|Mitigation of Disasters in Health Facilities: Volume 1: General Issues (PAHO-OPS, 1993, 60 p.)|
|Chapter 5: risk mitigation in hospitals|
The level of risk can be reduced if it is understood as a combination of the hazard or probability of occurrence of disaster and the vulnerability to it of the elements exposed, or as an estimate of the severity of the possible impact on those elements. Structural measures such as the construction of protective works or alterations designed to diminish the vulnerability of the elements at risk, and non-structural measures, such as regulating soil use, incorporating preventive aspects into investment budgets, and making preparations for providing medical care during emergencies can all reduce the impact of a disaster on a region or a population.
All this should be done before a disaster occurs. Everything that is done to reduce or prevent the damages that a disaster may cause is called "mitigation of risks." Everything done afterwards is known as "response." This section focuses only on mitigation in the case of health facilities, and, in particular, hospitals.
Mitigation of the impact of disasters by the adoption of preventive measures is a highly cost-effective activity in areas where disasters are frequent. For every dollar well spent on mitigation before a disaster occurs, much more will be saved in terms of losses prevented. Mitigation is not, in fact, a cost. In the long run it pays for itself. And it does so in real money, and in lives saved.
Traditionally, functional distribution of areas within hospitals does not include as one of its design criteria the treatment of large numbers of injured persons. If this aspect is taken into account, certain adjustments can be made in the relationship between areas and, in some cases, it will be necessary to make some design changes that could help mitigate disasters in the building.
Not only for purposes of mitigation and prevention, but also for administrative reasons, the possibility of separating the general services sector from the main hospital building should be explored, for the following reasons:
· The general services sector usually houses boilers, which can become dangerous time bombs capable of doing untold damage should they explode.
· Similar considerations apply to a hospital's gas plant. Although it is true that this modification would be costly, when compared with the costs of the damage that could be avoided the costs involved should be considered minor.
· Another service commonly located in this sector is the emergency generator. This is a service that could also be housed in a separate building, not so much because of the risks associated with it but in order to ensure that it can be used at critical moments.
· For the same reasons, it may also be advisable to put telephone, radiocommunication, and other facilities in this separate area. As with the electric generator, this would enhance the possibility of such services being available after a disaster.
· It also is desirable to locate a hospital's water storage tanks in this area, whenever possible. In most cases they are located on the upper floors of buildings, increasing the load on the structure, and thereby constituting one more risk.
· It follows that it also would be desirable to put kitchen services in the same area, given that they require water, light and gas.
· If the same thing were done with the laundry service that would complete the package of services available and in operation, capable of serving either all or some areas of the hospital affected by a disaster or in the case of the need for an open-air hospital.
Such modifications are possible if there is a multidisciplinary team made up of engineers, architects, planners, etc., as well as medical and paramedical personnel, striving to work out a set of actions, responsibilities, movements and physical solutions. Obviously this is more feasible in the case of new designs, but it can also be implemented in certain types of existing installations.
One of the most important aspects from the functional point of view is proper posting of signs inside the hospital. This is important not only to guide people during normal use of hospital services, but for also the evacuation of the building when a disaster occurs. The signs should point to evacuation routes leading to stairs or emergency exits not normally used but designed especially for emergencies. In addition, there should be signs pointing to fire extinguishers, hoses and other fire equipment, fire doors wherever they exist, emergency telephones, etc. Signs should be posted not only inside the building, but outside and in the surrounding urban area.
After identifying a non-structural element that can suffer or cause damage, and its priority either functionally or in terms of loss of human lives or of property, appropriate steps should be taken to reduce or eliminate the danger. We list below 12 applicable mitigation measures which, in many cases, has been shown to be effective:
3. Restricted mobilization
5. Flexible couplings
12. Rapid response and repair
1. Removal is probably the best mitigation option in many cases. For example, a dangerous material that could be spilled could be stored off the premises. Another example would be the use of heavy stone or concrete veneer on the outside of the building or along some balconies, which could easily come loose during an earthquake endangering everything beneath it. One solution would be to use better anchorage or stronger supports, but the most effective solution would be removal and substitution.
2. Relocation would reduce danger in many cases. For example, a very heavy object on a shelf could fall and cause serious injury, or it could become damaged, causing economic losses. If the object were to be relocated to a floor level shelf, it would not endanger human lives or property. It is also advisable to keep bottles containing dangerous liquids on the floor, if possible.
3. Restricting movement of certain objects, such as gas cylinders and electricity generators, is a good measure. It does not matter if cylinders shift so long as they do not fall and break their valves, releasing their contents at high pressures. Sometimes it seems desirable to install emergency generators on springs in order to reduce the noise and vibrations when they are operating, but the springs would amplify seismic tremors. Restrictive supports or chains should be placed around such springs in order to keep the generator from shifting or being knocked off its stand.
4. Anchorage is the most widely used precaution. It is a good idea to fasten objects with bolts or to tie them down using cables or other materials to keep objects of value or of considerable size from falling or sliding. The heavier an object is, the more likely it is to move owing to forces of inertia. A good example would be a water heater, of which there may be several in a hospital. Since they are heavy and if they fall could break a water main, an electric wire or a pipe carrying fuel, they constitute a fire or flood hazard. A simple solution is to utilize metal strips to fasten the lower and upper parts of the heater against a wall or other support.
5. Flexible couplings are sometimes used between buildings and exterior tanks, between separate parts of the same building and between buildings. These are utilized because separate objects each move independently in response to an earthquake, some move rapidly or at high frequencies, others slowly at low frequencies. If a tank is connected to a building by a rigid pipe, the tank will vibrate at frequencies and in directions and amplitudes different from those of the building, causing the rigid pipe to break. A flexible pipe would prevent ruptures of this kind.
6. Supports are appropriate in many cases. For example, ceilings are usually hung from cables that withstand only the force of gravity. When submitted to the multitude of horizontal and distorting forces that result from an earthquake, they fall easily. Although electrical boxes are not heavy, sometimes they may have heavy lights fixtures attached to them. If they fall, they can seriously injure the people underneath. The electric connections may also be torn out of the ceiling and constitute a fire hazard.
7. Substitution by something that does not represent a seismic danger is the correct solution in some situations. For example, a heavy tile roof not only makes a building heavy, but also more susceptible to the movement of the earth in an earthquake. The individual tiles tend to detach themselves creating a danger for the people and objects below. A solution would be to switch to a lighter and safer roof.
8. Modification of an object that represents a seismic hazard is feasible. For example, the movements of the earth twist and distort a building, possibly causing the rigid glass of its windows to shatter, throwing sharp glass splinters at the occupants. Clear plastic can be used to cover the internal surfaces; it is invisible and reduces the likelihood of a glass window causing injuries.
9. Isolation is useful for small loose objects. For example, if lateral panels are placed on open shelves or latches on cabinet doors, their contents will remain isolated and will probably not be thrown about in the event of an earthquake.
10. Reinforcements are feasible in many cases. For example, an unreinforced fill-in wall or an unreinforced chimney can be strengthened at no great cost by covering the surface with wire mesh and by filling it in with cement or some other mixture. Not only will these non-structural objects be protected against failures; in the case of the fill-in walls the structural elements will also be strengthened.
11. Redundancy of supplies is advisable for emergencies. It is possible to store additional quantities of certain products in boxes in places that will be accessible after an earthquake.
12. Rapid response and repair is a mitigation tactic often used for long pipelines. Sometimes it is not possible to do anything to prevent a pipe breaking in a given site, so parts are stored nearby and the necessary arrangements are made to ensure rapid access to the area in case of rupture of the pipeline during an earthquake. In a hospital, spare parts for plumbing, electricity, and other repairs, together with the appropriate tools should be kept on hand, so that if something is damaged, it can easily be repaired. For example, during an earthquake water pipes may burst; it may be impossible to couple each of the tubes and take each one of the measures necessary to eliminate this risk altogether, but it should be possible to ensure that everything necessary for a quick repair is at hand. By planning before an emergency it is possible to save the enormous cost of damage caused by water with a minimum investment in a few articles and by thinking in advance about what could occur.
The general measures discussed above are applicable to almost all situations. However, in many cases, one simply has to be creative and think up one's own way to mitigate the effects of disasters.
In most countries there already exists some awareness of the importance of health facilities being properly equipped to meet future needs. Many of these facilities are probably vulnerable in variable degrees to damage from earthquakes, hurricane winds, or other natural hazards. However, it is possible to reduce that vulnerability. Experience shows that applying relatively inexpensive measures has increased safety and improved existing structures. To be really efficient beneficial, the adaptation or alteration of existing installations should be carried out systematically and consistently.
Many existing buildings do not meet the current technical requirements. Their vulnerability to certain natural hazards can be so great that associated risks may far exceed currently accepted levels. Remedial action based on scientific knowledge should, therefore, be taken in order to reduce the risk and guarantee that buildings behave as they should. Likewise, this adaptation or strengthening of existing buildings should be consistent with current engineering requirements and in accordance with the requirements established by the design codes of each country.
The usual methods for retrofitting existing structures generally include the insertion of the following elements:
Walls on the outside of the building. This solution is usually used when space limitations and continuity in the use of the building make it preferable to do construction work around the building. In order to ensure the transmission of seismic forces from the old structure to the new structural walls, beams are used at the edge of each slab.
Buttresses. Unlike the previously mentioned walls, they are placed perpendicular to the face of the building. Apart from stiffening the building, they are useful in order to keep tall buildings from tipping over. Due to space limitations, however, they are not always feasible.
Walls in the interior of the building. If conditions permit construction work inside the building, these are an alternative that must be considered in the case of long buildings, in which the structural flexibility of the floors is to be reduced. These walls are usually inserted by means of perforations in the plates of the floors through which the reinforcement bars of the new structural elements are passed.
Portico fill-in walls. Both on the inside and the outside of buildings, a practical solution to the problem of rigidity and resistance is the filling in of empty portico spaces with concrete or strengthened masonry walls. Because they are joined to columns, the stresses borne by the latter will change substantially. If the reinforcement steel in the columns is strong enough to support the new loads, the connection to the wall may be made using soldered braces only. If not, the columns will have to be sealed monolithically within the wall.
Specially anchored frames. Another frequent solution consists of including several steel frames with diagonals firmly anchored to the floors, as a substitute for the rigid walls. Also, diagonals only, joined to existing porticos, can be constructed when the porticos prove capable of withstanding the stress placed on them by the new system.
Covering of columns and beams. Used for portico systems, this technique is usually applied to most of the columns and beams of a building, in order to increase their rigidity, resistance and ductility. These systems are mostly differentiated basically by the way in which the new covering is connected to the existing column.
Construction of a new frame system. Sometimes it is possible to carry out a total restructuring by attaching the old structure to new external parametric frames. Usually this is combined with the incorporation of internal structural walls perpendicular to the longitudinal direction of the frames.
There are several reasons why altering the seismic vulnerability of the structure of a hospital building is usually more complex than a similar operation in another type of building:
· Normally the building cannot be vacated in order to carry out retrofitting.
· The scheduling of the construction work must take into account the need to keep different medical services operating, and to avoid seriously disrupting hospital activities or unjustifiably interrupting certain types of services.
· The need to perform a large number of unforeseen tasks due to the difficulty of identifying in advance precise details of the construction process.
· The complexity of the non-structural elements and the difficulty of identifying changes or effects on architectural elements prior to the beginning of the structural alteration.
It follows from the above that should be based on a very detailed work plan that includes keeping medical services going at each stage of the process. In the same way there must be coordination between administrative personnel, the medical staff, and the maintenance department of the hospital.
It is not possible to know the cost of reducing the vulnerability of a hospital unless there is a detailed design of the structural solution and of its implications with regard to non-structural elements. However, this does not preclude drawing up a plan in advance with enough precision to ensure that it will only require minimal adjustments as the work proceeds.
Usually reinforcement costs are relatively high if they are carried out all at once. However, if the work is carried out by stages, it makes it possible for funds to be assigned more gradually and more in line with a hospital's maintenance budget.
In general, it is possible to divide mitigation recommendations into two categories:
· Those that are easy to implement in the short term, for example providing windows with shutters and extra locks for doors; installing additional fasteners to roof tiles; fixing external plants; or relocating storage systems to safe buildings if the building where they are is vulnerable. These tasks should be carried out by the maintenance staff of the health center or by small contractors.
· Those that require the advice of specialists or major capital investment, such as expensive modifications or new constructions to be built in the medium and long term.
In many cases, it is up to the maintenance staff to take such steps, which can be an advantage given their knowledge of the site and their ability to carry out periodic reviews of the measures adopted. Indeed, the improvement of existing buildings and structures can be carried out through routine repairs and maintenance.
The additional costs involved in making a building resistant to hurricanes, earthquakes, and floods can be considered a form of insurance. Comparative studies show that the difference in costs between a building constructed according to anti-seismic specifications and a similar building where the code has been ignored may vary by between 1% and 4% of the total cost of the building. If the cost of the provision of the hospital's equipment is considered, the percentage could be much lower, because equipment costs may represent around half the total cost of the building.
If one analyzes the problem in terms of the cost of protecting a specific piece of equipment, the difference could also be surprising. For example, a power outage in a hospital as a consequence of severe damage to an emergency generator which could cost US$50,000 to repair, can be avoided by installing seismic insulators and other fixtures to keep the generator from overturning, the cost of which may be as little as US$250.
The high economic and social returns of improving the structural behavior of vulnerable hospital buildings have been demonstrated. The cost of retrofitting, although it may seem high, will always be significantly less than the services budget or the alternative cost of repairs or physical replacement. Some good figurative questions to ask might be, how many scanners could be bought for an amount equivalent to the cost of retrofitting? And how many scanners does the hospital have? The replies could yield surprising results, without taking into account all the other elements, equipment and goods that the building normally contains, not to mention the human lives involved directly or indirectly and, in general, the social cost of a loss of hospital services.