This paper presents the performed enhanced parametric reanalyses of the concrete single-cell shor... more This paper presents the performed enhanced parametric reanalyses of the concrete single-cell short and medium span bridge box girders with side cantilevers by the improved Maisel model. The box structures loaded by an unsymmetrical load regarding the vertical axis of the girder in the cross-section have been separately analyzed with regard to symmetric load and to antisymmetric load. Regarding symmetric load the structure has been analyzed by the engineers’ theory of bending taking into consideration the shear lag effect. The torsional warping analysis was analyzed using thin-walled beam theory and the distortion warping using the beam on elastic foundation analogy. The following box girder characteristics have been varied: the span length of the box girder, the box width, the length of the side cantilevers and the box web thickness. In the performed parametric analyses almost 600 different combinations were investigated and the appropriate conclusions were drawn.
Građevinar : časopis Hrvatskog saveza građevinskih inženjera, 1992
Prikazana je upotreba dvodimenzionalnih preslikanih beskonacnih elemenata u kombinaciji sa standa... more Prikazana je upotreba dvodimenzionalnih preslikanih beskonacnih elemenata u kombinaciji sa standardnim konacnim izoparametrickim elementima u primjeni pri rjesavanju problema s neogranicenim podrucjima kod analize linearnog i nelinearnog stanja naprezanja i deformacija. Posebno je izvrsena analiza oko podzemnih otvora uz osvrt na ukljucivanje gravitacijskog opterecenja. Pokazano je da kombinirana upotreba konacnih i beskonacnih elemenata daje tocnije rjesenje od onih dobivenih standardnom metodom konacnih elemenata.
This paper deals with the analysis of shape of the charge welds in the extrusion of tubes by mean... more This paper deals with the analysis of shape of the charge welds in the extrusion of tubes by means of hollow dies (bridge dies) as a function of extrusion parameters, such as temperature, extrusion ratio and height of welding chamber. The experiments were performed by extrusion of Al99.5 tubes in laboratory conditions. The charge welds are graphically modelled by computer. Results of experiments supported by graphical modelling are used for making optimization of the extrusion parameters, taking the minimal length of the charge welds as criteria. The results of optimization have showed that decrease of the length of the charge welds, i.e. better metal flow through hollow dies, can be obtained by increasing the extrusion temperature, reducing extrusion ratio and lowering the height of the welding chamber.
In the large spectrum of practical engineering geomechanical problems, there is always a problem ... more In the large spectrum of practical engineering geomechanical problems, there is always a problem about how to treat unbounded continua in the most rational way in order to get accurate results. This paper considers the use of mapped infinite elements in conjunction with finite elements in both linear and non-linear stress analysis. It summarises previous research on the use of mapped infinite elements in the linear elastic and non-linear stress analysis. Material non-linear behaviour is described by Perzyna's elasto-visco-plastic model in widely accepted standard finite element formulation. Additional attention is given to gravity loading and its common action with other loadings. The gravity loading can be treated in two different ways: (a) by evaluating element nodal forces from the actual values of gravity stresses in causs points or element volume weight; (b) by incorporating gravity stress from causs points directly in the total stress vector as initial ones. In the linear and non-linear analysis when the problem is discretized only with finite elements both strategies give the same results. Discretizing the half-space under consideration with infinite elements too, only the second strategy gives the correct results. The applicability of the suggested technique is examined and the benefits of employing proposed finite/infinite element approach in both linear and non-linear analysis is then illustrated by the solution of few unbounded geomechanical problems. (TRRL)
The paper describes ten large bridges for each specific type of construction: suspension bridges,... more The paper describes ten large bridges for each specific type of construction: suspension bridges, cable-stayed bridges, arch bridges, truss bridges and beam bridges. They are classified by the length of span. Besides present records, tentative sketches for maximum possible spans and the construction and design of large span bridges are shown. (TRRL)
Pri određivanju stanja naprezanja i deformacija u tlu i oko podzemnih otvora veliki utjecaj kod n... more Pri određivanju stanja naprezanja i deformacija u tlu i oko podzemnih otvora veliki utjecaj kod numericke analize ima velicina promatranog podrucja i pripadni rubni uvjeti. U sirokom spektru prakticnih inženjerskih problema iz podrucja geomehanike, cesto se postavlja pitanje kako tretirati neograniceno podrucje na najoptimalniji nacin da bi se dobili sto tocniji rezultati. U tom kontekstu, ovaj rad opisuje upotrebu preslikanih beskonacnih elemenata kako u linearnoj tako i u nelinearnoj analizi stanja naprezanja i deformacija u tlu i oko podzemnih otvora.
One of the every day present engineering structure is cantilever usually loaded with concentrated... more One of the every day present engineering structure is cantilever usually loaded with concentrated force at the free end for which the deflection at that point had to be determined. For example, these structures are reinforced concrete poles of the overhead electric distribution network, reinforced concrete wind turbine towers, etc. When the cross-section is constant along the length of the cantilever, there is no problem in determining the deflection of the cantilever’s end point using some classical methods (analytical, grapho-analytical, graphical or numerical). Problems emerge when the cross-section is not constant, i.e. in the situations when the cross-section is linearly variable, especially in the situations when we have nonlinearly variable circular hollow cross-section. All possible situations which can appear are: (a) solid circular cross-section linearly variable along the length ; (b) hollow circular cross-section with constant radius of the inner cavity and linearly variable outer radius (variable thickness of the wall) ; (c) hollow circular crosssection with equally linearly variable inner and outer radiuses (constant thickness of the wall) ; (d) hollow circular cross-section with uneven linearly variable inner and outer radiuses (variable thickness of the wall). This paper describes several possible models for deflection determination of the cantilever end point with variable circular hollow cross-sections. Some investigations have been performed through few diploma theses, and obtained results were compared with experimental ones.
The finite element methods are well established in many branches of engineering and are now routi... more The finite element methods are well established in many branches of engineering and are now routinely used in the solution procedure of many large scale industrial problems. Computational procedures, which are almost exclusively based on the finite element method, are now increasingly employed in the modelling of the elastomers due to (in addition to improving computational power) remarkable recent advances in the numerical treatment of large starin elastic and elasto-plastic deformation phenomena in the presence of frictional contact. Therefore, this paper discusses in short, some computational aspects of the nonlinear finite element analysis of the elastomers, namely: material behaviour, automatic determination of the material parameters from test data, damage and failure, dynamics and vibration, automated contact analysis techniques, and automated solution strategies. Although the main focus of the paper is on the elastomers (or rubber-like materials) and foams, many of these concepts are also applicable to the finite element analysis of glass, plastics, and biomaterials. At the end, areas which still required further research and development are mentioned. The paper is concluded with some questions which should be asked when selecting a code for nonlinear finite element analysis of elastomers or rubber-like materials.
Different types of box girders with constant cross-section and material characteristics along spa... more Different types of box girders with constant cross-section and material characteristics along spans are used for bridge span structures. The paper analyzes box girder bridges using the mindlin finite strip formulation. The applicability of the proposed procedure is illustrated with a single-cell box girder. For the covering abstract of the conference see IRRD 812301.
Relevant factors and procedures used in quality assurance during design, construction and use of ... more Relevant factors and procedures used in quality assurance during design, construction and use of bridges are presented. A special emphasis is placed on the importance of responsible and professional verification in every stage of the work process, on testing activities and permanent monitoring of changes during realization and use, and on the need for the automated and programmed collection, analysis and archiving of bridge-related information. A significance of systemic economic management of bridges is
stressed, which is in fact resolved through an efficient management system.
Nowadays, we are witnesses of significant projects and engineering works connecting different par... more Nowadays, we are witnesses of significant projects and engineering works connecting different parts of Croatia with the network of fast and safe motorways. These motorways incorporate a large number of bridges which have already been built or are in the construction phase. The construction process always has twofold effects; on one side it has great influence on the economical and social development of the country and on the other side it has negative influence on the environment changing it forever considering its different aspects, i.e. visually, biological, ecological, cultural and functional. Hence, it is necessary to protect inherited environment not only by legislation but by a detailed and carefully developed management procedure. Also, it is important and necessary to built structures of long-lasting esthetical and functional values with lowest possible financial costs. This paper proposes the possibility of improving the bridge management and organization system by introducing new appropriate standards and by constituting a special institution employing skilled experts. Based on the clearly developed and prescribed procedures and standards and after consultations with the investors such professional institution (or institutions) should bring decisions concerning full bridge management from the very first idea to the end of its service life including bridge demolition and environment recovery.
This paper presents the performed enhanced parametric reanalyses of the concrete single-cell shor... more This paper presents the performed enhanced parametric reanalyses of the concrete single-cell short and medium span bridge box girders with side cantilevers by the improved Maisel model. The box structures loaded by an unsymmetrical load regarding the vertical axis of the girder in the cross-section have been separately analyzed with regard to symmetric load and to antisymmetric load. Regarding symmetric load the structure has been analyzed by the engineers’ theory of bending taking into consideration the shear lag effect. The torsional warping analysis was analyzed using thin-walled beam theory and the distortion warping using the beam on elastic foundation analogy. The following box girder characteristics have been varied: the span length of the box girder, the box width, the length of the side cantilevers and the box web thickness. In the performed parametric analyses almost 600 different combinations were investigated and the appropriate conclusions were drawn.
Građevinar : časopis Hrvatskog saveza građevinskih inženjera, 1992
Prikazana je upotreba dvodimenzionalnih preslikanih beskonacnih elemenata u kombinaciji sa standa... more Prikazana je upotreba dvodimenzionalnih preslikanih beskonacnih elemenata u kombinaciji sa standardnim konacnim izoparametrickim elementima u primjeni pri rjesavanju problema s neogranicenim podrucjima kod analize linearnog i nelinearnog stanja naprezanja i deformacija. Posebno je izvrsena analiza oko podzemnih otvora uz osvrt na ukljucivanje gravitacijskog opterecenja. Pokazano je da kombinirana upotreba konacnih i beskonacnih elemenata daje tocnije rjesenje od onih dobivenih standardnom metodom konacnih elemenata.
This paper deals with the analysis of shape of the charge welds in the extrusion of tubes by mean... more This paper deals with the analysis of shape of the charge welds in the extrusion of tubes by means of hollow dies (bridge dies) as a function of extrusion parameters, such as temperature, extrusion ratio and height of welding chamber. The experiments were performed by extrusion of Al99.5 tubes in laboratory conditions. The charge welds are graphically modelled by computer. Results of experiments supported by graphical modelling are used for making optimization of the extrusion parameters, taking the minimal length of the charge welds as criteria. The results of optimization have showed that decrease of the length of the charge welds, i.e. better metal flow through hollow dies, can be obtained by increasing the extrusion temperature, reducing extrusion ratio and lowering the height of the welding chamber.
In the large spectrum of practical engineering geomechanical problems, there is always a problem ... more In the large spectrum of practical engineering geomechanical problems, there is always a problem about how to treat unbounded continua in the most rational way in order to get accurate results. This paper considers the use of mapped infinite elements in conjunction with finite elements in both linear and non-linear stress analysis. It summarises previous research on the use of mapped infinite elements in the linear elastic and non-linear stress analysis. Material non-linear behaviour is described by Perzyna's elasto-visco-plastic model in widely accepted standard finite element formulation. Additional attention is given to gravity loading and its common action with other loadings. The gravity loading can be treated in two different ways: (a) by evaluating element nodal forces from the actual values of gravity stresses in causs points or element volume weight; (b) by incorporating gravity stress from causs points directly in the total stress vector as initial ones. In the linear and non-linear analysis when the problem is discretized only with finite elements both strategies give the same results. Discretizing the half-space under consideration with infinite elements too, only the second strategy gives the correct results. The applicability of the suggested technique is examined and the benefits of employing proposed finite/infinite element approach in both linear and non-linear analysis is then illustrated by the solution of few unbounded geomechanical problems. (TRRL)
The paper describes ten large bridges for each specific type of construction: suspension bridges,... more The paper describes ten large bridges for each specific type of construction: suspension bridges, cable-stayed bridges, arch bridges, truss bridges and beam bridges. They are classified by the length of span. Besides present records, tentative sketches for maximum possible spans and the construction and design of large span bridges are shown. (TRRL)
Pri određivanju stanja naprezanja i deformacija u tlu i oko podzemnih otvora veliki utjecaj kod n... more Pri određivanju stanja naprezanja i deformacija u tlu i oko podzemnih otvora veliki utjecaj kod numericke analize ima velicina promatranog podrucja i pripadni rubni uvjeti. U sirokom spektru prakticnih inženjerskih problema iz podrucja geomehanike, cesto se postavlja pitanje kako tretirati neograniceno podrucje na najoptimalniji nacin da bi se dobili sto tocniji rezultati. U tom kontekstu, ovaj rad opisuje upotrebu preslikanih beskonacnih elemenata kako u linearnoj tako i u nelinearnoj analizi stanja naprezanja i deformacija u tlu i oko podzemnih otvora.
One of the every day present engineering structure is cantilever usually loaded with concentrated... more One of the every day present engineering structure is cantilever usually loaded with concentrated force at the free end for which the deflection at that point had to be determined. For example, these structures are reinforced concrete poles of the overhead electric distribution network, reinforced concrete wind turbine towers, etc. When the cross-section is constant along the length of the cantilever, there is no problem in determining the deflection of the cantilever’s end point using some classical methods (analytical, grapho-analytical, graphical or numerical). Problems emerge when the cross-section is not constant, i.e. in the situations when the cross-section is linearly variable, especially in the situations when we have nonlinearly variable circular hollow cross-section. All possible situations which can appear are: (a) solid circular cross-section linearly variable along the length ; (b) hollow circular cross-section with constant radius of the inner cavity and linearly variable outer radius (variable thickness of the wall) ; (c) hollow circular crosssection with equally linearly variable inner and outer radiuses (constant thickness of the wall) ; (d) hollow circular cross-section with uneven linearly variable inner and outer radiuses (variable thickness of the wall). This paper describes several possible models for deflection determination of the cantilever end point with variable circular hollow cross-sections. Some investigations have been performed through few diploma theses, and obtained results were compared with experimental ones.
The finite element methods are well established in many branches of engineering and are now routi... more The finite element methods are well established in many branches of engineering and are now routinely used in the solution procedure of many large scale industrial problems. Computational procedures, which are almost exclusively based on the finite element method, are now increasingly employed in the modelling of the elastomers due to (in addition to improving computational power) remarkable recent advances in the numerical treatment of large starin elastic and elasto-plastic deformation phenomena in the presence of frictional contact. Therefore, this paper discusses in short, some computational aspects of the nonlinear finite element analysis of the elastomers, namely: material behaviour, automatic determination of the material parameters from test data, damage and failure, dynamics and vibration, automated contact analysis techniques, and automated solution strategies. Although the main focus of the paper is on the elastomers (or rubber-like materials) and foams, many of these concepts are also applicable to the finite element analysis of glass, plastics, and biomaterials. At the end, areas which still required further research and development are mentioned. The paper is concluded with some questions which should be asked when selecting a code for nonlinear finite element analysis of elastomers or rubber-like materials.
Different types of box girders with constant cross-section and material characteristics along spa... more Different types of box girders with constant cross-section and material characteristics along spans are used for bridge span structures. The paper analyzes box girder bridges using the mindlin finite strip formulation. The applicability of the proposed procedure is illustrated with a single-cell box girder. For the covering abstract of the conference see IRRD 812301.
Relevant factors and procedures used in quality assurance during design, construction and use of ... more Relevant factors and procedures used in quality assurance during design, construction and use of bridges are presented. A special emphasis is placed on the importance of responsible and professional verification in every stage of the work process, on testing activities and permanent monitoring of changes during realization and use, and on the need for the automated and programmed collection, analysis and archiving of bridge-related information. A significance of systemic economic management of bridges is
stressed, which is in fact resolved through an efficient management system.
Nowadays, we are witnesses of significant projects and engineering works connecting different par... more Nowadays, we are witnesses of significant projects and engineering works connecting different parts of Croatia with the network of fast and safe motorways. These motorways incorporate a large number of bridges which have already been built or are in the construction phase. The construction process always has twofold effects; on one side it has great influence on the economical and social development of the country and on the other side it has negative influence on the environment changing it forever considering its different aspects, i.e. visually, biological, ecological, cultural and functional. Hence, it is necessary to protect inherited environment not only by legislation but by a detailed and carefully developed management procedure. Also, it is important and necessary to built structures of long-lasting esthetical and functional values with lowest possible financial costs. This paper proposes the possibility of improving the bridge management and organization system by introducing new appropriate standards and by constituting a special institution employing skilled experts. Based on the clearly developed and prescribed procedures and standards and after consultations with the investors such professional institution (or institutions) should bring decisions concerning full bridge management from the very first idea to the end of its service life including bridge demolition and environment recovery.
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stressed, which is in fact resolved through an efficient management system.
stressed, which is in fact resolved through an efficient management system.