Review of Multihazard Considerations in Civil Infrastructure by Mohammed M. Ettouney and Sreenivas Alampalli

Civil infrastructures have numerous common attributes including that they all are subject to multitudes of hazards/demands that degrade their performance with time. In their constant battle against these hazards, the stakeholders realized that those hazards seldom afflict the system on hand in an isolated manner. Hence, there is a need for all-hazard interaction processes or multihazard processes and considerations that account for such interactions, which has been a research topic for long time. This potential has resulted in the well-known loading factors approach in civil infrastructure analysis and design processes, but there have been no other objective efforts to study other potential aspects of multihazard interaction effects in the field of civil infrastructures until Ettouney and Alampalli offered a comprehensive study of the subject matter in their recent book Multihazard Considerations in Civil Infrastructure, which was published by CRC Press in December 2016.

Chapter 1 provides an introduction to the multihazard aspects as well as a summary of the book. The authors make it very clear from the start that they have no interest in the prevailing concept in the literature that multihazard coverage is akin to covering several hazards in parallel. They offered that such a coverage, without addressing the potential links between hazards, should not be considered multihazards. The rest of the chapter was devoted to a discussion on various attributes to describe the hazards in a systematic fashion.

Chapter 2 introduces the objective basis of multihazard considerations. This basis has two theories that appear to be similar at first glance, but they are very different in reasoning and application. The multihazards physical theory (MPT) looks at how hazards interact through the physical systems under considerations, whereas the multihazard decision theory (MDT) explores hazard interactions via decision-making processes.

One of the most common engineering undertakings in the field of civil infrastructures is arguably the structural analysis practice. In Chapter 3, the authors started their multihazard considerations studies by addressing an important structural analysis query: What is the affinity (or consistency) of a structural system response to a hazards pair? An objective answer to this query can help the analyst understand and perhaps optimize the structural system in a multihazard environment. They introduce a multihazard interaction matrix (MHIM) as a solution and developed several forms of MHIM for different types of analyses. A set of detailed case studies showed the versatility of the methods.

To show that multihazard considerations permeate throughout existing design practices, the authors explored design issues from multihazard viewpoints in Chapter 4. They first tackled multihazard interactions for civil infrastructure vulnerability followed by practical examples of mass transit stations and tunnels that are exposed to several artificial and natural hazards. The authors then showed that the design equations used on a daily basis by civil engineering designers have built-in multihazard capabilities that can, if exploited properly, aid the designers in attaining higher understanding as well as optimal designs of the systems under consideration.

The authors used analytical methods to quantify multihazard interactions in Chapters 2–4. In Chapter 5, they introduced more versatile graph network (GN) methods to further study multihazard interactions. They briefly described several GN methods including Bayes networks (BNs), Markov networks (MNs), chain graphs (CGs), influence diagrams (IDs), and dynamic graph networks (DGNs) with illustrative case studies. The next four chapters in the book explore numerous concepts of multihazard considerations as applied to four components of risk and resilience management: assessment, acceptance, treatment, and monitoring.

In Chapter 6, the authors provided several methods to extract multihazard effects while performing risk assessment. These included the multihazard risk difference and multihazard risk rate of change concepts. The authors apply both MPT and MDT to develop multihazard risk matrices for mass transit stations and tunnels. The remainder of the chapter explored several risk and resilience modeling examples that would provide multihazard objective measures.

Can the potential of multiple hazards affecting a single or network of civil infrastructures control acceptance limits of different paradigms (reliability, risk, exposure, etc.)? This is the subject of Chapter 7. The authors present several methods and case studies to evaluate multihazard acceptance thresholds, which is a very difficult and rarely addressed issue. Included among the different practical examples presented are the presence and need for accommodating lower limit states and network multihazard risk acceptance.

Reducing risks and/or increasing resilience is perhaps one of the most desired goals of civil infrastructure management. In Chapter 8, the authors try to address the important and neglected issue of how to account for the risk/resilience due to other hazards while treating risk/resilience of a particular hazard.

All components of risk and resilience change as time progresses; hence, monitoring risk and resilience are integral parts of infrastructure management. In Chapter 9, the authors address the essentialities of monitoring (risk and resilience) in a multihazard environment. They argued that multihazard monitoring should be addressed in two steps: first as a snapshot in time and then the snapshot progresses as time passes (essentially a forecasting problem). This two-step approach seems to simplify a fairly complex problem without any loss in any needed generalizations or undue assumptions that might degrade the desired results.

Many of the civil infrastructures are subjected to multiple issues and facets at any given instance, for example, security of suspension cable bridges or progressive collapse of bridges. The common thread between those case studies is that they are all subjected to multihazards of different types. The last and concluding Chapter 10 illustrates, through case studies, the complexities and vast reaches of multihazard needs and considerations as they afflict different civil infrastructures in varying forms.

Overall the book introduces new concepts to the field of multihazards in civil infrastructure. It not only explains multihazard issues from both theoretical and practical aspects, it also uses the latest concepts, such as GNs, to explore these issues. Both researchers and practitioners will equally benefit from the book.