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Earthquake in West China and lessons for us!

In Singapore, I have seen students who lost their relatives in last earthquake. I am very sorry about this, but I think there should be lessons for us in such disasters.  Is'nt any cheap and easy way to reinforce building in the face of earthquakes? I hope such disasters make researchers concentrate on such important topics.

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Zhigang Suo's picture

Indeed, we have had little discussion on iMechanica on topics related to Civil Engineering, even though Civil Engineering has always been a major playing field for mechanics.  Is it because we don't have many users with expertise in Civil Engineering?   Or is there anything deeper going on that troubles Civil Engineering?  Or is it just becasue we as a species have this perpetual need for novelty, rather than focus on what is truly important?

The NAE has identified aging infrastructures as a grand challenge for engineering.  Do any of you have any thoughts on these issues?

Mahdi Kazemzadeh's picture

Here we are! I actually have been waiting for this question!! It is a very sharp point and needs some discussion, I will try to mention few points here about Civil Engineering. I personally have always been interested in civil engineering as it is some sort of practical view of mechanic rules! In recent years civil engineering and structural engineering has improved a lot but I have a more handy example of that which I think can explain why the research method is different in these two subjects. If we assume that the civil engineering is like a tree and by doing research we are granting more branches to it then I can say:" In the research of Mechanics we grow the trunk of the tree, In Civil Engineering we add to the branches and leafs and the trunk stays more or less how it was" !!!!

I can remember when for the first time my supervisor told me he is having trouble to find fresh post graduate reserah topics for his students in structural engineering! I think in Civil we have reached a point that the related subjects are improving the mother knowlege, this is not enough in many aspects of our profession. There is a lot into this, I will post my idea in "grand challenge for engineering" on this, as I think the next challenge for engineers is to mix nanomechanics and civil engineering for the best of our life!!

I think the answer to the question that why we dont have quite number of civils here is: the engineers who are in idustry are usually far away from research topics and if not the work is not realted to the mechanics itself directly. But this is changing I myself have a policy and I welcome any civil engineer who joins iMechanica and I try this to be by the first hour of their joining! So I have sent quite a few and I think we have some to take action in cases of civil engineering question. thank you for raising this question, we will discuss this further. 

I am willing to make a difference, are you?

Would you be willing to join a team to develop an evolving co-operative construction program, which meets or exceeds US Building standards?

One which is nationally and internationally proven to resists; fire, mold, wind, water, earthquakes (Richter-4), hurricanes (CAT 5)?

(Let's just suppose, you haven't seen this system, even though it's been around for 8 years or more).

Do you have the engineering and/or financial skills to implement a proven global construction delivery solution with me; from scratch?

This building system is referred to, as "the fastest, lightest, cheapest, most energy efficient construction system; meeting the LEEDS Gold Standard", (although there are now some alternatives attempting to compete, and they are very well funded).

 The system requires little-to-no use of wood or concrete, (except for traditional foundations), yet even foundations may be manufactured, just as the walls and roof with similar materials); although you most certainly may add either material to it, as specifiers.

This process is considered environmentally friendly and is highly regarded by the East of US1 Building Code, in Florida, where it has been approved. It has also been approved for the NAFTA and CAFTA Free Trade Zones, as they are signatory to the same agreements as The State Of Florida.

There are many advantages and speed-of-completion, is just one of them.  Customer satisfaction is another highly regarded feature, when consumer complaints are entered into the building buying experience.

I'm considering giving this project another go, however I lack interested, co-operative, team-members who desire to complete this project. The system designer has offered me the opportunity to continue his work, (Our team will remunerate his work, as consulting expenses to an LLC, should we become funded).

I'm seeking fresh perspective from iMechanic members.

  As of this date, I have been unsuccessful in securing funding, or location of the first plant, for this venture. I have recent contacts with prominent international interest, to our advantage; yet there is much work to be done before we are able to tender a proper arrangement.

If you have spare time and will work under non-disclosure, (with no guarantee of compensation unless a deal is tendered and terms are agreed to, by all co-operative partners); you are invited to please email me with your thoughts, special skills and how you would like to help drive this concept forward.

iMechanica members may email me directly. Engineers with International certification will be required, on a per client basis.

Please understand, this system has been formally shown and re-designed over the past eight years. It requires acceptance of proprietary technology agreement between every member who is willing to develop the project.

If you think this is poor timing or have reservations about whether it is appropriate to develop such an advanced construction system for international delivery, please explain in detail; "why not now", and "if not now, when"?

Your emails and suggestions will not be posted here or forwarded to anyone, (unless you suggest a willingness that I do so, in your email).

Perhaps we may elaborate more on the topic of safe, co-operative, proven, cost-effective, energy saving construction solutions, developed under a non-compete / non-disclosure arrangement?

What might we use the proceeds for, should this and other projects like it, be allowed to complete as a co-operative?

Space, science, infrastructure, medical, schools, libraries, housing?

If you have desire or funding for such a venture, I'd like to open a closed discussion on resolving this topic, one building at-a-time.

I would rather attempt the task, than elaborate about the problems with society or how we are failing to act decisively at a political or professional level, unless it furthers the project, directly.

If this is the wrong place to post this comment and invitation, please pardon my interruption.

 

Onward and upward,

M. James Dupont

NJ USA

 

MichelleLOyen's picture

Zhigang, fascinating question.  It has been hard not to notice in recent years that civil engineering deparments have expanded to include topics outside their traditional scope, some of which have recently been discussed on iMechanica by Roberto Ballarini and Markus Buehler , both in Civil Eng. departments and working on structural aspects of biological materials.  I guess if new topics are being included, then it makes sense that traditional topics are being de-emphasized, although I think there are very strong arguments to be made that the world's built infrastructure needs work.  (I used to live a few blocks from the collapsed Minneapolis Bridge , after all.)  I suspect you are correct that the problem here is at least somewhat related to the perception of civil engineering as not novel, although it seems like this is a branding problem.  Architecture is constantly pushing the limits of mechanics when it comes to cutting-edge design.  Reliability is a well-established field of study with many open questions at macroscopic length scales, and need not just examine MEMS and other new technologies.  Bridges and cranes still collapse, which means we don't have quite the handle on the materials or mechanics or reliability issues that are necessary to understand in order to  fuel basic current construction and maintenance.  Again, as with many recent discussions on iMechanica, we are left to feel that basic engineering problems are being neglected in favor of the new and different.  I don't know how the funding structure could be adjusted to deal with this but I fear that many more human lives will be lost before there is a shift in priorities.

It is certainly the case that we don't have a complete handle on materials, mechanics or reliability to fully understand all the civil engineering structures that we build, but I am not sure that's really the root cause of most engineering failures we see. Much of the time we observe failures, the root causes are mistakes in the design, construction, or maintainance of structures or actual design loads being exceeded. In the cases of the Minneapolis bridge or today's crane collaspse, forensic engineers have not yet determined how these disasters took place, but I would be somewhat surprised if the reasons were beyond our understanding of how structures work.

To shift gears a bit, I'd note there are still a lot of people doing practical, traditional civil engineering research. They do not seem to be here much, but this sort of makes sense. Civil engineers working with mechanics issues directly affecting practical design often do not really think of themselves as mechanicians. Also, someone who works in a traditional area might be less likely to participate in something like iMechanica, which is somewhat a reflection of modernity.

 

Just my 2¢ as a student in civil engineering.       

Aaron Goh's picture

Zhigang, last week I was at the conference in Minneapolis organised by the Engineering Mechanics Institute of ASCE, and thought I saw a lot of mechanics there.  Perhaps it is just a matter of engaging these engineers/scientists to participate here.

Rui Huang's picture

While good civil engineers could very much reduce the loss of lives during a disaster like this, I have been mostly saddened by the debates about capability/incapability in predicting earthquakes. What are the fundamental difficulties? Can mechanics and mechanicians help?   

RH

Rui Huang's picture

National Geographical News:

Study Warned of China Quake Risk Nearly a Year Ago

An article published in Journal Tectonics last year: Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau: "They also suggest that activity on the margin-parallel faults in
eastern Tibet may represent a significant seismic hazard to the densely populated Sichuan Basin."

Apparently, papers and results from earthquake research should be taken more seriously! 

RH

Predicting a quake is similar to predicting the exact instance in time at which a crack will grow.  I don't think we have a good handle on either.

Does anyone on iMechanica know whether we can predict the exact time when a preformed crack in a double cantilever test specimen will begin to grow when all other quantities are closely controlled (such as displacement rates and material properties etc.)?  If so, how close is the predicted time to experimentally observed values? Also, what signs of the impending growth of the crack can be observed at the boundaries of the specimen?

An interesting analysis on a recent claim about earthquake prediction in a Nature paper by Silver and coworkers can be found at Green Gabbro

-- Biswajit 

At the least, the requisite education could be made more accessible.  I remember trying to get into an earthquake engineering class as an undergrad, and there were a lot of prerequisites.

Mahendra Gattu's picture

I have a question regarding designing buildings. A building is modeled as comprised of structural components. The structural components are designed to take load: gravity,wind,earthquake,impact loading etc. The input matrix usually consists of the forces. The global stiffness matrix of the structure is determined and the output matrix consisting of the displacements or internal forces like shear,moments acting on the structural components are obtained by solving the matrix equations.

I think the present basic criteria in designing buildings is the none of the structural components fail due to the given loadings. This is a good way to design buildings when we know for sure the loads coming on structure during its lifetime doesn't exceed the loads we design for. However, when we design for upredictable loads like earthquake or say some unknown accident(fire,etc), is there not a necessity to study how the failure of a single structural component affects the entire structure as a whole( i.e is there any redundancy in the structure)? Is there a necessity to look at analysis and design of structure in a different manner while considering unpredictable loads?

Temesgen Markos's picture

Hi Mahendra,

Structures can be designed to have alternative load paths so that if a member fails, the load is rerouted to the other members. I think this is a recommended practice. There is a lot of literature in that area, but personally I am not aware if building codes have explicit requirements to that effect. Any body familiar with the major building codes? 

Mehendra,

I started writing a reply to you trying to describe the overarching philosophy of building design and seismic design in particular (in the US, at least; this varies greatly throughout the world). I found myself being quite longwinded so I am going to try to reply briefly, but I can try my best to describe more broadly if you would like.

Modern civil engineering structures do have redundancy (many old structures are not redundant because it was necessary to design statically determinate structures), but we do not typically design buildings so new members take on the loads of failed members. In the case of high-performance seismic design, we wish to build very ductile structures to try to avoid fracture occurring. If successful, the building can deform a lot during a large earthquake. Because of this, the failure mode of concern is not local failure of one element, but a collapse due to global or semi-global instability. Members must still resist some level of load, but it is my understanding the common limiting design issue is drift, too big of deflections, because there is so much focus on ductility, which enables buildings to withstand extreme loads with minimal damage and to utilise plastic behaviour to dissipate energy.

There are some times when a structure is designed to stand despite a member failing. The most similar example to what you are talking about I can think of are column removal analyses, which are just what they sound like—a structure is designed to be strong enough not to collapse when one or more exterior columns are removed. The scenario here is something like a truck hitting the building or a small bomb destroying a member. This sort of analysis is a rare case when a designer can deal with a truly local failure of a member which resides in the main load path.

In such cases, there is a need to look at worst case scenarios.  A precise description of the actual loading might not be known, but one can assume that it will take a form that poses the greatest threat to the integrity of the structure.  Then it is just a matter of how conservative to make the design, at which point one may use what has happened as a guide to what can happen.  This is what building codes refer to as a 50-year occurrence, a 100-year occurrence, etc.

I am not a civil engineer, so the following is just my understanding of problems with buildings in rural China.

People in rural and small towns in China build their houses by themselves or unprofessional construction teams. I don't think building standards are observed. Bricks and mortar are used for walls, which perform poorly under tensile and shear forces. Almost no concrete and steel is used for walls to save money. The roofs are long concrete panels reinforced with steel rods, which sit on the top of the walls. When earthquake strikes, walls can easily fail in shear. Tons of concrete and bricks will fall on the persons inside.

With advaced analytical and numerical tools, I am pretty sure solutions can be found to reinforce current buildings. However, the real solution needs to be CHEAP. Otherwise, they still cannot afford it.

Concrete and steel are not used for walls in most houses in developed nations (or at least in America), either, but houses typically use wood moment frames to resist earthquake loading. It stands to reason that it's conceivable that cheaper materials could be appropriate.

I suspect that  something like reinforced concrete, though, may be in order. A brick-and-mortar wall is pretty similar in behaviour to unreinforced concrete, I believe. (It is my understanding that the same basic techniques are used for reinforced masonry design as reinforced concrete design in the US.) Perhaps a material cheaper than steel could be found reinforce this masonry construction.

Is bamboo a feasible option, or is it too weak or degradable? A stick of bamboo reminds me of a stick of steel rebar: it is long and skinny and has most of it's strength in tension. Bamboo is cheap and renewable, and I suspect it could be bent into hooks and such using water and/or steam. At the same time, it is degradable and not nearly as ductile as steel. 

In any event, an internal reinforcing scheme might work for new construction, but it would also be nice to think of retrofits. I saw a presentation once where methods were being developed to use expoxy painted onto the walls of a house to provide extra strength, specifically geared towards use for houses in South America (as best as I can recall). This is also not a very ductile design, but is applicable to new or old construction and is a very simple technique, though potentially expensive. If you are very interested, I can try to find the research I'm talking about.

Mike Ciavarella's picture

 

Civil engineers did embark into a sharp discussion about WTC collapse, for example, led by Bazant the day after Sept.11 and later joined in by a more controversial theory by Cherepanov.  This was covered even in Wikipedia.  There are huge programs now about safer structures, see Southampton University

 

 

Blastproofing Britain :: University of Southampton

‘No UK government research funding body has so far issued a call for ... It was the fire which caused the WTC towers to collapse, rather than the impacts. ...
www.soton.ac.uk/research/southamptonstories/engscimaths/blastproofing_britain.html

Collapse of the World Trade Center - Wikipedia, the free encyclopedia

a b c Bažant, Zdeněk P.; Mathieu Verdure (March 2007). "Mechanics of Progressive Collapse: Learning from World Trade Center and Building Demolitions". ...
en.wikipedia.org/wiki/Collapse_of_the_World_Trade_Center - 145k -

 

Mechanics of the WTC collapse
September 11 and Fracture Mechanics by Dr.Cherepanov.

September 11 and Fracture Mechanics by Dr.Cherepanov.

Microsoft PowerPoint - Progre-RebutCherepanovCritiqueOfBazZhouWTC ...Formato file: PDF/Adobe Acrobat - Versione HTML
On Cherepanov’s
Critique (emailed to USNCTAM. Participants on 6/17/06) of Bazant &
Zhou’s Analysis. 2 slides presented in Discussion at Symposium on WTC ...
www.civil.northwestern.edu/people/bazant/PDFs/Papers/Progre-RebutCherepanovCritiqueOfBazZhouWTC-06.pdf

Bazant, Z.P. (2001a). ”Why did the World Trade Center collapse?” SIAM News (Society for ...
www-math.mit.edu/~bazant/WTC/WTC-asce.pdf

Humint Events Online: The Other Fatal Flaw in Bazant's WTC Analysis

6 dic 2007 ... Bazant's WTC
analysis can be found here. The other fatal flaw in his model, besides
his concrete pulverization analysis, is his "crush down, ...
covertoperations.blogspot.com/2007/12/other-fatal-flaw-in-bazants-wtc.html

[PDF]

Why Did the World Trade Center Collapse?—Simple Analysis

Formato file: PDF/Adobe Acrobat - Versione HTML
Why Did the World Trade Center Collapse?—Simple Analysis. 1. Zdenek P. Bazant, F.ASCE,. 2. and Yong Zhou. 3. Abstract: This paper presents a simplified ...
www.civil.northwestern.edu/people/bazant/PDFs/Papers/405.pdf -

 

 

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www.aboutcivil.com

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