Span Bridge Structures Research Articles

Modelling of Work of Cut and Stretchy Sheet in Span Beam Structures with the Mixed Reinforcement

The constant growth of the intensity and volumes of automobile transportation causes the necessity of the increasing the requirements to the serviceability of transport facilities. The issue of the serviceability and safe operation of the existing highway or pedestrian bridges, which were built many years ago, is always relevant. Therefore, there is a choice: either to restore and strengthen the existing facilities or to replace them completely. It is expedient and efficient to use a steel cut and stretchy sheet in the form of the external ribbon reinforcement at the strengthening of the reinforced concrete span bridge structures. In the future, the steel cut and stretchy sheet is properly attached to the surface of the structure and the filling of the sheet cell is done by the layer of the cement and sandy solution (the process of concrete spraying) or protected by a concrete layer for the prevention of the sheet corrosion. Such a cut and stretchy sheet can be effectively used in new structural elements at new construction as a working longitudinal or transversal reinforcement. An effective version of the use of the cut and stretchy sheet is possible for the strengthening not only bending structures but also compressed and compressed out of center reinforced concrete and stone ones. Thus, the issue of the research and modeling of the work of the steel cut and stretchy sheet in the array of concrete under the linear stressed state conditions is of vital importance. The article presents the results of the experimental and theoretical research of the work of the steel cut and stretchy sheet under load; provided the physical model of such a process; substantiates the effectiveness of its use and the placement in span beam bridge structures.

PREVENTION OF METAL BRIDGE SPANS FROM FATIGUE CRACKING

At present, more than four thousand metal bridge spans are in operation all over the Russian railway network. Through the years of operation, about thirty types of fatigue cracking were identified. The dynamics of the types Т-9 and Т-10 cracks formation has increased significantly in recent years. The formation and growth of fatigue cracking is influenced by such factors as residual welding stress, stress-strain state of the bridge structure, defects, damages, and non-observing the operation and maintenance standards, bridge location and bridge span structure. At present, neither measures nor repair are performed to prevent fatigue cracking not exceeding 20 mm in length. Only when a creak reaches a certain length, the regulatory documents require to drill a hole at a crack mouth in order to prevent its further development. The hole diameter should be equal approximately to the doubled wall thickness. In order to prevent further crack growth and cover the hole, a high-tensile bearing type bolt is fixed into it, creating a volume stress. As a rule, such a repair is not enough to stop the cracking process. The article suggests a number of measures based on induction heating that allows to prevent cracking (including forging reducing gaps between connecting plates and horizontal sheets in a truss), to carry out repair (crack mouth soldering) and reinforcement (fixing metal plates onto a wall with a hole).

Numerical simulation of the transverse flow over spans of girder bridges

Introduction. The technique of numerical modeling of the transverse flow over span structures of bridges on the basis of the two-dimensional URANS (Unsteady Reynolds-averaged Navier-Stokes) approach used in the modern methods and software packages for computational fluid dynamics is verified. The work objective was debugging and experimental substantiation of this technique with the use of the database on the aerodynamic characteristics of the cross-sections of span structures of girder bridges of standard shapes pre-developed by the authors.Materials and Methods. A numerical simulation of the transverse flow of low-turbulent (smooth) and turbulent air flows around the bridge structures in a range of practically interesting attack angles is carried out. SST k − ω turbulence model was used as the closing one. The technique was preliminarily tested on the check problem for the flow of the rectangular crosssection beams. Calculations were carried out using the licensed ANSYS software.Research Results. The calculated dependences on the attack angle of the aerodynamic coefficients of forces (drag and lift) and the moment of the cross sections of the girder bridges of standard shapes are obtained. These data refer to the span structures at the construction phase (without deck and parapets, without parapets) and operation phase, under the conditions of model smooth and turbulent incoming flow. The latter allows us to outline the boundaries for more weighted estimates of the aerodynamic characteristics of thegirder bridges in a real wind current. The best agreement with the experimental data was obtained from the drag of the cross-section. The magnitude of the lifting force is more sensitive to the presence and extent of the separation regions, so its numerical determination is less accurate. The reproduction of the angle-of-attack effect on the aerodynamic moment of the cross-section is the most challenging for the majority of configurations.Discussion and Conclusions. Comparison of the calculated and experimental data indicates the applicability of the URANS approach to the operational prediction of the aerodynamic characteristics of the single-beam span structures. In the case of multi-beam span structures, where the aerodynamic interference between separate girders plays an important role, the URANS approach must apparently give way to more accurate eddy-resolving methods. The results obtained can be used in the aerodynamic analysis of structures and in practice of the relevant design organizations in the field of transport construction.

Methods of regulating thrust in design of arch bridges

The paper deals with the identification of the optimal forms of arch span structures of bridges in terms of minimizing the expansion in their foundations. The calculations of thrust at different ratio boom lift for stairs in various arch design schemes (fully articulated, two-hinged, and hingeless arches). A graph of the dependence of the thrust on the ratio of the rise to the span for the bridge reinforced concrete arch, on the basis of which one can choose the most effective ratio of the boom to span for a particular case. A comparison of the distribution of the spread value for multi-span arch bridges with a constant and variable span width is performed. It is concluded that such ratio of the magnitudes of spans is the most effective for the equalization of forces, transmitted to the foundations of the arches of multispan bridges.

Methods of regulating thrust in design of arch bridges

The paper deals with the identification of the optimal forms of arch span structures of bridges in terms of minimizing the expansion in their foundations. The calculations of thrust at different ratio boom lift for stairs in various arch design schemes (fully articulated, two-hinged, and hingeless arches). A graph of the dependence of the thrust on the ratio of the rise to the span for the bridge reinforced concrete arch, on the basis of which one can choose the most effective ratio of the boom to span for a particular case. A comparison of the distribution of the spread value for multi-span arch bridges with a constant and variable span width is performed. It is concluded that such ratio of the magnitudes of spans is the most effective for the equalization of forces, transmitted to the foundations of the arches of multispan bridges.

PERSPECTIVES OF THE USE OF MODERN BUILDING MATERIALS IN ROAD CONSTRUCTION

The authors analyzed the foreign experience of using keyed joints in reinforced concrete span structures of bridges. Fiber concrete with polypropylene fibers was chosen as the investigated material. Such fibers are chemically neutral, water-resistant, have a high resistance to dynamic loads, reduce the risk of formation and development of cracking, increase abrasion what is important in the manufacture of road construction. Optimization of concrete composition with polypropylene fibers for concreting joints by physical and mechanical parameters was carried out. Parameters of optimization were compressive strength, tensile strength at bending, axial tensile strength, prism strength and abrasion. The authors performed a series of tests to study the behavior of fiber concrete in keyed joints. The analysis of obtained results out depending on the nature of failure, the value of the ultimate load and fiber concrete deformations were carried out. The influence on the joints strength of the cross-section reinforcement percentage and the nature of placement of the reinforcing rods was considered. It was established if to place a cross-reinforcement in two levels it increases the strength of joints in comparison with a single level with the same percentage of reinforcement. It was noted that the fracture of all samples occurred from the sear key. Cracking of fiber concrete experimental samples occurred at later stages of loading compared with samples of ordinary concrete, and the fracture was not brittle, without tearing off parts of concrete. Increase in strength is due to the chaotic placement of polypropylene fibers in concrete, and therefore, to remove fibers from concrete, it is necessary to spend more energy, which ultimately leads to an increase in strength of joint. Experimental data suggest possibility and feasibility of polypropylene fibers in concrete joints in precast concrete structures of bridges

Numerical evaluation of multi-metric data fusion based structural health monitoring of long span bridge structures

This work focuses on structural health monitoring of long span bridges for damage detection. A feature extraction level data fusion based damage isolation strategy is presented using multi-metric sensing. The multi-metric sensing uses two types of sensors, namely strain sensors and accelerometers. The methodology combines the advantages offered by each type of sensors, while at the same time overcomes their limitations. The flexibility index method is applied and the flexibility matrices based on the strain and displacement data are combined after performing co-ordinate transformation. A study has been carried out on a simulated finite element model of the Great Belt East Bridge where realistic damage scenarios like damage in the girder, breaking of hanger cables, pier settlement, and loss of cable pretension were introduced on the structure. The study indicates that multi-metric sensing is indeed necessary as it reduces the possibility of false detections and increases the sensitivity and robustness of the methodology.

IMPROVEMENT OF BOARDWALK NAILED – SPAN BRIDGE STRUCTURES

The article is devoted to the implementation in practice of the construction of the new bridge boardwalk timber - nail span structures that meet the modern requirements of load capacity, reliability and durability. The authors propose and describe a new design of the span timber-beam-peg–nailed blocks with longitudinal-transverse orientation of the belt boards and carrying transverse reinforced concrete slab of the carriageway. The represented materials show the effectiveness of the proposed solutions.

DETERMINATION OF DAMAGES ACCUMULATION MEASURE OF RAILWAY BRIDGES TAKING INTO ACCOUNT OF ARMATURE CORROSION

Purpose. Determination of damages accumulation measure of reinforce-concrete span structure on the criterion of armature corrosion for estimation of actual state of struction. Methodology. For the achievement of the put aim reasons are considered and analyzed appearances of cracks in a concrete, influencing on longevity of reinforce-concrete structure which works at repeatedly iterative loads. Findings. For determination of damages accumulation measure with procorroded armature critical area of bridge span structure are offered the relationships. In them taken into account width of cracks opening in the reinforce-concrete beam of cpan-structure, term of bridge exploitation and depth of armature bar corrosion. Originality. Possibility to define the depth of corrosion by, non-destructive method in the armature bar of bridge reinforce-concrete structure was realized. Practical value. After defining of damages accumulation measure on the criterion of span structure armature corrosion, it is possible to forecast the terms of it repair works.

Design analysis of the optimum configuration of self-anchored cable-stayed suspension bridges

This paper describes a formulation to predict optimum post-tensioning forces and cable dimensioning for self-anchored cable-stayed suspension bridges. The analysis is developed with respect to both dead and live load configurations, taking into account design constrains concerning serviceability and ultimate limit states. In particular, under dead loads, the analysis is developed with the purpose to calculate the post-tensioning cable forces to achieve minimum deflections for both girder and pylons. Moreover, under live loads, for each cable elements, the lowest required cross-section area is determined, which verifies prescriptions, under ultimate or serviceability limit states, on maximum allowable stresses and bridge deflections. The final configuration is obtained by means of an iterative procedure, which leads to a progressive definition of the stay, hanger and main cable characteristics, concerning both post-tensioning cable stresses and cross-sections. The design procedure is developed in the framework of a FE modeling, by using a refined formulation of the bridge components, taking into account of geometric nonlinearities involved in the bridge components. The results demonstrate that the proposed method can be easily utilized to predict the cable dimensioning also in the framework of long span bridge structures, in which typically more complexities are expected in view of the large number of variables involved in the design analysis.

Bearing Capacity Analysis of Reinforcement for the Double Curvature Arched Bridge in Service

According to the disease status of a dilapidated double curvature arched bridge in Baotou city, the reinforcement scheme of Shotcrete Increasing the Section is proposed. The finite element model was established by Midas software. The simulation analysis results show that for the bridge span structure after reinforcement, the bearing capacity and stiffness is increased significantly, the displacement and stress is reduced effectively, the overall mechanical performance is improved, the reinforcement scheme is practicable.

WEATHER-RESISTANT ROLLING STOSK OF STRENGHT CLASSES C355-500 FOR METALLIC CONSTRUCTIONS OF BRIDGES

Purpose. Application for span structures of bridges, steel with increased corrosion resistance. Methodology. To achieve the research purpose was used methodology and documents are accepted at building of bridges.Findings. Researches are presented of service properties, weld ability, as well as corrosion resistance of 06G2BDP steel of strength class C390-500, conducted weld ability studies, and developed technologies of submerged-arc and mechanized welding for fabrication and mounting of bridge metal structures. Originality. Sparsely-alloyed 350-500 MPa steel of 06G2BDP grade with increased atmospheric corrosion resistance was recommended for fabrication of bridge metal structures. Practical value. Choice steel for fabrication of bridge metal structures.

Dynamic Characteristics of Hybrid Girder Cable-Stayed Bridge

This paper is made after the dynamic test on Jing hang Channel Bridge in Wujiang, Jiangsu Province. Based on the test on this bridge, we get dynamic characteristics of the bridge span structure. We will analysis the vibration generated from the steel and concrete box girders of the bridge while the car is running on it. Based on the different characteristics of vibration from the two kinds of girders, we can analysis the influence of this hybrid girder on driving comfort.

Study on Condition Assessment of Highway Bridge, Normal-Speed and High-Speed Railway Bridge

There are lots of theories and methods about condition assessment for highway bridge, and gradual perfection for normal-speed railway bridge, but only little for high-speed railway bridge, especially large-span and special structures. After studying on the contents, methods, theories and evaluation indexes of highway bridge and normal-speed railway bridge, combined with the characteristics of high-speed railway bridge, index system for high-speed railway bridge(medium and small span, large-span or special bridge structures) was conceived and discussed, which laid the foundation for the development of condition assessment of high-speed railway bridge.

Preliminary Numerical Study on TRID System for Flutter Vibration Control of Bridge Structure

Based on the recently proposed innovative Tuned Rotary Inertia Damper (abbreviated as TRID) control system, the possibility of its application for the wind induced flutter vibration control of long span bridge structure is discussed in this paper. Firstly, the background and current methods for wind induced flutter vibration control of bridge structures are summarized. Then, equations of motion of the bridge segment model are developed based oon the classical Lagrange principle, and the critical wind speed of flutter vibration of Humen Bridge is solved using both Scanlan and state space baased methods. Furthermore, the TRID control system is incorporated into the system model, where the TRID inertia mass can be physically installed between connections of consecutive bridge deck sections. Optimal parameters of TRID control system and their interactions, i.e. tuning frequency ratio, damping ratio and rotary inertia ratio, are analyzed through numerical approaches. Based on thorough numerical analysis, the results show that the TRID control system is feasible and effective on enhancing the flutter vibration stability of long span bridge structures, e.g. the ultimate critical wind speed of the illustration can be increased by 10% at the cost of adding an additional 5% rotary inertia to the bridge structure.

Active/Robust Control of Longitudinal Vibration Response of Floating-type Cable-stayed Bridge Induced by Train Braking and Vertical Moving Loads

The active/robust control of the longitudinal vibration response of the deck of floating-type cable-stayed bridges induced by train braking and vertical moving loads has been investigated in this paper. Controlled objects of large structures such as long span bridges generally have high orders of controlled variables and this may lead to high costs and complications of controllers. Hence, a reduced controlled model of lower orders based on a modal reduction method has been proposed. Because the controller designed from the reduced model may influence the control effect of the original controlled system; the stability and error of the reduced model have been studied. The results indicate that when a sufficient number of modals are included in the model, the influence is very small. In view of parameter uncertainties in long span bridge structures, the active robust control equations based on frequency uncertainties have been derived, and the active robust control of longitudinal vibration responses of the deck, which are induced by train braking and vertical moving loads, has been simulated for Tian Xingzhou Yangtze River Bridge in China. Simulated results have been compared with results of the active control based on the linear quadratic regulator (LQR) algorithm. Comparisons have shown that the robust control is more effective and efficient than the active control based on the LQR algorithm.

METHOD OF WORKS CONDUCTING ON ASSESSMENT OF TECHNICAL CONDITION OF CONCRETE BRIDGE SPANS AND THE DEFINITION OF THE VOLUME AND STRUCTURE OF THEIR CURRENT CONTENT

The article proposes fundamentals of working method of assessment of technical state of reinforced concrete span structures of bridges and determination of the volume and structure of their current maintenance, developed with the use of methods of reliability theory and mathematical statistics. The method stipulates that the planning of obligatory repairs and changes of the span structures on the bridge is carried out on the basis of an analysis of the state of the facility in a certain period of time and its behavior during all of the service life, by way of minimization of the costs of the repair works or changes. Expediency of further operation of the facility is determined, provided that the costs of its repair do not exceed the incomes from its operation.

On the use of steel-free concrete bridge decks in continuous span bridges

This note discusses the use of the steel-free concrete bridge deck technology in continuous span bridge structures. Conventional slab-on-girder design often utilizes the longitudinal steel reinforcement in the deck to resist the negative bending moments created at the internal piers of continuous bridges. The steel-free bridge deck is devoid of all internal steel reinforcement and hence requires an alternate design approach which is presented in this note. A key aspect of this approach is the recommended use of fibre-reinforced polymer reinforcement to control cracking of the deck over the intermediate supports. Limiting these crack widths is essential to the durability performance of the concrete, particularly in freeze-thaw environments. The results of an experimental program are also reviewed. The tensile stresses from the global longitudinal negative moment are shown to have little effect on the punching behaviour of the slab. It is noted that the concepts presented in this note were utilized in the construction of a three-span highway bridge which incorporated the steel-free bridge deck technology.Key words: bridges, design, continuous span, concrete decks, punching-shear, fibre-reinforced polymers.

On the use of steel-free concrete bridge decks in continuous span bridges

This note discusses the use of the steel-free concrete bridge deck technology in continuous span bridge structures. Conventional slab-on-girder design often utilizes the longitudinal steel reinforcement in the deck to resist the negative bending moments created at the internal piers of continuous bridges. The steel-free bridge deck is devoid of all internal steel reinforcement and hence requires an alternate design approach which is presented in this note. A key aspect of this approach is the recommended use of fibre-reinforced polymer reinforcement to control cracking of the deck over the intermediate supports. Limiting these crack widths is essential to the durability performance of the concrete, particularly in freeze-thaw environments. The results of an experimental program are also reviewed. The tensile stresses from the global longitudinal negative moment are shown to have little effect on the punching behaviour of the slab. It is noted that the concepts presented in this note were utilized in the construction of a three-span highway bridge which incorporated the steel-free bridge deck technology.Key words: bridges, design, continuous span, concrete decks, punching-shear, fibre-reinforced polymers.