Concrete Continuous Bridge Research Articles

Vehicle Parameters Influence on Railway Double-Track Pre-Stressed Concrete Continuous Bridge Vertical Load-Carrying Natural Frequency

When two lines with 20 same high-speed passenger vehicles are traveling on the 40 m+4×72 m+40 m party pre-stressed concrete continuous box-girder bridge from both ends, this bridge vertical load-carrying frequency is calculated with the vehicle-bridge system mode1. When the vehicle parameters, such as the unsprung mass of each wheel-set of the vehicle, the suspension spring stiffness, the vehicle length and the mass of the vehicle, are changed, the bridge vertical load-carrying frequencies are changed too. But when the train speed is changed, the bridge vertical load-carrying frequencies aren’t changed. It is shown that the bridge vertical load-carrying frequency is the vehicle-bridge system natural frequency, it is only depend on its natural parameters.

Stress Monitoring on Cantilever Construction Stage of the Main Bridge of South-to-North Water Transfers Canal

This paper presents the importance of stress monitoring in cantilever construction stage of concrete continuous bridge. The stress analysis model based on the actual bridge is established by the beam elements. The measuring measurement scheme and influencing factors of stress monitoring are introduced. The measured results matched the calculated results very well, which meet the needs of construction safety.

Structural behaviour of segmental concrete continuous bridges with unbonded prestressing and dry joints

This work presents a finite-element method (FEM) analysis of the behaviour of continuous segmental concrete bridges with external prestressing and dry joints, focusing on the response under combined shear and flexure, at the service limit state (SLS) and at the ultimate limit state (ULS). A previously validated FEM model has been applied to simulate the structural behaviour of continuous bridges until failure. A geometrically non-linear analysis has been performed, where the particular behaviour of the dry joints, the concrete plasticity and the slipping of the prestressing tendons at the deviators have been considered. Results of the analysis have been compared with the available data of the modelling of simply supported bridges, and the different behaviour introduced by the support redundancy has been pointed out. Analysis proves that the SLS can govern the design of the prestressing force, whereas in simply supported bridges, it is the ULS that always governs the design. Concrete and steel remain essentially linear under ultimate loads, which implies that there is an extra safety factor against failure. Before failure, when support and mid-span joints are opened, moment redistribution has occurred and an arch springing from the bearings is formed within the concrete, which equilibrates the external loads.

Vertical Load-Carrying Natural Frequency of Railway Double-Track Pre-Stressed Concrete Continuous Bridge

The railway double-track continuous bridge vertical load-carrying frequency is theoretical derived with the vehicle-bridge system mode1. The vertical load-carrying frequencies of the 40 m+4×72 m+40 m party pre-stressed concrete continuous box-girder bridge are calculated, when two trains with 20 same high-speed passenger vehicles are traveling on the bridge from both ends. The change regularity of this double-track continuous bridge vertical load-carrying natural frequency with two trains on it is similar with that of the single-track simply supported bridge and this bridge as one train on it. This bridge vertical load-carrying frequency when two trains on it is smaller than that only train on it. The maximum deviation percentage between the vertical load-carrying natural frequency and the vertical natural frequency is 1.17837%.This bridge vertical load-carrying frequency can be replaced by its natural frequency, and there isn’t obvious error. If the vertical load-carrying frequency should be calculated, it can be replaced by the average value.

Study on Fatigue Load and Fatigue Life Estimation for Concrete Bridges

Using truck weigh device, the data of traffic stream was collected from a toll station in Shaanxi province for 24 hours. A standard fatigue truck was developed based on the regular traffic data. Then S-N curves and Palgrem-Miner summation method was introduced in assessing fatigue life of the reinforcement in negative region of one continuous concrete bridge. It was concluded that the welding detail of reinforcement in negative region had long service life under normal traffic state. The fatigue life of reinforcement would be weakened considering overloading vehicles.

Analysis of Sensitive Factors of Long-Span Continuous Rigid Frame Bridge’s Stability with Thin-Wall Piers in the Construction Stage

Analyzing the basic theory of stability, with a high pier of large span prestressed concrete continuous bridge as the example, the stability was analyzed when constructing, considering wind load, hanging basket, pier etc. Both eigenvalue and mode are got for the longest cantilever ting condition, the sensitivity of stability to various loads being analyzed. It is concluded that the unbalanced weight and the falling of basket are the main factors.

The Key Technology of Skew Continuous Prestressed Concrete Box Girder Bridges with Incremental Launching Method

Incremental launching method is a construction technology for prestressed concrete continuous bridges widely used in China. In the incremental launching method, the superstructure of a bridge is erected from one side of bridge longitudinally to the opposite bank. Compared with other technology for bridge erection methods, it may reduce the cost of labor, shorten the construction period and save the assembly yard. So it is a competitive construction method for medium-span prestressed concrete continuous bridges. A large number of skew bridges will be built especially at mountain area, so it is very necessary to research on incrementally launching method for skew bridges. The objective of the study presented in this paper is to introduce the method used in the Lishui Bridge in Zhangjiajie city of China.

Analysis of curved incrementally launched box concrete bridges using the Transfer Matrix Method

The incrementally launching technique is today widely used for the construction of continuous concrete bridges. During construction, the static scheme of these bridges varies continuously, with the advance of the deck above piers producing temporary stresses rather different from those occurring in service. An approach to analyse the construction phases of curved incrementally launched bridges is presented for concrete single box girder. A procedure based on the Transfer Matrix Method (TMM), already developed for straight launched bridges, has been extended to curved beams, allowing engineers to estimate the effects of horizontal curvature during the entire launching process. This procedure allows engineers to carry out parametric studies for the optimization of structural design of curved concrete launched bridges.

Stress Variation of External Tendons under Live Load in Prestressed Concrete Bridges

By using a computer program especially developed for externally prestressed concrete bridges, the stress variation of external tendons under live load in several typical spans of externally prestressed concrete box-girder bridges is analysed. The influence of span-to-depth ratio, the level of bonding between external tendons and the structure, and the spacing between deviators on externally prestressed concrete simply-supported bridges is discussed. The influence of the construction method, the ratio of external tendons to internal tendons, the number of continuous spans, and the layout of external tendons on externally prestressed concrete continuous bridges is investigated. The comparison of results between externally prestressed concrete bridges to similar conventional internally prestressed concrete bridges is also made.

Hybrid Reinforcement System을 이용한 콘크리트 교량상판 슬래브의 거동

This study describes the basic concept and the applicability of Hybrid Reinforcement System using conventional steel reinforcing bars and Fiber Reinforced Polymer bars. The concrete bridge decks are assumed to be supported by beams and reinforced with two layers of reinforcing bars. In concrete bridge deck using HRS, the top tensile force for negative moment zone on beam supports is assumed to be resisted by FRP reinforcing bars, and the bottom tensile force for positive moment zone in the middle of hem supports is assumed to be resisted by conventional steel reinforcing bars, respectively. The FRP reinforcing bars are non-corrosive. Thus, the steel reinforcement is as far away as possible from the top surface of the deck and protected from intrusion of corrosive agent. HRS concrete bridge deck has sufficient ductility at ultimate state as the following reasons; 1) FRP bars have lower elastic modulus and higher ultimate strain than steel re-bars have, 2) FRP bars have lower ultimate strain if provided higher reinforcement ratio, 3) ultimate strain of FRP bars can be reduced if FRP bars are unbonded. Test results showed that FRP and HRS concrete slabs are not failed by FRP bar rupture, but failed by concrete compression in the range of ordinary reinforcement ratio. Therefore, in continuous concrete bridge deck using HRS, steel reinforcing bars for positive moment yield and form plastic hinge first and compressive concrete fail in the bottom of supports or in the top of the middle of supports last. Thus, bridge deck consumes significant inelastic strain energy before its failure.

Dynamic behavior of two-span continuous concrete bridges under moving high-speed train

Experimental and theoretical studies have been performed to determine the dynamic behavior of bridges crossed by the Korean high-speed train (KHST). Through this study, significantly amplified dynamic responses compared to static responses of the bridge crossed by trains running at speed close to the critical speed have been obtained. The numerical method technique presented in this study shows reasonable results concerning the dynamic behavior analysis of bridges under trains running at high-speed. In the case of the KHST, train–bridge interaction effects related to the dynamic response of the bridge appeared to be significant at every speed.

A displacement‐based approach for the seismic design of continuous concrete bridges

AbstractA displacement‐based design procedure for continuous concrete bridges is proposed which can be incorporated into a performance‐based design philosophy. The procedure is applicable to multi‐degree‐of‐freedom bridges with flexible or rigid superstructures, and for varying degrees of abutment restraint. The background and development of the design procedure is presented first, followed by a series of examples and validation studies using dynamic inelastic time‐history analysis. The procedure is applied to the transverse response of bridge structures; however, it is equally well‐suited for longitudinal response. The results indicate that the process is able to capture non‐linear deformation patterns and thus reasonably control damage. Copyright © 2001 John Wiley & Sons, Ltd.

Restraint Moments in Precast/Prestressed Concrete Continuous Bridges

To eliminate deck joints and shoulder piers, continuous span (jointless) bridges are becoming an attractive option. Different continuity methods and construction sequences have different time-dependent effects on the behavior of the bridge system. These effects are illustrated in this paper. To achieve a favorable performance of bridges made continuous for deck loads, recommendations for achieving continuity and for desirable construction sequence are presented. A new continuity detail using high strength threaded rods is proposed. Based on a cost comparison with currently available continuity methods and a full-scale NU1100 I-beam experiment, this continuity detail is shown to eliminate the potential for bottom concrete creep restraint cracking at pier locations and to increase the span capacity by as much as 20 percent.

Time-dependent reliability of deteriorating reinforced concrete bridge decks

A structural deterioration reliability model is developed to calculate probabilities of structural failure (flexure) for a typical reinforced concrete continuous slab bridge. Corrosion may be initiated from the application of de-icing salts or atmospheric exposure in a marine environment. It is assumed that corrosion will lead to a reduction in the cross-sectional area of the reinforcing steel. Monte Carlo simulation is used to calculate probabilities of failure for annual increments over the lifetime of the structure (75 years). The application of de-icing salts or atmospheric marine exposure is shown to cause significant long-term deterioration and reduction in structural safety. Reducing the cover from that currently specified for design results in a significant increase in failure probabilities.

Lift System for Raising Continuous Concrete Bridges

Due to road resurfacing a significant number of highway bridges throughout the nation violate underneath clearance requirements. A bridge lifting/monitoring system was developed as one solution to this problem. The system was designed to uniformly raise continuous 4‐span/4‐girder reinforced concrete deck/girder bridges. It is relatively lightweight, easy to set‐up and operate, reusable and designed to fit most bridge slopes, skew angles, girder spacings, and abutment/bent configurations. The major components of the lift system are: (1) A modular set of jack support and lift hardware; (2) a hydraulic system; and (3) a displacement monitoring system. The lift system performed very nicely when field tested on an experimental test bridge. The system was refined based on the results of the field testing. Detailed descriptions of the lift system components along with the systems capabilities, and lift procedure are presented.