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Incremental Integrated Seismic Rehabilitation

Significant progress has been made in the development of techniques for the seismic evaluation and rehabilitation of existing hazardous buildings as a result of the National Earthquake Hazard Reduction Program (NEHRP) and the NEHRP documents noted above. However, there are still significant barriers to the implementation of seismic rehabilitation. Initial cost, loss of normal use, and uncertainty of cost recovery have been the principal obstacles to seismic rehabilitation investment. The concept of Incremental Integrated Seismic Rehabilitation is specifically designed to reduce the obstacles of high initial cost and the cost of service interruption. Integration of seismic rehabilitation into the normal cycle of building operation and maintenance significantly reduces the cost of work specifically assigned to seismic rehabilitation because in many maintenance procedures scaffolding and other construction equipment are in place, work surfaces are exposed, and use interruptions are accommodated. Incremental phasing of seismic rehabilitation significantly reduces the obstacle of initial cost and allows for the accomplishment of improved seismic safety over a period in which it may be accommodated in maintenance budgets or as an increment of normal capital improvement. An incremental approach is a reasonable response to the uncertainty of cost recovery. This is because the seismic risk is probabilistic over time, as a function of earthquake recurrence periods, and so are the benefits of the reduction of this risk.

It is important to recognize that "the normal cycle of building operation and maintenance" referred to in the preceding paragraph may vary with organization type and occupancy category of the buildings. In the case of schools, based on case studies that delved into the actual experience of school districts, it was possible to categorize "the normal cycle of building operation and maintenance" into eight broad categories:

  • Roofing maintenance and repair/re-roofing.
  • Exterior walls maintenance and repair/window replacement.
  • Fire and life safety improvements.
  • Modernization/remodeling/new technology.
  • Underfloor and basement maintenance and repair.
  • Energy conservation/weatherization/air conditioning.
  • Hazardous materials abatement.
  • Accessibility improvements.

Similar analysis will be carried out for each use category in the proposed project.

Incremental Integrated Seismic Rehabilitation recognizes that financing and administration are determining factors in the accomplishment of earthquake safety that are as important as design and construction. The modification of rehabilitation strategies to accommodate administrative and finance practices in the organizations which make investment decisions for mitigation is an important new dimension in implementing seismic safety.

The approach proposed consists of five basic parts that are summarized below:

  • Establishing the concept's validation and currency---The NSF funded conceptual development of the Incremental Integrated Seismic Rehabilitation approach drew on the experience of selected school districts in the early 1990s. Research findings from this study were documented and enjoyed limited prototype application. It is now appropriate to evaluate and update those initial findings and recommendations for broad application nationally. The proposed approach is described more fully as Task 3, and consists of four parts: Empirical Validation, Analytical Validation, Benefit/Cost Validation, and Currency Validation.

  • Establishing the basis for selection of other occupancies---In the NSF project, the applicability of the Incremental Integrated Seismic Rehabilitation concept to school buildings was based on the favorable condition of three sets of generally shared characteristics:

    Occupancy/use characteristics
    Building type/structural characteristics
    Institutional/organizational characteristics

    Though there is clearly variation in each of these sets of characteristics over the national stock of school buildings there has proven to be adequate commonality to allow useful generalization in the development of rehabilitation process models and the identification of specific rehabilitation opportunities. In terms of occupancy/use characteristics, most lower, middle and upper schools in the United States contain similar aggregations of spaces and spatial relationships and similar patterns of use. In terms of building type/structural characteristics, most school buildings in the United States are one to four stories in height, have a relatively high ratio of floor area to perimeter wall area and share several seismically vulnerable structural characteristics that are a function of when they were built (for example, unreinforced load-bearing masonry, and precast concrete roof elements over long-span spaces such as gymnasiums). In terms of institutional/organizational characteristics, most public school districts in the United States have similar organizational structures and similar methods of financing.

    In order to apply the concept of Incremental Integrated Seismic Rehabilitation to occupancies and contexts beyond schools, we propose to examine the clustering of various occupancies within a 3-dimensional matrix with the three sets of characteristics on the respective axes. We propose to start this matrix analysis with occupancy types for which seismic safety is a high societal priority: emergency facilities, nursing homes, office buildings, and hotels/motels.

  • Collection of information pertinent to other occupancies -- The approach proposed for this task is to obtain information from the respective trade and professional associations concerned with each occupancy. The information will not be obtained by means of the distribution of survey instruments. This information will be validated and reinforced on the basis of actual seismic rehabilitation experience.

  • Preparation of manual -- The manual will lay out the general concept of Incremental Integrated Seismic Rehabilitation, and will include targeted sections for each occupancy type. Each section will address two specific audiences within each of the occupancy/use categories: policy makers and senior executives, and facility and risk managers.

  • Development of dissemination plan -- The approach proposed is to develop the dissemination plans in close collaboration with the respective trade and professional associations concerned with each occupancy type.