Pitilakis K.1, Anastasiadis A.2, Alexoudi M.3, ArgyroudisS.4
The "smart" organization of the health network through modern hospital units is of special importance as it represents the level of social welfare of a country. Modern hospital units are not only characterized by the infrastructure (buildings) or the installations inside them, but also by a multitude of parameters such as their "smart" location within the urban fabric, population criteria, proper architectural design of the individual buildings as well as the hospital complex, transportation means and by their independence of any lifelines (e.g. by possessing of alternative power sources). Efficient planning of the health care system is a multidimensional task, as it includes land-planning as well as organization and management of the system in regional and local level for normal, crisis and recovery periods.
Earthquakes constitute emergency situations with particularly harmful consequences on human life, living conditions, economic and cultural activities and the built environment. The Hellenic area is characterized by high seismicity and a significant frequency of catastrophic seismic events within large (e.g. Thessaloniki, 1978, Athens, 1999) and medium size (e.g. Kalamata, 1986, Aeghio, 1995, Kozani, 1995) urban environments and touristic (e.g. Lefkas, 2003) areas. Facing of such disastrous events requires an efficient operational plan that will be based on a multi-level approach, taking into account the distinctive features of the study area and of the other elements at seismic risk. The health care system and especially the hospital units play a primary role in successfully facing the direct effects of a catastrophic earthquake concerning the most valuable resource, human life. Thus, they constitute an essential factor in operational planning, while the minimization of damages in all the components of the system and the ensuring of its access and function conditions are of vital importance.
The damages that are usually recorded as a result of seismic events could be classified as:
- Damage to the structural elements, meaning damage to the bearing system of the building
(e.g. columns, beams and slabs for reinforced concrete buildings).
- Damage to the non-structural elements (e.g. internal walls or glass partitions).
- Damage to the installations and lifelines (e.g. elevators, water networks, electric power networks).
Table 1 presents common types of damage in lifeline networks and non-structural elements of hospital units, as observed in earthquakes all over the world. Table 2 shows indicative cases of damage in four hospitals, as recorded after the 1997, Umbria-Marce (Italy) earthquake.
The damage observed after strong earthquakes in hospital complexes all over the world in combination with the importance of the medical care system, contributed to the activation of various state authorities/services and research groups. Indicative research studies are those of Masri et al. (2004), Lewis and Wang (2004), Kuwata and Takada (2003), Guevara and Alvarez (2000), Poland (1994) egarding the seismic risk assessment and management of hospitals. In Greece, no integrated study for the seismic risk of hospitals has been performed, however there are cases where the structural seismic fragility was examined (Stylianidis et al., 2003).
Methodology for the seismic risk analysis of hospitals
In the present study an integrated methodology is proposed (Figure 1) which is offered for the improvement of the existing hospitals’ management sufficiency in crisis period (earthquake), while it can also significantly contribute to the design and construction of new hospital facilities.
The basic steps of the proposed methodology are developed below:
1. Identification of the functions performed in each hospital or each building, in the case of a complexfacility, and inventory of the structural characteristics. All hospitals together should be treated as a global network.
2. Seismic hazard analysis - Selection of the seismic scenarios: The design of hospitals, like the design of standard buildings, is based on regulations (e.g. Greek Aseismic Code 2000) and special provisions that define the imposed seismic loads. However, the realistic seismic design, the vulnerability assessment of existing structures and the development of emergency plans, require a more advanced and specialized description of the expected seismic hazard. The seismic hazard is defined as the probability P of a certain ground motion parameter (acceleration, velocity, displacement) exceeding a specific value within a period of T years.
It can be performed deterministically (selection of seismic events that occurred in historical or modern years) or probabilistically. The analytical assessment of the seismic ground motion parameters is performed through specialized microzonation studies, taking into account the local soil conditions. In figure 2, together with the locations of the hospitals and clinics, the distribution of the expected peak ground accelerations for the central area of Thessaloniki is illustrated, as derived from the microzonation study of the city for a return period of 475years (Anastasiadis et al. 2002). The microzonation study is based on the results of the seismic hazard analysis and the probabilistic study of the greater area's seismicity (Alexoudi et al., 2002)
3. Definition of the elements and sub-elements that comprise the hospital and the relation between them through"logic diagrams". The basic elements of a hospital complex, mainly in a crisis period, are the operating theaters, radiology departments, laboratories, pharmacies, critical installations and lifelines that serve the needs of the complex hospital facilities and connect it with the urban fabric (e.g. water and waste water, electric power, communication networks). Moreover, internal installations (e.g. elevators) and medical equipment could be considered as sub-elements of the hospital. An indicative “logic diagram” (Figure 4) was produced by Nuti et al. (1999) for a hospital complex in Italy.
4. Definition of the “Fault Tree”. The “Fault tree” graphically defines the organization of the hospital, while its branches define all the possible ways in which a “top event” may occur. The failure of the hospital, which can be characterized as a “top event”, is based on serial or parallel connections between the elements or the sub-elements. If there is a serial connection, the failure of one element influences all the other elements or sub-elements that depend on it. Otherwise, a parallel connection provides several alternative routings that can improve the final response of the hospital complex. The failure of each element or sub-element is defined by fragility curves, which correlate the strong motion parameters with the probability of exceeding a specific damage state (minor, moderate, extensive, complete damage). Fragility curves can be defined analytically, statistically or by engineering judgment using the “logic diagrams” mentioned above. Finally, the site and case-specific fragilities can be obtained for the particular organization and structure of the hospital facilities, equipment and buildings. An example of a fragility curve for a complex hospital is illustrated in Figure 5.
5. Calculation of urban vulnerability: Although a hospital is mainly influenced by the medical equipment and personnel, it interacts directly with the urban environment from which its patients come. Lifelines can act as a link between the hospital and the urban environment as they supply water, energy and communication (Figure 6). Moreover, the transportation system is essential for transporting patients and injured persons to the hospital facilities (Figure 7).
The response of the road network includes the estimation of potential damage to bridges, tunnels and roads and more generally the determination of road blockage as a result of building debris (Αrgyroudis, 2004). The definition of serviceability level of the transportation network is accomplished through the calculation of travel time for the transfer of injured people to the hospital. The optimization of time through the definition of more secure and faster routes appoints the extent of interaction between the urban environment and an effective hospital network.
6. Estimation of hospital’s ‘global value’: The classification of the hospital’s importance is based on various criteria such as the provided services (e.g the type of clinics), operational (e.g number of beds, available personnel) and urban (distance from urban areas, location in urban environment). The hierarchy of importance plays an important role in emergency situations. The “urban system analysis” that classifies the importance of the elements at risk is carried out for three periods: a) Normal: It includes the phase before the catastrophic event. b) Crisis: it is the disaster period and the following few hours. c) Restoration: It starts immediately after the crisis and is related to the recovery progress of facilities and activities that were damaged or malfunctioned during crisis period.
The definition of hospital’s global value is directly connected to the urban organization of the city, the population and building density, the distribution of open spaces, land uses and with the framework of building provisions in general.
The hospitals are classified in to two categories, according to urban and building organization:
- inside the urban agglomeration, placed in central areas of the city, with high densities and buildingcoefficients.
- in areas with low structural density, inside the urban agglomeration, or outside, in the urban unit of the city.
7. Proposals for the mitigation of seismic risk through appropriate pre-earthquake interventions in the weak parts of the system together with the preparation of emergency plans and efficient restoration policies. For all of the above a full cooperation of Public Authorities and the Organisations managing the networks is needed.
Conclusions - Suggestions
The medical care system is undoubtedly of vital importance, especially in emergency situations (e.g. earthquakes). International experience reveals that this system could be quite vulnerable in earthquakes not only because of its structural vulnerability, but mainly as a result of the non-structural vulnerability of elements and sub-elements within hospital units. Moreover, the internal and external interactions between hospital networks and lifelines or transportation systems of the urban fabric, greatly influence the response of the system.
In this paper, the basic principles of an integrated methodology for the seismic risk assessment of the medical care system were presented, considering the various parameters that define the response not only of individual hospital units but of the global network as well. This kind of approach is deemed essential, as it proposes effective and technologically viable solutions for the ‘smart’ design, improvement and organization of hospitals.
An efficient management policy includes the following:
- Mitigation of the seismic risk through:
- Seismic retrofitting of the bearing system of the buildings, in cases of high structural vulnerability and importance (global value).
- Pre-earthquake reinforcement measures and anchorage of the critical hospital equipment.
- ‘Intelligent’ building organization and architectural design of hospitals.
- Functional sufficiency according to the basic regulations or codes such as fire safety, escape routes etc.
- Application of safety measures against environmental pollution or technological accidents.
- Efficient function of the transportation networks.
- Development of emergency plans with emphasis placed on:
- Anticipation of outdoor open areas in order to temporarily house some of the hospital services if evacuation of the buildings is required after the earthquake.
- Usage of new technologies (e.g. GIS, GPS) for the efficient transit of ambulance to the hospitals.
- Definition of emergency routes and, possibly also emergency traffic lanes and helicopter landing locations for the transportation of injured persons.
- Special well-organized areas for the reception of the public (first aid) inside the hospitals.
- Measures against dysfunction/ malfunction of lifeline networks by predicting alternative routing, second supply tanks and mobile communication.
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