UNDERSTANDING VULNERABILITIES : I (Vulnerability of Physical Structures)

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1 UNDERSTANDING VULNERABILITIES : I (Vulnerability of Physical Structures) Goals To develop an understanding of the vulnerability of the physical structures and their causes Learning outcomes After completing this session you will be able to understand the: Structural vulnerability of physical structures Non-structural vulnerability Functional vulnerability Learning objectives As you work through this session you will learn to Describe engineered, non-engineered, owner built buildings, critical facilities and life lines and criteria to be considered for their design Explain causative factors of structural vulnerability Understand building typology and list characteristics and vulnerability functions of different building types Describe non-structural vulnerability and its assessment Describe functional vulnerability and its assessment Keywords/phrases Engineered construction Non-engineered construction Owner-built buildings Critical facilities Lifelines Structural vulnerability Causative factors Assessment Building typology Vulnerability functions Masonry buildings Framed buildings Non-structural vulnerability Assessment Functional vulnerability Assessment 1. Concepts Engineered Constructions: These are the structures (e.g., buildings) that is designed and constructed as per standard engineered practices. In case of buildings, engineered construction are those that are supposed to have undergone the formal process of regular building permit by the municipal or other pertinent authority. The formal building permit process is supposed to require involvement of an architect/engineer in the design and construction for ensuring compliance to the existing building code and planning bylaws. In most developing countries, formal building permit process is observed only in urban areas. In developing countries, building codes (with earthquake safety consideration) either do not exist, or not implemented strictly. Therefore, consideration of seismicity on building design depends upon the individual initiative of the designers and the availability of fund. In case clients require(d) design against earthquakes in a country does not (did not) have regulation to govern the design of 1

2 strength of structures, it is (was) a common practice for the engineer to use the code of the country in which he was trained. Under such conditions, there is no consistency in the design of structures. While they may be significant proportions of well designed structures that can withstand the earthquake forces, some percentage of engineered construction have been designed for only vertical loads of gravity and not for the horizontal/vertical load that an earthquake exerts on the building. The 85 high-rise buildings that collapsed during the Bhuj Earthquake of January 2001 are evidence to this fact. It is thought that there are not consistent anti-seismic measures applied to the design of many bridges in several developing countries. Seismic code for bridges simply does not exist in many countries. Site-specific studies to assess seismic risk are usually carried out in donor-funded larger projects (e.g., hydroelectric dam and important bridge sites). Non-engineered Constructions: These are physical structures (e.g., buildings) the construction of which usually has not been through the formal building permit process. It implies that the construction of non-engineered building has not been designed or supervised by an architect/engineer. Such buildings are obviously prevalent in the rural or non-urban (including urbanizing areas in the periphery of municipal areas. However, a large percentage of the building stock (in some case a vast majority) even urban areas of many developing countries are non-engineered constructions. In the urban areas of Kathmandu, it is estimated that more than 90 percent of existing building stock are non-engineered (partly because there are many old historic buildings), and every year about 5000 more such non-engineered buildings are added. Owner-built buildings: These are buildings constructed by the owner at the guidance and with the involvement of a head-mason or a carpenter who lacks comprehensive knowledge on earthquake resistant construction. Traditional construction materials such as timber, stone rubble or brick (fired or un-burnt) and mud as mortar are used. There is usually no input from any engineer. These are usually rural constructions. However, such constructions are seen also in the poorer part of a city, or in the city suburbs. Needless to say that these buildings are usually highly vulnerable to earthquakes. 2

3 Critical Facility A critical facility has a specific functionality requirements and lifesafety protection during or following an earthquake. Hospitals, water supply, electricity, telephony are example. Usually one talks about a critical system. Components of a critical system could be 1) the building structure, 2) ancillary structures such as pipes, ducts, etc.; 3) equipment, and a human action that is required to provide function of the critical system. Usually, it is regarded necessary to require stricter regulations for earthquake-resistance of buildings belonging to critical facilities because of their occupancy (schools), function after a major disaster (hospitals and communication centers), or because they are nationally important (museums) or they house toxic materials. Lifeline These are the critical facilities on which a city depends for the continued existence of its population. Roads/bridges and water supply systems are referred to as the lifeline systems. 2. Vulnerability For a systematic understanding it is necessary to distinguish the following categories of vulnerabilities: 2.1 Structural Vulnerability Definition Structural vulnerability Non-structural Vulnerability Functional Vulnerability This category of vulnerability pertains to the structural elements of the buildings, e.g., load bearing walls, columns, beams, floor and roof Causative Factors 1. Location of the Structure (building): Location determines the type and extent of the expected hazard (liquefaction, earthquake-induced landslide or tsunami run off). A building located in soft soil, or over liquefiable sand stratum, is likely to be more vulnerable than that located on firmer foundation soil strata. 2. Number of Buildings (in the system) and Space in between: If the buildings at abutting against each other, the behavior of one during the earthquake will influence that of the other. A well 3

4 designed and well constructed earthquake-resistant will be affected adversely by the vibration of the weaker building that is abutting against it. Usually, a structural joint (a gap) is allowed between two adjacent buildings to avoid such mutual influence during earthquake shaking. In case of tall buildings, lack of proper space in between buildings gives rise to pounding effect: part of the collapsed building may fall onto the next. In high rise buildings, the top parts of the buildings may hit one another during an earthquake if the street in between the buildings is not sufficiently wider that the height of the buildings. 3. Number of Stories: In the condition of the lack of control over the design and quality control during construction in developing countries, it can be said that the vulnerability of a building increases with its height. 4. Shape (Configuration): Complex shapes (e.g., L-shape, Y- shape, H-shape etc.) increase the building s vulnerability to damage and destruction during an earthquake. The re-entrant angles attract excessive concentration of stresses during the earthquake. Solid circular, square, and triangular plans are the best. Rectangular building plan should have its length not more than 3-times its width. Structural joints (separation) should be provided if such overall configuration can not be avoided due to any constraint. 5. Symmetry: A building that is symmetrical in plan as well as in elevations (both directions) performs much better than an asymmetrical building during an earthquake. 6. Age of Buildings: Buildings are typically designed for 30 years. Many buildings do stand more than 30 years, no doubt. However, vulnerability increases with the age. It is a wise practice to conduct vulnerability assessment of old buildings. 7. Construction Typology (type of Building): Timber, Adobe, brick-masonry, stone masonry, cement-block masonry, and concrete frame are the principal types of building construction in cities of Asia. As the building type and the construction materials employed is the most important factor while considering seismic vulnerability, it will be treated in a separate section below. 8. Alteration: Alterations are frequently done due to the changes in the requirements with time. Unfortunately, not all of the alterations are done at the advice of cognizant technical personnel. This practice leads to increased vulnerability of buildings. One important form of alteration is adding stories to the existing building to gain additional floor space. This practice appears to be rampant in developing countries. Even hospital buildings have been modified by adding stories. This is a dangerous practice as it may shapely increase seismic vulnerability. Many times the structural joints between buildings are found to be rendered ineffective by the provision of structural connections (e.g., by constructing a corridor) linking the two building parts. 4

5 Alterations and /or remodeling done within the hospital in an attempt to create new spaces or fit new structures or equipment without considering the effect these alterations would have on the general strength of the structure may become a liability (on a long term 1 rather than an improvement for the hospital. There had been cases in which the structural walls that were part of the original design of a building were broken in order to install air-conditioning units. These alterations might have been done afterwards when the original design engineers were no longer associated with the construction. Even small openings for window-type air conditioners made through an important loadbearing wall may spell disaster. The results of these openings are weaker structural walls that could result in a failure or partial collapse during an earthquake, even if the initial design was seismic-resistant. PAHO, Mitigation of Disasters, Volume 3, Maintenance: A poorly maintained building becomes gradually vulnerable as the unattended weak element accelerates deterioration causing the whole structure to become weak. Closure of the structural joints by construction debris during subsequent modifications is seen frequently 3. Building Typology and Vulnerability The outstanding characteristic of the structural damage of 1988 earthquake is that it was limited to clay, brick or stone buildings in mud mortar and the structures were shattered to ground. Life loss was severe in these buildings than newly constructed timber or RC framed buildings. Among the small number of wooden or reinforced buildings that existed, no serious damage was observed which leads to the conclusion that the intensity of the shock was not great enough. But, because the material of these constructions do not have good lateral strength, low tensile strength and shear strength, inferior ductility so they cannot survive the excitation. Should a shock with an intensity higher than 1988 earthquake be experienced, catastrophic damage leading to complete collapse similar to observed in masonry buildings might take place in RC framed buildings. Fuziwara et al., Load bearing masonry buildings Most of the load-bearing masonry structures are un-reinforced. This is a very common building type which can be distinguished into two major categories, notably, 1) traditional buildings (low strength masonry (LSM), and 2) modern masonry. 1 Modification to original text 5

6 3.1.1 Traditional buildings/low strength masonry buildings Coincidentally, these buildings are in general symmetrical in plan and elevation, lack heavy projections; openings are small and well positioned. These are good features from earthquake point of view. Stone in mud is the most common construction material for walling in mountains and hills. Sun dried or fired brick in mud mortar is common in plains, hills, and valleys where stone is not available. Wall thickness varies from 350mm to 600mm in general. These buildings are in general one to two story plus attic. Floors are generally made of thick layer of soil on timber structure. Roofs are generally duo pitched with gable walls at ends. Slate, clay tiles and thatch, wood shingle are used for roofing. Floors and roofs are flexible in nature. Vulnerability: These buildings are generally found to be deficient in earthquake resistance because of the poor quality of their construction and lack of aseismic features. The material lacks ductility, tensile- or shear strength. These building behave as if stacked construction material. The deficient features include: Weak Wall Junctions: The bond between orthogonal walls is weak as these walls are erected independently for large heights, weak mortar, no connecting elements between them. It suppresses development of box effect and walls behave as if these are free standing cantilever walls and during shaking, walls normal to the earthquake force splits and topple down (out of plane failure). Gable walls are even more susceptible to shaking as these stand at the top of the building almost without any connection with roof. Studies shows that, in case of a gable wall in three story building, these may topple at basic seismic coefficient of to Lack of Integrity between Load-bearing Elements Lack of a diaphragm Long unsupported walls Delamination of walls Large and unsymmetrical opening Note: These buildings are not to be confused with the historic buildings of archaeological importance, such as in Kathmandu, Bangkok or in cities of China and Japan, which do incorporate seismic-resistant elements, and are made predominantly of timber. 6

7 They are considerably earthquake-resistant. Their vulnerability comes mainly from aging Modern masonry buildings These are generally made of fired brick or stone in cement or lime mortar with one brick thick walls (250 mm). Lime mortar is less and less used now. With some part or some stories in mud mortar and other in cement mortar can be seen very often. These buildings are generally limited up to three stories. Story height is usually 3-3.6m. Floor and roofs are, in general, flat made of cast-in-situ reinforced concrete, reinforced brick and concrete slab. Openings are large and more in number. These are usually constructed for residential purposes so room sizes are small but many time half brick thick walls are used for cross walls. Shifting of wall position in upper stories is very common. In general these buildings are irregular in plan and elevation. Vulnerability: Vulnerability of these buildings to earthquake is caused by: Weak wall Junctions Long Unsupported walls Large and unsymmetrical opening Soft-story effect Improperly anchored parapets In addition to this buildings with flexible floor have following deficiencies: Lack of Integrity between Load-Bearing Elements Lack of diaphragm actions 3.2 Framed buildings Traditionally timber or bamboo was used for construction of framed buildings, especially in the plain areas of the tropics and the subtropics. In recent years, as a result of the depletion of timber, increased cost of a lot in the urban areas, increased economic activity, urbanization, accessibility to information and material, construction of transportation facilities even in remote areas, there is an increased desire for higher building and use of modern materials such as steel and concrete, and hence RC framed buildings are gaining popularity Reinforced concrete (RC) framed buildings The present trend of building construction in urban areas for residential, shop-cum-residential and shop-cum-office-cumresidential buildings is to use reinforced concrete (RC) beam column 7

8 frames and RC slab with randomly placed unanchored brick walls in two directions. It is usual to have shops in ground floor, with large openings in one or more adjacent faces in market areas. Also cantilevered projection up to 1.2 m is common in upper stories along all open faces especially along the urban streets. Unanchored thin brick walls of full height are erected on the edge to increase size of the room. Window size is generally big. Story height is usually m. These structures usually comprise a very light concrete frame generally with column sizes 22.5x22.5 cm or slightly more, and four to six number of 12mm diameter reinforcing longitudinal bars and 6mm diameter stirrups at the spacing of 20 to 25 cm. The detail of reinforcing does not follow the accepted practices in other highly seismic countries. These types of buildings up to six stories are very common. Vulnerability: RC frame construction type has become prevalent in the past two or three decades, and it has introduced a myth that the buildings of this type are infinitely strong and can be constructed as high as needed. Such false sense of safety has led to severe deficiency in strength. The size of the columns and beams usually constructed for as high as five stories, are in fact adequate only for two to three stories if seismic load is to be considered. Additionally, the structural components (columns and beams) badly lack ductile detailing and quality control. The other deficiencies are: Short Column effect: when any or all of the beam-column portions are filled up with masonry brick wall only partially leaving wide opening e.g., for windows. This situation leads to excessive concentration of stresses during earthquakes, at the corners of the openings. Soft-story effect: This is the situation when there is no infill masonry wall in the column-beam frame. Such conditions prevail in the developing countries allowed openings Out of plane failure of infill walls (because the are not joined with the beam (vertical) or the column (horizontal) Strong column-weak beam system not maintained. The beam rests on columns. Hence, it is logical to have stronger columns in comparison to the strength of the beam. Many times the opposite is prevalent due to some unknown reason. Lack of ductile detailing. This means: i. Anchorage problem ii. Lack of confining bars iii. Steel congestion problem iv. Lack and deficiency in shear stirrups The above discussed deficiencies have made the buildings severely vulnerable to seismic shaking. 8

9 3.3 Summary of deficiencies that cause vulnerability of built structures Planning deficiencies The deficiencies are (common to both load bearing and masonry buildings): i. Pounding effect (along urban streets). ii. Large length to breath ratio (torsional effects!). iii. iv. Large height to breathe ratio (instability!). Large offsets in plan and elevation (unequal distribution of stiffness, torsional effects!). v. Soft story effect (concentration of deformation!). vi. Unequal/unbalanced distribution of lateral load resisting elements (torsional effects!) Deficiencies of load bearing masonry buildings i. Large and unsymmetrical opening (lack of lateral load resisting elements & torsional effects!). ii. Weak Wall Junctions (loss of box action!). iii. Long unsupported walls (behave as cantilever wall!). iv. Delamination of walls (reduction in load carrying capacity!). v. Improperly anchored parapets (toppling of wall). Buildings with flexible floor have following additional deficiency: i. Lack of Integrity between Load-Bearing Elements (scattering of members, loss of box action!). ii. Lack of diaphragm actions (no proportionate distribution of lateral load!) Deficiency in RC Framed Building i. Strength deficiency ii. Out of plane failure of infill walls iii. Short Column effect (shear failure!) iv. Strong column weak beam not maintained v. Splash effect vi. Lack of ductile detailing (no energy dissipation!) a. Anchorage problem b. Lack of confining bars c. Steel congestion problem d. Lack and deficiency in shear stirrups (bursting of columns). 3.4 Vulnerability assessment (structural) Vulnerability assessment involves first identifying all the elements of a building which may be at risk from earthquake. 9

10 As the first step, a qualitative assessment is usually done. The results of a qualitative assessment help identify the priority problems that should be addressed. Likely benefit-cost ratio can be estimated preliminarily based upon the qualitative assessment. Survey formats have been developed for qualitative assessment. Loss functions in the form of vulnerability curves or damage probability matrices are available for obtaining the damage ratio for different types of buildings at different intensities of earthquake shaking. These are prepared based on actual observation of damage due to an earthquake at various localities. (Note: Damage ratio is expressed in terms of economic loss to a single building unit with respect to its reconstruction cost). A Buildings in field stone, rural buildings, adobe house, and mud house (1 to 1.5 stories). A- A-type building but with 3 storey height (2 storied in between A and A-). A+ A-type clay buildings but with horizontal and vertical timbers incorporated. B Buildings with mud mortar, ordinary brick, large blocks, natural dressed stone or half-timbered buildings with height up to 1 to 1.5 stories, or with cement mortar in brick masonry and height up to 3 stories. B- B-type rural buildings with traditional materials and height up to three stories, or brick masonry buildings in cement mortar with large openings with irregular plans and height up to five stories. B+ B-type rural buildings with improved configurations in case of rural buildings, or brick masonry buildings in cement mortar with compact plans, permissible openings and height up to three stories. B++ Strengthened initially, or retrofitted as for earthquake-resistant brick buildings of B, B-, B+ C1 Strengthened good quality brick buildings in cement mortar (with seismic reinforcement, up to 3 stories) C2 Normally designed Reinforced Concrete (RC) buildings (designed for normal load only) or mason-designed 3 storey RC buildings (Kathmandu Valley) C3 Specially designed RC buildings. C(k5) Mason-designed 5 storey RC buildings (Kathmandu Valley). (Source: HMGN/ MHPP, 1994d.) Quantitative assessment of structural vulnerability of buildings involves detailed analysis using computer software. Several programs exist. NSET-Nepal used the software MASONRY (developed by the University of Roorkee, India) for the analysis of masonry buildings, and the software SAP2000 for the analysis of other two hospital buildings of Kathmandu Valley. Many aspects of vulnerability cannot be described in monetary terms, such as personal loss of family, home, income and related 10

11 human suffering and psychosocial problems, but these should not be overlooked. 4. Non-Structural Vulnerabilities 4.1 Basic concepts "Nonstructural" usually refers to things that are designed by someone other than the structural engineer; however, nonstructural walls are required to have some strength. For example, interior non-bearing partitions are generally required to be designed to resist a minimum design lateral force. This is intended to provide some resistance to seismic forces perpendicular to the wall and to ensure a minimum stiffness to the walls. Non-structural elements of a building include ceilings, windows, doors, non-structural partition walls, and electrical, mechanical, plumbing equipment and installations, and other contents. A building can remain standing after a disaster but still be unserviceable due to non-structural damage. Moreover, the non-structural elements could also lead to structural damage to the building and cause physical injury to the occupants. The cost of the damage to non-structural elements in residential buildings is estimated at 30% of the total loss. In offices and critical facilities, such cost may be considerable higher than that of the structural elements. This is especially true for hospitals where 85% to 90% of the value of the installation is not in the support column, floors and beams, but in the architectural design, mechanical and electrical systems and in the equipment contained in the building (Dr. Reinaldo Flores, in introduction to the newly prepared draft Protocol for assessment of the Health Facilities in Responding to Emergencies: Making a Difference to Vulnerability, WHO, 1999, Geneva). 4.2 Vulnerable non-structural elements The following sections list the non-structural vulnerable elements (after ATC-22) Partitions Masonry and Tile. These partitions can have severe cracking or loss of units. Compression failures can occur at the tops of the partitions, or at the joints. These partitions may collapse and fail due to perpendicular wall-to-wall loads. This is a life-safety concern! Gypsum Board or Plaster. These partitions may overturn due to local ceiling failures. Finishes may crack or detach from the studs. Demountable Partitions of Metal. Wood, and/or Glass. These partitions may separate from the supporting channels, possibly 11

12 resulting in overturning. Fixed glass may crack or separate from remainder of partition Ceilings Suspended Lay-In Tile Systems. Hangers may unwind or break. Tiles may separate from the suspension system and fall. Breakage may also occur at seismic joints and at building perimeters. Suspended Plaster or Gypsum Board. Plaster may have finish cracks that could lead to spalling. Hangers may break. Gypsum board or plaster may separate from the suspension system and fall. Surface Applied Tile. Plaster, or Gypsum Board. Plaster may crack and spall. Ceiling tiles may fall due to adhesive failures Light fixtures Lay In Fluorescent. Ceiling movement can cause fixtures to separate and fall from suspension systems. Parts within the fixtures are prone to separate from the housing. Stem or Chain Hung Fluorescent. The stem connection to structural elements may fail. Fixtures may twist severely, causing breakage in stems or chains. Long rows of fixtures placed end to end are often damaged due to the interaction. Long stem fixtures tend to suffer more damage than short stem units. Parts within the fixture may separate from the housing and fall. Surface Mounted Fluorescent. Ceiling mounted fixtures perform in a fashion similar to lay-in fixtures. Wall fixtures generally perform better than ceiling fixtures. Parts within the fixture may separate from the housing and fall. Stem Hung Incandescent. These fixtures are usually suspended from a single stem or chain that allows them to sway. This swaying may cause the light and/or the fixture to break after encountering other structural or nonstructural components. Surface Mounted Incandescent. Ceiling movement -can cause fixtures co separate and fall from suspension systems. Wall mounted fixtures perform well Doors and frames Frames can warp from warp from deformations, possibly causing the doors to bind Mechanical equipment Rigidly Mounted Large Equipment (e.g., Boilers. Chillers, Tanks. Generators) : Shearing of anchor bolts can occur and lead to horizontal motion. Unanchored equipment may move and damage connecting utilities. Tall tanks may overturn. Performance is generally good when positive attachment to the structure is provided. 12

13 Vibration Isolated Equipment (e.g., Fans, Pumps):. Isolation devices can fail and cause equipment to fall. Unrestrained motion can lead to damage. Suspended equipment is more susceptible to damage than mounted equipment. This is a life-safety concern! Piping Large diameter rigid piping can fail at elbows, tees, and connections to supported equipment. Joints may separate and hangers may fail. Hanger failures can cause progressive failure of other hangers or supports. Failures may occur in pipes that cross seismic joints, due to differential movements and adjacent rigid supports. The increased flexibility of small diameter pipes often allows them to perform better than larger diameter pipes, although they are subject to damage at the joints. Piping in vertical runs typically performs better than in horizontal runs if regularly connected to a vertical shaft Ducts Breakage is most common at bends. Supporting yokes may also fail at connection to the structural element. Failures may occur in long runs due to large amplitude swaying. Failure usually consists of leakage only and not collapse Electrical equipment Tall panels may overturn when they are not bolted or braced. Equipment may move horizontally if not positively anchored to the floor Elevators Counterweights and Guide Rails. Counterweights may separate from rails. Counterweights may also damage structural members, cables, and cabs. This is a life-safety concern! Motor/Generator. The motor (or generator) may shear off the vibration isolators. Control Panels. Control panels can overturn when they are not anchored. Cars and Guiding Systems. Cars and guiding systems generally perform well, except that cables may separate from drums and sheaver. Hoistway Doors. Doors can jam or topple due to shaking or excessive drift. Hydraulic Elevator Systems. These systems usually perform well except that the cylinders may shift out-of-plumb Exterior cladding/glazing or veneers 13

14 Exterior wall panels or cladding can fall onto the adjacent property if their connections to the building frames have insufficient strength and/or ductility. This is a life-safety concern! If glazing is not sufficiently isolated from structural motion, or above 12 feet, it can shatter and fall onto adjacent property Parapets, cornices, ornamentation and appendages If any of these items are of insufficient strength and/or are not securely attached to the structural elements, they may break off and fall onto storefronts, streets, sidewalks, or adjacent property. This is a life-safety concern! Means of egress Hollow tile or unreinforced masonry walls often fail and litter stairs and corridors. This is a life-safety concern! Stairs connected _to each floor can be damaged due to inter-story drift, especially in flexible structures such as moment frame buildings. Veneers, cornices, ornaments, and canopies over exits can fall and block egress. This is a life-safety concern! Corridor and/or stair-doors may jam due to partition distortion. Lay-in ceiling tiles and light fixtures can fall and block egress Building content and furnishings Desk-Top Equipment. Desk-top equipment, such as computers, printers, plotters, may slide off and fall if it is not sufficiently anchored to the desk. File Cabinets. Tall file cabinets may tip over and fall if they are not anchored to resist overturning forces. Unlatched cabinet drawers may slide open and fall. Storage Cabinets and Racks. Tall, narrow storage cabinets or racks can tip over and fall if they are not anchored to resist overturning forces. This is a life-safety concern! Plants. Artwork and Other Objects. Plants, artwork and other objects that are located on top of desks or cabinets can fall if they are not anchored to resist their lateral movement. Items Stored on Shelves. Items stored on shelving, such as in laboratories or retail stores, can fall if they are not restrained from sliding off the shelves. Computers and Communications Equipment. Tall, narrow equipment can overturn and fall if it is not anchored to resist overturning forces. 14

15 Hazardous materials Because of the secondary dangers that can result from damage to vessels that contain hazardous materials, special precautions should be considered for the proper bracing and restraint of these elements. Compressed Gas Cylinders. Unrestrained compressed gas cylinders can be damaged such that the gas is released and/or ignited. This is a life-safety concern! Laboratory Chemicals. Unrestrained chemicals can mix and react if they are spilled. This is a life-safety concern! Piping. Piping that contains hazardous materials can leak if shut-off valves or other devices are not provided. This is a life-safety concern! 4.3 Other vulnerable conditions The following provide some additional discussion of vulnerable conditions in a building due to other factors. Improper Location: The presence of heavy equipment on a particular floor of a building alters its response to shaking during earthquakes. On higher floors, in addition to the stress concentration the heavy machinery may cause on the ceiling or floors, the heavy objects attract greater force at the point and may contribute to greater possibility of damage or collapse. A wrongly placed cupboard may overturn and block exit during an earthquake. Locating a working desk within the reach of a non-structural partition wall or under a ceiling fan, or near un-curtained windows is also a vulnerable condition. Inside-opening doors in a meeting rooms or class rooms create a vulnerable situation. Loosely placed flower-pot on the parapet walls could be hazardous to the passers-by or even to the residents while getting out of the building during an earthquake. 4.4 Vulnerability assessment (non-structural) Investigation of nonstructural elements for critical facilities is timeconsuming. Usually, the non-structural elements are not shown in the plans (in our country even basic architectural plans are difficult to dig!). Even if plans exist and the elements are shown on it, many times the mechanical and electrical items are often concealed. Nevertheless, it is essential to make the investigation because in the 15

16 past little attention has been paid to seismic support of these elements and they are potentially hazardous. Of particular importance in the nonstructural element evaluation efforts are site visits to identify the present status of nonstructural items; this effort will take on added importance because nonstructural elements of structures may be modified many times during the life of the structure. MCCER 1999 provide detailed guideline on seismic reliability assessment of critical facilities. WHO, 1999 provides a detailed format for the assessment of non-structural vulnerabilities in hospitals. 5. Functional Vulnerability 5.1 Basic Concept Functional vulnerability needs to be considered and eliminated for institutions, especially the critical facilities such as hospitals, emergency operation centers, communication centers etc., to ensure that the services provided by the facilities would keep on running to meet the demands of the community at the time when these are most needed. The following section discusses Functional Vulnerability in case of hospitals. While assessing functional vulnerability, consideration is made of 1) location, accessibility, and distribution of the services within the system, 2) individual services, both medical (equipment and supplies) and non-medical (utilities, transportation and communication), that are vital to the continuous operation, and 3) public services and safety measures available inside the hospital. 5.2 Site and Accessibility The following are the disadvantageous situation in terms of hospital s location. Location in a congested area of a city with vulnerable buildings around Narrow secondary access road Presence of a bridge separating hospital from the city Only one road leading to the hospital Poor condition of the access road Presence of an industrial firm in the catchment area of the hospital 5.3 Service Areas Within the Hospital 16

17 Proper zoning of different areas (outpatient service, emergency department, surgical are, kitchen, morgue etc.) that make up the hospital would guarantee adequate level of operation even during emergencies. Improper zoning creates the possibility of overcrowding. Presence and condition of specific areas that can be converted into spaces for patients during emergencies. o These areas should have best utilities to remain operational. 5.4 Equipment and Supplies Availability of minimum supplies of essential equipment. Such list is available. Regular inventory of the items. Proper labeling of the equipment and supplies. Period of time taken by the hospital to procure equipment and supplies. Presence of a system for emergency procurement Presence of emergency kit containing essential drugs recommended by the WHO. Presence of a blood bank in the hospital. 5.5 Utilities Water Availability of adequate quantity of water (@ liters/person/day for patients plus others for performance of medical and surgical procedures) Presence of water storage Presence of alternate source of water other than the city supply Presence of treatment system for water from alternate source Length of time hospital can run on the water storage Electricity Proper location of electric control panel and its marking in the floor plan Alternate source of electrical supply Percentage of hospital energy requirements that can be supplied by the alternate source Inventory of generators and related equipment, periodic choking of functionality Presence of a system of emergency light Ventilation system Medical Gas Supply and management Form of gas supply (individual tanks, piped gas) and system to manage and prevent their leakage Warning System and Safety Equipment 17

18 Presence of sign system (indicators for escape route, firefighting equipment, building lay-out diagram) Presence of fire detection system and its location in strategic places Presence of fire extinguishers and fire safety plan Transportation and Communication Presence of communication systems (regular telephone, cellular phone, Pager, Public address system, short wave radio, intercoms) including runners for international and external communication Presence of alternate communication system for use during emergency Adequate means of transportation for patients and staff Capabilities of ambulances Public Information Presence of public information system in normal times Possibility of continued use of the PI system during emergencies 5.6 Assessment of functional vulnerability of institutions The discussions in the sections above provided a list of items upon which the functionality of a hospital depends. The checklist can be used as a guide for developing similar lists for other institutions considering the specifics of that particular facility. Methods of functional vulnerability of hospital are detailed in WHO, Similarly, MCEER, 1999 provides a methodology and format for detailed assessment of functional reliability of critical facilities. These guidelines can very easily be modified to suit any particular critical facility. Obviously, common sense should prevail in case of lack or inaccessibility of required data. 18

19 References 1. Amir-Mazaheri, D., General Aspects Of Seismic Risk Reduction In Threatened Regions, Paper Number 2695, Proc. 12 WCEE, Auckland 2. NSET, 1999, Seismic Hazard and Risk Management in Kathmandu Valley, Nepal; proceedings of Seminar on Urban Earthquake Damage Assessment, Building Research Institute, Tsukuba, Japan, Vol Bothara, J. K., Parajuli, Y. K., Sharpe, R. D. Arya, A. S., 2000, Seismic safety in owner built buildings, 12 th World Conference on Earthquake Engineering, Paper no. Auckland, New Zealand. 4. Coburn, A. & Spencer, R. J. S. 1992, Earthquake protection, J. Wiley & Sons, New York, USA 5. EERI, 2001, Encyclopedia of Housing Construction Types in Seismically Prone Areas of the World, Earthquake Engineering Research Institute (EERI) and IAEE. 6. Johnson, G. S., Sheppard, R. E., Quilici, M. R., Eder, S. J. and Scawthorn, C. R., 1999, Seismic Reliability Assessment of Critical Facilities: A Handbook, Supporting Documentation, and Model Code Provisions, MCEER, Buffalo, NY. 7. NZS 4219:1983. Seismic Restraint of Building Contents, Standards New Zealand. 8. NZS 44104:1994, Specification for Seismic Resistance of Engineering Systems in Buildings, Standards Association of New Zealand. 9. PAHO, 1992, Disaster Mitigation Guidelines for Hospitals and Other Health Care Facilities in the Caribbean, Pan American Health Organization (PAHO). 10. PAHO, 1993, Mitigation of Disasters in Health Facilities Evaluation and Reduction of Physical and Functional Vulnerability (four volumes), Pan American Health Organization (PAHO). 11. WHO, 1999, Protocol for assessment of the health Facilities in Responding to Emergencies: Making a difference to Vulnerability. 12. WHO, 1999, Protocol for assessment of the Health Facilities in Responding to Emergencies: Making a Difference to Vulnerability, World Health Organization (WHO), 1999, Geneva (Draft). 13. WHO, Earthquakes and People s Health, Proc. WHO Symposium, Kobe, January 1997, WHO, Kobe ABK, 1984; Methodology for Mitigation of Seismic Hazards in Existing Unreinforced Masonry Buildings: The Methodology Topical Report 08, National Science Foundation, Washington, DC. 19

20 16. ACI, 1983, Building Code Requirements for Reinforced Concrete (ACI ), American Concrete Institute, Detroit, Michigan. 17. Army, 1986, Seismic Design. Guidelines for Essential Buildings, Departments of the Army (TM ), Navy (NAVFAC P355.1), and the Air Force (AFM 88-3, Chap. 13, Sect. A), Washington, DC. 18. Army, 1988, Seismic Design Guidelines for Upgrading Existing Buildings, Departments of the Army (TM ), Navy (NAVFAC P355.2), and the Air Force (AFM 88-3, Chap. 13, Sect. B), Washington, DC. 19. ATC, 1987, Evaluating the Seismic Resistance of Existing Buildings, Applied Technology Council Report ATC-14, Redwood City, California. 20. ATC, 1988, Rapid Visual Screening of Buildings for Potential Seismic Hazards: A Handbook; Applied Technology Council Report ATC-21, Redwood City, California. (FEMA 154) 21. ATC, 1989, Seismic Evaluation of Existing Buildings: Supporting Documentation, Applied Technology Council, Redwood City, California. 22. BSSC, 1988, NEHRP Recommended Provisions for the Development of Seismic Regulations for New Buildings. Building Seismic Safety Council, Washington, DC. (Parts I, II, and Maps) 23. GSA, 1976, Earthquake Resistance of Buildings, Vol. I-III, General Services Administration, Washington, DC. 24. SEAOC, 1988, Recommended Lateral Force Requirements and Tentative Commentary, Seismology Committee, Structural Engineers Association of California, San Francisco, California. 25. SSC, 1985, Rehabilitating Hazardous Masonry Buildings: A Draft Model Ordinance, Report No. SSC 85-06, State of California Seismic Safety Commission. 26. Stratta, James L., 1987, Manual of Seismic Design. Prentice-Hall, Inc., Englewood Cliffs, New Jersey. Reader Materials See attached files 20