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    See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/225671965

    Structural Engineering: Seeing the Big Picture

     Article  in  KSCE Journal of Civil Engineering · December 2007

    Impact Factor: 0.48 · DOI: 10.1007/s12205-008-8025-7

    CITATIONS

    8

    READS

    78

    1 author:

    Wai Fah Chen

    University of Hawaiʻi at Mānoa

    377 PUBLICATIONS  6,191 CITATIONS 

    SEE PROFILE

    All in-text references underlined in blue are linked to publications on ResearchGate,

    letting you access and read them immediately.

    Available from: Wai Fah Chen

    Retrieved on: 27 May 2016

    https://www.researchgate.net/institution/University_of_Hawaii_at_Mnoa?enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2&el=1_x_6https://www.researchgate.net/profile/Wai_Chen2?enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2&el=1_x_5https://www.researchgate.net/?enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2&el=1_x_1https://www.researchgate.net/profile/Wai_Chen2?enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2&el=1_x_7https://www.researchgate.net/institution/University_of_Hawaii_at_Mnoa?enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2&el=1_x_6https://www.researchgate.net/profile/Wai_Chen2?enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2&el=1_x_5https://www.researchgate.net/profile/Wai_Chen2?enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2&el=1_x_4https://www.researchgate.net/?enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2&el=1_x_1https://www.researchgate.net/publication/225671965_Structural_Engineering_Seeing_the_Big_Picture?enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2&el=1_x_3https://www.researchgate.net/publication/225671965_Structural_Engineering_Seeing_the_Big_Picture?enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2&el=1_x_2

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    KSCE Journal of Civil Engineering

    Vol. 12, No. 1 / January 2008

     pp. 25~29

    DOI 10.1007/s12205-008-8025-7

     Structural Engineering 

    Vol. 12, No. 1 / January 2008   − 25 −

    Structural Engineering: Seeing the Big Picture

    By W. F. Chen*

    ···································································································································································································································

    Abstract

    The state-of-the-art of progress of structural engineering over the last 50 years is examined in three areas: (1) The spatialidealization of structural elements in the form of kinematical assumptions; (2) The constitutive idealization of materials in the form of generalized stresses and generalized strains relations; and (3) The computational implications of solution strategy in the form of closed form, approximate, and numerical procedures on the structural level.

    Keywords: structural engineering, stress-strain, kinematics, finite element, strength of materials, modeling and simulation, state-of-

    the-art 

    ···································································································································································································································

    1. Introduction

    Structural engineering is a part of the broad and fascinating

    subject of mechanics of materials or continuum mechanics,

    which spans the spectrum from the fundamental aspects of 

    elastic and inelastic behavior of materials to the practical solution

    of engineering problems in engineering practice.

    Mechanics is a branch of applied physics involving

    mathematical formulation of a physical problem and its solution

    strategy for engineering applications. The process must involve

    three basic conditions or equations for solutions:

    1. Equilibrium equations or motion reflecting law of physics

    (Newton’s law or Physics).

    2. Constitutive equations or stress-strain relations reflecting

    material behavior (Materials or Experiments).

    3. Compatibility equations or kinematical assumptions reflect-

    ing the geometry (Continuity or Logic).

    The required simplicity of equilibrium, material behavior, and

    kinematics to be usable with the most powerful computers, for 

    the analysis or design of engineering structures over their life

    cycle simulation, requires drastic idealizations and simplifications

    to achieve realistic and practical solution for engineering design.

    This paper shows how structural engineering field has been

    evolved and progressed over the last 50 years along with the

    rapid growth and development of computing power over the last

    several decades.

    2. Strength of Materials Approach to StructuralEngineering in the Early Years

    The methods of formulation and calculation of a structural

     problem must be adapted to a wide class of structural forms so

    that the basic equations to be written for a structural element are

    manageable and not too excessively complex. To this end, the

    concept of  generalized stresses  and  generalized strains  were

    introduced in the 1950’s for solutions of strength of materials

    types of problems including beams, columns, beam-columns that

    form the basis of analysis for frame design. This was later 

    extended to include plate and shell types of structural analysis

    and design.

    In the case of simple beam theory, for example, the stressed

    state in a beam element is determined by only one generalized

    stress, the bending moment, instead of six stresses; while the

    corresponding deformation is defined by one generalized strain,

    the curvature, instead of six strains. This drastic simplification is

    achieved through the powerful kinematical assumption of plane

    section remains plane after bending. This generalized stress and

    generalized strain concept for a simple beam element can be

    easily extended to the case of column element, for example, with

    combined generalized stresses of bending moment and axial

    force with the corresponding generalized strains of bending

    curvature and axial shortening.

    As a result of this simplification, the equilibrium equations are

    used to relate the stresses in an element to its generalized

    stresses, while the kinematical assumption is used to relate the

    strains in an element to its generalized strains, and the stress-strain

    relations of materials are then used to derive the generalized

    stresses and generalized strains relations for a structural element.

    The basic formulation for a structural member is now reduced to

    a one-dimensional problem instead of six dimensions in the sense

    of continuum mechanics approach to a structural engineering

     problem.

    *Professor, Department of Civil Engineering, University of Hawaii, Honolulu, Hawaii 96822 (E-mail: [email protected])

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    W. F. Chen

    − 26 − KSCE Journal of Civil Engineering

    For an elastic problem, most of strength of materials problems

    can be solved in closed form by power series expansion as well

    documented in the famous work of Timoshenko. Many of these

    well known classical solutions for beams, columns, beam-columns,

     plates and shells were reported in a series of widely popular 

     books by Timoshenko (1951, 1953, 1961, 1962), among others.

    For high rise building frames, the entire length of a structural

    member is selected as the basic element for engineering analysis.

    To this end, the corresponding relationships between the

    generalized stresses (member end moments and end forces) and

    the corresponding generalized strains (member end rotations and

    relative end lateral displacements) for a structural member were

    represented in the form of the well-known “ slope-deflection

    equations” for elastic structural system analysis (Chen and Lui,

    1987, 1991). The slope deflection equations were simple and

     powerful and thus widely used in engineering practice for building

    frame design based on the Allowable Stress Design codes in

    early years.

    In engineering practice, a more powerful companion approxi-

    mate method known as the “moment distribution method ” was

    also developed by Hardy Cross at the University of Illinois

    (Gere, 1962). It was based on the St. Venant principle in that the

    moment distribution in a particular structural member in a high

    rise building frame is affected mostly by the surrounding

    members adjacent to it. The influence of other members in some

    distance from the member under consideration is relative small

    and may be ignored after a few cycles of iteration.

    For inelastic problems, a further simplification of material

     behavior is made by ignoring strain hardening and also to

    eliminating entirely the factor of time from the formulation. This

    leads to the time independent idealization for plastic behavior 

    and enables us to use the simple plastic theory to determine the

     plastic collapse load with the equilibrium methods for lower 

     bound solutions and the mechanism methods for upper bound

    solutions.

    For low rise building, simple plastic theory was developed in

    which the material model used was elastic perfectly plastic

    (ASCE Manual 41, 1971). The kinematical assumption used was

    the powerful concept of “ plastic hinge.” Upper and lower bound

    solutions were obtained by the simple mechanism methods

     bounded above; and the simple equilibrium methods with

    moment check bounded below (see for example, Chen and

    Sohal, 1995). The Plastic Design method was officially adopted

     by the American Institute of Steel Construction in the early

    1960’s (see, for example, ASCE Manual 41, 1971).

    As a result of this advancement, plastic design methods for 

    steel structures were spread widely and introduced quickly in

    various new codes around the world for steel design; while the

    companion ultimate strength design for reinforced concrete was

    advanced quickly and adopted widely in the reinforced concrete

    codes for building design. Similar advancements were also made

    for the plate theory for plate type of steel structural design; while

    the yield line theory was introduced at the same time for slab

    design in reinforced concrete code.

    Based on these simple and practical solution techniques using

    drastic simplifications and idealizations for materials, geometry

    and equations of equilibrium, the traditional “ Allowable Stress

     Design Method ” and the newly developed “ Plastic Design

    Method ” were widely used in engineering practice in those years.

    These simple and powerful design methods are ideal and suitable

    with the basic computing facility available at the time such as

    slide rule and calculators. Drastic idealizations and simplifications

    were the key elements for a rapid and successful implementation

    of these methods for design of real world engineering problems.

    In summary, the idealizations and simplifications used in the

    strength of materials approach to structural engineering problems

    can be highlighted by the following seven steps of progress:

    1. Structural elements – beam, column, beam-column, plate

    and shell.

    2. Generalized stresses – stress resultants such as moment and

    axial force.

    3. Generalized strains – strain resultants such as curvature and

    axial displacement.

    4. Stresses to generalized stresses – through equilibrium equa-

    tions.

    5. Strains to generalized strains – through kinematical as-

    sumptions.

    6. Generalized stress and generalized strain relations – 

    through stress-strain relations of materials.

    7. Solution strategy – series expansion, approximate and

    numerical.

    3. Finite Element Approach to Structural Engi-neering in Recent Years

    In the 1970’s, our computing power changed drastically with

    mainframe computing. The “ Finite Element methods” were well

    developed and widely used in structural engineering. The basic

    material model used was the extension from linear elasticity to

    inelasticity, or plasticity in particular. The basic kinematical or 

    compatibility condition used for a finite-element formulation

    was known as the “ shape function.” The equilibrium condition

    was achieved through a weak format of “equation of virtual 

    work ” instead of the usual free body equilibrium formulation.

    As a result of these simplifications, the force displacement

    relation for a finite element was expressed in the form of the

    generalized stress and generalized strain relationship. This basic

    relationship for an element in a discrete continuum of a structural

    system is known as the “nodal force and nodal displacement 

    equation.” The stresses in elements were related to the

    generalized stresses or nodal forces through the virtual work 

    equation. Elemental strains were related to the generalized strains

    or nodal displacements through the kinematical assumption, or 

    shape function. The incremental generalized stress and generalized

    strain relation for a finite element was then obtained through the

    constitutive equation of a particular material.

    In summary, the three basic conditions for a valid solution of a

    typical finite element formulation are achieved with the following

    https://www.researchgate.net/publication/246379698_History_of_Strength_of_Materials?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/246379698_History_of_Strength_of_Materials?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/44725858_The_Theory_of_Elasticity?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2

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    Structural Engineering: Seeing the Big Picture

    Vol. 12, No. 1 / January 2008   − 27 −

    idealizations and simplifications:

    (1) Equilibrium Condition (Newton’s Law or Physics)

    The virtual work equation is used exclusively to establish the

    relationship between the stress in an element to the generalized

    stresses or nodal forces at nodal points.

    (2) Kinematics Condition (Continuity or Logic)

    The shape function is introduced to establish the relationship

     between the strains in an element to the generalized strains of 

    nodal displacements at the nodal points.

    (3) Constitutive Relations (Material or Experiment)

    The theory of plasticity or viscosity is used to relate the

    generalized stresses to generalized strains or the nodal forces and

    nodal displacements relationships through the use of constitutive

    equations of engineering materials.

    The two-volume treatise on constitutive equations for engineer-

    ing materials by Chen and Saleeb (1982), and Chen (1994) covers

    most of these developments, among others (Chen and Baladi,

    1985). During this period, we were able to solve almost any kind

    of structural engineering problems with computer simulation.

    For the first time in the history of computing, the physical theory

    is lagging behind the computing power. By now, engineers need

    to develop a more refined theory of constitutive equations for 

    engineering materials for their special finite element types of 

    applications.

    As a result of these simplifications, the structural engineering

     problem is now reduced to the solution of a set of simultaneous

    incremental equations for a structural system. Since the solution

    includes the inelastic behavior of materials which is load path

    dependent, the numerical scheme used was an incremental and

    iterative process (Chen and Han, 1988). Many numerical proce-

    dures were developed during the period, most notably the

    “tangent stiffness method”, among others.

    With a large amount of numerical data so generated, it became

    necessary for engineers to use probability theory and reliability

    analysis to analyze the data and develop design procedures for 

     practical implementation. As a result of this development, a new

    generation of codes based on an extensive computer simulation

    and reliability analysis was developed and adopted around the

    world. For the first time in engineering practice ever, the load

    effect and structural resistance effect were treated separately in

    design, each with its own safety or load factor. The new code in

    US, for example, was adopted by the American Institute of Steel

    Construction entitled “the load and resistance factor design

     specifications for steel buildings” in 1986.

    The following is a brief summary in a tabular form of the

    impact of the applications of finite element methods with

     plasticity theory on structural engineering practice.

    3.1 In the 1970s: Development of Structural Member 

    Strength Equations

    • Beam strength equation – beam design curve.

    • Column strength equation –column design curve.

    • Beam-Column strength equation – beam-column interaction

    design curve.

    • Bi-axially loaded column strength equation for plastic design

    in steel building frames.

    These developments were summarized in the two-volume

     beam-columns treatise by Chen and Atsuta (1976, 1977) and the

    SSRC Guide edited by Galambos (1988), among others.

    3.2 In the 1980s: Limit States to Design

    • Development of reliability-based codes.

    • The publication of the 1986 AISC/LRFD Specification.

    • The introduction of the second-order elastic analysis to the

    design codes.

    • The explicit consideration of semi-rigid connections in frame

    design (now known as the PR Construction) (Chen and Kim,

    1998).

    These developments were summarized in the structural

    stability books by Chen and Lui (1991) and Chen (1993), among

    others.

    3.3 In the 1990s: Structural System Approach to Design

    • Second-Order inelastic analysis for steel frame design was

    under intense development (White and Chen, 1993).

    • The theory of plasticity is combined with the theory of 

    stability for a direct steel frame design (Chen and Kim,

    1997).

    • The advanced analysis considers explicitly the influence of 

    structural joints in analysis/design process (Chen, 2000).

    These developments were summarized in the structural

    stability books by Chen and Toma (1994), and Chen and Lui

    (2005), among others.

    4. Model-Based Simulation in Civil Engineering:Challenges and Opportunities

    We are now in a desk top environment for free computing. We

    are able to do a large scale simulation of structural system over 

    its life-cycle performance analysis. Computer simulation has

    now joined theory and experimentation as a third path for 

    engineering design and performance evaluation.

    The development of model-based simulation for any civil

    engineering structures or facilities must involve the following

    four steps:

    4.1 Modeling of Materials

    The constitutive equations for materials are now moving from

    time-independent to time-dependent behaviors such as creep,

    relaxation, temperature variation, and deterioration or aging.

    These equations must be developed by engineers on the basis of 

    mechanics, physics, and materials science. In a numerical

    analysis of these materials in a structural system, the proper 

    modeling of discontinuity and fracture or crack for tension-weak 

    materials becomes increasing important.

    4.2 Solution Algorithm

    For a realistic life-cycle simulation of constructed facilities, it

    https://www.researchgate.net/publication/37408257_Soil_Plasticity_Theory_and_Implementation?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/37408257_Soil_Plasticity_Theory_and_Implementation?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/265620704_Plasticity_for_Structural_Engineers?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/245304235_Practical_Analysis_for_Partially_Restrained_Frame_Design?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/245304235_Practical_Analysis_for_Partially_Restrained_Frame_Design?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/279957993_Design_of_Steel_Structures_with_LRFD_Using_Advanced_Analysis?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/279957993_Design_of_Steel_Structures_with_LRFD_Using_Advanced_Analysis?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/265620704_Plasticity_for_Structural_Engineers?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/245304235_Practical_Analysis_for_Partially_Restrained_Frame_Design?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/245304235_Practical_Analysis_for_Partially_Restrained_Frame_Design?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/279957993_Design_of_Steel_Structures_with_LRFD_Using_Advanced_Analysis?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/279957993_Design_of_Steel_Structures_with_LRFD_Using_Advanced_Analysis?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/37408257_Soil_Plasticity_Theory_and_Implementation?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/37408257_Soil_Plasticity_Theory_and_Implementation?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2

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    W. F. Chen

    − 28 − KSCE Journal of Civil Engineering

    is not uncommon for engineers to deal with the mathematical

    modeling of radically different scales, in time and/or space. The

    computational effort for different parts of a large structural

    system may be drastically different. For example, in the analysis

    of reinforced concrete bridge system under seismic loading, a

    macro scale is necessary to model the overall behavior of the

    structure-soil interaction. Yet, a micro scale is needed at a local

    level to trace crack initiation and propagation.

    Computation efficiency can be achieved in this case by using

     parallel finite-element analyses for the structural system. Parallel

    macro and micro analyses can be performed by multiple machines,

    such as PC cluster systems. This computational method requires

    repartitioning of the domain during the course of the analysis,

    making the development of suitable interfaces, data communica-

    tion tools, or central databases with different levels for different

    scales in time and in space is of critical importance.

    As another example, the finite-element method is preferred in

    structural engineering and solid mechanics, while the finite-

    difference method is more commonly used in fluid mechanics.

    When dealing with structure-fluid interaction problems, as

    frequently encountered in offshore structural engineering, the

    development of suitable data translators or data communication

    tools is necessary in order to use existing codes, which are based

    on two different methodologies.

    4.3 Software Development

    There are hundreds of software systems on the market to

    support software development. A software support system is a

    compatible set of tools, usually based on a specific software

    development methodology, which can be employed for several

     phases of software and operation.

    The key to a domain-specific software development environ-

    ment is software reuse. Software reuse enables the knowledge

    obtained from the solution of a particular problem to be accu-

    mulated and shared in the solution of other problems. If software

    components accumulated from previous software development

    can be utilized readily in the development of new applications,

    substantial applications can be built more efficiently. This is an

    ideal environment for university research and education. This

    idea was carried out and implemented, for the first time, at

    Purdue University with my former colleagues, D.W. White and

    E. Sotelino (1994), and former doctoral students, H. Zhang and J.

    Lu, among others with major financial supports from the

     National Science Foundation (NSF).

    At present, the key to software development is software in-

    tegration. Since most commercial software has its own particular 

    function and input/output formats, it may prohibit direct data

    access. It seems very necessary to unify the documentation from

    different software and to make the newest and largest efforts in

    the development of standard models, such as Industry Founda-

    tion Class (IFC). Following the development of grid computing,

    the interoperability of facilities and software at different location

    in the network can be realized.

    4.4 Visualization and Verification

    Modeling is science, simulation is computing, and computing

    requires solution algorithms and software development. Visual-

    ization is a necessary step to aid in the interpretation of the

    simulated results. Validation of the simulation of an engineering

     problem must be verified by experimental work.

    Model-based simulation is inherently interdisciplinary in

    science and engineering, where computation plays the key role.

    The entire process of model-based simulation involves the

    following seven steps:

    1. Experimental measurements as the basis for the devel-

    opment of relevant constitutive equations for a physical

    system;

    2. Design of a proper algorithm for its numerical solutions;

    3. Implementation of the procedures with necessary docu-

    mentation and software interface development;

    4. Selection of appropriate hardware to run the computer 

    simulation of the physical system;

    5. Validation of the computer model with physical testing;

    6. Graphical visualization of the simulated results; and finally;

    7. Sharing of the simulation model with others through high

    speed network communication.

     In the current high-performance computing environment, the

    major challenges of modeling, simulation and validation are the

    integration of material science, structural engineering and com-

     putational mechanics with proper simplifications and idealizations

    for practical applications. As mentioned previously, modeling is

    science, simulation is computing, and validation is experi-

    mentation. All these three areas of further development require

    structural engineer’s own effort and focus including, for 

    example, the following issues for future structural engineering

    implementation:

    • From structural system approach to life-cycle structural

    analysis of structures covering construction sequence

    analysis during construction, performance analysis during

    service, and degradation and deterioration analysis during

    maintenance, rehabilitation, and demolition (Chong et al .,

    2002).

    • From finite element modeling for continuous media to finite

     block modeling for tension-weak materials with tensile crack 

    development and subsequent changing of structural geometry

    and topology.

    • From time-independent elastic and inelastic material model-

    ing to time-dependent modeling reflecting material degrada-

    tion and deterioration science (Montero et al., 2001).

    5. Concluding Remarks

    Advancement in computer technology in recent years has

    spurred the development of scientific simulation and visualization

    in science and engineering. Such capability has spurred similar 

    developments in structural engineering and allowed the solutions

    of many structural engineering problems before thought of 

    “unsolvable”, and consequently, are now driving progress in a

    https://www.researchgate.net/publication/285193331_Initiative_on_long_term_durability_of_materials_and_structures?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/285193331_Initiative_on_long_term_durability_of_materials_and_structures?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/285193331_Initiative_on_long_term_durability_of_materials_and_structures?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2https://www.researchgate.net/publication/285193331_Initiative_on_long_term_durability_of_materials_and_structures?el=1_x_8&enrichId=rgreq-3d0d9ff5-073f-47af-9525-757c06796158&enrichSource=Y292ZXJQYWdlOzIyNTY3MTk2NTtBUzo5OTE2NzQxNDI1OTcyMkAxNDAwNjU0NzYyNTg2

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    Structural Engineering: Seeing the Big Picture

    Vol. 12, No. 1 / January 2008   − 29 −

    number of challenging areas of structural engineering including,

    for example, life-cycle type of analysis for cost estimate and life-

    cycle design considerations, finite block type of analysis for 

    structures with tensile crack development and topology change

    under an increasing loading, and degradation type of analysis for 

    deterioration and aging of structural materials with time, among

    others.

    Good progress has been made in recent years in structural

    engineering, but much more remains to be done in terms of 

    simplification and idealization in constitutive modeling of 

    materials, structural modeling of elements, and computing

    strategy for reliable solution scheme of large scale simulation in

    time and space for large constructed facilities.

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