Implementation of Seismic Isolation Earthquake Protection_5 doc

STRATEGIES FOR EARTHQUAKE PROTECTION 217 improvement projects, community action plans and others described in more detail in Section 6.6. Traditional Buildings The greatest earthquake risk throughout the world is faced by traditional rural communities that build their own houses from locally gathered materials. These houses, variously described as ‘traditional’, ‘earthen’, ‘vernacular’, ‘owner-built’, ‘non-engineered’, ‘low-income’ or ‘low-quality’, form a high proportion of the building stock of many developed countries. Their earthquake performance is notoriously poor, as outlined in Chapter 1 and touched on in each of the subse- quent chapters of this book. It is estimated that over 75% of the world’s population lives in housing of this type. 19 Houses are built by the family itself, perhaps employing a skilled builder from within the community to direct operations. Traditional construction materials for this type of house are naturally occurring and used in building construction with only limited processing or quality grading, such as earth, stone, wood and fibre. Increasingly commonly used are modern building materials: cement, steel, concrete blocks, fired clay bricks, roof tiles, sheeting, processed timber and other materials bought for cash from nearby markets. These types of communities similarly tend to be beyond the control of urban building regulations or planning requirements imposed from central or urban authorities. Instead development programmes based on capacity building and incentives for self-protection against earthquakes have been more successful. There have been a number of development projects focusing on improving the earthquake protection for traditional rural communities by increasing the capability of local craftworkers and the builders in each community to build earthquake-resistant structures with the skills and materials they have available. These types of projects, discussed in Section 6.6, have been mainly pioneered by development agencies but increasingly adopted by governments as regional development initiatives. Government support can help extend the take-up rate of such programmes of education and training builders with building improvement grants, materials, subsidies and other incentives to establish earthquake-resistant construction techniques within the building traditions of the hazard-prone areas. 6.5.2 Education and Training The overall level of competence of the design professionals and personnel in the construction industry has a major effect on the vulnerability of the built environ- ment. In the longer term, the quality of the buildings that will be constructed in 19 Razani (1981). 218 EARTHQUAKE PROTECTION 5–10 years’ time depends largely on the standards of training being received by the students and apprentices of today. Engineering Education Engineers’ curriculum and vocational training achievement levels are usually established by national authorities and in a seismic country all engineering stu- dents should have a thorough grounding in earthquake engineering as part of their core curriculum. The standard of earthquake engineering being taught is impor- tant and should be reviewed as an integral part of the longer term earthquake protection strategy. Mid-career training for engineers in practice is also impor- tant in order to increase awareness of earthquake issues, update them on recent developments in earthquake engineering and explain code revisions or regulatory procedures. Professional engineering institutions or colleges are useful vehicles for increasing education standards, and mounting mid-career training courses for practising professionals. Education of Other Professions It is also important to spread seismic design knowledge out wider than the engineering professions. Architectural education should also include earthquake design principles in the undergraduate course of student education and post- qualification training. Building surveyors, property managers, real estate agents and construction contractors could also benefit from a knowledge of earthquake- resistant design principles developed through college courses, further education and professional groups. Vocational training or on-the-job skills development for building supervisors, tradespeople and construction labourers also increases the quality of building construction and improves earthquake resistance. Require- ments for certain skills to be represented in trade certification and basic training also help develop an earthquake awareness at every level of the building industry workforce. 6.5.3 Public Awareness Public awareness of earthquake risks and support for the measures needed to be taken for protection are a necessary prerequisite for action to be taken. The support of the community and its participation in protecting itself and mandat- ing its representatives to take actions to protect it are the essential elements of earthquake protection. It is clear from studies of perception of risk, presented in Chapter 10, that the actions communities take to reduce risk and the support they give to reduce unacceptable risk are related to the nature of the risk and perception of its degree and severity. Availability of information about the actual STRATEGIES FOR EARTHQUAKE PROTECTION 219 level of risk faced, demystification of the threat and familiarisation with pro- tection capability are important aspects of motivating the community to protect itself. Studies of some communities at risk, particularly rural groups, developing societies and communities with limited access to information, suggest that their perceptions may distort and underestimate earthquake risk – individuals may be more at risk from earthquakes than they realise. Earthquakes are rare events and few people are likely to have personal experience of them. They may have an incorrect image of earthquakes being all-powerful and totally devastating. Psychologists suggest that hazards like earthquakes which embody high levels of ‘dread’, which are perceived to be uncontrollable and that few of the commu- nity have personal experience of, are difficult to protect against. These hazards may be mentally rejected or perceived fatalistically or in other ways that reduce the motivation to take action to reduce them (see Section 10.6). It is clear that increased access to factual information can increase perception of risk, and affect what is considered safe. Public information campaigns, increased exposure of earthquake issues in the media, including disaster safety in school teaching and encouraging civil protec- tion to become more a part of public life, raise awareness in general. Some elements of public information campaigns for earthquake preparedness were discussed in Chapter 3, Section 3.6, including drills, practice emergencies and anniversary remembrances. Information on earthquakes can increase familiarity with the hazard and reduce its dreadfulness, and it can demonstrate that mitiga- tion is effective and necessary. Public information campaigns can also address the more pragmatic issues of what to do in the event of an earthquake and other response activities that may save lives and reduce damage. But without a preparatory background programme to increase familiarity with earthquakes, the what-to-do type of information is unlikely to be well received or the need for it comprehended. The primary focus of public awareness campaigns is to motivate the community to protect itself as far as possible (see Section 6.2). 6.5.4 Earthquake Hazard and Engineering Research At a national level, it is important to understand the nature of the earthquake threat. There are many countries that suffer repeated destructive earthquakes in which basic seismological data is poorly gathered, and national observato- ries under-resourced and understaffed. Hazard research (outlined in Chapter 7) can define the areas where earthquakes are most likely to strike, the rates at which earthquake activity can be expected, the characteristics and severity of future earthquakes and the probable consequences of seismic activity. Such research is best carried out and coordinated at a national level, or even at an international level where several neighbouring countries cooperate in hazard assessment. A national seismological observatory maintaining its own network of seismometers, or coordinating networks of different universities and research 220 EARTHQUAKE PROTECTION agencies, can observe patterns of seismic activity over time and across the whole country or region and contribute to everybody’s understanding of the hazard they face. Earthquake engineering may be an important area of research, as the con- struction types, preferred materials and design practices are different in each country and often differ from region to region within a country. The develop- ment of earthquake design building codes based on those of another country is common practice, but adapting them to the local building types needs research. Structures, e.g. concrete frame structures, are likely to be similar from one country to another and design methods may be transferable, but construction practices, e.g. infill construction, construction of engineering movement joints, etc., and the local building forms and typologies vary considerably from one region to the next. It is clear from earthquake engineering research that local construction techniques affect seismic performance significantly and studies are needed to optimise earthquake safety measures for local building types. Tra- ditional building types and the non-engineered building stock that makes up most of the risk of earthquake damage tend to be very poorly researched and largely dismissed by the engineering community in most countries. Research is needed to develop earthquake-resistant techniques, design principles and con- struction details that are appropriate to the types of buildings normally built in that country. Coordination and support for a broad programme of independent research, involving universities, public utility companies, government research institutes, private companies and other research establishments, may also be an area of government initiative or budgeting. Research activities are a vital part of national earthquake protection efforts. 6.5.5 Budgeting for Losses and Mitigation The degree of influence that national or local authorities can bring to bear on improving earthquake safety is likely to be related to the budget avail- able. Many measures available for earthquake protection require the commitment of significant resources. The establishment and sustaining of institutionalised safety councils, the implementation and policing of adequate building codes, the construction of earthquake-resistant public buildings, and the use of grants for building improvement, establishing research institutes and many other mea- sures advocated here, require adequate funding. These measures, as an integrated package, represent the cost of public safety against earthquakes. The spending of public finances to improve public safety is justifiable on its own but financial costs of earthquakes are themselves high and there is additional justification for spending on earthquake protection in reducing these costs. In addition to the unquantifiable but considerable costs to society, intangible losses STRATEGIES FOR EARTHQUAKE PROTECTION 221 of injury and the loss of human life, there are costs in the destruction of property, both public and private, costs of emergency mobilisation, relief and recovery, the disruption to the economy, loss of earnings and lost production, and costs of lost opportunity and delayed developmental progress. The few studies that have been made of the costs and benefits of spending on earthquake protection have shown that well-targeted investments in areas of high hazard can be cost-effective in reducing losses – that is, the financial savings can exceed the costs of investment. There are therefore economic arguments for earthquake protection measures quite apart from civil protection and saving human life. Chapter 10 presents the use of cost–benefit analysis and other methods of calculating the value of earthquake protection measures. Budgeting for Earthquake Losses Few governments cost future earthquake losses systematically, but a number of countries maintain some disaster budget or contingency account used mainly for relief and emergency needs. Most disaster losses are funded through borrowing and there is a convention that disaster losses are unforeseeable, and so are not planned for on the budget sheet. By not budgeting explicitly for earthquake losses, it is harder for the economics of earthquake protection to be shown or to be argued for. Systematic costing of earthquake losses is both possible and necessary in a country that has repeated earthquakes. Earthquakes, of course, happen irregularly and there can be many years between major events. When a large earthquake occurs it can cost billions of dollars. Smaller earthquakes occurring more frequently add smaller costs to the damage total. Averaged out as a cost per year, the losses due to earthquakes can be significant, and seismological hazard studies, historical experience and future risk analysis (see Chapter 9) can predict with a fair degree of accuracy what the annual average loss is likely to be over a 10-, 20- or 100-year period. Such studies cannot, however, predict when this loss is likely to occur – the need to budget on an annual basis, or even for a multiple year administration, means that the probability is low that the expenditure will come within that particular, short time frame. This tends to lead to it being ignored in short-term accountancy. Longer term accountancy and policy development, such as that being increasingly practised by government administrations in areas like environmental policy, energy and mineral resource exploitation and transportation policy, is needed for national protection policies against earthquakes and other natural hazards. Deciding on levels of budget that are appropriate to commit to protection against earthquakes is a matter of the severity of the risk, the prioritisation of that risk against other calls on the resources available, and the social and political judgements that each community uses in making decisions. In Chapter 10 there is further discussion of decision-making on risk, perception of risk and comparable levels of risk that communities find acceptable. 222 EARTHQUAKE PROTECTION Protection Fundraising Apart from direct treasury allocation, government budgets can be raised in a number of ways to fund protection measures. In some countries, specific lotteries or an added tax on tobacco or consumables have been used to raise a budget specifically for disaster measures. Disaster budgets, however, are not always spent on disasters, and if not spent are liable to be used for other things. Civil protection programmes that are allowed to draw from a range of budget sources are more sustainable and should be one of the main beneficiaries of the disaster budget. Inevitably the funding for protection programmes will be disbursed piecemeal, with hazard observatories funded from higher education and research budgets, code administration funded from local administration, building improvement grants from capital funds, and so on. Some individual initiatives to raise local funds for building improvement from development tax and to encourage partner- ships of public and private sector funding have been discussed above. The main key to funding is motivation and belief that earthquake protection is possible and desirable. If the community at large and the individuals at funding level believe that earthquake protection is a valid activity, then funding will become a higher priority. The role of national and local government authorities is central to estab- lishing earthquake protection as a credible, achievable and essential part of life in a hazard-prone country. 6.5.6 Supporting the Design Professions The design of buildings and facilities to protect them against earthquakes (described in Chapter 8) is a skilled job and requires a thorough understanding of the destructive power of an earthquake and the mechanisms that operate. Specialist earthquake engineers in the fields of civil, structural and geotechnical engineering have a vital role, both in the structures they design and in promoting earthquake protection to be adopted more widely. Some of the strongest advocates for seismic legislation, community preparedness and earthquake protection measures are the earthquake engineering specialists. But earthquake-resistant design has to become a broader, general skill within the general engineering profession for a truly safer community to result. The standards of earthquake- resistant design of the average engineering practitioner are what determine the safety of our towns and cities. Understanding the principles of earthquake-resistant design also has to be widened to include all the other design professions: architects, surveyors, ser- vices engineers, interior designers. It is now well established that a good engineer cannot make a bad architectural design earthquake resistant. All the members of the design team need an understanding of earthquake issues to make a safe build- ing – the architectural form of the building, the location of the service runs, the STRATEGIES FOR EARTHQUAKE PROTECTION 223 materials specifications and the non-structural fittings all need to be designed with an understanding of how they affect earthquake safety. Most countries have professional institutions that represent each of the vari- ous design disciplines, regulate professional qualification standards and lobby for their interests. A full endorsement by professional institutions of the role played in earthquake protection by their members will enable that profession to move more fully into earthquake protection activities. The professional institutions may require competence in design for earthquake safety as a qualification or mem- bership requirement. Continuing professional education or mid-career training should also include earthquake-related topics, particularly following the intro- duction of a new building code or in the aftermath of a destructive earthquake which has had lessons for design professionals. All these activities depend on the support of national governments. Persuading Clients to Protect The client, when commissioning the design of a building or other facility, com- monly relies on the advice of the design professional for a range of matters. Structural safety and functional reliability are factors in which clients are likely to be influenced by professional recommendations. The professional engineer, architect or other designer is an advocate for earthquake protection and has an important role to play in educating the client about the risks involved and per- suading the client to take earthquake protection seriously in the design process. A client may be unwilling to pay for the additional costs involved in incorporat- ing appropriate levels of earthquake resistance unless convinced of the necessity and benefit of doing so. The design professional may be able to convince the client of the need for design safety by demonstrating the hazard faced and the risks of earthquake damage. The client should be encouraged to protect the facil- ity to the fullest extent practicable. The client also should be made aware of the protection levels afforded by the statutory minimum design requirements and encouraged to protect the facility to higher standards where this is appropriate or justifiable. 6.6 International Aid and Development Organisations Earthquake disasters frequently reach international proportions. The scale of a major disaster often exceeds the capabilities and resources of a national gov- ernment and the international aid community is usually quick and generous in its response. Aid from the richer countries to the poorer is commonly given for emergency relief to assist recovery after a major earthquake or other disaster. At other times and in non-disaster circumstances assistance is given by the countries of the developed world to help other countries generate economic 224 EARTHQUAKE PROTECTION development and to improve the lifestyle and safety of communities. It is being increasingly realised that assistance to developing countries to help them reduce the effects of future disasters before they occur is more effective than providing aid afterwards: prevention is better than cure. Disasters are closely related to economic development. The great majority of casualties and disaster effects are suffered in developing countries. Develop- ment achievements can be wiped out by a major disaster and economic growth reversed. The promotion of earthquake protection in the projects and planning activities of development safeguards development achievement and assists pop- ulations in protecting themselves against needless injury. There are many organisations and operations devoted to development assis- tance and these have an important role to play in helping countries and com- munities protect themselves against future earthquake disasters. Organisations representing multi-lateral economic assistance (i.e. funded by contributions from several countries) include the many United Nations agencies and regional organ- isations of the globe including the European Community, Pan-American, Pan- Arab, Pacific Cooperation, and other multi-nation technical, cooperation, eco- nomic and development organisations. International organisations like the Red Cross and Red Crescent have significant involvement in most disasters. Bilateral aid programmes – provided by a single country directly to another – make up a very large proportion of the economic assistance that passes between countries. Most of the industrialised nations, the members of the Organisation for Economic Cooperation and Development, maintain a government ministry or department responsible for development assistance to other countries, and maintain depart- ments, attach ´ es or representatives in the embassies and consulates of the countries to which they disburse aid. Other organisations that are instrumental in interna- tional development include non-governmental organisations (NGOs), agencies like CARE, Oxfam, GTZ, and very many other private organisations which are humanitarian, religious or developmental in nature. Often these NGOs are the channel for implementing projects in the recipient areas funded by the bilateral or multi-lateral aid organisations. In addition to the international NGOs there are also large numbers of NGOs within each developing country that implement development projects and assist in humanitarian activities. The number and types of development organisations are considerable. Each can, if it directs its efforts in the right direction and is motivated to do so, bring about effective, sustainable achievements to make communities safer against future earthquakes. Incorporation of disaster protection into the activities of devel- opment organisations can be achieved without major shifts of emphasis in their work, providing the issues of protection are understood. Earthquake Relief Many development agencies have an extensive involvement in disaster relief and any major earthquake is likely to involve development organisations working STRATEGIES FOR EARTHQUAKE PROTECTION 225 in that country or region in helping the worst affected communities to recover from its effects. Increasingly such organisations are implementing programmes to reduce the effects of future earthquakes as part of their operations. Relief and reconstruction programmes can contribute to the future safety of the affected community if they are orientated towards long-term revitalisation of the economy and sustainable development as discussed in Chapters 4 and 5. Short-term needs, such as shelter and food, are undeniable, but provision of emergency assistance will not result in any sustainable community recovery unless this is followed up with help to the community to reknit the social structure, re-establish the economic activities and regenerate the damaged buildings and structures through the normal construction processes and building workforce. The objective for any reconstruction programme in a development context is to assist the community to rebuild its own economy, houses and workplaces. Reconstruction programmes have rarely been successful where outside agencies have made the major decisions for the affected community or have built houses for it or relocated damaged settlements, or introduced new, rapidly built building types in order to accelerate the reconstruction process. Only by allowing the affected community to maintain control over its own reconstruction can an outside agency assist a recovery which will be sustainable and seen to be beneficial 10, 20 and more years later and that will result in a community less vulnerable to a future earthquake than it was. In practice this means consultation and community-led decisions on issues like priorities for the assistance that is available, location of new facilities, labour available and timing. Community consultation and decision- making can be a lengthy process and may appear to place undesirable delays on the reconstruction operation – delays that it is tempting to short-cut with centralised planning – but the benefits of having a committed and participating community will be seen in the sustainability and developmental achievements of the project. In housing, for example, the argument has been made in Chapter 5 that rebuild- ing damaged houses should be carried out by the normal building construction industry, expanded if necessary to meet the large-scale demand. In many rural areas and developing regions, houses are built by householders themselves or by village craftworkers or small-scale contractors. Assistance projects by develop- ment agencies to help these builders meet the reconstruction need is far preferable to the donation of several-thousand housing units. Protection Beyond the Reconstruction Area It is important in a reconstruction that the processes of building more strongly are established as well as the houses being built strongly. The next major earthquake in the region is likely to be nearby – in the next valley or in a neighbouring district. The opportunity should be taken to use the earthquake to introduce protection measures to as broad an area as possible in the neighbouring seismic 226 EARTHQUAKE PROTECTION region. Builders trained in strong construction may be encouraged to use their skills and qualifications to build for other clients in the neighbouring region, or to train other builders in nearby villages. Development agencies can promote earthquake protection over a broader region, using the earthquake reconstruction as the initiating opportunity. Establish Long-term Protection Apart from broadening the scope of protection activities geographically beyond the reconstruction area, it is important that the processes of building more strongly are well established so that they are sustained over time. Earthquakes gener- ally have long periods between occurrence, and protecting against them through improving the quality of the built environment is a long-term process. The build- ings likely to be affected by a future earthquake may not be this generation of structures, but those that exist in 20 or 50 years’ time. Many more buildings are likely to be built during the period between earthquakes and if the process of building them has been improved, then future earthquakes will result in lower damage levels. But the improved construction skills will need to be maintained throughout the next 20 or 50 years. Development organisations involved in post-earthquake emergency and recon- struction operations can help to instigate protection against future earthquakes by establishing regional and sustainable building improvement programmes as part of the community-based reconstruction. Building Improvement Programmes The most vulnerable parts of the built environment are the non-engineered build- ings constructed by householders, craftworkers or small-scale contractors, from a wide range of locally available and purchased building materials. The poor earthquake performance and lethal consequences of these building types are well known. Research, analysis and testing of these building types has iden- tified their behaviour in earthquakes and the vulnerability of their construction practices. Technical methods of improving the construction of these types of buildings to make them less vulnerable to earthquakes are described in Chapter 8. The greatest priority for development organisations concerned with reducing earthquake dis- asters is to implement improved construction techniques in the many thousands of houses being built across the seismic regions of the developing world. There are a variety of ways, described below, to encourage a community to improve its construction techniques. The most appropriate measures will depend on the type of community, its normal construction processes and the resources and technical capability of the assisting agency. [...]... magnitudes Smaller earthquakes will always be more frequent than larger earthquakes, and the recurrence frequency of smaller earthquakes tends to be related to the recurrence frequency of larger earthquakes Thus, a graph showing the number of earthquakes of each size against the size of the earthquake will tend to have a fixed shape Gutenberg and Richter12 postulated, on the basis of statistical recurrence... historical record 7.3.3 Seismic Source Zones Any earthquake catalogue with a sufficiently long period of observation is likely to show a distribution of seismic events by time, space and size A range of different magnitudes is likely to have occurred unevenly across a region and at various times during the duration of the catalogue An example of a plot of the seismic activity of a region is given in... tools to support earthquake protection The general procedure on which they are based involves the following steps: • • • • Compilation of a regional catalogue of earthquakes and their effects Definition of a set of earthquake source zones Determination of the expected earthquake recurrence rate for each source zone Definition of attenuation relationships for the required parameters of ground motion •... rate of earthquakes of given magnitude within a geographical area Site-specific hazard is the probability of the site experiencing a certain level of ground motion specified in a way that enables design loadings for buildings to be calculated Both are elements of a seismic hazard assessment 7.3.1 The Framework for Seismic Hazard Mapping Today’s seismic hazard maps, developed through many years of collaborative... settlement in an earthquake area There are a number of earthquakerelated hazards which should always be considered when choosing a site, together with the influence of the ground conditions at the site on the ground motion which the building may experience in a future earthquake An assessment of the extent of the earthquake hazard should always form a part of the overall site assessment and of the specification... give an indication of extent and general degree of damage The highest intensity level observed, the epicentral intensity (I0 ), represents the severity of the earthquake and maps of I0 can be used as an indication of the location of the most severe earthquakes which have occurred historically Both the epicentral intensity I0 and the felt area can be used to assess the magnitude of earthquakes in the... of liquid or gas in the pipelines can be rapidly shut off in the event of a rupture 7.2.2 Liquefaction Earthquake- induced soil liquefaction has been the cause of catastrophic damage in a number of earthquakes Certain types of soils, when they are saturated with water and then suddenly shaken by an earthquake, completely lose all shear strength, and flow like a liquid The support to the foundations of. .. Number of Events per Year 1.0 of greater than or equal to Magnitude ML 0.1 Gumbel III analysis 4.0 5.0 6.0 Magnitude ML 7.0 Figure 7.3 Seismicity of southern Italy, 1900–1980, expressed as cumulative frequency (log N vs M) of earthquake occurrence The area covered is shown in Figure 7.2 242 EARTHQUAKE PROTECTION The definition of source zones involves a review of all available information on the earthquake. .. know about earthquakes and data from the past century or more of earthquake records, it is now possible to make a reasonably accurate estimate of the rate of earthquake activity in any area of the world For government authorities or agencies responsible for a region, the concern is how often earthquakes are likely to occur within that region and how severe they are likely to be Regional seismicity... location of the effects of all earthquakes Within this general framework, different methods have been adopted for each of these steps depending on the extent of historical and scientific information available and the analytical resources available Some of the issues affecting the approach to each stage are discussed in the following sections 7.3.2 Compilation of Earthquake Catalogues For any seismic . nature of the risk and perception of its degree and severity. Availability of information about the actual STRATEGIES FOR EARTHQUAKE PROTECTION 219 level of risk faced, demystification of the. be an area of government initiative or budgeting. Research activities are a vital part of national earthquake protection efforts. 6 .5. 5 Budgeting for Losses and Mitigation The degree of influence. civil protection and saving human life. Chapter 10 presents the use of cost–benefit analysis and other methods of calculating the value of earthquake protection measures. Budgeting for Earthquake