1st Edition

Analysis and Optimum Design of Metal Structures



ISBN 9789054106692
Published December 31, 1996 by CRC Press
350 Pages

USD $250.00

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Book Description

Detailing a number of structural analysis problems such as residual welding stresses and distortions and behaviour of thin-walled rods loaded in bending, this text also explores mathematical function minimization methods, expert systems and optimum design of welded box beams.

Table of Contents

ABOUT THE AUTHORS -- LIST OF SYMBOLS -- INTRODUCTION -- Part 1: Analysis -- 1 RESIDUAL WELDING STRESSES AND DISTORTIONS -- 1.1 Simple examples of thermoelasticity -- 1.2 The Okerblom's analysis -- 1.3 Multi-pass welding -- 1.4 Effect of initial strains -- 1.5 The effect of external loading on the welding residual stresses -- 1.6 Reduction of residual stresses -- 1.7 Numerical examples -- 1.7.1 Suitable welding sequence in the case of a welded asymmetric I-beam -- 1.7.2 Welding in a clamping device -- 1.7.3 Welding in prebent state in a clamping device -- 1.8 Weld improvement methods -- 1.8.1 Weld geometry modification methods -- 1.8.2 Residual stress methods -- 2 THIN-WALLED RODS -- 2.1 Introduction -- 2.2 Bending and shear, shear center -- 2.3 Torsion -- 2.3.1 Saint Venant torsion -- 2.3.2 Warping torsion -- 3 STABILITY -- 3.1 Introduction -- 3.2 Classes of cross-sections -- 3.3 Compression members -- 3.3.1 Flexural buckling -- 3.3.2 Flexural-torsional buckling -- 3.4 Lateral-torsional buckling of beams loaded in bending -- 3.5 Beam-columns -- 3.6 Plate buckling -- 3.6.1 Classic results for plate buckling -- 3.6.2 Post-buckling behaviour of compressed plates -- 3.6.3 Limiting plate slendernesses -- 4 VIBRATION AND DAMPING, SANDWICH STRUCTURES -- 4.1 Measures of damping -- 4.2 Relations between the measures of damping -- 4.3 Classification of damping -- 4.4 Material damping -- 4.4.1 Characterization of viscoelastic materials -- 4.5 Material property measurements -- 4.6 Material damping in structures -- 4.7 Nonmaterial damping -- 4.8 Damping of welded structures -- 4.9 Sandwich structures -- 4.9.1 Vibrations of three-layered damped beam structures -- 4.9.2 Static behaviour -- 4.9.3 Dynamic behaviour -- 4.9.4 Measurements on an experimental sandwich beam -- 5 FABRICATION COSTS -- 5.1 Introduction -- 5.2 Fabrication times for welding -- 5.2.1 Formula proposed by Pahl & Beelich -- 5.2.2 The method based on COSTCOMP data -- 5.3 Surface preparation time -- 5.4 Painting time -- 5.5 Cutting and edge grinding times -- Part 2: Optimum design -- 6 MATHEMATICAL METHODS FOR STRUCTURAL SYNTHESIS -- 6.1 Historical background -- 6.2 Design variables, objective functions, constraints and preassigned parameters -- 6.2.1 Design variables and preassigned parameters -- 6.2.2 Constraints -- 6.2.3 Objective function -- 6.3 Divisions in optimization techniques -- 6.4 Methods without derivatives -- 6.4.1 Complex method -- 6.4.2 Flexible tolerance method -- 6.4.3 Hillclimb method -- 6.5 Methods with first derivatives -- 6.5.1 Penalty methods: SUMT, exterior, interior penalties -- 6.5.2 Davidon-Fletcher-Powell method -- 6.6 Methods with second derivatives -- 6.6.1 Newton's method -- 6.6.2 Sequential quadratic programming -- 6.7 Optimality criteria methods -- 6.8 Discrete optimization techniques -- 6.8.1 Backtrack method -- 6.8.2 Discretization after continuous optimization -- 6.9 Sensitivity analysis -- 6.10 Approximation techniques -- 6.11 Multiobjecti ve optimization -- 6.12 Description of the methods of multiobjective optimization -- 6.12.1 Method of objective weighting -- 6.12.2 Method of distance functions -- 6.12.3 Min-max method -- 6.12.4 Constrained method -- 6.12.5 Hybrid methods -- 6.12.6 Selection of the 'best' solution -- 7 EXPERT SYSTEMS -- 7.1 Artificial intelligence -- 7.2 Expert systems -- 7.3 Comparison of conventional programs and expert systems -- 7.4 Architecture of an expert system -- 7.5 Advantages of expert systems -- 7.6 Capabilities of expert systems -- 7.7 Inference engine -- 7.8 Steps for the development of expert systems -- 7.9 Knowledge representation -- 7.9.1 Semantic networks, object orientated systems -- 7.9.2 Object-attribute-value triplets -- 7.9.3 Production rules -- 7.9.4 Frames -- 7.9.5 Certainty factors -- 7.10 Knowledge acquisition -- 7.11 Expert system shells and ES-s for structural design -- 7.12 Overview on Personal Consultant -- 7.13 Overview of Level 5 Object -- 7.14 Application of an es for the optimum design of the main girders of overhead travelling cranes -- 7.14.1 Objective functions -- 7.14.2 Design constraints -- 7.14.3 Main data of an example solved by Personal Consultant -- 8 STATICALLY DETERMINATE BEAMS SUBJECTED TO BENDING AND SHEAR -- 8.1 Optimum design neglecting shear -- 8.1.1 Analytical method -- 8.1.2 Graphoanalytical method -- 8.1.3 Some comparisons -- 8.1.4 Effect of painting costs -- 8.2 Optimum design considering shear -- 8.3 Multicriteria optimization of a welded box beam -- 9 TUBULAR MEMBERS -- 9.1 Compression -- 9.1.l Centrally compressed steel struts -- 9.1.2 Unsafe design using the Euler buckling curve -- 9.1.3 Absorbed energy of CHS and SHS braces cyclically loaded in tension-compression -- 9.1.4 Optimum design and imperfection-sensitivity of centrally compressed SHS and CHS aluminium struts -- 9.1.5 Tubular columns prestressed by tension ties -- 9.2 Bending of CHS beams -- 9.2.1 Elastic range -- 9.2.2 Plastic range -- 10 STEEL AND ALUMINIUM STRUCTURAL COMPONENTS WITH FATIGUE CONSTRAINTS FOR WELDED JOINTS -- 10.1 Factors influencing the fatigue of welded joints -- 10.2 Fatigue design rules of the Eurocode 3 -- 10.3 Compression square hollow section strut connected to gusset plates -- 10.3.1 Steel structure -- 10.3.2 Aluminium structure -- 10.4 Compression rod of circular hollow section with a welded splice -- 10.4.1 Steel structure -- 10.4.2 Aluminium structure -- 10.5 Welded I-section cantilever connected to a column by fillet welds -- 10.5.1 Steel structure -- 10.5.2 Aluminium structure -- 10.6 Welded box beams -- 10.6.1 Steel structure -- 10.6.2 Aluminium structure -- 10.6.3 Numerical example -- 11 TUBULAR TRUSSES -- 11.1 Effect of cross-sectional shape on the optimum geometry of truss structures -- 11.2 A tubular truss of parallel chords -- 11.3 A truss with non-parallel chords -- 12 STIFFENED AND CELLULAR PLATES -- 12.1 Main characteristics of stiffened and cellular plates -- 12.2 Optimum design of a cellular plate of square symmetry by simplified hand calculation -- 12.3 Cost comparisons of stiffened and cellular plates -- 12.3.1 Introduction -- 12.3.2 A brief literature survey -- 12.3.3 Minimum cost design of a square cellular plate -- 12.3.4 Minimum cost design of a square stiffened plate -- 12.3.5 Numerical example for both structural versions -- 12.4 Effect of fabrication cost on the optimum dimensions of a stiffened Plate -- 12.5 Minimum cost design of rectangular cellular plates -- 12.5.1 The cost function -- 12.5.2 The design constraints -- 12.5.3 The optimization procedure -- 12.5.4 Numerical examples -- 12.5.5 Conclusions -- 13 WELDED STEEL BRIDGES -- 13.1 Survey of selected literature -- 13.2 Main tubular truss girder of a belt-conveyor bridge -- 13 .3 Minimum cost design of Vierendeel SHS trusses -- 13.3.1 Introduction -- 13.3.2 The cost function -- 13.3.3 Design constraints -- 13.3.4 An illustrative numerical example -- 13.3.5 Conclusions -- 14 WELDED STEEL SILOS -- 14.1 Introduction -- 14.2 Design and cost calculation of structural parts -- 14.2.1 Roof -- 14.2.2 Bin -- 14.2.3 Hopper -- 14.2.4 Columns -- 14.2.5 Ringbeam -- 14.3 Numerical example -- 14.4 Consideration of earthquake load -- 14.5 Conclusions -- APPENDICES -- Appendix A -- Appendix B -- Appendix C -- REFERENCES & BIBLIOGRAPHY -- NAME INDEX -- SUBJECT INDEX.

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Author(s)

Biography

Dr Jozsef Farkas is a professor of Metal Structures. He graduated in 1950 at the Faculty of Civil Engineering of the Technical University of Budapest. He teaches at the University of Miskolc since 1950, as a university professor since 1975. His academic scientific degrees: Candidate of technical science 1966, doctor of technical science 1978. His research field is the optimum design of metal structures, residual welding stresses and distortions, tubular structures, stiffened plates, vibration damping of sandwich structures. He has worked out expert opinions for many industrial problems, especially in the case of storage tanks, silos, cranes, welded press frames and other machine structures. He is the author of a university textbook about metal structures, an English book 'Optimum design of metal structures' (Ellis Horwood, Chichester 1984) and about 140 scientific articles in journals and conference proceedings. He is a Hungarian delegate of the International Institute of Welding (IIW), member of the International Society for Structural and Multidisciplinary Optimization (ISSMO) and a presidential member of the Welding Division of the Hungarian Scientific Society of Mechanical Engineers. Dr Karoly Jarmai is a professor in the Faculty of Mechanical Engineering at the University of Miskolc, Hungary. He graduated as a certified mechanical engineer and received his doctorate (dr. univ.) in 1979 at the University of Miskolc. He teaches design of steel structures, welded structures, composite structures and optimization in Hungarian and in English language for foreign students. His research interest includes structural optimization, mathematical programming techniques and expert systems. He made his C.Sc. (Ph.D.) dissertation at the Hungarian Academy of Science in 1988. He became European Engineer (Eur. Ing., FEANI, Paris) in 1990. He has got the habilitation (dr habil.) at the University of Miskolc, in 1995. He has defended his D.Sc. thesis at the Hungarian Academy of Science with the economic design of different steel structures, optimization and expert systems in 1995. He has published over 120 technical papers, student aids, textbook chapters and conference papers. He is member of ISSMO and the Hungarian delegate in IIW. He is the Deputy Secretary General of the Scientific Society of Mechanical Engineers (GTE) in Hungary and president of this society at the University of Miskolc.