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Sunday, 23 January 2022
How to make infrastructure more Resilient against Climate Change
By Robert L. Reid
United Nations Secretary-General António Guterres describes the latest Intergovernmental Panel on Climate Change report on global warming as “a code red for humanity.” Civil engineers are working to limit the emission of greenhouse gases, preserve resources, and promote resiliency to ensure that the infrastructure they design and build today will withstand the impacts of a changing environment tomorrow.
This is the first in a series of articles on infrastructure resilience that Civil Engineering plans to publish this year. Future articles will focus on specific climate threats and how civil engineers are working to mitigate the potential damage and keep critical infrastructure systems in operation.
The world’s climate is changing — and those changes are bringing significant impacts that will affect the way infrastructure is designed and constructed. Civil Engineering spoke with more than a dozen engineers — from the public and private sectors, academia, and advocacy groups — who are involved in studying the potential impacts of climate change and working to develop the proper engineering responses. They make it clear that the civil engineering profession has a significant role to play in helping the world adapt to these new conditions.
On Aug. 9, 2021, the United Nations’ Intergovernmental Panel on Climate Change released its latest report — Climate Change 2021: The Physical Science Basis — warning that climate change “is widespread, rapid, and intensifying.” Prepared by 234 scientists from 66 countries, the IPCC report declared that human-induced climate change “is already affecting many weather and climate extremes in every region across the globe ... in the atmosphere, in the oceans, (in) ice floes, and on land.”
Many of the observed changes “are unprecedented,” the report states, “and some of the shifts are in motion now, while some — such as continued sea level rise — are already ‘irreversible’ for centuries to millennia ahead.”
U.N. Secretary-General António Guterres described the report as “a code red for humanity,” adding that the “alarm bells are deafening, and the evidence is irrefutable.”
Feeling the impact
The world is already experiencing the effects of climate change, the report noted, in the form of prolonged droughts, increased numbers of wildfires, extremes in precipitation, extensive flooding, intense tropical cyclones, and the loss of Arctic sea ice, snow cover, and permafrost. Such effects will likely increase if action is not taken to limit warming.
At 1.5 degrees Celsius of global warming, there will be “increasing heat waves, longer warm seasons, and shorter cold seasons,” the report concluded.
At 2 degrees Celsius of global warming, “heat extremes are more likely to reach critical tolerance thresholds for agriculture and health,” the report stated. Rainfall patterns will also be disrupted, with “more intense rainfall and associated flooding, as well as more intense drought in many regions.”
The effects of climate change “may be magnified” in the world’s cities, especially coastal cities, which could face increasing heat and heavy precipitation, the report noted. “Moreover, coastal areas will see continued sea level rise throughout the 21st century, contributing to more frequent and severe coastal flooding in low-lying areas and coastal erosion,” the report warned. “Extreme sea level events that previously occurred once in 100 years could happen every year by the end of this century.”
Reference Link:
Architecture Discipline Different from Engineering
In the realm of design and construction of buildings architecture as a discipline is meant to be practiced only by registered and licensed individuals. Architecture cannot be claimed by any technical profession as an adjunct to any technical engineering course as it is illegal and criminal as provided for in The Architecture Act of 2004, also known as Republic Act 9266.
Around the world, architecture is practiced and accepted due to the role played by the architect as the prime professional in the design and construction of buildings whom clients talk to directly when in need of architectural design services instead of talking to technical engineers. Engineering consultants are hired directly by the architect to perform the engineering part of the proposed project.
An architect's creative, artistic and intuitive mind is antipodal to the rectilinear mind of a technical engineer. The creative mind of the architect is comparable to the mind of a poet-philosopher, while a technical engineer is similar to the mind of an accountant which is all linear and mathematical in nature. While the architect's mind encompasses both the general aspects of spatial and formal style of building design, the technical engineer's mind is only limited to that particular detailed quantitative and qualitative portion of building design called structural designs or even MEPFS (mechanical electrical plumbing fire and safety) designs.
In this case, an architect cannot be a technical engineer and neither can a technical engineer be an architect. As far as the east is from the west, the mind of an architect functions differently to the mathematical mind of a technical engineer in the process of creative and artistic building design.
An architect creates, a technical engineer calculates. Though there are architects who are structural engineers at the same time but often started as civil engineer first before becoming an architect. Most of their minds are yet technical in nature and most of them teach math if not theory of structures rather than architectural design in the colleges of architecture.
There are exceptionally gifted architectural geniuses who are innovative structural engineers at the same time. Such artists-technologists like the famous Spanish architect-civil engineer Santiago Calatrava, the German architect-civil engineer Frei Otto, or the Uruguayan architect-civil engineer Eladio Dieste, or the Mexican architect Felix Candela were PhD degree holders in structural engineering aside from being masters of architecture. Great architecture of the past was created not through quantitative mathematical theory, but first by that powerful tool of the architect, which is the creative and intuitive imagination of design and second is the structural design of the engineer.Just as the Theory of Relativity of Einstein was first a product of his intuitive and creative imagination, truth in architecture is the aesthetic awe it brings and its satisfaction to the end user.
If we shall go back in time some five hundred years ago to the birthplace of the Italian High Renaissance in the 16th century Italy, this was the manifestation of the flowering of the architect's creative genius-even a hundred year hence before the appearance of the professional civil engineer in the 18th century.
Civil Engineering News - Sensors To Speed Up Construction Timeline
Civil Engineering News - Sensors To Speed Up Construction Timeline
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Mauris ut vestibulum metus. Quisque et tellus ultrices, gravida diam in, tristique augue. Nulla facilisi. Phasellus tincidunt velit sapien, sit amet porttitor lectus dictum ac. Ut nisl nisi, ultricies at malesuada id, gravida non lacus. Pellentesque blandit magna lacus, a sodales eros lobortis a. Etiam egestas nisl id sem finibus vehicula. Vestibulum non elit eu est vestibulum posuere. Vivamus rutrum tincidunt semper.
Reference Link:
Study helps builders reduce carbon footprint of truss structures
Timber or steel? Study helps builders reduce carbon footprint of truss structures
New analysis could help identify optimal materials for the crisscrossing struts that bolster bridges, towers, and buildings.
November 29, 2021 Massachusetts Institute of Technology A new analysis could help architects and builders reduce the carbon footprint of truss structures, the crisscrossing struts that bolster bridges, towers, and buildings. - FULL STORY
Buildings are a big contributor to global warming, not just in their ongoing operations but in the materials used in their construction. Truss structures -- those crisscross arrays of diagonal struts used throughout modern construction, in everything from antenna towers to support beams for large buildings -- are typically made of steel or wood or a combination of both. But little quantitative research has been done on how to pick the right materials to minimize these structures' contribution global warming.
The "embodied carbon" in a construction material includes the fuel used in the material's production (for mining and smelting steel, for example, or for felling and processing trees) and in transporting the materials to a site. It also includes the equipment used for the construction itself.
Now, researchers at MIT have done a detailed analysis and created a set of computational tools to enable architects and engineers to design truss structures in a way that can minimize their embodied carbon while maintaining all needed properties for a given building application. While in general wood produces a much lower carbon footprint, using steel in places where its properties can provide maximum benefit can provide an optimized result, they say.
The analysis is described in a paper published in the journal Engineering Structures, by graduate student Ernest Ching and MIT assistant professor of civil and environmental engineering Josephine Carstensen.
"Construction is a huge greenhouse gas emitter that has kind of been flying under the radar for the past decades," says Carstensen. But in recent years building designers "are starting to be more focused on how to not just reduce the operating energy associated with building use, but also the important carbon associated with the structure itself." And that's where this new analysis comes in.
The two main options in reducing the carbon emissions associated with truss structures, she says, are substituting materials or changing the structure. However, there has been "surprisingly little work" on tools to help designers figure out emissions-minimizing strategies for a given situation, she says.
Wood performs very well under forces of compression, but not as well as steel when it comes to tension -- that is, a tendency to pull the structure apart. Carstensen says that in general, wood is far better than steel in terms of embedded carbon, so "especially if you have a structure that doesn't have any tension, then you should definitely only use timber" in order to minimize emissions. One tradeoff is that "the weight of the structure is going to be bigger than it would be with steel," she says.
The tools they developed, which were the basis for Ching's master's thesis, can be applied at different stages, either in the early planning phase of a structure, or later on in the final stages of a design.
The new system makes use of a technique called topology optimization, which allows for the input of basic parameters, such as the amount of load to be supported and the dimensions of the structure, and can be used to produce designs optimized for different characteristics, such as weight, cost, or, in this case, global warming impact.
As an exercise, the team developed a proposal for reengineering several trusses using these optimization tools, and demonstrated that a significant savings in embodied greenhouse gas emissions could be achieved with no loss of performance. While they have shown improvements of at least 10 percent can be achieved, she says those estimates are "not exactly apples to apples" and likely savings could actually be two to three times that.
"It's about choosing materials more smartly," she says, for the specifics of a given application. Often in existing buildings "you will have timber where there's compression, and where that makes sense, and then it will have really skinny steel members, in tension, where that makes sense. And that's also what we see in our design solutions that are suggested, but perhaps we can see it even more clearly." The tools are not ready for commercial use though, she says, because they haven't yet added a user interface.
Carstensen sees a trend to increasing use of timber in large construction, which represents an important potential for reducing the world's overall carbon emissions. "There's a big interest in the construction industry in mass timber structures, and this speaks right into that area. So, the hope is that this would make inroads into the construction business and actually make a dent in that very large contribution to greenhouse gas emissions.''
Story Source:
Materials provided by Massachusetts Institute of Technology. Original written by David L. Chandler. Note: Content may be edited for style and length.
Journal Reference:
- Ernest Ching, Josephine V. Carstensen. Truss topology optimization of timber–steel structures for reduced embodied carbon design. Engineering Structures, 2021; 113540 DOI: 10.1016/j.engstruct.2021.113540
Cite This Page:
Massachusetts Institute of Technology. "Timber or steel? Study helps builders reduce carbon footprint of truss structures: New analysis could help identify optimal materials for the crisscrossing struts that bolster bridges, towers, and buildings.." ScienceDaily. ScienceDaily, 29 November 2021. <www.sciencedaily.com/releases/2021/11/211129155105.htm>.
Buildings are a big contributor to global warming, not just in their ongoing operations but in the materials used in their construction. Truss structures -- those crisscross arrays of diagonal struts used throughout modern construction, in everything from antenna towers to support beams for large buildings -- are typically made of steel or wood or a combination of both. But little quantitative research has been done on how to pick the right materials to minimize these structures' contribution global warming.
The "embodied carbon" in a construction material includes the fuel used in the material's production (for mining and smelting steel, for example, or for felling and processing trees) and in transporting the materials to a site. It also includes the equipment used for the construction itself.
Now, researchers at MIT have done a detailed analysis and created a set of computational tools to enable architects and engineers to design truss structures in a way that can minimize their embodied carbon while maintaining all needed properties for a given building application. While in general wood produces a much lower carbon footprint, using steel in places where its properties can provide maximum benefit can provide an optimized result, they say.
The analysis is described in a paper published in the journal Engineering Structures, by graduate student Ernest Ching and MIT assistant professor of civil and environmental engineering Josephine Carstensen.
"Construction is a huge greenhouse gas emitter that has kind of been flying under the radar for the past decades," says Carstensen. But in recent years building designers "are starting to be more focused on how to not just reduce the operating energy associated with building use, but also the important carbon associated with the structure itself." And that's where this new analysis comes in.
The two main options in reducing the carbon emissions associated with truss structures, she says, are substituting materials or changing the structure. However, there has been "surprisingly little work" on tools to help designers figure out emissions-minimizing strategies for a given situation, she says.
Wood performs very well under forces of compression, but not as well as steel when it comes to tension -- that is, a tendency to pull the structure apart. Carstensen says that in general, wood is far better than steel in terms of embedded carbon, so "especially if you have a structure that doesn't have any tension, then you should definitely only use timber" in order to minimize emissions. One tradeoff is that "the weight of the structure is going to be bigger than it would be with steel," she says.
The tools they developed, which were the basis for Ching's master's thesis, can be applied at different stages, either in the early planning phase of a structure, or later on in the final stages of a design.
The new system makes use of a technique called topology optimization, which allows for the input of basic parameters, such as the amount of load to be supported and the dimensions of the structure, and can be used to produce designs optimized for different characteristics, such as weight, cost, or, in this case, global warming impact.
As an exercise, the team developed a proposal for reengineering several trusses using these optimization tools, and demonstrated that a significant savings in embodied greenhouse gas emissions could be achieved with no loss of performance. While they have shown improvements of at least 10 percent can be achieved, she says those estimates are "not exactly apples to apples" and likely savings could actually be two to three times that.
"It's about choosing materials more smartly," she says, for the specifics of a given application. Often in existing buildings "you will have timber where there's compression, and where that makes sense, and then it will have really skinny steel members, in tension, where that makes sense. And that's also what we see in our design solutions that are suggested, but perhaps we can see it even more clearly." The tools are not ready for commercial use though, she says, because they haven't yet added a user interface.
Carstensen sees a trend to increasing use of timber in large construction, which represents an important potential for reducing the world's overall carbon emissions. "There's a big interest in the construction industry in mass timber structures, and this speaks right into that area. So, the hope is that this would make inroads into the construction business and actually make a dent in that very large contribution to greenhouse gas emissions.''
Story Source:
Materials provided by Massachusetts Institute of Technology. Original written by David L. Chandler. Note: Content may be edited for style and length.
Journal Reference:
- Ernest Ching, Josephine V. Carstensen. Truss topology optimization of timber–steel structures for reduced embodied carbon design. Engineering Structures, 2021; 113540 DOI: 10.1016/j.engstruct.2021.113540
Cite This Page:
Massachusetts Institute of Technology. "Timber or steel? Study helps builders reduce carbon footprint of truss structures: New analysis could help identify optimal materials for the crisscrossing struts that bolster bridges, towers, and buildings.." ScienceDaily. ScienceDaily, 29 November 2021. <www.sciencedaily.com/releases/2021/11/211129155105.htm>.
Saturday, 22 January 2022
How building houses on flood plains could be the ‘best choice’
How building houses on flood plains could be the ‘best choice’
A recent Guardian article about housing being planned in areas at risk of flooding may raise eyebrows – but an ICE expert explains how it might not be the harebrained scheme it first appears.
Building resilience is another option if there is no option but to build on flood plains. Image credit: Shutterstock
Updated: 25 November, 2021
Author: Fiona Barbour, ICE Flooding Community Advisory chair
Concern was raised earlier this week when the Guardian reported that thousands of new houses would be built on flood plains, with the housing crisis being blamed for the decision. It referred to 5,000 homes within flood risk areas in England that have been granted planning permission.
However, the Local Government Association’s housing and environment spokesman, David Renard, said almost 99% of applications were decided in line with the Environment Agency’s (EA) risk advice, while Andrew Whitaker, the planning director of the Homes Builder Federation, stated “development have to meet extremely stringent mitigation requirements”.
What I would like to understand is are these houses now at flood risk as the headline suggested? Have they been built with disregard to the flood risk? Were any of these houses replacing old houses that were already at flood risk?
The reality of each situation may be complex. The EA’s indicative flood maps are very high level, and the more detailed assessment may have identified the flooding as not as severe. The proposed mitigations may have resulted in these new houses having an acceptable level of risk. I would like to see the research, but the article does not cite the source or provider to allow me to do so.
‘We need to acknowledge the housing crisis’
While I agree that we are dealing with legacy issues regarding previous practices of building on flood plains and we should do all we can to reduce this impact and certainly not make it worse, we need to acknowledge the housing crisis. These issues cannot be examined in isolation. As civil engineers, we have a duty to examine the systems of infrastructure required to serve society holistically and respond with pragmatic solutions.
The IPCC identifies that the climate change already locked in is hitting us harder and faster than previously predicted.
We need to look at the resilience of our existing and new development, particularly our housing. We have established communities who may have traditionally been developed around ports and river crossings for trade reasons, and these commercial hubs cannot easily be relocated outside of flood plains for economic and political reasons.
The focus must be on increasing resilience
Where relocation is not possible, and relying on higher defences alone for protection is neither effective nor sustainable, the focus must be on increasing resilience, as the Environment Agency recognises in its Draft National Flood and Coastal Erosion Risk Management Strategy for England.
While there is general consensus new homes should not be built on flood plains that are still ‘green’, there is little agreement on how to increase flood resilience in areas where they have already been developed.
The crunch question is how do we help these communities to withstand flood events, maintain continuity of services, and recover more quickly? A counterintuitive answer is to allow new development, creating additional infrastructure which can itself play a defensive role.
When infrastructure can improve resilience
New or upgraded infrastructure, for example, could reroute flood water away from residential buildings. Sustainable drainage systems (SuDS) that collect and discharge rainwater safely will counteract run-off effects caused by existing hardstanding surfaces.
This leads to the thought: will allowing redevelopment within existing flood-prone brownfield land be the best way to increase resilience for these communities? If we design for exceedance philosophy, our resilience will improve.
That is, if we design where excess water will go if we experience greater rainfall than we are currently designing for, and communities agree to accept there will be water in their streets in extreme weather events (provided it is kept out of their living rooms), we can break the cycle of repeated, disruptive and damaging flooding.
The more stringent mitigations referred to by Whitaker may mean the houses are constructed with raised electrics and concrete floors, significantly reducing the impact of infrequent flooding and allowing people to return to their homes in an acceptable timeframe. I would prefer this lower impact scenario over an existing house built without these considerations.
The reality of climate change is that whether we are considering new or existing housing, flood risk is increasing and we cannot protect everyone, so increasing resilience is the answer. Therefore, if the process is robust, the correct flood professionals are involved in the decision making and the developments reduce the extent and impact of flooding, then perhaps it is our best choice?
Updated: 25 November, 2021
Author: Fiona Barbour, ICE Flooding Community Advisory chair
Concern was raised earlier this week when the Guardian reported that thousands of new houses would be built on flood plains, with the housing crisis being blamed for the decision. It referred to 5,000 homes within flood risk areas in England that have been granted planning permission.
However, the Local Government Association’s housing and environment spokesman, David Renard, said almost 99% of applications were decided in line with the Environment Agency’s (EA) risk advice, while Andrew Whitaker, the planning director of the Homes Builder Federation, stated “development have to meet extremely stringent mitigation requirements”.
What I would like to understand is are these houses now at flood risk as the headline suggested? Have they been built with disregard to the flood risk? Were any of these houses replacing old houses that were already at flood risk?
The reality of each situation may be complex. The EA’s indicative flood maps are very high level, and the more detailed assessment may have identified the flooding as not as severe. The proposed mitigations may have resulted in these new houses having an acceptable level of risk. I would like to see the research, but the article does not cite the source or provider to allow me to do so.
‘We need to acknowledge the housing crisis’
While I agree that we are dealing with legacy issues regarding previous practices of building on flood plains and we should do all we can to reduce this impact and certainly not make it worse, we need to acknowledge the housing crisis. These issues cannot be examined in isolation. As civil engineers, we have a duty to examine the systems of infrastructure required to serve society holistically and respond with pragmatic solutions.
The IPCC identifies that the climate change already locked in is hitting us harder and faster than previously predicted.
We need to look at the resilience of our existing and new development, particularly our housing. We have established communities who may have traditionally been developed around ports and river crossings for trade reasons, and these commercial hubs cannot easily be relocated outside of flood plains for economic and political reasons.
The focus must be on increasing resilience
Where relocation is not possible, and relying on higher defences alone for protection is neither effective nor sustainable, the focus must be on increasing resilience, as the Environment Agency recognises in its Draft National Flood and Coastal Erosion Risk Management Strategy for England.
While there is general consensus new homes should not be built on flood plains that are still ‘green’, there is little agreement on how to increase flood resilience in areas where they have already been developed.
The crunch question is how do we help these communities to withstand flood events, maintain continuity of services, and recover more quickly? A counterintuitive answer is to allow new development, creating additional infrastructure which can itself play a defensive role.
When infrastructure can improve resilience
New or upgraded infrastructure, for example, could reroute flood water away from residential buildings. Sustainable drainage systems (SuDS) that collect and discharge rainwater safely will counteract run-off effects caused by existing hardstanding surfaces.
This leads to the thought: will allowing redevelopment within existing flood-prone brownfield land be the best way to increase resilience for these communities? If we design for exceedance philosophy, our resilience will improve.
That is, if we design where excess water will go if we experience greater rainfall than we are currently designing for, and communities agree to accept there will be water in their streets in extreme weather events (provided it is kept out of their living rooms), we can break the cycle of repeated, disruptive and damaging flooding.
The more stringent mitigations referred to by Whitaker may mean the houses are constructed with raised electrics and concrete floors, significantly reducing the impact of infrequent flooding and allowing people to return to their homes in an acceptable timeframe. I would prefer this lower impact scenario over an existing house built without these considerations.
The reality of climate change is that whether we are considering new or existing housing, flood risk is increasing and we cannot protect everyone, so increasing resilience is the answer. Therefore, if the process is robust, the correct flood professionals are involved in the decision making and the developments reduce the extent and impact of flooding, then perhaps it is our best choice?
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