not only bridges

2012-01-30T12:00:00.003+01:00

Stanford University is offering free on-line courses in engineering and computer science. No prerequisites are necessary. Some courses seem to grant a statement of accomplishment after passing the quizzes and the final exam. The courses are:

Technology Entrepreneurship
Making Green Buildings
The Lean Launchpad
Introduction to Computer Science
Machine Learning
Model Thinking
Software as a Service
Human-Computer Interaction
Natural Language Processing
Game Theory
Probabilistic Graphical Models
Cryptography
Information Theory

Join and enjoy.

LNG storage tanks

2011-10-23T18:35:00.006+02:00

Post taken from Manufactured landscapes: LNG storage tanks and totally written by PC Gladiator

LNG tanks are the biggest type of storage tanks in the world. LNG stands for Liquid Natural Gas. These tanks are specially designed to maintain the -163 degrees celcius temperature to keep the natural gas liquid. The relatively high cost of production of LNG and the need to store it in expensive cryogenic tanks ( to maintain the low temperatures ) gives the need of big tanks ( larger then in the oil industry ) to minimize costs. LNG tanks are always of double-wall construction with extremely efficient insulation between the walls. Large tanks are low aspect ratio (height to width) and cylindrical in design with a domed roof. There are a lot of safety measures to these tanks because if it escapes from a storage tank or ship, it can quickly vaporize. If this vapor ignites, it can create an immense fireball that would incinerate everything in its path.

The biggest LNG storage tank in the world is situated on Elbas Island near Savannah in the U.S. Below you can see some pictures ( from live search maps birdview) during it's construction:

The world's largest LNG export terminal is called the Sakhalin II terminal and is situated on the Sakhalin island in the Russian Far East. The storage tanks on this project belong to the largests in the world and have a storage capacity of 1.2 mln barrels (190,000 m³ ), The picture below shows what a giant impact these structures have on the once peaceful beach of the village nearby:

Another large LNG terminal is the Bontang LNG Plant in Bontang in Indonesia. The 6 tanks on this site are all more then 80 metres in diameter:

And what about the liquefied natural gas storage tanks at the Yemen L.N.G project which was recently build near (not yet visible in google maps) Balhaf in Yemen. These storage tanks are aboslutely huge as you can see in the pictures below (Click to enlarge)

Here you can see a worker who walks through one of two main storage tanks:

Another large liquid gas storage tank was build in the Senboku LNG terminal II in the harbour of Osaka. This thing was build in 2000 and was the world's largest aboveground LNG storage tank for a long time. This thing is 60 metres high and has diameter of 80 metres.

To view the size of these LNG tanks even better you can enlarge the picture below by clicking on it. The people on top are dwarved by the huge tank. This thing stands here in the harbour of Guangdong in China:

More than mere engineers

2011-05-20T17:22:00.003+02:00

We have entered a new era that is changing the role of the engineer on the job and the engineer’s relationship to society. To be successful in the new era of engineering we are going to need to be more than mere engineers. That will be true whether we are a student, a fresh graduate or a senior engineer. The inmediate changes are:

- Eco-responsiblity: Core design specifications will soon require to minimize environmental impact and carbon footprint.
- Information Technologies (IT): Many new software projects may consider using open source software. The Internet also broadens the scale of engineering collaboration. We now have instant access to the thoughts, insights, and feedback of other engineers.
Numerical methods will be unified: finite difference & finite element methods and solid & fluid mechanics. Also the differences between civil, mechanical, computational engineering and physics will fade.
- Communication: The impact as an engineer will increasingly depend on the ability to communicate, collaborate, and participate across the organizations and communities, not just within the engineering department. It is our duty to make the effort to have a continuous dialog with the shareholders of our projects.
- Business skills: Engineering increasingly requires more direct involvement with every aspect of business, including finance, sales and marketing, channels, customer support, and competitive analysis. For example, the most common undergraduate degree for CEOs of Fortune 500 companies is not marketing, sales or finance—it’s engineering, with 20% of all CEOs being engineers; and the richest man in the world -Carlos Slim- got a degree in civil engineering.
- Political action: Engineers are beginning to realize how important it can be to educate and influence those who make public policy decisions (nuclear energy, floods, climate change, data security, etc...) about technology.

Society keeps changing, so society’s needs are changing and enginering should change as well.

Parallelism

2011-02-06T18:37:00.003+01:00

Today, material non-linearities, large strains and deformations, high-velocity impact problems are almost routinely treated by sophisticated finite element tools.
The progress in the field would be unthinkable without the availability of computer platforms, especially the parallel ones.
However, parallelism shows a new worrying phenomenon appearing with the implementation of finite element codes on MPP machines: The dependency of results on the number of CPUs used.

The figure represents results of a car crash simulation – a comparison of engine bottom accelerations computed using different numbers of CPUs and a commercial software (taken from a Proper Misuse of Finite Element Analysis by Miloslav Okrouhlik).

We should not believe in a dependence of FE results on the number of CPU’s used and we should admit that a good parallelization of nonlinear dynamic problems can be difficult to master.

Bias cut and the triumph of anisotropy

2010-12-11T21:47:00.006+01:00

The bias cut (or byesse cut) is a technique used by designers for cutting clothing to use the greater extensibility in the diagonal direction of the fabric. Woven fabric is more deformable in the bias direction (the Poisson modulus is larger), compared to the on-grain direction.

Every piece of woven fabric has two biases, perpendicular to each other. Non-woven fabrics such as felt or interfacing do not have a bias. If cloth is pulled on one of the bias direction it stretches in that direction and gets shorter in the perperdicular direction. Like this the shear deformation of the cloth accentuates body lines and fits better to the figure. Also, this property facilitates details that require extra elasticity, drapability or flexibility, such as neckties, trims, decorations, boundaries and seams.

French fashion designer Madeleine Vionnet (in the picture below) popularised the bias cut clothes and dominated haute couture in the 1930s setting trends with her sensual dresses worn by stars as Marlene Dietrich, Katharine Hepburn and Greta Garbo. Vionnet's vision of the female form revolutionised modern textile industry.

Note: Based on the story published in Structures or why things don't fall by Prof. J.E. Gordon, 1987.

Project Management: PMP certification or not?

2010-12-06T19:43:00.003+01:00

Even though many engineering professionals hate to admit it there comes a time in life when one needs to think about being certified in project management. PMP certification or something like that seems to be the way to go, but the requirements are extensive and the tests are fairly expensive. Here is what I have got surfing the net:

http://corporategeek.info/what-you-will-not-earn-pmp-certification

http://pmtips.net/pmp-certification-worth-analysis/
http://pmtips.net/project-management-pmp-certification-worth/

http://techrepublic.com.com/5208-12848-0.html?forumID=102&threadID=277912&messageID=2632563

http://www.eng-tips.com/viewthread.cfm?qid=264620&page=1

Stability isn't everything in fluid dynamics or is it?

2010-05-30T18:50:00.013+02:00

Lets consider a prismatic channel with the following data:
Length of the channel = 100 km
Width of the rectangular cross-section = 100 m
Bed slope = 1%
Manning’s roughness n = 0.035

The downstream boundary condition is a rating curve shown below:
Depth Discharge
(m) (m3/s)
0.0 0.0
0.5 142.8
1.0 450.5
1.5 900.0
2.0 1426.6
2.5 2100.0
>3.0 2797.0

The discharge hydrograph at the upstream boundary point is shown in the following figure

One way to estimate the appropriate time step for the simulation is to look at the Courant-
Friedrich-Levy (CFL) criterion. This criterion is usually applied to explicit numerical schemes but the CFL criterion may nevertheless serve as a guideline for implicit algorithms.
dt < (dx / v)

A realistic peak velocity could be guessed as twice or three times the steady velocity (v=4.64 m/s).

Chosen numerical parameters:

dx= 5 km

dt= 10 min

In HEC-RAS 4.0, an intermediate theta (a.k.a. numerical damping parameter) was chosen in order to ensure a compromise between accuracy and stability: theta=0.5 is the Crank-Nicholson method and theta=1.0 fully implicit scheme. Also, the model needs some warm-up time at the beginning of the simulation to adjust to initial and boundary conditions.

So, here we have the expected results at X= 50 km (the midpoint):

Neither the computed depth nor the velocity seem realistic and the HEC-RAS implicit algorithm is unable to calculate the magnitude and exact period of the steep water waves. Any solution?

The 7 main causes of numerical rubbish

2010-01-16T19:14:00.004+01:00

Finite element analysis (FEA) is an everyday engineering tool but it is very easy to make mistakes. I expose the seven most common traps I have found in engineering consultancy and suggest ways of working aroud them:

1- The virtual reality trap. Analyst can become so involved in FEA that the link between the real structure and the model may be forgotten.

2- The time trap. It is usual that the modelling takes so much time and effort that little is left for verification and validation of results, alternative designs, writing reports and documentation, backups and reviews by other analysts.

3- The "we-use-FEA-on-everything" proud. FEA is an expensive method and it s easy to forget that in large structures FEA tend to offer a deceiveing level of detail. Other methods, such as calculating stresses from equations in Roark's formulas for stress and strain or a simple model of linear elastic bars can be faster, less expensive and more reliable.

4- Averaging stresses. Stress averaging provides visually pleasant results but does little to improve accuracy and masks the highests stresses providing misleading results. In fact, comparing averaged to nonaveraged stresses gives a intuitive measure of the quality of the numerical solution.

5- The CAD trap. The geometry should be defined explicitly and clearly: it is absolutely impossible to calculate anything without a previous design. The use of preprocessors such as Patran or Catia gives the engineer the abily to generate complex geometries but this does not necessarily mean that they will be more accurate that simple AutoCAD generated models. On the other hand, oversimplification can leave out critical load paths. The geometrical model should represent a realistic compromise between the accuracy of the source of geometry and the correctness of the model.

6- Coarse mesh + low order elements + few modes of vibration. This is probably the worst possible combination when shear analysis is critical (f.ex. in walls under seismic load) so my advice is use a fine mesh, use at least second order elements if possible and ensure that the masses are at their centre of gravity, that shear-locking has been avoided and that the participation factor in all directions is close to 100%.

7- The management trap. Economic competition among engineering firms implies low time with which calculations are executed. However, the attitude of the manager must ensure through policy and example that engineering staff can allocate time to check analyses that are sufficiently accurate and correct for design of new structures and investigation of existing ones instead of simply putting pressure on the analysts.

I, therefore, recommend to the computer analyst that she or he adopt procedures to ensure meaningful and accurate analysis results and to the management of structural design firms that they enforce validation and verification procedures as a matter of quality control.

Santander infrastructure fund cancelled

2009-10-09T10:53:00.004+02:00

Santander has canceled the Infrastructure Fund II. The idea behind the infrastructure fund was very similar to the disastrous real estate funds: to make a benefit from participating in expanding roads, ports, water systems, etc...

Fundraising for Santander Infrastructure Fund II was being wound down by its placement agent, Atlantic Pacific Capital, after reaching just less than half of its 1.5 billion euro target, people familiar with the fundraising have said. Although infrastructure assets often benefit from government support that makes them attractive, funds that choose assets exposed to market risk - such as toll roads that rely on car traffic - are viewed more sceptically in an economic downturn.

Santander together with Spanish infrastructure group Abertis, bought stakes in two Chilean toll roads from Spanish builder ACS in December 2008 in a 728 million euro deal. Also, Santander Infrastructure Fund II bought Chilean water company Aguas Nuevas from the Solari Group.

Wind & water power, a perfect match

2009-08-25T18:59:00.015+02:00

With great gorges and high wind energy potential, the Canary Islands (Spain) prove to be a very suitable place for the implementation of a hydroeolic power station. It is also the first wind & water power station that will be providing close to 80% of the total electricity demand of an isolated island.

The key advantage of such a mixture is that the system overcomes the characteristic problems of variability, discontinuity and unpredictability of winds. When the energy produced by the wind farm exceeds the demand, the surplus is used to pump desalinated water in a reservoir situated 700 m above sea level. Conversely, if the energy produced by the wind farm is insufficient to meet the demand, the water stored in the upper reservoir is released through the turbines to a lower reservoir, converting the potential energy of the water into electrical energy. In this way, thanks to the potential energy storage and the controllable power output of the turbines, it is possible to establish a steady voltage that matches the demand at any time. It is the worthwhile to notice that the weather pattern does not usually hit wind and water simultaneously.

All these ecologic reasons together with the record time to deliver the final project made me feel quite proud of this work in the end. I enclose some pics of the pumping building (8777 m2) and turbining station (1344 m2) that were calculated on my own. Very heavy machinery, wind pressure, earthquake and a difficult volcanic geology have been the main conditionants of design.

General scheme of the complex

Pumping building - Floor plan

Pumping building - Office block - Model of the structure in Cypecad
Pumping building -Pump station - Model of the structure in SAP2000

Turbining station - Floor plan

Turbining station - Model of the structure in Cypecad

Engineering commercial frameworks

2009-06-28T20:37:00.002+02:00

One of the keys to understand the main differences between the British and Spanish civil engineering markets is to compare the award procedures of public works:

I – Separate design award and execution award.
Spain 75%
UK 10%
EU 60%

II – Joint design and execution award.
UK 70%
Spain 12% (nearly all for concessions of highways and airports).
EU 35%

III – Negotiated procedure and direct award.
UK 20%
Spain 13%
EU 5%

All these numbers were obtained, aggregated and rounded from the vast work of Daniel Raccah at the University of Rome La Sapienza.

Integrated contract – or Design & Build – is the formula that has recently seen the greatest rise in the United Kingdom and other northern countries, where it is now decidedly the most prevalent form of award. On the other hand, the traditional formula of prior award of the design (meaning the design adjusted to the tendering of the work) separate from its execution is still the method most utilised in Spain. But something is changing: in recent years I have seen that the direction of civil works, the technical assistance and the project management are usually joint-awarded to the same consultant company. Based on my own experience, between 30% and 50% of the fees go for the project and 50% to 70% go for the direction of works.

Finally, it must be said that the Spanish engineering consultancy market is highly competitive and provides a favourable investment climate for foreign groups. In fact, some engineering companies from the U.K. (Arup), France (Eyser) and U.S. (CH2M Hill, Fluor Daniel, Foster Wheeler and URS) are present in the Spanish market with great success.

Related: A brief history of engineering consultancy.

The skew (or non-orthogonal) reinforcement problem

2009-05-27T17:53:00.007+02:00

Reinforcement that is not perperdicular or that is arranged in more than two directions occurs frequently in the design of slabs for skew bridges. In such cases, reinforcement can be calculated with an equivalent orthogonal reinforcement.

Given n arbitrarily oriented groups of paralel bars r1, r2, ...., rn, an equivalent reinforcement (ru, rv, ruv) for an auxiliar set UV of perpendicular axes are obtained by projection:

ru = r1*(cos(a1))^2 + ... + rn*(cos(an))^2
rv = r1*(sin(a1))^2 + ... + rn*(sin(an))^2
ruv = r1*cos(a1)sin(a1) + ... + rn*cos(an)sin(an)

These values are transformed into the principal directions of reinforcement XY (that are obviously orthogonal) like this:

rx = ru*(cos(b))^2+rv*(sin(b))^2+ruv*sin(2*b)
ry = rv*(sin(b))^2+rv*(cos(b))^2-ruv*sin(2*b)

where

b= 0.5*arctan(2*ruv/(ru-rv))

Now, the axial and flexural resistance should be confronted with the forces and moments given in the XY system of coordinates. Changing the local axis of the shell elements we obtain Nx, Ny, Nxy and Mx, My, Mxy.

The Wood and Armer rule (or any other similar) can be applied now.

rx should resist Nx' and Mx'
ry should resist Ny' and My'

For a symmetric ultimate reinforcement with Nxy and Mxy not extremely large, Wood and Armer rule becomes.

Nx' = Nx +/- |Nxy|
Ny' = Ny +/- |Nxy|
Mx' = Mx + sign(Mx)*|Mxy|
My' = My + sign(My)*|Mxy|

IT revolution, creativity and recession

2009-04-14T19:53:00.005+02:00

Let's not pretend that things will change if we keep doing the same things (...)

Creativity is born from anguish (...)
It's in crisis that inventive is born (...)

Einstein's quotes on crisis.

The global recession is hitting almost everyone. Few months ago Sky News reported that there were nearly 15,000 job losses from June 2008 to December 2008 in the UK civil engineering sector. What is more, not only are the low-tech manufacturing jobs being shifted overseas but the high-tech jobs like mine as well.

Are there some remedies to overcome the crisis? All of us should understand that austerity and belt tightening alone will not solve most of our problems. Any integral solution passes through encouraging an optimistic creativity.

Given that Information Technologies (IT) are having a lot of relevant effects on the way of thinking of a generation of digital born graduates, I have always felt that companies should take advantage of their freshness. Generaly speaking, the mid age managers I met tend to see IT as a mere time and cost reducer forgetting that the main competitive advantage is other: with the computer we can go into our creative juices, explore our wildest imaginations, create the most fabulous designs, solve complex challenging problems and drive inexpensive innovation. Knowledge is transferred from the digital model to the real world and all kind of good and stupid solutions are tested virtually with no harm. Obviously, IT tools cannot totally substitute experience-gained human intuition but natural creativity and learning from mistakes can be boosted thanks to simulation and computer modelling.

Zienkiewicz (1921 - 2009)

2009-01-30T16:32:00.005+01:00

Olek Zienkiewicz, the civil engineer acclaimed as one of the pioneers of the computational modelling technique known as the Finite Element Method, passed away on 2 January 2009. Despite being sometimes in the same building during my MSc year I have never had the chance to meet him in person. Anyway, I really enjoyed his books and it is surprising the lack of recognition on the media for a man who represented a strong influence in a generation of young computational optimists and who made important contributions to the development of a top-one computational commnity not only in Swansea but in Barcelona as well.

Chaos in Barajas

2009-01-14T19:33:00.009+01:00

Last weekend a bit of snow made more evident than ever before that the modern terminal of the fourth largest European airport, without the appropriate management, will be absolutely useless. Many claim that the millions of euros that have been invested in infraestructures during the past good years are at risk of becoming a precious waste of money if they are not accompanied by a wise administration.

Snowflakes over the lanes

Long queues of angry travellers (like me) asking for information

Dozens of tickets, no departure

Policemen trying to cool down people

Nealy all fligths were delayed and then cancelled

The emotional handicap of some engineers

2009-01-06T13:05:00.002+01:00

Generally speaking, I have always believed that we engineers tend to be quite rude and several examples are mentioned by Goleman his world-known bestseller. Under finantial pressure, behind the schedule, exhausted and with too much caffeine in the blood, very few use to say hello/goodbye or please/cheers. Even less come with a big smile and a warm handshake.

However, are engineers (and students of engineering) homogeneous all around the world? According to "Dilbert's principle", scientists, engineers and programmers are simply not good at socializing but googling about engineering on the net shows a differential fact: US, UK and Portuguese fora and blogs are at least politically correct whilst Spanish, Italian and Latin American ones are full of slang, insults, complaints and insane rivalry between universities, between degrees or between companies.

Certainly, we should overcome these deffects because not only can the jerk engineers harm others but they do damage themselves. Emotional disabilities are insidious. The jerks are blind and deaf to their social deficiencies but every one of them will be eager to recognize and point out these mistakes in others.

In conclusion, my main emotional purpose for the New Year will be to resist the pandemic pessimism and the bad manners.

Shape of concrete water tanks

2008-12-30T12:27:00.019+01:00

Which are the optimum dimensions of a water tank built with concrete? This is a very common question posed during the design of water structures. A generally accepted thumb rule (Ref.1) is the following one:

Volume less than 500 m3: Rectangular+Reinforced concrete. Height=2-3m
Volume between 500 m3 and 10.000m3: Circular + Reinforced concrete. Height=3-5m
Volume more than 10.000 m3: Circular + presstresed concrete. Height=5-8m

Additionally, it can be said that one tank is cheaper than two tanks with half of the capacity as it is shown in the figure.

Cost of the tank with cover per cubic meter of water (Ref.2)

Optimum Diameter/Height ratio (Ref.2)

However, there are some objections to the given thumb rule. Hydraulic constraints must be taken into account for the final design because water machinery and gadgets (I mean pumps, pipes, valves, expert and remote control systems and such) may be more expensive than the structure. What is more, cylinders are more difficult to be built than straight walls and, in fact, my latest design was an enormous reinforced concrete retangular structure to store 30.000 m3 of clean water.

Floor plan
Cross section

(Ref. 1) Yges, Diseño de depósitos de agua desde 100 m3 a 40.000 m3. Ed. Bellisco, Madrid, 1991

(Ref. 2) Riba, Cálculo y elección óptima de un depósito de agua, Master thesis, UPC, 2005

You cannot handle the truth

2008-12-23T16:40:00.007+01:00

After the latest meeting of the Institution of Civil Engineers in Spain one of the colleagues sent me by e-mail this funny adaptation of the confrontation between Jack Nicholson and Tom Cruise in the film A Few Good Men.

It made me laugh and remember the definition of Rui Wamba: structural engineering implies calculating loads whose magnitude and exact position we do not know for materials whose behaviour we barely understand with a simplified physical model which is plenty of false assumptions in such a sophisticated way that the general public cannot have the slightest suspicion of our degree of ignorance.

Discrete Maths in Civil Engineering Curriculum

2008-12-17T17:41:00.004+01:00

Last weekend I made a fantastic acquisition at Casa del Libro. I bought one of those old books of mathematics from the Sobolev Institute of the former USSR: Mathematical foundation of cybernetics. This reminded me many calculus exams I had passed with the invaluable help of Makarenko, Demidovich and others when I was a student of civil engineering. Later, I had to read and study a small part of the work of Galerkin -another relevant Soviet engineer- in order to start the master thesis.

The ackward title could be changed into "Discrete Mathematics" for marketing purposes but the approach is more straight forward, applied and concise than that of other discrete mathematics books. Discrete mathematics is the study of countable things such as integers, graphs, combinatorics, etc... Many of the civil engineering mathematics are based on the notion of continuity whereas objects studied in computer science mathematics are discrete.

During my professional practice I have slowly realized that some of the CS Math concepts are easy to understand and can be useful if applied to daily civil engineering problems such as traffic control, urban planning, FEM programming or logistics. Clearly, teaching Maths to civil graduates should include less topology and differential geometry (an absurd waste of time from my point of view) and more discrete stuff (for example, the shortest path problem) .

The book that serves as an excuse to open this post was first published by MIR Moscow, a casualty of the demise of the former USSR but fortunately there is another publishing house which continues their work: http://urss.ru/

Pitfalls

2008-11-20T19:53:00.005+01:00

Consultant engineers with specialized knowledge like to use their technical skills to the upmost and there is nothing wrong with this. Being mainly interested in the backoffice tasks and structural modelling is not a mistake but one must assume that in order to build a good work it is required more than a good computer model. In fact, a wise contractor with a bit of structural sense can help a lot.

For instance, I had the chance to analyze a clean water reservoir. The contractor provided a poorly defined project and a 3-d Cypecad model (left) to justify the proposed solution. Then, I had to modify the proposal using a fast Sap2000 model (right) to check results.

After long and tedious discussions, in the end what the contractor built was this...

A "mild" segregation problem.

[ironic] A very sophisticated gadget engineered and crafted by the contractor to ensure proper cover of the reinforcement [/ironic].

So, what I have learnt this week is that no matter how sophisticated a computer model can be: public works are usually constructed by experienced teams with less-than-required formal education and they can make mistakes impossible to take into account in a simple and optimistic computer model.

GMAT, GRE and other prometrics

2008-10-09T14:25:00.004+02:00

Taking advantage of living in the downtown of Madrid I gave GMAT and GRE examinations a try last week. GMAT or GRE scores, university performance, sponsorization letters and work experience are the typical selection criteria one should pass in order to get into MBA or similar programs. When top masters boast about the quality of their students, they almost always refer GMAT (or GRE) scores but many people question whether they really measure managerial potential.

GMAT means Graduate Management Admission Test and GRE stands for Graduate Record Management. Both are quite similar and assess the ability to give quick solutions to multiple choice numerical and verbal problems accompanied by two short writing tasks. GRE is a bit cheaper but its verbal section is more difficult. Anyway, the funny and odd conclusion is that instead of practicing management the wannabe-MBAs practice tests.

Good managers should be intelligent and the tests measure some kind of fast-thinking intelligence but, indeed, anyone can be intelligent and become a horrible manager. So, from my point of view, GMAT and GRE constitute useful but overrated tools to identify successful management students and other critical characteristics are not adequately considered. This is more dramatic when English is not your mother language.

What is more, GMAT and GRE encourage a uniformization of post-graduate education provided that the most popular rankings use the minimum admission score as a standard of how good postgraduate schools are.

PS: my scores were GMAT = 680 and GRE = Quant 750 + Verbal 490 which are acceptable for a non-native English speaker.

Destination Madrid

2008-08-19T20:21:00.004+02:00

Yes, I am moving to Madrid in 6 weeks due to my girlfriend but this is not the sole reason.
It is well known that Madrid is the third most populous urban area in the European Union (after Paris and London) and the most dynamic financial centre in the Iberian peninsula. The city is inhabitated by people full of dreams and ambition. This means the latest opportunities of attractive engineering projects when the real estate fiesta is over.

A brief history of engineering consultancy

2008-07-29T13:58:00.016+02:00

"Consultants are like Mr. Wolf (Harvey Keitel) in Pulp Fiction: they tell you what you already know and they expect to be paid for it." - Anonymous

The origins of technical consultancies date from the middle of the 19th century as a result of large and complex projects of the railway companies. In those days of Brunel and Stephenson, construction was not separate from the tasks of the project engineer and the entrepreneur but the expansion of railway exceeded the capacity of those pioneers to supervise each aspect of the business. Latter, project engineers began to work on specific areas (structures, water, traffic design, project management, etc...) as consultants.

British engineers were the first engineer consultants but the idea soon spread among other countries. In its beginnings, consultancy was synonymous of civil engineering as this was the main field of activity. In Europe, two different engineering methods emerged. On one hand, the British model was based on a self-taught, empirical and inductive approach. On the other, the French one, a sector dominated by a highly institutionalized education with a strong academic background. The French administration regulated the activity of consultancy and became the most important client of local consulting. Thus, the sector was dominated by British and French firms until the World War II, when US consultancies emerged as the leaders of the sector.

Global top firms

Consulting in

Spain

developed later than in other European and American countries and it was not until the 1960s that this activity began to be known. Civil engineering is still the most important field, followed by industry, energy, and, more recently, environmental engineering. The preparations of the Olympics in Barcelona and the International Expositions in Seville and Zaragoza had great influence on the expansion and internazionalization of the companies. The main overseas markets where Spanish firms operate are less developed countries in Latin America and the North of Africa. Only few Spanish consultancies are carrying out high-tech projects in very competitive European countries and only the future will say if complex projects designed from a peripheral country can meet the demands from more advanced economies.

Spanish top firms

Roundabouts, small structures and small details

2008-07-02T14:11:00.014+02:00

Solutions to road engineering problems involve how to conserve space, harmonize with the site and provide cheap and safe traffic solution. Since the contruction of the carrefour de l'arc the Triomphe (Paris) at the dawning of the 20th century, roundabouts are thought to be safer than both traffic circles and traditional intersections but they require a lot of space and here comes the task of the structural engineer.

The first example is a roundabout over a stream in a dense urban area. In this case the drainage requirements, a poor DPSH resistance of the soil and how to mix the bad quality old structure and the new one were the main causes of my headaches during the project phase.

The second example is placed in a rural landscape so I chose a green wall to respect the environment. The cost of this wall is about 120 € per square meter of covered surface which is more or less the cost of reinforced earth.

If Mies van Rohe is right, God is in the details and I totally agree in this case. A well designed roundabout can result in a complete disaster without the appropriate structures, lateral protection barriers and traffic signals. As for the last point, I encourage to borrow some of the ideas about signalling from the web site of Prof. Manuel Mateos and to use bigger and more understandable road signs.

Although the galvanized steel barrier (left) is the preferred solution by our administations, it seems clear that the classical New Jersey made of concrete (right) is safer in most of the accidents.

Left: Speed limit for roundabouts found in the Spanish norm 8.1 IC. Right: Alternative fonts proposed by Manuel Mateo.

Note: All the comments - even the caustic criticism - can be valuable on this point.

Is there a global deficit of engineers?

2008-06-05T16:22:00.011+02:00

United Kingdom

Japan

Germany

Argentina

Italy

Portugal

Spain

The global shortage of all kinds of engineers -from bricks to clicks- comes as no surprise to me. Engineering is a difficult degree everywhere without clearly appealing prospects. What is more, it seems that only Asians go into science and technology because we are creating a culture that talks long on technology management but views those creating new technologies as nerds.

So what is the solution? It is a simple supply and demand law that requires some time to reach the equilibrium point. If one spends enough money rising salaries and improving working conditions engineering will be attractive and the shortage will disappear in the mid term. However, engineering work is not visible to the general public and sometimes can be outsourced easily and those are the main reasons why we have little scarcity power specially when compared to physicians, air controllers or dentists. As long as the discrepancy between engineering and other career paths exists the engineering skills shortage will remain.

Finally, let me tell you a personal theory. In general the quality of the coffee and the cleanliness of the toilet are the mirror of how the company is treating its employees. It seems clear that the brightest people tend to choose the best places to work so if you want to know how good a company is I strongly recommend you to visit the restroom and ask for one capuccino.

Bridge Management Systems

2008-04-24T18:23:00.006+02:00

The management and conservation of bridges in a transportation network is a duty that every concessionaire, both public and private, has to fulfil in compliance with the various regulations on the subject. It is therefore vital to manage and store the information about these structures in order to devote the available budget to the most deficient ones.

Figure 1. Three possible strategies.

But the fact is that the most used Bridge Management Systems (BMS) typically rely on closed source modules that are difficult to customize for special bridges and advanced evaluation methodologies. Furthermore, it is difficult, when not impossible, to extend such systems to incorporate the latest information technology for applications such as bridge health monitoring. Probably one of the most popular closed BMS is Pontis that can be purchased at $30.000/license.

Figure 2. BMS developed by 4emme (Italy)

On the other side, Oregon Department of Transportation and Prof. Michael H. Scott are developing an Open BMS since October 2007. The open system will be able to utilize finite element model updating strategies for state-of-the-art applications in reliability-based bridge rating. The result is expected to be released next October.
If someone from the Administration reads this blog, please never ask for close BMS because does not ensure free competition.

Related: Pontes e preocupações relativas (António Aguiar).

Expo-08: Work in progress (II)

2008-04-21T23:11:00.020+02:00

First of all, a bit of self-propaganda. Here you have the 3rd Millenium bridge and the author of this blog. I was fascinated by the quality of the materials and the carefulness put into every single detail of this complex work.

Secondly, the extremely realistic wind model tested by Western Ontario Univ. (Canada) and University of Granada (Spain).

Guillermo Capellán -left and with long hair under the helmet- leading the on-site work and proving that he has become one of the most prominent mid-age structural engineers in our days.
And last but not least, the Bridge Pavilion seen from under the 3rd Millenium Bridge. Its metal structure was defined as a huge and expensive piece of junk by a colleague of mine.
It seems they are running behind schedule but they hope to finish in time.

On 14th June the Expo opens. No delays allowed.

Related:

Benchmarking virtual campuses

2008-04-14T11:30:00.000+02:00

After visiting three on-line campus in my longlife learning process I made the following comparison:

a) UNESCO - Delft (by Edumedia)

- Designed only for Internet Explorer users.
- Participants do not need to have any particular software on their computers for using the learning system and taking modules.
- 100% multimedia slides are offered in nearly all the modules.
- Lecturers can be reached by e-mail, phone and Skype and they use to be kind and patient.
- Colours of the learning environment are nice and everything seems easy to find.
- Continuous evaluation.

b) UNED - Spanish Open Univ. (by Webcat)

- Mainly thought for Internet Explorer users but Firefox can be used in most of the cases.
- Most of the teaching material is under HTML/PDF format but traditional books are still the main source of information.
- Very little multimedia materials (mp3 and videos) are offered.
- Professors can be contacted by e-mail and phone, but it is not an easy task to get their attention.
- Nice colours and fonts of the learning environment.
- Interaction among students is frequent but there is very little (or no) dialogue between students and lecturers at the fora.
- Some items (tests, examinations, downloadable software, etc...) are difficult to be found.
- Continuous evaluation is rare. Lots of tests and former exams are offered for self-evaluation.

c) UPM - Technical Univ. of Madrid (by Moodle)

- Given that platform is W3C compliant, it is fully independent of the browser of the student.
- The students need to have MS Office, AutoCAD or similar software to run some educational materials.
- The courses do not offer 100% multimedia materials. The course is great for deaf people!!!
- Lecturers can be reached by e-mail and fora easily and at any time.
- Combination of colours is a bit boring, some items are difficult to find and participation of the students is not fully encouraged.
- Continuous assesment.

Related: Benvic project

Inspirational quote of the day

2008-04-03T18:55:00.003+02:00

Avoid software. The problem with software is that everyone has it.

Bruce Mau's incomplete manifesto

Digital democracy only for Internet Explorer

2008-03-19T16:13:00.010+01:00

I am not a fanatic of open source software but I use Mozilla Firefox web browser for my daily net surfing because it is an easily extensible navigator. You can download and install extensions which add the features you want.

Firefox, unlike Internet Explorer, is a more or less standard-compliant browser and one of the first things you are likely to discover is a small bunch of poorly designed sites which refuse to let you in because you are not using IE. One of these pages is the electronic voting web of the Spanish Institution of Civil Engineers (Colegio de Ing. de Caminos). The original idea - choosing the President of the Colegio on-line - was brilliant but badly implemented: a quarter of the civil engineers do not use IE and we will not able to e-vote without using some trick. What is more antidemocratic, it was assumed that we all should use IE in such important elections.

You need Internet Explorer otherwise you cannot vote electronically

The only solution I have found was to set up an add-on called User Agent Switcher, which is like using IE embedded in Firefox. No doubt, I will complain loudly to the Colegio about being discrinated for not using IE and I hope they will begin to pay attention to most of the web standards.

Free Science? Show me the money man!

2008-03-03T18:42:00.011+01:00

1- E-mail from the author of this blog to NAFEMS.

Dear XXX,
I found your free webinar about FE & common sense very interesting but unfortunately I have been off-line part of the time due to a bad internet connection. I was wondering whether it would be possible to obtain the slides of the event.
Thanks a lot. Sincerely,
XM Carreira

2- Good-intentioned reply from NAFEMS.

Hi Xose,
Thank you for taking an interest in the course. I’m sorry to hear you were disconnected during the webinar. I am working on the upload right now and will send you an email when the process is complete.
Best regards,
XXX

3- What NAFEMS did in the end.

A copy of this webinar is now available on our website (members only).

Notes: NAFEMS is a non-profit association dedicated to Finite Element and Computational Fluid Dynamics but the actual fact is that individual membership costs about 550€ per year.

Modulor and I

2008-02-25T22:00:00.008+01:00

"Working by calculation, engineers employ geometrical forms, satisfying our eyes by their geometry and our understanding by their mathematics; their work is on the direct line of good art."

Towards a New Architecture.

After the war, Le Corbusier became interested in the Golden Section and he proposed his own proportional scale based on the male figure. The standard figure was called Modulor and it was nice to have a picture with him. Modulor is a bit taller than me, so you can guess my height.

For the Swiss artist, what European industry needed at that difficult moment was a system of measurement according to the needs of the humans and the aesthetics of the Golden Ratio. He believed that numbers - like Pythagoras- and geometry -like Plato- underlie the harmony and the beauty of objects. But he was also a follower of Leonardo, respecting the principles of engineering, seeking the divine proportion in the calculations. All objects should be measured in their relation to the Modular norm. From my point of view, it is a conceptually engaging idea: standardization has a lot of advantages and does not necessarily imply boring or ugly designs.

Expo-08: Work in progress

2008-02-20T00:31:00.002+01:00

The Expo is an international exposition where countries, non-government organizations and some private companies take part to show their best. This year the world exposition will be held in Zaragoza, Spain, with the topic of "Water and sustainable development".

The event is being placed in a meander of the river Ebro and the most emblematic structures over the river are the 3rd Millenium Bridge designed by the engineering firm Arenas&Partners (left part of the pic) and Zaha Hadid's Bridge Pavilion(right). Both of them are not completed four months before the opening ceremony but it is interesting to see the progress -like a disputed competition- of the construction and the different contemporary approaches to the same problem: the minimalist engineering of Arenas and the futuristic baroque architecture of Hadid. The aerial photography was taken by a colleague this month and then gently borrowed by me.

Related: Arenas vs Hadid controversy.

Packaging of stones

2008-02-02T17:25:00.000+01:00

One of the common issues posed in the practice of civil engineering is how to estimate the volume of holes - porous volume - between more or less regular solid particles. Sometimes this hot topic originates long debates with reluctant contractors and picky consultants.
Recently, I have needed to give a number for the spare space in a stone wall like that in the image below. In the project, the interstitial space was required to be filled with cement mortar until certain height to ensure the stability of the base. A bit of mathematics and Wikipedia were useful to justify the necessary amount of the concrete.

Left: Masonry wall in a Roman path somewhere in Germany. Right: Well, needless to say that those are oranges.

The majority of the stones in a wall have similar weight and appearance and, in fact, they are usually defined by a characteristic diameter. If we assume that stones are like oranges -I mean spheres- and that the maximum density of packaging is achieved, the problem can be transformed into the Kepler's conjecture that was proved by Prof. Thomas Hales a decade ago.
It is clear that stones are not spheres -ellipsoids would be a better approximation- but this value of the porosity is close to experiments referred for coarse non-graded gravel in several books. At least, if the on-site engineer asks for the origin of the famous 25% of holes I will have something interesting to say.

A bridge for our high speed train

2008-01-17T23:00:00.000+01:00

General view of the construction (upper image).
Reinforcement of the hinges of the arch (lower image).

The most beautiful bridge for the Galician high speed train was finished successfully and I was there, having a look and talking to our on-site partners that usually give advice to the contractor. It was concluded by laying down the two halves of the central arch last December. The bridge is placed in a rural valley close to Santiago de Compostela.

As one of my on-site colleagues explained us, the arch serves to create a fixed point to resist the horizontal braking forces from the deck. Without the arch, an enormous abutment would be necessary. Undoubtedly the arch also helps to improve the visual impact on the landscape.

Video of the lowering stage. Heigth of the arch = 80 m, Span of the arch= 120 m, Time = 2 days.

View of the deck from the ground (left). My colleagues and I having a look (right).

Building an arch bridge is always tricky since the structure is completely unstable until the two parts meet in the middle. In this particular case, the arch was cast and laid using a German cable stayed system over the head of the closest pier and tensioned from the base of the next pier. Once the two semi-arches were connected by a hinge joint at the key to form a three-hinged arch, the key and arch springs were concreted to reduce this to a two-hinged structure. Displacements of the arch and the head of the pier have been computed in a quite sophisticated way for each time step. Unfortunately, real behaviour can be more complicated than the most complicated theory and the sophisticated calculations of the deformations barely coincided with the real ones.

Usually arch bridges employ vertical supports (a.k.a. spandrels) to distribute the vertical loads of the deck to the arch below, but the Natchez Trace Bridge was designed without spandrels to create a more open and aesthetically pleasing appearance and, indeed, that bridge has strongly influenced the contemporary bridge design.

Picture from the edge of the deck.

I am confident that these infra-structures will provide positive possibilities for the residents of Galiza. New business opportunities will inevitably be created as investors from Madrid and the North West can open up new commercial ties. It is true that we Galicians/Spaniards are not a train culture but perhaps things may change if we can enjoy the fast and affordable transportation of our French and German neighbours.

Note: I did not publish this post in December due to the odd requirement of confidenciality although the process was seen from all the places of the valley and, in fact, lots of videos were recorded and uploaded by the villagers. Copying pictures without a polite acknowledgement is not allowed .

Passed

2008-01-09T00:52:00.000+01:00

I've got it. I have just confirmed that I passed the last exam of the 3-year degree in IT engineering and I will start the 2nd cycle next September. Let me celebrate the good news with a bad HTML joke: yeah, the civil&freaky engineer in the picture is me.

Which specialty has the best future?

2007-12-27T22:03:00.000+01:00

In a recent poll in this blog about the most promising specialization fields in civil engineering, the majority of the readers and visitors has chosen water and environment as best area. Structures and transportation issues seem to have a quite shiny future. On the other hand, most have considered that urban planning, construction management and the traditional generalist engineer are clearly the least attractive paths.

Indeed, the sample was not huge and it is based on personal experiences and beliefs but it shows an interesting prediction to keep in mind. All the best for the New Year.

HEC-RAS & HEC-HMS vs SWMM

2007-12-18T19:30:00.000+01:00

Today I feel brave so I will dare to be politically incorrect and to give my sincere opinion about the analysis of drainage with two main free and open source tools: HEC (this is, HEC-HMS and HEC-RAS) has been proposed by the US Army and SWMM has been developed by the Environmental Protection Agency, this is the same people that released EPANET. So, what are the main differences between both? When should you use one or the other?

Pic 1: HEC models are not fully integrated. Firstly HMS is used for hydrology, then RAS is run for hydraulics.

From my point of view, HEC-HMS is the best choice to compute rainfall-runoff at each hydraulic component in large basins. HEC-HMS can create random rains while SWMM is deterministic. What is more, SWMM cannot analyse properly open channel flows around inline and lateral structures such as dams, bridges, gates, etc... The main disadvantage of HEC models is that they are not utterly integrated (HEC-RAS is one program and HEC-HMS is another) and cannot take into account the effect of minor drainage systems primarily composed of closed conduits (i.e. pipe networks), but SWMM can calculate them well.

Pic 2: The user interface of SWMM has a flavour of EPANET.

Generally speaking, SWMM is better for urban drainage systems with a lot of continuous closed pipes mixed with open channel whereas HEC software behaves better in pure channels (I mean channels that look like rivers) with short culvert lengths.

About ants and birds

2007-12-15T19:55:00.000+01:00

During a recent lunch...

Senior manager: We need more guys with just a professional training in our country instead of youngsters with a lot of useless degrees from the university.
Me: With due respect, sir, I strongly believe that young graduates can add more value to our economy than people without a bachelor degree. Fresh engineers have learnt new ideas and methods during the academic period. Have you heard about knowledge economy?
Senior manager: Nonsense. You seem a bit elitist and full of prejudice. What society wants are people like those Portuguese labourers. In fact, they may be earning more money than you.

Needless to say that the old manager knows little about the remuneration and working conditions of the Portuguese manpower. Needless to say that he comes from a bourgeois family while my family is full of on-site workers that have never had the chance to go to the university, like my beloved uncle in the above picture.

Marketing and construction materials

2007-12-13T20:30:00.000+01:00

Cementos la Unión is a well known producer of cement from Valencia (Spain) with a very aggressive and controversial advertising campaign starred by a manga girl named Carol Cluni; Cluni is the acronym of the company. Models in bikini used to promote the brand and this enterprise also have sponsored a succesful female team of handball. I am afraid they have gone too far but I am not surprised provided that competition among manufacturers is like a war.

Main source:
Marketing News

Your structures on Google Earth

2007-12-05T14:30:00.000+01:00

Yesterday my short period of "holidays" started. As I told you, on Monday I will take a flight to Madrid to do a terrible examination but, finally, I decided to post some food for thought about a good tool I discovered last week.

I am sure all of you know that visualization of structures is becoming more and more relevant to communicate alternatives during the first stages of our projects. For this purpose, Sketch Up is an easy and free 3D tool developed by the Google IT crowd. It enables you to import DXF drawings, to modify the 3D model quickly and to place it on Google Earth using world geocoordinates.

I have found this software very useful because it allows you to envision before and after scenes to demonstrate how a project will be portrayed. For example, I have created the following visualization on my own in less than half an hour for the preliminary design of a bridge over a river in the North of Galiza (Spain).

The location was chosen to ensure a good landscape integration. From my point of view, the variable sections of the deck and the piers give a touch of slenderness and elegance to the concrete structure. Feel free to comment: I am looking forward to hearing your sincere opinions and advices.

Added on 13rd December:

Stand-by status

2007-11-11T15:02:00.000+01:00

Readers and occasional visitors,
Due to a demanding examination of Operating Systems, all my free time after working should be spent on studying. Consequently, this blog is not going to be updated until mid December.
Meanwhile, you can try other excellent spaces on my blogroll.
A million of apologies. See you then.

Water structures diagnosis

2007-11-05T19:52:00.000+01:00

Municipal water and wastewater industries plan to invest millions of euros over the next decade to keep up with expected demand. Much of the money required goes for the rehabilitation of existing concrete structures that have suffered from bad designs and negligence due to the lack of funds.

Among the problems that affect the durability of concrete in water structures we have abrasion, chemical attack and freeze-thaw. These often forgotten actions can significantly reduce the life of the structures as you can see in the pictures of my latest on-site visit. Compare the fissure to the width of my ballpen.

Related: Masonry bridges diagnosis.

Bad vibrations

2007-10-20T13:11:00.000+02:00

As you probably know, vibrating concrete consolidates the material, avoids segregation, minimises holes and protects the steel reinforcement. High resistance cement mixtures are very difficult to place and it is required a careful combination of fluidificant and vibrating. Although over-vibration of the concrete is not a good thing, generally speaking, it is worse to under-vibrate than to over-vibrate concrete.
I found a couple of interesting pics that show the rapid growing of the holes in the deck of a bridge.

If you understand a bit of Spanish, I recommend you have a look at the desperate on-site engineer's rant at the Urbanity forum.

Olde Fortran vs Matlab

2007-10-11T21:00:00.000+02:00

If you have never used your computer to solve home-made numerical simulations, you probably do not have any compiler installed. There are a few programming languages to choose from. Matlab and Fortran are probably the most widely used languages among civil engineers but they are quite different.

The old Fortran runs considerably faster than Matlab does. If you know that you will need a lot of computing power and that computing speed will be important, you may want to go with Fortran instead of Matlab. I chose Matlab for my master thesis and it was a nightmare. Another good advantage of Fortran is that if you use Linux you will find a lot of excellent compilers for free. Matlab is not cheap and there are a couple of free clones (Scilab and Octave) but the translation of the programs is not straightforward.

On the other hand, Matlab has a very easy to use interface and lots of libraries; it is possible to implement programs faster than with traditional programming languages and they are easy to read and to maintain (programs in Fortran are messy). After running your code, Matlab will graph the result for your variables. In Fortran you need extra routines to do this. In the absence of such routines, you will have to use a tedious spreadsheet to have anything to show.
Picture: Olde Fortran in Futurama. More images here.

What I cannot explain in this blog is why civil engineers still use Fortran and not C. Are we from the past?

Mean, median and mode of salaries

2007-09-30T12:00:00.000+02:00

Pic: Young British civil engineers do not believe the ICE's average salary. Full opinion here, in New Civil Engineer Magazine.

Although the intelligence quotient of the population fits a Gaussian bell well, the salary distribution is skewed and largest salaries are much too large to match a normal pattern. Plots of the population density of income distribution for various countries are well reproduced by a gamma function. In a Gaussian process, mean, median and mode coincide, but the same cannot be applied to a gamma distribution.

The arithmetic average of the salaries does not give us the information we want. Suppose you are looking for a job. You have an interview with a company that has ten employees, and the interviewer tells you that the average daily salary is 200€. Wow, that seems good money! But for this particular company you could work for a quarter of that. Imagine that seven employees make 50€ each, two managers each make 400€, and the owner makes 850€. Yes, the average salary is 200€ but note that the median and the mode are 50€ and that is probably what you would get.

It is clear that the mean alone is a bad salary estimator and some staticians (i.e. Gini) tried to measure the dispersion of incomes. However, the mean provides optimistic expectations and no goverment or institution dares to change it.
Pic: Gross annual salary distribution in Spain (2002). Click on the image to enlarge.

Egg shaped pipes

2007-09-25T09:44:00.000+02:00

What I learnt on Monday is that some precast producers make concrete ovoid pipes. My fist impression was "what's the point in using such an odd section?". As fas as I know they are very rare in Spain. After flicking through an old book on hydraulics I realised that the ovoid pipes have better velocity characteristics at low flow than the equivalent circular pipes and this feature implies two great advantages:

• Better self cleaning and less risk of blockages.
• Reduced costs of excavation.

The moral of this post is: be reluctant and never trust traditional solutions blindly.

Pic: Ovoid pipes, around 100 € per metre.

The story of Philip Emeagwali

2007-09-20T16:00:00.000+02:00

I really enjoy reading biographies that sound like a story written by Dickens. The childhood of Philip Emeagwali is one of those. It seemed the dawn of a life destined for poverty in his native land of Nigeria. Unable to attend school, Philip spent most of his day in the public library studying maths and physics. After a period of study and general examinations, he decided to apply to colleges in Europe and the US and then was offered a scholarship by Oregon State University.

In the 1980s he worked as a civil engineer in Maryland and Wyoming, but his real success was yet to come. His work with parallel supercomputing to simulate the extration of oil, water and gas in reservoirs, led him to the Gordon Bell prize. Emeagwali has won several other awards and his achievements were quoted in a speech by Bill Clinton as an example of what poor but talented people can achieve when given an opportunity. Maybe Emeagwali is a media hype but there is something absolutely true in this story: self-education in maths, engineering or computing is the most effective way to pass the poverty line in many countries.

Here you have a short video of Emeagwali I found on YouTube.

Masonry bridges diagnosis

2007-09-16T17:37:00.000+02:00

Despite the common belief is that the language used by engineers exclusively consists of cold technical expressions; in masonry bridges the opposite occurs. Thus, engineers assign human qualities along the restoration and conservation phases of masonry bridges, playing the role of a doctor according to the illness of the structure. The metaphor between building techniques and medicine becomes evident in the terminological correspondences.

About one year ago, I have had the opportunity to design a solution to extend the use of a couple of stone bridges (in the pics you can see one of them) by performing a structural damage analysis. This is not an unfrequent situation: engineers can find many of these old contructions in the roads of Galicia and the North of Portugal and, believe me, it is a challenging issue.

Central arch of the bridge, close to Ourense (left). Analysis with RING (right).

FE Analysis with Cosmos/m

Unfortunately, masonry is quite difficult to analyse without proper tests that cost a lot of money and I realised that finite element models of stone arch bridges give good estimations of deformations but inaccurate ultimate failure loads. The best software tool I found was the RING program developed at the University of Sheffield that is based on the theory of Jacques Heyman. This software is freeware, easy and rapid to run and provides better results than common finite element packages.

Resonance in practice

2007-09-06T22:30:00.000+02:00

Second bending mode of vibration.
Twisting mode.
Putting all together, we have something like a Dutch roll.

From Allowable Stresses to Limit States

2007-08-31T16:58:00.000+02:00

My geothecnical colleagues get annoyed when I say that foundation engineering is a step behind structural analysis because they still use a permissible stress approach instead of a limit state approach.

For a working stress formulation, the real magnitude of service loads is used in the whole design and the strength of the material (i.e. soil, concrete, plastic...) is divided by a huge coefficient. Under such scenario, the resistance is not used in the full extent and the cheapest design can hardly be obtained.

For a limit state conception, for each material and load, a partial load factor is assigned individually depending on the material properties and the likehood of occurrence. The material strength can be utilized to its maximum design value during its lifespan. Therefore, the calculations are more refined and the construction cost of the structure is lower. In the future calculations should be based on fully probabilistic models.

As far as I know, (correct me if I am wrong), most of the American codes, the Italian ones and the British standards still use the allowable stress approach even for some structural analysis. My advice is to have always a critical eye on the codes.

Software engineers should be licensed

2007-08-29T20:15:00.000+02:00

Civil engineering puts heavy emphasis on being licensed and for good reasons. In most areas of engineering being a licensed professional is of great interest to employers.

There is ample evidence that defective software is a cause in many failures of critical systems. In 1996, the European Space Agency (ESA) spent 7 billion dollars to produce the Ariane V, a giant rocket. On its maiden launch, the Ariane V exploded just forty seconds after its lift. A board of inquiry investigated the causes of the explosion and in two weeks issued a report. It turned out that the cause of the failure was a software error.

Reliability is especially important in certain systems. I would not expect all the software to have been made and signed by software engineers but, I could reasonably expect that the software that controls the crossing of trains or airport operations were signed off by a licensed software engineer.

It is all about liability and risk assumption. A licensed software engineer could place his/her signature on a document and that makes the insurance industry a bit happier. Professor David Parnas stated: “In other technical fields the engineering professions were invented and given legal standing so that customers could know who was qualified to build technical products. Software customers deserve no less.” (in An Unconsummated Marriage, IEEE papers, November, 1997).

Certification is a voluntary process administered by a profession; licensing is administered by a governmental authority. The IEEE computer Society has developed a certification program for software engineers and strongly recommends SW engineering licensing.

There are legally certified SW Engineers in many parts of the world. In the UK the IEE, Institute of Electrical Engineers and the BCS, British Computer Society via the Engineering Council confer Chartered Engineer status in exactly the same way it does on Civil, Mechanical, Marine and Aeronautical engineers. There are more than 30 other countries which are harmonising their requirements for licensed, certified or registered Software engineers.

I am quite confident that licensing and certification of software Engineers will happen in the next decade in order to increase the safety of the critical software. At least it will start to become a legal requirement in more places and projects.

Do all engineers work under the hot sun?

2007-08-14T11:00:00.000+02:00

It is time for young students to choose degree and university and many of them avoid engineering courses due to misconceptions about the profession. Not all the engineers work under the sun or in greasy factories. As a matter of fact, many engineers spend their time in air-conditioned offices doing analysis and design. In some cases involving planning and management, engineers usually stay indoor nearly all the time. Of course, there are some civil engineers at the site, but nowadays a lot of us are employed by consulting companies, by the government and in a wide variety of industries, or maybe self-employed.

France is a very rare case because 70% of the civil engineers work for the administration.

My second bridge

2007-08-10T11:00:00.000+02:00

If you remember my recent post, you will find the deck of my second bridge similar to that first one. It is placed on a river with a wide flood area and this issue made the project more appealing. The soil was a mixture of mud and sand with poor bearing properties therefore a very deep pile foundations were the only choice. The deepest pile was fitted 21 m under the bed of the river. Sometimes I like to boast that my second bridge was much deeper than taller. The analysis of the components of the substructure were based on a thorough description of the geotechnical conditions obtained from borings and Standard Penetration Tests.

An unexpected difficulty was to persuade the river basin authority that the new structure would not increase the water level more than 10 cm upstream; a calibrated hydrological HEC-RAS simulation did the job.

General view of the bridge

Pier and piles

One of the abutments

Description: prestessed and reinforced concrete girders, deep pile foundations.
Length = 33+33+33+33 m
Width = 11.00 m
Depth = 1.70 + 0.25 m

Arenas vs. Hadid controversy

2007-08-01T11:00:00.001+02:00

Recently, I read the furious opinion of the well known Spanish engineer Arenas with respect to the Pavilion Bridge designed by the Iraqi architect Zaha Hadid for Expo 2008 in Zaragoza.

The argument was expected, because they plead opposed conceptions of the built environment: Hadid possesses a prominent imagination and she pays little attention to the structural issues; the structure calculated by Arup is a mere consequence of her aesthetical dream. However, Arenas embraces the Continental tradition. As a professor of civil engineering he firmly believes that structural art exists and to hide the skeleton implies an unpardonable sin. Even the election of materials was quite different: steel for the Iraqui, concrete for the Spaniard.

From my point of view both are right: the relationship between engineers and architects is critical to the design of singular structures. Leonhardt warns engineers that the often cited quote `form follows function’ is misunderstood if function is only defined structurally. On the other hand, putting consulting engineers behind the architects creates designs for fuss and provocation ignoring efficiency and soberness. One example of a bridge that is too architectural is the Millenium Footbridge in London by Foster.

Hadid's bridge (34 million €) will pass over the River Ebro very close to the roadway bridge by Arenas (25 million €). Soon, the people from Zaragoza will enjoy the pleasing comparison of these two different styles.

Third Millenium Bridge. Arenas & Partners.

Pavilion bridge. Hadid & Arup.

Windmill foundations

2007-07-24T08:35:00.000+02:00

Recently, I designed concrete foundations for several windmills in the NW of Spain using nonlinear finite element analysis.

First of all, I did a simple linear static analysis with nonlinear friction to estimate the amount of steel and the stability. Then, I confirmed the reinforcement using a 3D model with nonlinear materials for concrete and steel. The main problem was the deadline; the job must have been done in three weeks and running a nonlinear simulation took a while.

Square reinforced foundation are inefficient because the wind can blow in all directions and the diagonal load causes high moments. Circular reinforced rings are much more cost effective for wind turbine foundations. The reason why square windmill foundations are still used is because to dig a square hole is simple. An octogonal foundation was my proposal: it is nearly as efficient as a circular one and it is also easy to build. They would probably dig a square hole and backfill the corners. After long and hard talking it was impossible to change the mind of my client and the choice was a square foundation.
Sketch of the two load cases considered. The dimensions of the box are 12.5 x 12.5 x 1.6 m
Nonlinear model for the diagonal load case. (Only a half was modelled)

Nonlinear model for the parallel load case. (Only a half was modelled)
Drawing of the resultant reinforcement

Poor drainage and disaster in Brazil

2007-07-19T13:00:00.000+02:00

The plane accident in Congonhas (São Paulo) with 200 casualties is more than an isolated disaster. It represents a growing crisis of confidence with engineering and logistical consequences.

It was reported that the jet began to slip due to heavy rain and poor drainage conditions. Although maintenance works -including laying a new surface- had been carried out recently, the drainage system was not significantly updated.

The congestion of airport traffic and the accommodation of very large planes were solved by paving new surfaces but the matter of airport drainage has not received the due attention. It is an urgent necessity to upgrade old culverts and build new storm sewers in our airports.

Pic: Congestion in Congonhas, 1996

Britain's modern Brunels on BBC Radio 4

2007-07-16T18:00:00.000+02:00

I.K. Brunel is one of the heroes of engineering and was voted as the second greatest Briton in a recent BBC poll. The achievements of today's engineers are compared to those of Brunel and other victorian engineers on BBC Radio 4. The programmes of the serie can be listened by clicking here.

Bologna accord in engineering

2007-07-14T21:00:00.000+02:00

EU countries are in the transition phase of implementing the common educational framework of the Bologna process. In France, Italy, Portugal and Spain a five-year degree in engineering is the stardard. If I had stopped after the forth year, I would not have got any degree. After the process, all programmes will be divided into Anglo-Saxon scheme, bachelor (3-4 years) and master degrees (1-2 years), where our Continental integrated degree was the only one.

What if you plan to do an MSc in the US?. Nowadays there is no resistance to recognise five-year degrees at American graduate schools but the acceptance of the new European undergraduates is not ensured. This is a contradiction because the aim of Bologna accord was to americanise the European universities. In fact, it is funny to read in the blog of the Curious Cat that Yossi Sheffi, Professor of Engineering at MIT, proposed a five-year model to "learn how a subject fits into the grand scheme of things". Are we moving opposite?

Is this reform going to make us -the Southern European engineers- more skilled and competitive? I admit to be a bit reluctant.

The first bridge

2007-07-10T11:00:00.000+02:00

Indeed, my first bridge was not a Calatrava's. It required little amount of structural analysis but, as if it were a first-born child, I still love it.

Materials: prestessed and reinforced concrete, reinforced earth walls
Length = 25.35 + 25.35 m
Width = 11.00 m
Depth = 1.35 + 0.25 m

Someone told me it is going to be built soon. Great!

Fauna-friendly culverts

2007-07-04T16:00:00.000+02:00

Frogs, turtles, snakes, trouts and salmons among others are blocked by the culverts that lay beneath our roadways.

The importance of a good drainage is known since the work done by the Scottish engineer Mac Adam in the dawn of 19th century. Surface drainage would have to be completed by ditches and culverts as a mean of driving the drained water away from the road and into the streams that existed before.

Traditionally, culverts have been installed with consideration for their hydraulic capacity. The cross-sectional flow area is smaller than that of the stream approaching it and the velocity of the water entering the culvert is greater than that of the natural stream. However, culverts that are correctly designed and installed (see figures) do not hinder animal passage.

Upper pic: George Washington National Forest.
Lower pic: British Columbia Min. of Transp.

Ethics matters

2007-06-28T18:00:00.000+02:00

By chance I have read this nice classical document any honest engineer must keep in mind. It was written by the ACM (Association for Computing Machinery) on software engineering ethics but I am afraid it can be extended to many other professional practices.

The short version is like this,

1. PUBLIC - Software engineers shall act consistently with the public interest.

2. CLIENT AND EMPLOYER - Software engineers shall act in a manner that is in the best interests of their client and employer consistent with the public interest.

3. PRODUCT - Software engineers shall ensure that their products and related modifications meet the highest professional standards possible.

4. JUDGMENT - Software engineers shall maintain integrity and independence in their professional judgment.

5. MANAGEMENT - Software engineering managers and leaders shall subscribe to and promote an ethical approach to the management of software development and maintenance.

6. PROFESSION - Software engineers shall advance the integrity and reputation of the profession consistent with the public interest.

7. COLLEAGUES - Software engineers shall be fair to and supportive of their colleagues.

8. SELF - Software engineers shall participate in lifelong learning regarding the practice of their profession and shall promote an ethical approach to the practice of the profession.

Related: ASCE code of ethics

Dynamics resources for Human Resources managers

2007-06-26T16:00:00.000+02:00

Social systems are more difficult to understand than common engineering systems. Although the NASA would never send a space ship to the moon without first testing prototype models and making lots of computer simulations, HR managers still prefear to use intuition, limited mental reasoning, assumptions, etc...

In one of my assignments in the IT engineering course at the Spanish Open University I wanted to use the knowledge of system dynamics to simulate recruitment strategies in a common consultancy office. The image below shows the basic elements of a system dynamics loop: levels (state variables or integrals), flows (rates or derivatives) and information.
And this is the full model of the company in VenSim. Click on the pic to enlarge.
Two main policies are compared here,

In dark red: People are recruited based on the people that goes out of the enterprise (man out, man in) and the evolution of projects (this is, depending on the ratio between sales and production).
In blue: People are hired based on the evolution of projects that need to be developed and taking into account the productivity of the manpower.

A continuous growth of the sales was supposed for fifteen years of simulation.

As you can see from the figures above, the amplitude of the oscillations in the junior consultant population are always bigger than in the senior people (juniors always pay the bill!). The first strategy (recruitment based on production information) is the most usual and it behaves quite well in the beginning but dramatic delays appear after a couple of years; the second strategy (recruitment based on orders information) requires an investment period to train fresh graduates but gives better results after four years. Any resemblance to reality is pure coincidence.

Coding your own FE software

2007-06-22T17:00:00.000+02:00

Newmark’s family of implicit algorithms gives fast and accurate results for most of the common civil engineering problems such as earthquakes and low velocity impacts with small deformations.

Several industrial applications involve high velocity dynamics of solids, for example forging, machining, crash–tests, collision modelling and many others. Explicit methods are the most appropriate ones in this case.

This interesting topic was the aim of my MSc project that can be downloaded here. I tried to prove that it is not necessary to spend a lot of money to get a good finite element code with the capability to keep constant mass, momentum and energy and to represent very large deformations with complex material behaviours.

The code is completely open, free and easy to understand. Although it was written for Matlab -a bad choice for finite elements- in a couple of months I think the result was not too bad as you can see from the image (top: pressures in a square plate that is spinning all the time; bottom: pressures in a predeformed tube).

HEC-RAS with ArcMap

2007-06-20T21:30:00.000+02:00

Recently, I replaced my old ArcView 3.2 with the new ArcView 8.1. The main difference between the classical GIS software and the new version with ArcMap when using HEC-GeoRAS is the option to introduce the position of inline structures (i. e. bridges, culverts, weirs and dams) and lateral structures in the original GIS model. In most cases, hydraulic structures may be incomplete and must be finished with the HEC-RAS editor.

Indeed, ArcMap is a functional tool. However, to export HEC-RAS GIS results to AutoCAD, I still prefer Lamina. This is a free utility developed by the Technical University of Catalonia that translates the georeferenced floodplain into a dxf file. Using Lamina just takes one click so it is very convenient to refine the model and iterate until everything makes hydraulic sense (for example, the inundated areas cannot be disconnected from the main river).

Where is engineering going?

2007-06-18T11:00:00.000+02:00

After reading eng-tip fora with attention I can summarise three major conclusions about contemporary engineering:

Use and abuse of computers

Twenty years ago, most problems were broken down into small problems that could be solved using simple formulas. Nowadays we totally depend on computerized solutions. While this gives you a global vision of the system, it usually divorces the engineer from the solution process. Despite I have got an MSc in Computer Modelling, I am also a part-time student of IT engineering and I am mad about computing I must confess that because of the fast-life of consultancy projects we tend to use the software as a black box. Limitations of the model are not fully known and we end up with a fake sense of confidence.

Engineers became tools

Engineering has lost its reputation as a profession long ago. In a customer oriented industry, when our customers have the wrong idea about how long things will take, consultancy firms commoditize their engineers to cut down costs.

Young engineers reinvent the wheel

It is said that young engineers like me seem to reinvent the wheel rather than follow what was done by the old fellows of the place. That is a bit true. In the end, you get what you pay for. Decades ago engineering was a well paid job that attracted the best and brightest minds to the field. But things have changed, most of the old engineers moved to finance, business, sailing and such. The experienced and qualified engineers were displaced and only the low cost fresh graduates remained in the companies without anyone to use as a mentor.

Nobody can predict exactly where engineering is going in the next years but the best way to predict our future is to build it.

Not everyone appreciates an interexchange

2007-06-15T17:00:00.000+02:00

As a monthly reader of the magazine gently provided by the UK Institution of Civil Engineers to the affiliates, I do not pay much attention to the boring articles, which are the most. However, I am delighted by the way engineering companies advertise their services. At least in Spain, no engineering firm is going to spend a single cent in a professional advertisement.

Although Atkins is by far the largest British consultancy group, Arup is the best known all around the world. Maybe the huge publicity budget has to do with this. Beautiful ad, isn’t it?

The beginning

2007-06-10T12:00:00.000+02:00

This is the beginning of the blog. And these pictures of my graduate project represented the end of my student life and the beginning of my career as a civil engineer.

I must confess that I was very idealistic when I was just a student. Then, I promised to myself that all my bridges would be aesthetically correct. I dreamt with curved cable-stayed decks.

It seems that my first bridge to be built in the real world is going to be an I girder structure (something less pretencious than I expected but it is still ok).