Parameter Study on Weight Minimization of Network Arch Bridges

The article concerns optimization of network arch bridges. This is challenging optimization problem involving even for conventional scheme of network arch bridge the identification of some topological parameters as well as shape configurations and all sizing parameters of structural members, seeking the minimum weight. Optimal bridge scheme is sought tuning a large set of design parameters of diverse character: the type of hanger arrangement, the number of hangers, their inclination angles and placement distances, the arch shape and rise, etc. Mathematically, the optimization of the bridge scheme is a mixed-integer constrained global optimization problem solved employing stochastic evolutionary algorithm. Plane heavy/moderate/and light-deck bridges of 18, 30, 42 and 54 m spans were optimized using proposed optimization technique. The decisive design parameters and their promising ranges were revealed. Also, the influence of some simplifications is shown: changing the arch shape from elliptical to circular, placing the hangers at equal distances, etc

Static analysis and simplified design of suspension bridges having various rigidity of cables

Increased deformability can be considered as the basic disadvantage of suspension bridges. One of the ways to increase the rigidity of a suspension bridge is to transfer a part of stiffening girder rigidity to a suspension main cable. To give the suspension bridge more stable appearance, the authors propose to use the cables of varying bending stiffness. The main cables can be made of standard section shapes or have a composite section. The object of this work was to study a method for analyzing and determining the internal forces in the main cables and stiffening girder under static loading to provide recommendations for designing suspension bridges with stiffened cables. Simple formulas are presented for determining displacements, internal forces and stresses in the main cable and stiffening girder. Finite element modeling was performed. The final part of the paper discusses design procedures for such suspension systems. An example of a pedestrian suspension bridge is appended. Santrauka Esminis kabamuju tiltu trūkumas ‐ didelis ju deformatyvumas. Deformatyvumui sumažinti autoriai siūlo dali standumo sijos lenkiamojo standžio perduoti kabamajam lynui. Baigtinio lenkiamojo standumo lynai gali būti daromi iš standartiniu valcuotuju profiliuočiu arba sudetinio skerspjūvio. Šio darbo tikslas ‐ pateikti supaprastinta metodika kabamojo tilto standaus lyno ir standumo sijos elgsenos analizei atlikti bei rekomendacijas tokiems statiškai apkrautiems tiltams projektuoti. Pateiktos paprastos formules lyno ir sijos poslinkiams, iražoms ir itempiams apskaičiuoti. Atliktas kabamosios tilto siste‐mos modeliavimas baigtiniais elementais. Aptartos tokiu kabamuju tiltu projektavimo procedūros. Pateiktas pesčiuju via‐duko kabamuju konstrukciju projektavimo pavyzdys. Reikšminiai žodžiai: kabamieji tiltai, standūs lynai, poslinkiai, iražos, BE modeliavimas, projektavimas, pesčiuju viaduka

Unconventional double-level structural system for under-deck cable-stayed bridges

This paper presents a new morphology of a cable-staying system for an under-deck cable-stayed bridge. The computational method proposed in the paper has been derived for a one-strut conventional cable staying system and applied for an unconventional double-level cable-staying system. The paper describes an algorithm for the correct implementation of the interaction between the cable-staying system and the deck. The numerical examples demonstrate that the proposed computational method based on a non-linear analysis of a simply supported and additionally restrained beam-column can be used for obtaining deformation response to the considered structure. An analysis of the same problem using finite element (FE) software ANSYS was carried out to present the accuracy of the proposed method. The paper also demonstrates comparison analysis between the conventional and unconventional structural schemes for the under-deck cable-stayed bridge under symmetric and asymmetric loading

Experimental and Analytical Studies of String Steel Structure for Bridges

Due to their efficiency, suspension structures are widely used in both roof slabs and different kinds of bridges, from which stress ribbon pedestrian bridges can be distinguished. The main disadvantage of the latter is high deformability, especially under asymmetrical loads. Recently, string structures or their systems have been introduced into bridge building. Numerical and experimental analysis of string behaviour under symmetrical and asymmetrical loads is carried out in the article. Analytical expressions for the calculation of string displacements and tensile forces are presented. The impact of the string pre-stress on the state of its stresses and deformations was evaluated. The assessment of the accuracy of analytical expressions by applying the results of numerical and experimental research is presented. A methodology is proposed for calculating the pre-stressing force taking into account the operational requirements. Three main loading options at different string pre-stress values are analysed. It is worth mentioning that the difference (error) between the analytical and numerical results is not extensive, it does not exceed 3%. It is necessary to notice that in all cases, the analytically obtained results are somewhat higher than FEM (numerically) obtained results

Static behaviour analysis of masts with combined guys

The purpose of this study was to develop a new type of guyed mast that incorporates a complex guy cable system with a particular focus on the effect of static loading on the response mast behaviour. The intension of such solution is to increase a number of elastic supports for the mast shaft that will impact on its stability under loading. The static analysis of a one‐level guyed mast has been undertaken. The effects of geometrical and physical design parameters on the displacements of the mast were determined. The analysis is illustrated with two‐guyed masts: the bending moments and lateral displacements were determined for a typical guyed mast and guyed mast with combined guys. Stiebų, turinčių mišriąsias atotampas, statinė elgsenos analizė Santrauka Aptariama originali plieninio stiebo konstrukcinė sandara, kurioje vietoje įprastinių vientisų atotampų taikomos mišriosios, turinčios atšakas, atotampos, sutelkiant dėmesį į statinės apkrovos įtaką stiebo elgsenai. Pagrindinis šio sprendinio privalumas – paslankiųjų atramų kiekio kamiene padidinimas, kas tiesiogiai daro įtaką stiebo stabilumui esant apkrovai. Statinės analizės metu buvo išnagrinėta pagrindinių komponuojamųjų geometrinių ir fizinių parametrų įtaka vieno atotampų lygio kamieno ruožo paslankiųjų atramų poslinkiams. Atlikta įprasto ir naujo tipo stiebo poslinkių ir įrąžų lyginamoji analizė. Reikšminiai žodžiai: stiebas, mišriosios atotampos, statinė apkrova, geometriniai ir fiziniai parametrai, elgsenos modeliavimas. First Published Online: 14 Oct 201

Non‐linear analysis of suspension bridges with flexible and rigid cables

One of the main problems related to the design of suspension bridges is stabilisation of their initial form. The tendency of suspension bridges to deform is generally determined by the kinematical displacements of the suspension cable caused by asymmetrical loads rather than by the elastic deformations. There are some suspension bridges when the so‐called rigid (stiff in bending) cables instead of usual flexible cables are suggested for stabilisation of their initial form. The analysis methods of such suspension bridges with rigid cables are underdeveloped. For the analysis of classical suspension bridges analytical models can be applied. However, in case of concentrated forces, the numerical techniques are preferred. The article presents analytical expressions for the calculation of internal forces and displacements of suspension bridges with a rigid cable. The article also discusses the discrete calculation model for classical suspension bridges. Santrauka Viena iš pagrindiniu kabamuju tiltu projektavimo problemu yra pradinus ju formos stabilizavimas. Kabamuju tiltu deformatyvuma lemia iš esmes ne tiek tampriosios deformacijos, kiek asimetriniu apkrovu sukelti kinematiniai kabamojo lyno poslinkiai. Yra žinomi kabamieji tiltai, kuriu pradinei formai stabilizuoti siūloma vietoje iprastiniu lanksčiuju lynu taikyti vadinamuosius standžius lynus. Tokiu kabamuju tiltu su standžiaislynais skaičiavimo metodai nera iki galo parengti. Klasikiniams tiltams su lanksčiu lynu skaičiuoti taikomi daugiausia kontinualūs modeliai, kurie esant tam tikrai tilto sandarai ar veikiant sutelktoms apkrovoms nera pakankamai tikslūs. Straipsnyje pateikiamos analizines išraiškos kabamuju tiltu su standžiu lynu iražoms ir poslinkiams apskaičiuoti, aptariamas diskretusis klasikiniu kabamuju tiltu skaičiavimo modelis. Published Published Online: 24 Jun 2011 Reikšminiai žodžiai: kabamasis tiltas, lankstus lynas, standus lynas, netiesine analize, kontinualus ir diskretinis modeliai, iražos ir poslinkiai

Design of circular composite beams with a different concrete core considering the effect of concrete in tension

Currently, the bending resistance of composite steel and concrete circular beams and beam-columns may be analysed assuming the interaction between the steel shell and concrete core but ignoring the behaviour of the part of the concrete core in tension. Some natural and numerical experiments show that an influence of this part of the concrete core on the total value of bending resistance of a composite member may be rather important. Therefore, this paper pre- sents the method developed for the design of hollow and solid concrete-filled steel tubular beams based on the test data. It takes into account an effect of the part of the concrete core in tension and gives a better agreement with test results than EC4 (EN 1994-1-1 2004). Also, the paper presents the results of carried out analytical, experimental and numerical investigations of the hollow centrifuged and solid concrete-filled steel tubular beams

A feasibility study of using composite reinforcement in transport and power industry structures

About 92% of Lithuanian bridges are made of reinforced concrete. Therefore, the problem of increasing the reliability and service life of their structures is most important for ensuring effective operation of transport buildings. The main factor causing transport building structures’ failure is associated with high water permeability and low resistance to attack by corrosive media of concrete used in construction. Ports, bridges, tunnels, viaducts make a group of transport structures strongly attacked by the aggressive media, e.g. cold air, water, ice, salts, etc. Though the members of these structures (e.g. columns, beams) are usually designed for 50 years of service, they often require a major overhaul or strengthening, when less than the half of this period has passed. Most of the damaged structures are the destroyed protective concrete layer and the corroded steel reinforcement. The corrosion of steel reinforcement is the main problem, causing the decrease of strength in the structures’ and their brittle failure. Now, composite reinforcement is the alternative material used for reinforcing in the considered structures. Its mechanical properties, including the tensile strength and resistance to the attack of aggressive media, are similar to or even better than those of commonly used steel reinforcement. The experimental data on using composite reinforcement in the compression members or in the compressed zones of flexural members of the structures are lacking. Therefore, most of design codes do not mention or even do not recommend using composite reinforcement in these cases. The paper presents the analysis of the possibilities of using composite reinforcement in transport and power industry structures

Erratum on the article ‘A feasibility study of using composite reinforcement in transport and power industry structures’ (doi:10.3846/16484142.2017.1342689)

"Erratum on the article ‘A feasibility study of using composite reinforcement in transport and power industry structures’ (doi:10.3846/16484142.2017.1342689)." Transport, 32(4), p. 43

Kombinuotųjų stogo konstrukcijų lenkiamojo strypo racionalus projektavimas/Rational design of flexural rod in combined roof structures

The paper discusses a calculation of rational parameters of main flexural rod used in combined roof structures. Geometrical non-linearity can be discussed separately when the member is subjected either to tension or compression. It has been established that rational parameters for rods subjected to compression-bending or tension-bending have to be determined from the non-linear analysis calculation of the parameters using the slender- ness parameter, i.e. when kl ≤ 1. Also combined roof structures with a non-continuous main member are discussed. The rational parameters were calculated from the geometrically non-linear analysis. Numerical testing has shown that the non-continuous main members of the combined structures are more effective than the continuous ones. First Published Online: 26 Jul 201