Foundation, Concrete and Earthquake Engineering



Essential facilities are those facilities and parts of a community's infrastructure that must remain operational or can be restored quickly after an earthquake for a community to respond effectively. Categories of essential structures include those:

1. Structures and equipment in government communication centers and other facilities required for emergency response.

2. Hospital and other medical facilities having surgery and emergency treatment area.

3. Fire and police stations.

4. Tanks or other structures containing, housing or supporting water or other fire-suppression materials or equipment required for the protection of essential or hazardous facilities, or special occupancy structures.

5. Emergency vehicle shelters and garages.

6. Structures and equipment in emergency-preparedness centers, including cyclone and flood shelters.

7.Standby power-generating equipment for essential facilities.

8. Whose failure might be catastrophic, such as large dams or nuclear power plants;

9. Utilities whose continuing function is critical, such as roads, bridges, and overpasses, major electrical power plants and major power lines, water lines, sewer lines, and major fuel lines;

Location and Design Criteria for Essential Facilities

Those essential structures which are necessary for emergency response must not only survive a major earthquake, but must be able to function at full efficiency. Essential facilities should be located, designed, and constructed in such a manner that they can continue to function after a major earthquake. Designing a building to this higher standard entails not only a stronger structure, but also greater attention to non-structural items such as elevators, lighting, and storage facilities.

For essential structures the design of buildings must include whatever added cost is necessary to assure the continued functioning and safety of the structures. Such structures should never be located on a site of high seismic hazard. Those existing essential facilities which are identified as being potentially non-operable after an earthquake must be strengthened and their equipment secured so they will function after an earthquake. Sensitive equipment, such as main-frame computers, may have to be isolated from buildings so that it will not shake with the building.


During a disaster it is absolutely essential that an emergency communications system continue to function. The emergency operations center must be able to rapidly determine where the most serious problems are and quickly dispatch response teams for rescue, fire fighting, medical care, etc.

Following steps which will mitigate some of the communications difficulties can be taken:

1. Equipment at major radio sites have to seismically braced to increase the chances of operation survivability in the event of a major earthquake.

2. Microwave hotline system has to install.

3. The Public Safety microwave systems have to design with redundancy so that loss of a single major path does not result in catastrophic system failure.


In a really major disaster all of the hospitals in the region will have to operate at maximum capacity. Any damage which would seriously impair the ability of even one hospital to function effectively is not acceptable. Serious damage to equipment and supplies can impair medical response to an emergency. All back-up equipment such as electrical generators, fuel and water supplies, etc. must be securely fastened and in positions where they will not be damaged. Several days supply of food, water, medicines and other supplies must be on hand. These supplies have to be stored in such a manner that they are not damaged or thrown into disarray.


Fire stations, police stations, ambulance services, and emergency operation centers must have the ability to provide immediate response during an earthquake or other disaster. This means that they must be staffed at all times and have a means of automatically calling up reserve personnel in an emergency. In the event of a break in communications during a major earthquake, the earthquake itself serves as a call-up signal to off duty personnel.

Each emergency response center must be staffed with emergency supplies of food, water, and other supplies, and each must have an independent source of power. Both the power equipment and vehicles, such as fire trucks and ambulances, must be kept where they will not themselves be damaged.


Failure of a large dam or nuclear power plant as the result of a major earthquake would make the disaster much worse. Such structures must be designed so that they cannot fail during an earthquake, however large. An emergency evacuation plan for Nuclear Generating Station has to prepare. Copies are on file at all of the concerned agencies and an evacuation brochure has been provided for all residents within ten miles of the plant.


A major earthquake in a community would certainly cause serious damage to portions of the transportation network. A number of local streets might be temporarily blocked by collapsed buildings and downed electrical lines. Rockfalls and landslides would block short sections of the highways and some of the bridges and overpasses may collapse. The fills for Highway and the runways may be damaged by liquefaction of the underlying soil. On the rail lines some of the rails would be bent out of shape, cuts would be blocked by slumping, and fills distorted by lurching or liquefaction. Some of the harbor facilities would likely fail because of soil liquefaction, collapse of bulkheads, etc.

On the other hand, most of the freeway system should remain intact or repairable in a few days for limited use.

Very quickly after an earthquake the Office of Disaster Preparedness will determine which routes are open or can soon be opened. Within a few days, or even perhaps hours, massive amounts of aid-medical supplies, doctors, rescue workers, food, etc., will be available from the rest of the country or neighboring countries. The disaster coordinator will have to direct this outside relief so that the appropriate help is directed to where it is most needed, and at a rate which does not disrupt the remaining capacity of the transportation system.


In a large earthquake there will be damage to the utility (or "lifeline") systems that provide water, sewers, electricity, fuel, and transportation to the community. It is anticipated that entire communities will have their service interrupted for a few days until emergency repairs are made. To a large degree each individual residence, business, and institution will have to survive on its own for the first 72 hours.

Some facilities, such as the aqueducts which carry water from the River, are likely to be broken. During the months that it will take to make repairs, water rationing would be necessary.

Many essential facilities, particularly lifelines, are vulnerable to the effects of earthquakes. Landslides and rock falls, for example, can block highways and railways; surface fault ruptures can damage highways, runways, and railbeds or break sewer, water, or fuel pipelines and thereby cause pollution and fire hazards. Strong shaking can cause transmission lines and overpass structures to fail, and power transmission and highway and railway use will be interrupted; liquefaction and the resulting ground failures can cause failure of bulkheads, piers, and quays, thereby disrupting shipping.

If water, sewer, telephone, and electrical systems remain operational, or can be restored quickly, the difficulties of providing an effective emergency response to an earthquake, and of recovery, will be greatly reduced.

Another important aspect of damage to utilities is that their destruction could make a bad situation even worse. The most striking example of this is the 1906 San Francisco Earthquake where, because the fire fighting system was inadequate, far more damage was caused by the ensuing fire than by the earthquake.

To ensure effective, immediate fire fighting capacity the fire stations themselves must be quake-safe and there must be local sources of water available. Also, to the extent possible, major water distribution lines should be strengthened.


Failure of a single high-occupancy structure can result in hundreds of deaths and injuries. Seismic design is particularly important when the occupancy is involuntary, such as in schools or jails, or when the occupants are in some way disabled, such as in hospitals, nursing homes and mental institutions.

Unlike essential facilities necessary for emergency response, high-occupancy buildings do not have to function after an earthquake. They do not even have to be repairable, but it is very important that they do not collapse completely or catch on fire.

High occupancy buildings should be identified as part of a hazardous building inventory. Potentially hazardous buildings should be individually evaluated by a structural engineer and, if found hazardous, accorded high priority for strengthening under hazardous building abatement programs.

The degree of risk can be reduced by strengthening the buildings, reducing the occupancy, or by razing the buildings. It is important to remember that the goal is not for the buildings to function perfectly in an earthquake, but only that they not collapse on the occupants. It is not economically feasible to construct most buildings to survive without damage in an event so infrequent as a major earthquake.

Steps Required to Keep Functioning Essential Facilities

If essential facilities are to function adequately after an earthquake the following steps have to be taken before the earthquake:

1. Identification of essential facilities.

2. Establish standards for performance.

3. Assess vulnerability.

4. Determine what needs to be done to bring each facility up to an acceptable level.

5. Determine responsibility and schedule for remedial action.

The first steps in preparing essential facilities for survival in an earthquake are to identify the facilities. The essential facilities in the community can be mapped by the Department of Planning and Land Use.

The second step is to determine the ability of each facility to remain operable after a severe shaking. The vulnerability of each structure needs to be assessed. Usually a structural engineer, and often an engineering geologist or geotechnical engineer is needed. Evaluation of vulnerability includes site hazards, structural design, facility function, and relative importance of each facility.

The next step is to determine what needs to be done to bring each structure to a condition where it can function immediately after an earthquake. Some of the more common solutions are:

1. Add ties to secure ceilings to bearing walls;

2. secure heavy equipment to walls and floors;

3. provide redundancy in key equipment;

4. secure supplies so they cannot fall off of shelves;

5. containment for hazardous materials;

6. emergency generating and communications equipment;

7. flexible connection between pipes and containers and multiple shut-off valves;

8. provide additional lateral reinforcement.

The next step is to develop a schedule and determine responsibility for upgrading the essential facilities. Facilities intended for emergency response and those whose failure would entail a large loss of life should receive the highest priority.

The responsibility for the safety of facilities is fragmented. The Federal Government is responsible for all of the military facilities. The States should take care of safety measures for dams, public schools, and hospitals. Each city, and in the unincorporated area, the County is responsible for the safety of private schools, nursing homes, and high occupancy structures.

Each fire district, water district, and the gas and electric company has responsibility for its own facilities. But the County, because of its role in coordinating disaster preparedness and response, has an overall responsibility to try to get all of these jurisdictions and public utilities to make their essential facilities earthquake safe. The mechanism for doing this is not well developed.

The State Unreinforced Masonry Law mandates that each jurisdiction should have an ordinance on unsafe masonry buildings.


The Policies of a County should be to:

1. Ensure that facilities whose continuing functioning is essential to society, and facilities needed in the event of emergency, are so located and designed that they will continue to function in the event of a disaster.

2. Ensure that structures for involuntary occupancy (such as schools, hospitals, and jails) and structures for high voluntary occupancy (theaters, churches, offices, apartment houses, etc.) are so located and designed that they will not collapse or burn before the occupants can be evacuated.

3. Require periodic inspection of all essential facilities under County jurisdiction and to urge other jurisdictions to do the same for facilities which are their responsibility.

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