identify his/her profile at the beginning of the session).

The taxonomy team needs to develop a structure and content of the taxonomy, and the database presentation will be done by the GED4GEM team.

List of the attributes discussed at the meeting are included in the attached EXCEL spreadsheet. Note that some of these attributes are already included in the "Pre-Alpha" version of the taxonomy presented at the meeting.

GEM Taxonomy attributes for consideration.

3. Comments from the San Diego meeting
The questions raised by the IDTR and GED4GEM teams (represented by C. Huyck) were discussed and answered.

4. Next steps
a) Minutes of the meeting to be posted on the O&T Wiki by March 8
b) "Pre-Alpha" version of the taxonomy to be revised and shared with all relevant stakeholders by March 20, with a 10-day feedback period (followed by the release of "Alpha" taxonomy)
c) White papers to be finalized and/or prepared on existing taxonomies (Brzev and Charleson), building construction (engineered and vernacular) (Langenbach), taxonomy vision (Brzev and Scawthorn) - to be posted on the Wiki and published as a GEM report
d) "Beta" version of the taxonomy to be presented at the Workshop# 2 to take place at the end of May or early June (location TBD)