Ahmet Zeytinci, P.E., Ph.D., Fellow-NSPE, Fellow-ASCE is an award-winning professor, structural engineer, author and mentor living in Washington, D.C. Since joining academia, "Dr. Z", as he is known by his students and colleagues, has distinguished himself on campus and beyond. He is passionate about engineering, gifted in teaching, and is a true champion for professional licensure. Dr. Z. has extraordinarily high standards; has produced award-winning designs; is prolific in professional service; and infects others with these same values. He is the recipient of numerous local, regional and national awards, including recent national awards from the National Society of Professional Engineers (NSPE) and American Society for Engineering Education (ASEE). Since 2014, he has been regularly writing monthly articles for “Dr.Z’s Corner “ and offering hundreds of engineering problems, for free, every month for students, engineers and engineering educators worldwide. Dr. Z. also offers pro-bono Saturday classes for students and engineers; his free classes are open to all in the greater Washington metro area and cost nothing, nada, zilch! Starbucks coffee is always a must have for Dr. Z.
As stated by the famous mathematician and astronomer Leonhard Euler: “Nothing happens in the universe not relying on the rules of maximum or minimum.” The use of the mathematical term of optimization can be identified to the era of great mathematicians, physicists and astronomers like Cauchy, Lagrange, Kepler and Newton while minimization was presented a lot prior by Euclid. Notwithstanding these early advancements, engineers discovered the value of optimization not before 1950 when research innovation on optimization algorithms was supported by computing power. Nevertheless, civil engineers remain skeptical in incorporating optimization in their professional practices.
Trial and error vs optimization
The first production-worthy light globe was the outcome of a long and repetitive trial-and-error procedure by Thomas Edison for identifying the optimal material. While Edison had limited knowledge on material properties as electrical resistance and conductance, modern engineers present remarkable technical experience and knowledge that empowers them to deliver high-quality designs based on their expertise. Designs’ weaknesses are detected via testing and are corrected through experience-based make-it-and-break-it procedures.
Advancements in available computing hardware technology and software enabled the development of numerical prototypes of designs, used for performance assessment prior to construction while time and cost efficiency of the trial and error phase was improved. It is worth pointing out that there exist two constraints that restrict further efficiency improvement. The first one is the significant workload demand for interpretation of design cycles of the trial and error approach. The second factor concerns the balance between project complexity and uniqueness versus human intuition. The physical limitations of the human brain in combinatoratorial calculations have been exceeded by the computational abilities of available hardware technology. The inventive solutions of engineers are limited by time and cost but could be assisted in achieving near-optimal design solutions in an algorithmic manner.
The added value created by improved productivity and production of near-optimal solutions establish the need for algorithmic aid in structural design. The added value is generated by reducing design cost and time while increasing responsible material usage, eco-friendliness and construction cost efficiency of projects. Numerical optimization is the means of transportation from a far-optimal design to a near-optimal one with respect to predefined parameters, restrictions and goals.
Optimization in the engineering profession
Since the 1960’s many research studies on applied structural design optimization have been published, where structural design optimization was effective in various problems. However, civil engineers (especially structural engineers) seem susceptible to applying optimization-based design procedures. Nevertheless, mechanical and aerospace engineers have already adopted optimization into their profession practice. For instance, in the automotive industry, BMW has adopted optimization procedures in the development of new diesel engines. While in the aeronautic industry, Airbus used a design optimization approach for developing the wings of the aircraft A380.
First steps of optimization in AECI, what is the benefit
Aiming to identify the benefits of adopting optimization-based structural engineering by the Architectural, Engineering & Construction Industry (AECI), it is important to underline that: (i) The Building Sector (BS) is the higher contributor to global greenhouse gas (GHG) emissions (30% of GHG emissions) while it also consumes almost 40% of global energy, 25% of global water, 40% of global resources, (ii) BS estimated worth is around 10% of the global GDP (USD 7.5 trillion) with more than 120 million people employed, whereas (iii) AECI is expected to expand by 85% to USD 15.5 trillion worldwide in 2030, with U.S., China and India accounting for almost 60% of this growth. With respect to the above issues, the question for AECI is: “To optimize, or not to optimize?”. The answer to this question is straightforward, definitely Yes; if AECI adopts design optimization principles the environmental impact and economic development of AECI is expected to be severe. More specifically, a hypothetical scenario of 10% average material usage reduction is achieved on 5% of the project volume of AECI, the cost reduction translates to USD 15.0 billion for 2016; while the environmental benefit translates to 6.0 million metric tons of CO2 reduction, equal to the annual emission of cities like Pittsburgh, Paris, Milan or Athens.
Worth noticing are the pioneering steps in the field of structural engineering design optimization performed by OptiStructure, a startup recently established in London UK, that aims to institute value engineering revolution in AECI via structural design optimization. OptiStructure optimization services have recently been applied to a 535 meters high-rise reinforced concrete building, to be constructed in the Persian Gulf area. The environmental benefit achieved by the optimized design delivered corresponds to 12.7% and 11.2% reduction on GHG CO2 emissions and energy consumption, respectively; while cost reduction of 8% was achieved that corresponds to USD 6.8 million.
About the Author
Prof. Nikos D. Lagaros is the Dean of the School of Civil Engineering at the National Technical University of Athens (NTUA), Greece and advisor at OptiStructure.
Almost all engineering students know the Fundamentals of Engineering (FE) exam is a computer-based test (CBT), and the NCEES FE Reference Handbook (version 9.5) is the only resource material that will be displayed on your exam monitor as a searchable PDF file. In this month’s article we will talk about this important “ally” and even create a practical case study.
By now, our readers, students and practicing engineers who are preparing to take their FE exam for the first time know that the most important advice they is to review the FE Reference Handbook (v. 9.5) as often as possible before the exam day and becoming familiar with the formulas, tables, charts, and other information in the reference book.
As we have indicated in earlier newsletters, you will not be allowed to bring your personal hard copy of the Handbook into the exam room. You must rely on the electronic PDF version of the FE Reference Handbook, which will be very similar to the printed hard-copy version. Quite often students ask us about the best strategy to find a formula or specific information in the searchable PDF file as quickly as possible. For this, the keyboard shortcut “CTRL-F” comes to the rescue. Below, we will create an actual case study to decipher the whole search process.
When you use the keyboard shortcut “CTRL-F”, you will be prompted with a dialogue search box to enter the keywords you would like to search for. Once your keywords have been entered, the keywords will show up highlighted in the reference manual and you can skip from one result to the other until you find exactly what you are looking for.
Case Study: Searching for the numerical value of the Modulus of Elasticity of Steel in the FE Reference Handbook (v. 9.5):
Most of us who regularly use values for the Modulus of Elasticity know that the modulus of elasticity of steel is E = 29 x 106 psi (29.0 Mpsi) in the U.S. Customary Unit System or E = 200 GPa in the SI unit system. These values are found on page 89 of the FE Reference Handbook.
As a case study, let us try to find these values in the PDF version of the FE Reference Handbook. Here are the possible steps for the search:
1. First you open the PDF file and once you see the cover of the Reference Handbook on your monitor, enter the keyboard shortcut “CTRL-F”. You will be prompted with a dialog search box with PREVIOUS and NEXT keys.
2. Type “Modulus of Elasticity of Steel” and hit the ENTER key. Surprisingly you will get the following message: “Acrobat has finished searching the document. No matches were found.” Then what do you do?
3. One possible next step would be to remove the word “steel” and leave the “Modulus of Elasticity” part and hit the ENTER or NEXT key again. Immediately Page 67 of the Reference Handbook will open, and you’ll see the following highlighted definition: The elastic modulus (also called modulus of elasticity, Young’s modulus) describes the relationship between engineering stress and engineering strain during elastic loading. But this definition is not what we are searching for. We are searching for the numerical values of the modulus of elasticity of steel, not its definition. Then what do you do?
4. The easiest way would be clicking the ENTER key or NEXT key on the dialog box again, then you’ll see another reference on page 67.
5. Clicking the ENTER/NEXT key again, will open the page 88 of the reference handbook.
6. If you keep clicking the ENTER/ NEXT key several more times, you’ll see references on other pages as well and finally the unpleasant message “Acrobat has finished searching the document. No matches were found.”
Now let us try to use another term as the search word in the dialog box for the Modulus of Elasticity, that is: Young’s Modulus. Once you enter “Young’s Modulus” and hit the ENTER key repeatedly, you’ll see references on Pages 246 and 248 of the Mechanical Engineering section of the handbook. Still we are not getting the numerical values. If you keep clicking the ENTER/NEXT key repeatedly, you’ll see references on several pages of the handbook and finally, BINGO! You’ll see the page that you’re looking for, the “Typical Materials Properties Table” on Page 89.
And lastly, we remind our readers that the F.E. and P.E. are very fast-paced exams and you will have little time to look up information. Therefore, make sure you are familiar with the electronic and hard-copy versions of the FE Reference Handbook. This will help you to build your confidence and conquer the exam on your first attempt!
Ahmet Zeytinci (Dr.Z.)