Structural Theory

STRUCTURAL THEORY CREATES IDEALIZATION OF STRUCTURE FOR PURPOSES OF ANALYSIS
Structural modeling is an essential and important tool in structural engineering.
Over the past 200 years, many of the most significant contributions to the understanding of the structures have been made by Scientist Engineers while working on mathematical models, which were used for real structures.
Application of mathematical model of any sort to any real structural system must be idealized in some fashion; that is, an analytical model must be developed.
There has never been an analytical model, which is a precise representation of the physical system. While the performance of the structure is the result of natural effects, the development and thus the performance of the model is entirely under the control of the analyst. The validity of the results obtained from applying mathematical theory to the study of the model therefore rests on the accuracy of the model. While this is true, it does not mean that all analytical models must be elaborate, conceptually sophisticated devices. In some cases very simple models give surprisingly accurate results. While in some other cases they may yield answers, which deviate markedly from the true physical behavior of the model, yet be completely satisfactory for the problem at hand.
Structure design is the application of structural theory to ensure that buildings and other structures are built to support all loads and resist all constraining forces that may be reasonably expected to be imposed on them during their expected service life, without hazard to occupants or users and preferably without dangerous deformations, excessive sideways (drift), or annoying vibrations. In addition, good design requires that this objective be achieved economically.
Provision should be made in application of structural theory to design for abnormal as well as normal service conditions. Abnormal conditions may arise as a result of accidents, fire, explosions, tornadoes, severer-than-anticipated earthquakes, floods, and inadvertent or even deliberate overloading of building components. Under such conditions, parts of a building may be damaged. The structural system, however, should be so designed that the damage will be limited in extent and undamaged portions of the building will remain stable. For the purpose, structural elements should be proportioned and arranged to form a stable system under normal service conditions. In addition, the system should have sufficient continuity and ductility, or energy-absorption capacity, so that if any small portion of it should sustain damage, other parts will transfer loads (at least until repairs can be made) to remaining structural components capable of transmitting the loads to the ground.
(‘‘Steel Design Handbook, LRFD Method’’, Akbar R. Tamboli Ed., McGraw- Hill 1997. ‘‘Design Methods for Reducing the Risk of Progressive Collapse in Buildings’’. NBS Buildings Science Series 98, National Institute of Standards and Technology, 1997. ‘‘Handbook of Structural Steel Connection Design and Details’’, Akbar R. Tamboli Ed., McGraw-Hill 1999’’).

—–5.1 Design Loads
—–5.2 Stress and Strain
—–5.3 Stresses at a Point
—–5.4 Torsion
—–5.5 Straight Beams
—–5.6 Curved Beams
—–5.7 Buckling of Columns
—–5.8 Graphic-Statics Fundamentals
—–5.9 Roof Trusses
—–5.10 General Tools for Structural Analysis
—–5.11 Continuous Beams and Frames
—–5.12 Load Distribution to Bents and Shear Walls
—–5.13 Finite-Element Methods
—–5.14 Stresses in Arches
—–5.15 Thin-Shell Structures
—–5.16 Cable-Supported Structures
—–5.17 Air-Stabilized Structures
—–5.18 Structural Dynamics
—–5.19 Earthquake Loads
—–5.20 Floor Vibrations
—–5.21 Wiss and Parmelee Rating Factor for Transient Vibrations
—–5.22 Reiher-Meister Scale for Steady-State Vibrations
—–5.23 Murray Criterion for Walking Vibrations

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