A State of the Art Structural Engineering 2015/Metnet-Heinisuo.pdfFaculty of business and built environment, Department of Structural Engineering Research Centre of Metal Structures,

TAMPERE UNIVERSITY OF TECHNOLOGYFaculty of business and built environment, Department of Structural Engineering

Research Centre of Metal Structures, Seinäjoki, Tampere

METNET Hämeenlinna 18.02.2105 Markku Heinisuo 1

A State of the ArtStructural Engineering

Markku HeinisuoProfessor of Metal Structures

Tampere University of Technology




Main references

Roesset J., Yao J., State of the Art of Structural Engineering, Jornal of Structural Engineering, ASCE, Vol. 128, No 8, August , 2002, pp. 965-975.

Structural engineering – Wikipedia. 2.1.2014

Own experiences




Contents

• Brief history• Materials• Structural analysis• Structures, buildings, bridges• Economy and computing• Education• Predictions to future

(Emphasis in last)

Kuvaa ei voi näyttää nyt.




Brief history

• The first engineer in history known by name: Imhotep, builder of the step pyramid for Pharaoh Djoser, 2700 B.C.E.

• 1452-1519 Leonardo da Vinci

• 1638: Galileo Galilei: Two New Sciences.

• 1660: Hooke’s law, 1687: Newton’s laws of motion, 1700-… Bernoullis, Euler, 1800-… Navier, Castigliano, Mohr, 1900-… Timoshenko, Cross, Courant, …, 1956: Turner, Clough, Martin, Topp: Stiffness and Deflection of Complex Structures=> FEM




Robert Hooke: Turn loaded tension rods up-side down => youget structural form which can resist a lot of compression.

Famous application: Sagrada Família by Gaudi.




Brief history of steel standards in USA (Galambos, 2006)

• Allowed stress design 1923-;• Limit state design 1963-;• Performance based design

– Used especially in fire design– Can be used load for definition, resistance definition, risk analysis etc.

2010…2014Only EN in use

2002-2005ENV => EN

1.11.2007EN in use

parallel with national codes

1991-1998ENV in use

parallel with national codes

1989 Building directive

89/106/ETYAgreement with

CEN

1975EEC: Idea of Eurocodes

Consults made pre-standards

Brief history of Eurocodes




Brief history of Product Modelling (BIM)Osterriedr P., Richter S, IAI Project ST-5, Technical University of Cottbus, 2004.




Materials

• Traditional• Stone, wood, brick• 1800… iron, steel, reinforced concrete• 1900… steel yield about 1000 MPa, concrete about 100 MPa• 1900…composite materials (fiber-reinforced polymers)

• strengthening and retrofit • new forms of bridge decks• reinforcement in reinforced or pre.stressed concrete

structures• Smart materials

• Not much applications yet in civil engineering• Fire protection (intumescent) paint




What is high strength steel (HSS) = ?

• Up to 1950’ S355 were high strength steels• Now up to S460 are ”regular” steels (Eurocode classification)• Now up to S700 are high strength steels (HSS, Eurocodes

available up to S700)• S700 – S1200 ultra high strength steels (UHS, Standards

available up to S960)




Structural analysis

• Classical methods• Hooke and Mariotte in the 17 th century,• Coulomb, Euler, and Lagrange in the 18th century,• Airy, Betti, Boussinesq, Castigliano, Cauchy, Green,

Kirchhoff, Lamb, Muller-Breslau, Navier, Poisson, Rankine, Ritter, Saint Venant, Stokes, Voigt, and Young among others in the 19th century.

• In the first half of the 20th century Cross method (Cross, Kani) iteration for frames => major impact in structural engineering world wide.

• Timoshenko• Development of the elastic theory of shells Dischinger,

Krauss, Flugge, Novozhilov, Pfluger, Reissner, and Vlasov.




Structural analysis

• Computer methods, 1956 =>• Advent of the digital computer.• Formulation of matrix structural analysis.• Assemblies of linear members: plane and space trusses

and frames as well as plane grids.• Implementation in general purpose computer programs of

the finite element method (FEM) and the boundary element methods for two- and three-dimensional continua.

• Solving complex structures such as plates and shells of arbitrary shapes with their actual boundary conditions.

• Emphasis from continuous to discrete mathematical models.




Structural analysis

• Computer methods, 1956 =>• FEM: Who were the popularizers? • Four academicians: J. H. Argyris, R. W. Clough, H. C.

Martin, and O. C. Zienkiewicz are largely responsible for the “technology transfer” from the aerospace industry to a wider range of engineering applications during the 1950s and 1960s.

• Olek Zienkiewicz, originally an expert in finite difference methods who learned the trade from Southwell, was convinced in 1964 by Clough to try FEM.

• Perhaps the most known kill app: STRESS by StefenFenves, extension => STRUDL

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Structural analysis

• Non-linear analysis• Geometrical non-linearity

• Large deformations and displacements• Contact problems• Crack propagations• Stability problems, etc

• Material non-liearity• Plastification of materials• Ultimate failure in normal and accidental conditions

• Dynamic problems, e.g. collasions• Coupled problems, e.g. mechanical & thermal




Structural analysis

• Mechanics are the basis for structural analysis and should be taught to all engineering students.




Structures, buildings, bridges, dams

• Interaction of material and analysisdevelopment => engineering structures.












Economy and computing

Last 50 years: constructability as an attribute in designNot only the original cost of the structure but also the costs of maintenance and repairs during its intended lifetime

Software and hardware development: investigation of alternatives looking for an optimum solutionthe integration of the design of the different components of the system the coordination of the design and construction

Optimization started with weight optimizationNow in focus capital costs, life cycle costs, emissions, usability etcMulti-criteria optimization and related decision making methods coming to construction business

Reliability/robustness considerations started, including risk analyses, as well.




Education

In past rigorous theoretical treatment of basic and engineering sciences.

Most engineering professors had a substantial amount of practical experience and maintained themselves in touch with the practice of engineering as did the great engineers of the 19th

century.

Research was often motivated by real problems encountered in practice, rather than being dictated by funding agencies with the assistance of government panels, often consisting of other academic researchers.

At present most faculty members (e.g. in USA) are hired upon completion of their PhDs without any exposure to practice.

Enlightened institutions foresaw the problem and started many years ago hiring practicing engineers as adjunct professors to teach design courses.

The time has come for the case study approach, commonly used in other disciplines, to become more widely used in civil engineering education.

New type of closer industry-university cooperation, partnership, doctoral school.




Education




Predictions to future

Charles L. Miller at MIT: rather than attempting to predict the future, it is more important to decide what the future should be and to try to influence change in that direction.

So:

There will be taller buildings, deeper platforms in the ocean, and longer bridgesbuilt. There will also be new structures built in space and perhaps on other planets, as well as structures under water.

There will continue to be important progress in our analysis capabilities, allowing us to predict better the behavior of structures, mathematics&computers.

There will be an increased use of uncertainty and risk analyses in structural engineering.




Predictions to futureContinue

One can foresee buildings and bridges that are instrumented so as to be able to monitor their performance and diagnose potential troubles easily, and structures conceived so that they can be easily maintained, repaired, or replaced.

The time should come to see finally a fully integrated design process in which the engineer can look at the complete system and the interactions.

There should be a much larger concern of the structural engineer for issues that are not directly related to the resistance of the structure, but which are essential for the functional, economic, or aesthetic viability of the work, or for theacceptance of the project by the owners or the public at large.

Performance-based design codes will be further developed.




Predictions to future

Finally

About 30 years ago researchers used FEMNow it is routine in everyday design

About 30 years ago designers considered, should they start to use 3D modelling?Steel designers took 3D modelling as routine about 20 years ago. Others arenow following.

Researchers use optimization to other objectives than weight.

Our vision (in Research Centre of Metal Structures) is that multi-criteriaoptimization and connected decision making methods will be taken as routine in structural engineering without 20-30 years delay.




Multi-criteria optimization, 10000 m2 hardware store




In 1000-1700 builders where about next to king in the society.

Present ?

In UK the builders and covernment agreed 2013 that construction business should push the economics of UK to raise.They agreed clear actions to complete this. One key action is digitalization of the contruction business in the wide range.

Can we do something similar in Finland and other countries, as well?

Steel structures can show the way? Automated fabrication, export, etc

Some urgent issues for the future, steel structures




We are taking just the first steps in utilizing optimization of structures.

Steel business play with kilograms, intead deal with costs and emissions!


1053 kg 1379 kg1641 € 1408 €





Utilization of HSS in buildingsWe have shown 5-20 % savings in costs, 20-40 % savings in kilograms(=emissions). Contructors should be intrested in this.

Integrated design of joints of steel structures: to the same level as memberdesign, now using 50 years old techniques. => Cost efficient design, costknowledge for designers, validated and verified joint analysis models for 3D design.

Control and optimization of automatized manufacturing by BIM.

Modular constructions, reuse of components, hydrid solutions, accidental issues.

Multi-citeria optimization, frames, foundations, cladding, stressed-skin design, i.e. take into account the entire building, not just components.




Thank you

Applause?

Documents

A State of the Art Structural Engineering 2015/Metnet-Heinisuo.pdfFaculty of business and built environment, Department of Structural Engineering Research Centre of Metal Structures,