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The design in computer aided design
ii Civil and structural engineering Jirousek, J 'A family of variable section curved beam and thick-shell or membranestiffening isoparametric elements' Int. ]. Numer. Methods Eng. Vol 17 No 2 (February 1981) pp 171-186 A family of isoparametric curved beam elements of a general, compact cross-section is introduced. The formulation is based on beam theory and takes into account both transverse shear deformation and shear centre location. The eleTnents exhibit the required displacement compatibility with Ahmad's superparametric thick-shell elements and isoparametric membrane elements. Examples presented at the end of the paper illustrate the validity of the formulation and the possibility of practical application o f the elements.
Barrett, D and Soler, A 'A finite element model for thick beams' Comput. Methods Appl. Mech. Eng. Vol 25 No 3 (March 1981) pp 2 9 9 - 3 1 3 A general method for obtaining higher order beam theories is reviewed and cast in a form for creating a finite element model. Reissner's principle and Legendre polynomial series expansions are key features in the development. A thick beam element is produced capable of representing nonlinear distributions, through the thickness, of all stress and deformation variables. The model can be used to analyse most thick beams and localized stress conditions. Beam problems are solved and the performance of the thick beam element is assessed.
Gero, J S and Radford, A D 'The design in computer aided design' in Proceedings o f the first international conference on computing in civil engineering ASCE, New York, NY, USA (1981) This paper is concerned with the design aspect of CAD. It examines the role of computers in the provision of information for design decision making in CAD and compares the advantages and disadvantages of three design paradigms: simulation, generation and optimization. It shows that decision making using optimization is a particularly useful approach. Usually design problems have a number of distinct and disparate objectives which are important to a greater or lesser degree. To encompass them the concepts of single objective optimization must be extended to provide a framework for the multi-objective case. Such design problems can be handled through the use of Pareto optimality approaches.
efforts associated with developing astandard for software quality assurance plans; it examines the needs, summarizes the significant issues, and indicates some of the major items under consideration for the forthcoming revision.
Machover, C 'Current directions in CAD' in Proceedings of the first international conference on computing in civil engineering ASCE, New York, NY, USA (1981) CAD (computer-aided design/drafting) systems are now proving their worth in day-in, day-out engineering applications. Civil engineering CAD applications will grow at about 45 per cent per year over the next few years, and will represent about 14 per cent of a multi-billion dollar market by 1985. This paper discusses typical applications, and hardware, software and" system trends.
Akin, ] E 'Verification checks of finite element models' in Proceedings of the first international conference on computing in civil engineering ASCE, New York, NY, USA (1981) The verification of finite element solutions is of increasing importance. A number of verification checks are recommended. They are based on both theoretical and empirical studies. Most of the checks can be automated to enhance the reliability of finite element codes.
Lyons, P 'Large deflection elasto-plastic analysis of stiffened shells using semiloof elements' in Numerical methods for nonlinear problems: proceedings of the international conference, University College, Swansea, UK Vol 1 {1980) iron's semiloof elements have proved superior for linear thin shell analysis, and the author and co-workers have recently presented an effective nonlinear semiloof shell formulation. For stiffened shell analysis, a beam element is required and this paper describes the nonlinear semiloof beam. The employed geometric nonlinearity accounts for the large displacements using a total Lagrangian formulation. The elastoplastic rigidities are computed using a rigorous multifibre formulation for arbitrary eccentric stiffener cross-sections, and a subincremental technique for fibre plasticity is included to produce reliable results with fewer load steps. Several numerical examples demonstrate the validity of the nonlinear semiloof beam formulation.
Buckley, F J 'A standard for software quality assurances' in Proceedings of the first international conference on computing in civil engineering ASCE, New York, NY, USA. (1981 )
Dinis, L M S, Martins, R A F and Owen, D R J 'Material and geometrically nonlinear analysis of thin plates and arbitrary shells' in Numerical methods for nonlinear problems: proceedings of the international conference, University College, Swansea, UK Vol 1 (1980)
This paper presents an interim report on the
The semiloof shell element is considered for
v o l u m e 13 n u m b e r 6 n o v e m b e r 1981
the nonlinear large displacement analysis of plates and shells. Lagrangian and updated formulations are both used for describing the large displacement response. An initial stiffness conventional plasticity algorithm and an elasto-viscoplastic model are considered for material nonlinear analysis. For the combined effect of material nonlinearity and large displacements an incremental stiffness procedure is adopted, whereby the tangential stiffness matrix is modified every load increment. Some plate and shell problems are solved to assess the performance of the semiloaf shell element under nonlinear conditions.
Cope, R J, Rao, P V and Edwards, K R 'Non-linear finite element analysis techniques for concrete slabs' in Numerical methods for nonlinear problems: proceedings of the international conference, University College, Swansea, UK Vol 1 (1980) Implementation of non-linear finite element procedures for analysing reinforced concrete slabs is discussed with reference to specification of suitable convergence criteria, and errors introduced by numerical integration when material properties vary over an element. Comments are given on implementations based on non-conforming rectangular and quadrilateral elements, and the heterosis formulation.
Cope, R J, Rao, P V, Clark, L A and Norris, P 'Modelling of reinforced concrete behaviour for finite element analysis of bridge slabs' in Numerical methods for nonlinear problems: proceedings of the international conference, University College, Swansea, UK Vol 1 (1980) Strategies for predicting response of bridge slabs to multiple load patterns and repeated load application are described. To reduce the cost of computation, effects of composite action such as tension stiffening and aggregate interlock are simulated by modifying concrete properties. Results obtained by implementing these strategies are compared with experimental data.
Cesari, F, Gheduzzi, P, Vannini, L and Hellen, T K 'The feasibility of finite element codes for elasto-plastic analysis' in Numerical methods for nonlinear prob/ems: Int. Conf University College, Swansea, UK Vol I (1980) This paper describes results obtained from the elasto-plastic analysis of two benchmark tests which have previously been conducted experimentally. Two finite element inelastic computer programs, A D I N A and BERSAFE, were employed. The analysis procedures are briefly discussed and the computed results are presented and compared with those of experiment. The results demonstrate the feasibility of performing elastoplastic analysis for the kinds of problems discussed and indicate the level of agreement the analyst can expect when using inelastic computer programs.
391
Barrett, D and Soler, A 'A finite element model for thick beams' Comput. Methods Appl. Mech. Eng. Vol 25 No 3 (March 1981) pp 2 9 9 - 3 1 3 A general method for obtaining higher order beam theories is reviewed and cast in a form for creating a finite element model. Reissner's principle and Legendre polynomial series expansions are key features in the development. A thick beam element is produced capable of representing nonlinear distributions, through the thickness, of all stress and deformation variables. The model can be used to analyse most thick beams and localized stress conditions. Beam problems are solved and the performance of the thick beam element is assessed.
Gero, J S and Radford, A D 'The design in computer aided design' in Proceedings o f the first international conference on computing in civil engineering ASCE, New York, NY, USA (1981) This paper is concerned with the design aspect of CAD. It examines the role of computers in the provision of information for design decision making in CAD and compares the advantages and disadvantages of three design paradigms: simulation, generation and optimization. It shows that decision making using optimization is a particularly useful approach. Usually design problems have a number of distinct and disparate objectives which are important to a greater or lesser degree. To encompass them the concepts of single objective optimization must be extended to provide a framework for the multi-objective case. Such design problems can be handled through the use of Pareto optimality approaches.
efforts associated with developing astandard for software quality assurance plans; it examines the needs, summarizes the significant issues, and indicates some of the major items under consideration for the forthcoming revision.
Machover, C 'Current directions in CAD' in Proceedings of the first international conference on computing in civil engineering ASCE, New York, NY, USA (1981) CAD (computer-aided design/drafting) systems are now proving their worth in day-in, day-out engineering applications. Civil engineering CAD applications will grow at about 45 per cent per year over the next few years, and will represent about 14 per cent of a multi-billion dollar market by 1985. This paper discusses typical applications, and hardware, software and" system trends.
Akin, ] E 'Verification checks of finite element models' in Proceedings of the first international conference on computing in civil engineering ASCE, New York, NY, USA (1981) The verification of finite element solutions is of increasing importance. A number of verification checks are recommended. They are based on both theoretical and empirical studies. Most of the checks can be automated to enhance the reliability of finite element codes.
Lyons, P 'Large deflection elasto-plastic analysis of stiffened shells using semiloof elements' in Numerical methods for nonlinear problems: proceedings of the international conference, University College, Swansea, UK Vol 1 {1980) iron's semiloof elements have proved superior for linear thin shell analysis, and the author and co-workers have recently presented an effective nonlinear semiloof shell formulation. For stiffened shell analysis, a beam element is required and this paper describes the nonlinear semiloof beam. The employed geometric nonlinearity accounts for the large displacements using a total Lagrangian formulation. The elastoplastic rigidities are computed using a rigorous multifibre formulation for arbitrary eccentric stiffener cross-sections, and a subincremental technique for fibre plasticity is included to produce reliable results with fewer load steps. Several numerical examples demonstrate the validity of the nonlinear semiloof beam formulation.
Buckley, F J 'A standard for software quality assurances' in Proceedings of the first international conference on computing in civil engineering ASCE, New York, NY, USA. (1981 )
Dinis, L M S, Martins, R A F and Owen, D R J 'Material and geometrically nonlinear analysis of thin plates and arbitrary shells' in Numerical methods for nonlinear problems: proceedings of the international conference, University College, Swansea, UK Vol 1 (1980)
This paper presents an interim report on the
The semiloof shell element is considered for
v o l u m e 13 n u m b e r 6 n o v e m b e r 1981
the nonlinear large displacement analysis of plates and shells. Lagrangian and updated formulations are both used for describing the large displacement response. An initial stiffness conventional plasticity algorithm and an elasto-viscoplastic model are considered for material nonlinear analysis. For the combined effect of material nonlinearity and large displacements an incremental stiffness procedure is adopted, whereby the tangential stiffness matrix is modified every load increment. Some plate and shell problems are solved to assess the performance of the semiloaf shell element under nonlinear conditions.
Cope, R J, Rao, P V and Edwards, K R 'Non-linear finite element analysis techniques for concrete slabs' in Numerical methods for nonlinear problems: proceedings of the international conference, University College, Swansea, UK Vol 1 (1980) Implementation of non-linear finite element procedures for analysing reinforced concrete slabs is discussed with reference to specification of suitable convergence criteria, and errors introduced by numerical integration when material properties vary over an element. Comments are given on implementations based on non-conforming rectangular and quadrilateral elements, and the heterosis formulation.
Cope, R J, Rao, P V, Clark, L A and Norris, P 'Modelling of reinforced concrete behaviour for finite element analysis of bridge slabs' in Numerical methods for nonlinear problems: proceedings of the international conference, University College, Swansea, UK Vol 1 (1980) Strategies for predicting response of bridge slabs to multiple load patterns and repeated load application are described. To reduce the cost of computation, effects of composite action such as tension stiffening and aggregate interlock are simulated by modifying concrete properties. Results obtained by implementing these strategies are compared with experimental data.
Cesari, F, Gheduzzi, P, Vannini, L and Hellen, T K 'The feasibility of finite element codes for elasto-plastic analysis' in Numerical methods for nonlinear prob/ems: Int. Conf University College, Swansea, UK Vol I (1980) This paper describes results obtained from the elasto-plastic analysis of two benchmark tests which have previously been conducted experimentally. Two finite element inelastic computer programs, A D I N A and BERSAFE, were employed. The analysis procedures are briefly discussed and the computed results are presented and compared with those of experiment. The results demonstrate the feasibility of performing elastoplastic analysis for the kinds of problems discussed and indicate the level of agreement the analyst can expect when using inelastic computer programs.
391