This paper presents a conceptual framework to define seismic resilience of communities and quantitative measures of resilience that can be useful for a coordinated research effort focusing on enhancing this resilience. This framework relies on the complementary measures of resilience: “Reduced failure probabilities,” “Reduced consequences from failures,” and “Reduced time to recovery.” The framework also includes quantitative measures of the “ends” of robustness and rapidity, and the “means” of resourcefulness and redundancy, and integrates those measures into the four dimensions of community resilience—technical, organizational, social, and economic—all of which can be used to quantify measures of resilience for various types of physical and organizational systems. Systems diagrams then establish the tasks required to achieve these objectives. This framework can be useful in future research to determine the resiliency of different units of analysis and systems, and to develop resiliency targets and detailed analytical procedures to generate these values.

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Objectives:To investigate the relative distribution of hazards causing hospital evacuations, thereby to provide rudimentary risk information for hospital disaster planning.Methods:Cases of hospital evacuations were retrieved from newspaper and publication databases and classified according to hazard type, proximate and original cause, duration, and casualties. Both partial and full evacuations were included. The total number of evacuation incidents for all hazards were compared to the total number of hospital incidents for the one hazard, fire, for which national data is available.Results:There were 275 reported evacuation incidents from 1971–1999, with an annual average of 21 in the 1990s, the period for which databases were more reliable. The most, 33, were recorded in 1994, the year of the Northridge Earthquake. Of all incidents, 63 (23%) were attributable primarily to internal fire, followed by internal hazardous materials (HazMat) events (18%), hurricane (14%), human threat (13%), earthquake (9%), external fire (6%), flood (6%), utility failure (5%), and external HazMat (4%).Conclusions:More than 50% of the hospital evacuations occurred because of hazards originating in the hospital facility itself or from human intruders. While natural disasters were not the preponderant causes of evacuations, they caused severe problems when multiple hospitals in the same urban area were incapacitated simultaneously. Clearly, as hospitals are vulnerable to many hazards, mitigation investments should be assessed not in terms of single-hazard risk-cost-benefit analysis, but in terms of capacity to mitigate multiple hazards. In view of the many qualifications and limitations of the dataset used here, but value of such data for disaster planning, hospitals should be asked to submit standardized incident reports to permit national data gathering on major disruptions.

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The cyclic behavior of precast segmental concrete bridge columns with high performance (HP) steel reinforcing bars and that with conventional steel reinforcing bars as energy dissipation (ED) bars were investigated. The HP steel reinforcing bars are characterized by higher strength, greater ductility, and superior corrosion resistance compared with the conventional steel reinforcing bars. Three large-scale columns were tested. One was designed with the HP ED bars and two with the conventional ED bars. The HP ED bars were fully bonded to the concrete. The conventional ED bars were fully bonded to the concrete for one column, whereas unbonded for a length to delay fracture of the bars and to increase energy dissipation for the other column. Test results showed that the column with the HP ED bars had greater drift capacity, higher lateral strength, and larger energy dissipation than that with fully bonded conventional ED bars. The column with unbonded conventional ED bars achieved the same drift capacity and similar energy dissipation capacity as that with the HP ED bars. All the three columns showed good self-centering capability with residual drifts not greater than 0.4% drift. An analytical model referred to as joint bar-slip rotation method for pushover analysis of segmental columns with ED bars is proposed. The model calculates joint rotation from the slip of the ED bars from two sides of the joint. Good agreement was found between analytical predictions and the envelope responses of the three columns.CYCLIC BEHAVIOR OF SEGMENTAL COLUMNS WITH HP 1189 second, and third terms of Equation (8) represent displacements resulting from joint bar-slip rotations, shear deformations, and elastic flexural rotations, respectively.

SUMMARYPast experimental studies have shown that existing precast segmental concrete bridge columns possess unsatisfactory hysteretic energy dissipation capacity, which is an undesirable feature for applications in seismic regions. In this research, we propose new methods of precast segment construction for tall concrete bridge columns to enhance the columns' hysteretic energy dissipation capacity and lateral strength. This is accomplished by adding bonded mild steel reinforcing bars across the segment joints, strengthening the joint at the base of the column and increasing the height of the base segment (hinge segment). Four large-scale column specimens were fabricated and tested with lateral cyclic loading in the laboratory. Each specimen consisted of a foundation and 9 or 10 precast column segments. Test results of specimens with the proposed design concepts showed ductile behavior and satisfactory hysteretic energy dissipation capacity. In addition to the experimental study, an analytical study using the finite element method was conducted to understand the bond conditions, strain contours and deformation patterns of the specimens tested. Good agreement was found between the experimental observations and the results of the calibrated analytical study.

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