Abstract This paper summarizes new lifeline seismic risk assessment techniques. These combine the advantages of deterministic (i.e., scenario-based) analyses with those of probabilistic (i.e., risk-based) analyses. Modifying the elegant work of Moghtaderizadeh and others, the new techniques are compatible with continuous component fragility models rather than being limited to artificial discrete dichotomous fragility models. Mathematical simplifications limit the number of events required so that the systemic consequences of those events can be examined in sufficient detail to permit comparison of alternative mitigations. These new techniques are demonstrated in terms of a model application to an urban water system in a highly seismic environment.

(1985). A Review of: “Judgement in geotechnical engineering: The professional legacy of Ralph” B. Peck (Ed. John Dunnicliff and Don U. Deve). John Wiley, New York, USA, 1984, 332 pp, £49-45. Civil Engineering Systems: Vol. 2, No. 2, pp. 123-123.

Abstract An algorithm to trace the itinerary of a snow ploughing truck that respects street priorities is developed. It is based on the notion of an Eulerian circuit in a directed graph, the existence of which is guaranteed due to the nature of the snow ploughing problem. The algorithm can be easily programmed in an interactive form on a micro-computer. The computer output presents the truck itinerary, each street given with its priority and the cumulative percentage of the street length with the same priority already ploughed with respect to the total length for that priority.

(1984). A Review of: “Deterioration of dams and reservoirs: examples and their analysis” Ed. Laboratorio de Engenharia Civil, Lisbon, Portugal A. A. Balkema, Rotterdam, The Netherlands, 1984, 368 pp, £35.50. Civil Engineering Systems: Vol. 1, No. 6, pp. 343-343.

Abstract Operation of a tidal power scheme in ebb generation and double generation modes with or without pumping is described. Dynamic programming is used to formulate the control of the scheme to maximize its energy output when operated in any of these modes: in the formulation hydrodynamic effects within the scheme are neglected but real turbine characteristics are used. Optimal control was found to be unnecessary for ebb generation, but it is essential if the scheme is to be operated in any other mode.

Abstract The basic concepts of probability and utility, as well as their interrelationship, are reviewed. The duality embodied in the definitions of these quantities is emphasized. The assumptions of exchangeability as an alternative to independence, in assessing the implications of data sets and in problems of inference, is shown to offer the opportunity for considerable improvement in statistical analysis. Exchangeability implies that the order of a sequence of random events or quantities is not of significance. The use of a basic urn model in formulating problems involving exchangeability is demonstrated. The extension of the analysis to continuous random quantities as well as to problems of extremes is summarized. An example of the analysis of arrival of icebergs at discrete points in time at the location of an offshore structure is included and it is shown that the results include the uncertainty resulting from short data bases. The added risk associated with this uncertainty is acknowledged implicit...

Abstract This paper discusses a common network flow problem that arises in four areas of civil engineering. The problem is one of identifying arc flows that simultaneously satisfy the circuit and node law constraints for a given network. Applications and computational procedures in the areas of elastic structural analysis, hydraulic network analysis, traffic equilibrium and construction task scheduling are described. The interpretation of decision variables and mathematical functions will vary depending on the application, but the general priblem formulation and solution technique for each application remains essentially unchanged. Analogies between the different applications may enhance the conceptual understanding and intuition of engineers working in each area.

Abstract This study deals with the imprecision associated with estimating the risk of health effects due to environmental causes. The major thrust revolves around the notion that the calculation of statistical risk, itself a probability, contains significant imprecision because of the cascade of error through the computations on which the risk, or probability of contracting a disease, is based. The cascade or risk is an old problem in mathematics and physics, and the conventional issues involving round-off, truncation and related measurement errors are not discussed here. The potential inadequacy of the model by which risk is calculated, the inherent variability in the stochastic processes by which the disease mechanism or initiator is transported down-gradient, and the variability inherent in varying levels of human sensitivity are of more concern. These all conspire to develop a distribution of risk rather than a scalar value, and policy-makers must deal with this distribution in a rational and consiste...

Abstract The paper describes a computer program for analysis and simulation of large-scale water distribution networks. The simulation facility enables the evaluation of system hydraulic and cost operation over extended time periods. An efficient user interface has been provided which allows interactive operation with graphical displays. The program computations use well established network solution techniques together with a range of specially developed models. With these features, the program has now been accepted as a powerful tool with a number of practical applications throughout the water industry.