Session IVa – "A Seismic Rehabilitation Agenda for Older Hazardous Concrete Buildings" Richard McCarthy Executive Director California Seismic Safety Commission

Mitigation of Seismic Risk in Older Concrete Buildings EERI Concrete Building Coalition and NEESR Grand Challenge Craig Comartin and Jack Moehle

Project background California, 1994Turkey, 2003 “50% of the casualties are coming from 5% of the buildings.” Kircher et al., “Estimated Losses due to a Repeat of the 1906 San Francisco Earthquake, Earthquake Spectra, 2006.

Project background Operational Heavy Collapse Mexico City, 1985 Erzincan, Percentage Kobe, 1995 Luzon, 1990 Older Concrete Building Damage Rating Otani (1999) Otani, 1999 “Current guidelines identify most older concrete buildings as collapse risks.” Craig Comartin, EERI President, 2006 Earthquake Conference

Project thesis Available guidelines are too conservative –most buildings are found inadequate –retrofit costs are high This “always bad” message –is not credible –is impeding action Improved procedures –can reduce the problem –can make retrofit programs feasible What we learn can be translated to other building types and localities.

Project aims Develop a consensus on the “killer” buildings Demonstrate cost-effective retrofit Identify mitigation policy alternatives Promote active mitigation programs

Moehle Comerio Ramirez Mosalam Project Team Anagnos Hutchinson Leadership team Disciplines:  Seismic hazard  Inventory  Simulation  Laboratory  Field  Building  Regional  Public policy  EOT Stewart May Matamoros Steele Lopez

Research program overview Inventory –by structural type –by occupancy –by ownership Participants –building and safety –housing agencies –structural engineers –real estate professionals

Research program overview Testing to collapse –Multi-directional loadings –Realistic axial loads Simple retrofit methods

Research program overview Systems studies –SFSI –Membrane effects Flexible/Weak Foundation

Research program overview Improved simulation –model development –simulation capability Regional simulation Displacement Shear Monotonic Cyclic Envelope FEMA 356

Research program overview Crafting and evaluating appropriate policies –Identify different classes of the problem Structural configuration Occupancy Economic conditions –Identify feasible mechanisms –Model risk reduction impacts –Evaluate economic impacts Costs borne by building owners, governments, and other stakeholders Regulatory considerations

Collaborations with existing organizations ASCE Standards Committees American Concrete Institute Applied Technology Council EERI Concrete Coalition