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The results of a survey of climate change developments in South Africa and Germany from the perspective of its relevance to extreme actions on infrastructure are presented in this paper. It is concluded that the importance of climate change is broad and varied. However incorporation into practice is mostly nominal. Although general trends of climate change are confirmed, proper information on changes in extreme conditions is limited. Coastal engineering seems to be the field which is most active in providing for climate change. It is concluded that risk-based methodologies developed to treat the variability and uncertainties of extreme actions and consequences in present practice provide a sound basis for treating the effects of climate change in a rational and optimal manner. It is also clear that there is strong motivation for extensive research as the best action to be taken presently, anticipating appropriate adjustment of re-optimised design methodologies.
Solar energy represents a clean, natural and sustainable source of energy. Solar photovoltaic panels can be installed on roofs of structures or in the ground. This contribution focusses on ground-mounted systems, which are presently widely implemented. At present limited guidelines on the design of solar ground-mounted structures are available. Usually standards for the design of normal buildings are applied. However, the design of ground-mounted structures significantly differs from common structural design by: (1) a lower design lifetime (20-25 years) is accepted; (2) failure is not associated with the loss of human life; (3) resistance uncertainties need due attention; (4) uplift wind forces dominating structural reliability are associated with a large scatter. That is why the reliability analysis and optimal design of ground-mounted solar systems is investigated herein. The failure costs and especially their ratio to the initial costs are analyzed considering the data provided from the industry. Probabilistic reliability analyses are carried out and optimum design levels are computed for representative cost ratios. The optimal target reliability depends on the ratio between failure and initial costs; reliability index of 3.5 corresponds to a reasonable cost ratio of 10.
Specification of the target reliability levels is one of the key issues of the assessment of existing structures. ISO 13822:2010 and ISO 2394:1998 indicate procedures for deriving the target reliability levels by optimisation of the total cost related to an assumed remaining working life of a structure. In the submitted study this approach is applied to estimate the target reliability levels of an existing structural member in conjunction with the human safety criteria. Obtained results are critically compared with the recommendations given in present standards. It appears that the requirement on the same target reliability levels for existing structures as for new structures is uneconomical. Further, the cost optimisation seems to yield rather low reliability levels and human safety criteria become commonly decisive for specification of the target reliabilities of existing structures.
The Leonardo da Vinci Project, “Innovation Transfer in Risk Assessment and Management of Aging Infrastructures”, CZ/13/LLP-LdV/TOI/134014, addresses the urgent need to train students, young engineers and professionals in the assessment of existing infrastructures. The future of the construction industry lies in moving from new constructions towards the maintenance, repair and rehabilitation of existing structures, particularly of aging infrastructures. Risk management consisting of risk assessment and risk control of existing structure therefore plays thereby an important role. The assessment of existing infrastructures is an imperative issue of great economic significance in most countries around the world, as more than 50 % of all construction activities concerns existing buildings, bridges and other civil engineering works. At present, the Eurocodes which will be used in all CEN Member countries are primarily focused on the design of new structures. Additional operational rules for existing structures are still missing. The international standard ISO 13822 provides only general principles for the assessment of existing structures which should be further developed for their effective operational use in practice. The overall procedure of risk management of aging infrastructures is therefore an urgent issue of great economic significance in most countries around the world. This is primarily caused due to the fact that many infrastructures are affected by action effects, fatigue and environmental influences, and inevitably deteriorate. Moreover, available resources for the maintenance, repair or possible replacement of infrastructures are always limited. Typical questions and problems which must be solved in this context can be summarized as follows: • What is the current state of a particular infrastructure? • What is an acceptable level of the relevant risk? • Which aspects are critical to sustainable performance? • What is the optimum life-cycle cost? • What is the best long-term funding strategy? The proposed project highlights the above problems and focusses also on vocational training in risk management and assessment of aging infrastructure in the partner countries (CZ, DE, ES, IT and TR). The current project addresses the urgent need for practical implementation of principles of the management and risk assessment of existing infrastructures in all the partner countries. The project is supported by the Czech Chamber of Chartered Engineers (ČKAIT). The project consortium, under the leadership of the Klokner Institute of the Czech Technical University in Prague (KI CTU), consists of five other partners, including research institutions and universities from three EU Member States (DE, ES, IT) as well as one associated country (TR), and also the Secondary Technical School of Civil Engineering in Ceske Budejovice (CZ). All researchers within the partnership are involved in research projects dealing with reliability assessment of existing structures. They participate in the national and international standardization activities within the international organizations CEN (European Committee for Standardisation) and ISO (International Standardization Organisation). The project outcomes consist of vocational training materials based on international research and relevant standard committee’s activities, and on the significant experience gained from case studies, and on selected results obtained from the previous projects of the Leonardo da Vinci programme. In particular, the experience gained by the partners of the present consortium from the completed project on vocational training related to assessment of existing structures is utilized. Available innovations are transferred to undergraduate and graduate students, practising engineers and local government representatives. The developed training materials are of practical use in offering illustrative examples and several case studies. All the project outcomes are based on documents of the international research organization, Joint Committee on Structural Safety JCSS and international research projects, selected outcomes of the previous project of the Leonardo da Vinci programme (developed by five partners of the present consortium in 2013-2015) and also on background documents to the new European and international standards. Particular outcomes of the proposed project include practical handbooks, software tools, web-sites, e-learning, courses and seminars organized in the partners´ home countries. The project outcomes will also be offered to other European countries through code committees work, lectures and the project web-sites. It is foreseen that the outcomes being used by engineers, designers, technicians, and representatives of public authorities involved in planning and management will have an impact on the risk-based management of infrastructures. One of the important project outcomes is the present Handbook 1 “Methods for the Risk Assessment and Risk-Based Management of Aging Infrastructure”, which is focussed on general procedures of risk-management and assessment of aging infrastructures. The methodologies provided are independent of the type of structure and material, and are compatible with the background methodologies used in the Eurocodes. Operational techniques for the assessment of aging infrastructures supplemented by illustrative case studies are presented in Handbook 2 and Handbook 3, which also result from the mentioned project. Handbook 1 consists of ten chapters and one annex. Chapter 1 gives a brief overview of the basic concepts used in the management and risk assessment of existing structures, supplemented by the basic definitions and terminology. Chapter 2 summarizes current applicable standards, codes and recommendations related to actions and environmental influences on existing structures. Chapter 3 reviews the most important degradation models due to environmental influences. Fatigue effects are treated separately in Chapter 4. The following Chapters, 5, 6, 7 and 8, are devoted step by step to the entire procedure of risk management, including probabilistic reliability analysis, consequence analysis, risk evaluation and risk assessment based on risk acceptance criteria, and consequently provide important information supporting decisions concerning the safety of the structure. The last two Chapters, 9 and 10, illustrate instructive case studies concerning risk management and risk assessment of road tunnels. Annex A presents basic statistical methods and techniques used in the evaluation and updating of available data required for probability and consequence analysis. It is believed that the material of this handbook is presented in an understandable way, illustrated by several realistic examples. A number of references mentioned in each chapter provide additional background materials, further guidance and information useful for particular practical applications. Prague and Regensburg, 2014