Travanca and André
182
Therefore, a comprehensive public policy for critical infrastructure protection must
begin with an understanding that “protection” should not be the main goal. Unlikely
other civil structures, such as buildings and bridges, even if one accepts the word “protection”, it is important to understand that what is being protected is not the infrastructure
itself but the services provided. Unfortunately, our societies rarely reward investments
that reduce vulnerability, in particular with respect to events so exceptional that there
is no statistical basis for quantitative risk assessment. Management often focuses on
keeping expenditure to a minimum and increase short‐term revenues. Investments are
therefore short‐term intended, focusing on replacing and renewing as needed rather
than modernising key physical infrastructure, and expenditure takes place ultimately in
response to a crisis rather than proactively planning and managing key physical infrastructures. This is often ill‐justified in economic terms since the economic risk from
natural or man‐made causes perceived by network operators often represents a small
percentage of the capital at risk. Furthermore, the focus is on operating at near maximum operational capacity of the physical infrastructure, which is viewed as being an
optimal and efficient management decision. However, such an option causes the systems
to be less resilient against anticipated or unknown climatic and socio‐demographic
changes during the infrastructures lifespan. Investment in research and innovation
towards physical infrastructure resilience and climate change adaptation is given low
priority and only a small portion of the available amount is redirected to it. In the long
term, network operators often expect that climatic changes can be addressed when old
assets are replaced, using improved or, more likely, adapted technology.
8.4.2 Design Failures
The number of failures observed in communications structures is high when compared
with other structures of equal economic and social importance. A great number of the
failures observed are the result of poor design methods and practices, conducing to
unsafe structures that are prone to collapse, partial or full [3,5–7]. The analysis and
design of masts and towers require specific knowledge and expertise. In fact, a structurally sound definition of the basis of design of communication structures is a key issue. To
address this special need, proper communication between the designer and client is
necessary to create an economical structure with adequate reliability and performance.
Unfortunately, the combination of an inexperienced client and a designer who is not
familiar with the special problems associated with the design of communication structures is common. Over the years, this combination has created many structures that do
not fulfil their intended purpose [3,5,6]. From the analysis of the problems recently
observed in structures used in the communication sector, it is reasonable to conclude
that design errors are the most frequent cause of collapse or early replacement events [3].
In addition, market pressure demanding lighter and more economical solutions has generated structures with structural limitations in terms of fatigue safety [3].
The predominant loading for the analysis and design of such structures are actions
of random nature, namely the wind action or the combined action of wind and ice.
Wind is a dynamic action and slender structures are sensitive to the turbulent component of the wind. The dynamic response becomes important when these structures
exhibit a first natural frequency below 1 Hz. Therefore, dynamic analysis is necessary
to determine whether the resonance response could be significant compared with the
background response [3].
182
Therefore, a comprehensive public policy for critical infrastructure protection must
begin with an understanding that “protection” should not be the main goal. Unlikely
other civil structures, such as buildings and bridges, even if one accepts the word “protection”, it is important to understand that what is being protected is not the infrastructure
itself but the services provided. Unfortunately, our societies rarely reward investments
that reduce vulnerability, in particular with respect to events so exceptional that there
is no statistical basis for quantitative risk assessment. Management often focuses on
keeping expenditure to a minimum and increase short‐term revenues. Investments are
therefore short‐term intended, focusing on replacing and renewing as needed rather
than modernising key physical infrastructure, and expenditure takes place ultimately in
response to a crisis rather than proactively planning and managing key physical infrastructures. This is often ill‐justified in economic terms since the economic risk from
natural or man‐made causes perceived by network operators often represents a small
percentage of the capital at risk. Furthermore, the focus is on operating at near maximum operational capacity of the physical infrastructure, which is viewed as being an
optimal and efficient management decision. However, such an option causes the systems
to be less resilient against anticipated or unknown climatic and socio‐demographic
changes during the infrastructures lifespan. Investment in research and innovation
towards physical infrastructure resilience and climate change adaptation is given low
priority and only a small portion of the available amount is redirected to it. In the long
term, network operators often expect that climatic changes can be addressed when old
assets are replaced, using improved or, more likely, adapted technology.
8.4.2 Design Failures
The number of failures observed in communications structures is high when compared
with other structures of equal economic and social importance. A great number of the
failures observed are the result of poor design methods and practices, conducing to
unsafe structures that are prone to collapse, partial or full [3,5–7]. The analysis and
design of masts and towers require specific knowledge and expertise. In fact, a structurally sound definition of the basis of design of communication structures is a key issue. To
address this special need, proper communication between the designer and client is
necessary to create an economical structure with adequate reliability and performance.
Unfortunately, the combination of an inexperienced client and a designer who is not
familiar with the special problems associated with the design of communication structures is common. Over the years, this combination has created many structures that do
not fulfil their intended purpose [3,5,6]. From the analysis of the problems recently
observed in structures used in the communication sector, it is reasonable to conclude
that design errors are the most frequent cause of collapse or early replacement events [3].
In addition, market pressure demanding lighter and more economical solutions has generated structures with structural limitations in terms of fatigue safety [3].
The predominant loading for the analysis and design of such structures are actions
of random nature, namely the wind action or the combined action of wind and ice.
Wind is a dynamic action and slender structures are sensitive to the turbulent component of the wind. The dynamic response becomes important when these structures
exhibit a first natural frequency below 1 Hz. Therefore, dynamic analysis is necessary
to determine whether the resonance response could be significant compared with the
background response [3].