Continuous Composite Bridges Research Articles

Experimental Behavior of the Curved Continuous Twin I-Girder Composite Bridge with a Precast Concrete Slab Subjected to Bending, Shear, and Torsion

In order to investigate the mechanical behavior, ultimate load carrying capacity, and failure mode of the intact curved continuous twin I-girder composite bridge (TGCB) with a precast concrete slab, one curved continuous composite bridge model with a scale ratio of 1 : 5 of a prototype bridge was designed and manufactured considering the influence of the construction sequence. Four symmetric point loads’ test was carried out. In this paper, load-deflection relationship and strain development of steel girders, concrete slab, and reinforcement at key sections were tested and analyzed. Failure mode, crack development, and major crack width at the top surface of the concrete slab in the hogging moment region were also reported. The experimental results demonstrated that the load capacity under the initial cracking level, cracking level with the width of 0.2 mm, and steel girder yielding state is about 1.7, 5.0, and 6.3 times of the design load, respectively. Due to the influence of curvature, the stiffness of the external girder is less than that of the internal girder. However, the ultimate bearing capacity is basically the same, approximately 13.6 times of the design load. During the loading process, plastic hinge was first observed at the intermediate support section as a result of the hogging moment which should be emphasized in design. The local buckling took place after yielding, indicating a class 2 section according to Eurocode 4. In addition, the TGCB had good ductility since the displacement ductility coefficients of the external and internal girders were 4.40 and 4.06, respectively.

Structural health monitoring on a steel-concrete composite continuous bridge during construction and vehicle load tests

This study presents the structural health monitoring system of an I-shaped steel-concrete composite girder bridge during construction and vehicle load tests. Strains and deflections were monitored. A finite element model was built and calibrated. Vehicle load tests were carried out for various load conditions. Measured results show that the strains in the concrete slab and steel beams changed rapidly in the first 15 days and stabilized. The composite girder was in an elastic working state under the vehicle load tests. This research provides guidance for the construction control and safety evaluation of similar I-shaped steel-concrete composite bridges in the future.

Structural behavior of CFST arch foots under pumping pressure of concrete infills

Prestressed concrete (PC) continuous girder-arch composite bridges, using concrete filled steel tubes (CFST) as the arch ribs to support the PC main girder, have gained their popularity in recently constructed large span bridges. The adoption of CFSTs brings many advantages, such as the concrete infill help to prevent the occurrence of local buckling in steel tubes, while the steel tubes can serve as framework for concrete core and strengthen the encased concrete. In order to achieve the above merits, the arch foots connecting the CFST arch ribs and PC girder are supposed to have sufficient strength and stiffness. However, the extensive use of CFST arch ribs showed that concrete cracking are commonly found at the arch foots. This paper studied the structural behavior of arch foot by employing a comprehensive numerical model. The influence of pumping pressure from concrete infill at construction stage on local stress of the arch foots was presented and discussed. The results indicated that the radial stress produced by pumping pressure at the joint zone squeezed the concrete around the arch foots, which resulted in significant hoop tensile stresses in the surrounding concrete. The outcomes of this study can provide technical support to improve the construction quality and structure stability, and optimize the construction procedures for this type of bridges.

Analysis of Influence Factors on Line Shape of High-speed Railway Beam-Arch Combination Bridge

<p align="justify">Taking the prestressed continuous beam-arch composite bridge on the Zheng Wan High-speed Railway as a research object, which across the South-to-North Water Transfer in Zhang Liang Town, the space finite element model of the bridge was established by Midas/Civil, the cantilever casting construction process of the main beam was simulated, and the influence of many different parameters on beam line shape of the bridge was investigate. The results show that the unbalanced weight of the hanging basket and the prestressed steel bar parameters have less influence on the beam line shape; the bulk density of concrete and the arrangement length of counterweight have a great influence on line shape, therefore, these should be considered as key control parameters during construction, the counterweight of boom beam can reduce the deformation of bridge’s mid-span, it is advantageous for the Analysis of Influence Factors on Line Shape of High-speed Railway Beam-arch Combination Bridge line shape control of the bridge.</p>

Evaluation of safety performance during construction and servicing stages of Liuxi river bridge

Prestressed concrete continuous beam-arch composite bridge with concrete-filled steel tube is a new type of bridge developed in recent years. It has the characteristics of strong spanning ability and large in-plane stiffness, but the lateral stiffness of the arch ribs for this type of bridge is relatively weak. In order to effectively improve the construction quality and structure stability, and optimize the mechanical properties, and in addition of realize the design of large span continuous beam-arch composite bridge, a comprehensive safety assessment of the Liuxi River bridge during construction and serving stages located in China was conducted in this paper. The results show that the bridge had favorable safety margin during the construction and severing stages. The outcomes of this study can provide technical support for the safety and smooth implementation of the bridge’s safeguard, which has important theoretical significance and engineering application value.

Prediction of vibration and noise from steel/composite bridges based on receptance and statistical energy analysis

The noise from the elevated lines of rail transit has become a growing problem. This paper presents a new method for the rapid prediction of the structure-borne noise from steel or composite bridges, based on the receptance and Statistical Energy Analysis (SEA), which is essential to the study of the generation mechanism and the design of a low-noise bridge. First, the vertical track-bridge coupled vibration equations in the frequency domain are constructed by simplifying the rail and the bridge as an infinite Timoshenko beam and a finite Euler-Bernoulli beam respectively. Second, all wheel/rail forces acting upon the track are computed by taking a moving wheel-rail roughness spectrum as the excitation to the train-track-bridge system. The displacements of rail and bridge are obtained by substituting wheel/rail forces into the track-bridge coupled vibration equations, and all spring forces on the bridge are calculated by multiplying the stiffness by the deformation of each spring. Then, the input power to the bridge in the SEA model is derived from spring forces and the bridge receptance. The vibration response of the bridge is derived from the solution to the power balance equations of the bridge, and then the structure-borne noise from the bridge is obtained. Finally, a tri-span continuous steel-concrete composite bridge is taken as a numerical example, and the theoretical calculations in terms of the vibration and noise induced by a passing train agree well with the field measurements, verifying the method. The influence of various factors on wheel/rail and spring forces is investigated to simplify the train-track-bridge interaction calculation for predicting the vibration and noise from steel or composite bridges.

Sensitivity Analysis of Cantilever Construction Process of Long-Span Continuous V-Structure Composite Bridge

As a large and complex structural system, each change of physical parameters will have a certain degree of influence on the whole structure. Taking the navigable hole bridge of the main bridge of Yueqing Bay No. 1 Bridge in Zhejiang Province as an example, the influence of concrete bulk density, temperature change, elastic modulus, prestress tensioning, shrinkage plus creep of concrete on the bridge deformation is considered, that is, the sensitivity analysis of parameters. Thus, the parameters together with their effects which have a great influence on the structure in the process of bridge construction are determined and adjusted in time to ensure the linear smoothness of the bridge, the safety of the structure, and the improvement of the driving comfort and the aesthetics of the bridge.

Behavior of composite box bridge girders under localized fire exposure conditions

This paper presents results from experimental and numerical studies on the response of steel-concrete composite box bridge girders under certain localized fire exposure conditions. Two composite box bridge girders, a simply supported girder and a continuous girder respectively, were tested under simultaneous loading and fire exposure. The simply supported girder was exposed to fire over 40% of its span length in the middle zone, and the two-span continuous girder was exposed to fire over 38% of its length of the first span and full length of the second span. A measurement method based on comparative rate of deflection was provided to predict the failure time in the hogging moment zone of continuous composite box bridge girders under certain localized fire exposure condition. Parameters including transverse and longitudinal stiffeners and fire scenarios were introduced to investigate fire resistance of the composite box bridge girders. Test results show that failure of the simply supported girder is governed by the deflection limit state, whereas failure of the continuous girder occurs through bending buckling of the web and bottom slab in the hogging moment zone. Deflection based criterion may not be reliable in evaluating failure of continuous composite box bridge girder under certain fire exposure condition. The fire resistance (failure time) of the continuous girder is higher than that of the simply supported girder. Data from fire tests is successfully utilized to validate a finite element based numerical model for further investigating the response of composite box bridge girders exposed to localized fire. Results from numerical analysis show that fire resistance of composite box bridge girders can be highly influenced by the spacing of longitudinal stiffeners and fire severity. The continuous composite box bridge girder with closer longitudinal stiffeners has better fire resistance than the simply composite box bridge girder. It is concluded that the fire resistance of continuous composite box bridge girders can be significantly enhanced by preventing the hogging moment zone from exposure to fire. Longitudinal stiffeners with closer spacing can enhance fire resistance of composite box bridge girders. The increase of transverse stiffeners has no significant effect on fire resistance of composite box bridge girders.

Fatigue Assessment of Continuous Composite Bridges Accounting for Slab Casting Sequences

The paper presents a procedure for the fatigue assessment of continuous steel–concrete composite bridges which accounts for concrete slab casting sequences. Cracking, tension stiffening, creep and shrinkage (thermal, endogenous and drying) effects are included in the analysis in order to correctly evaluate the stress state of steel girders. The purpose of the paper is to present a method that, based on the analysis of a number of models developed according to the structure’s evolution, leads to a more effective and realistic fatigue assessment than that usually performed in practice. The method proposed is applied to a case study of a continuous, twin-girder, composite bridge deck, showing the influence of three different slab casting modalities on fatigue assessment.

A study on thermal stresses of two span continuous Steel-Concrete composite deck bridge

A study on thermal stresses of two span continuous Steel-Concrete composite deck bridge

Optimized Prestressed Continuous Composite Girder Bridges with Corrugated Steel Webs

AbstractThis paper proposes different optimization schemes for enhancing the performance of conventional continuous composite girder bridges with corrugated steel webs. In particular, for the positive moment region, the substitution of a ribbed steel plate for the reinforced concrete bottom flange is proposed for optimizing such bridges. Three-dimensional finite-element analysis was used to preliminarily validate this optimization scheme based on the background project, Dongbaohe Xinan Grand Bridge. An experimental study revealed that the optimization scheme can afford advantages, such as reduced self-weight, avoidance of cracking in the bottom flange, and convenient construction. If the steel plate with proper thickness is used, higher flexural stiffness and load capacity can be achieved as additional advantages due to the enhanced steel ratio of the cross section. For the negative moment region of the bridge, the optimization scheme was implemented in two parts identified as Optimization Schemes I and I...

Effects of inclination angle on buckling of continuous composite bridges with inclined parabolic arch ribs

The effects of the inclination angle on the buckling of continuous composite bridges (CCBs) with parabolic arch ribs remain to be elucidated. Static tests were conducted on an on-site prototype of a CCB with parallel arch ribs to verify the validity of proposed numerical finite element method models of CCBs with inward and outward arch ribs. We found that the expressions for the equivalent slenderness ratios and buckling coefficients should consider the interactions between the in-plane and out-of-plane buckling, given the inclination of the arch ribs. With respect to the buckling modes, the arch ribs of all the models buckled in the first lateral mode. In addition, two types of interactions were observed between the buckling modes, namely, that between in-plane and out-of-plane buckling and that between global and local buckling; these were affected by the inclination angle, especially in the case of the CCB with the outward arch ribs.

The Influence of Slab Concreting Sequence on a Continuous Composite Girder Bridge

This paper deals with the slab concreting sequence and its influence on a composite steel and concrete continuous highway girder bridge. The bridge has a symmetrical composite two-girder structure with three spans of 60 m, 80 m, 60 m (i.e. a total length between abutments of 200.0 m). The horizontal alignment is straight. The top face of the deck is flat. The bridge is straight. The transverse cross-section of the slab is symmetrical with respect to the axis of the bridge. The total slab width is 12 m. The slab thickness varies from 0.4 m on main girders to 0.25 m at its free edges and 0.3075 m at its axis of symmetry. The center-to-center spacing between main girders is 7 m and the slab cantilever on either side is 2.5 m long. Every main girder has a constant depth of 2800 mm and the thicknesses of the upper and lower flanges are variable. The lower flange is 1200 mm wide whereas the upper flange is 1000 mm wide. The two main girders have transverse bracing at abutments and at internal supports and at regular intervals in every span. The material of concrete slab is C35/45 and of steel members S355. The on-site pouring of the concrete slab segments is performed by casting them in a selected order and is done after the launching of the steel two girder bridge. The paper presents several concreting sequences and their influence on the normal stresses and deflections of the composite bridge girder.

Time-dependent Composite Effect of the Curved Steel-concrete Composite Beams in Construction Stage

In order to accurately analyze the mechanical behavior of the steel-concrete composite beams in construction stage, firstly the change law of the shear strength of the stud connectors with the concrete age was studied using the push-out test, in which the time-dependent shear strength formula of the stud connectors was obtained. Secondly, model tests of two simply-supported curved composite beams were carried out during the casting process of concrete slab, the ANSYS finite element models were build with the time-dependent shear strength formula applied in it, and then the experimental and numerical results were verified for each other. On the above basis, a three-span curved continuous composite beam bridge was taken as the sample, by which the influence of the stud connector’s timedependent shear connector strength on the stress behaviors of composite beam in construction stage was studied. The analysis results indicate that the shear strength and stiffness of stud connectors cannot be ignored even when the concrete is in rather early stage, and the early shear strength increases more quickly, whereas the later shear strength slowly. During the segmental casting process of concrete slab, if the casting time interval is between 6 hours and 7 days, the time-dependent characteristics of the early composite action should be considered in the stress behaviors analysis of composite beam in construction stage. Meanwhile, for the hardened concrete segment, the relative slip between the steel girder and concrete slab should also be considered, or else unsafe calculation results will be induced.

Rapid prediction of deflections in multi-span continuous composite bridges using neural networks

This paper proposes closed form expressions for the rapid prediction of deflections in steel-concrete composite bridges of large number of spans subjected to service load. The proposed expressions take into account shear lag effect, flexibility of shear connectors and cracking in concrete slabs. Three separate neural networks have been developed for right exterior span, left exterior span and interior spans. The closed form expressions have been obtained from the neural networks developed in the study. The training, validating and testing data sets for the neural networks are generated using finite element software ABAQUS. The proposed expressions have been validated for number of bridges and the errors are found to be small for practical purposes. Sensitivity studies have been carried out using the proposed expressions to evaluate the suitability of input parameters. The use of the proposed expressions requires a computational effort that is fraction of that required for the finite element analysis, therefore, can be used for rapid prediction of deflection for everyday design.

Arch-to-beam rigidity analysis for V-shaped rigid frame composite arch bridges

We proposed the concept of nominal rigidity of a long-span V-shaped rigid frame composite arch bridge, analyzed the effects of structural parameters on nominal rigidity, and derived a theoretical nominal rigidity equation. In addition, we discussed the selection of the arch-to-beam rigidity ratio and its effect on the distribution of internal forces, and analyzed the influence of the ratio on the internal forces. We determined the delimitation value between rigid arch-flexible beam and flexible arch-rigid beam. We summarized the nominal rigidity and arch to beam rigidity ratios of existing bridges. The results show that (1) rigid arch-flexible beam and flexible arch-rigid beam can be defined by the arch-to-beam rigidity ratio; (2) nominal rigidities have no obvious differences among the continuous rigid frame composite arch bridge, V-shaped rigid frame bridge, and arch bridge, which shows that nominal rigidity can reflect the global stiffness of a structure.

Cracked span length beam element for service load analysis of steel concrete composite bridges

For instantaneous non-linear analysis of steel concrete composite bridges that are subjected to a service load, a cracked span length beam element has been proposed. The element consists of two cracked zones at the ends and one uncracked zone between the cracked zones. The element has been used to develop a hybrid analytical–numerical procedure for composite bridges. The procedure yields crack lengths and deflections as well as redistributed moments. The procedure would lead to a considerable reduction in the computational effort in the case of continuous steel concrete composite bridges that consist of a large number of spans.

Effects of Dynamic Fluid-Structure Interaction on Seismic Response of Multi-Span Deep Water Bridges Using Fragility Function Method

This paper employs the fragility function method to study the effects of dynamic fluid-structure interaction on seismic response of multi-span deep water bridges. Currently, two approaches are widely used to study the dynamic fluid-structure interaction effect of structures: the analytical ‘added mass’ method and full-scale two- or three dimensional finite element modeling. This paper offers a computationally economical yet adequate procedure. In this procedure, Morrison equation is employed to calculate the added mass for piles and columns, and a water-foundation coupling system is modeled to calculate the added mass for pile cap. In this water-foundation coupling system, a pile beam-element was adopted to avoid the thorough water domain modeling. A typical multi-span continuous composite girder bridge in China lying in deep water environment is used as a case study. The uncertainty of modeling parameters is considered using an experimental design method. The limit state functions are derived through a simple fuzzy model. Fragility functions of pier column and pile foundation are developed using nonlinear time history analysis. Fragility curves conditioned on different parameters in fuzzy models and different water depth are then compared to illustrate the effects of fuzziness and seismic hydrodynamic pressure. In general, for bridges with only pile surrounding water, the influence of water on potential damage of bridges is small and can be practically negligible. However, for the cases which the pile cap is under the water, increasing the water depth can generally increase the damage probability. It is concluded that for deep water bridges, the influence of dynamic fluid-structure interaction can be harmful to bridge responses, which aggravates with water depth by increasing the displacement of pile cap and introducing larger seismic demands on pier columns.

Numerical study on horizontally curved steel-concrete composite beams subjected to hogging moment

The horizontally curved continuous composite steel-concrete beams, for instance, curved continuous composite bridges, have excellent qualities, such as quick construction, good seismic performance, saving construction formwork and convenience in spatial arrangement etc. At present, the application research of this kind of structures is becoming more of a concern, but very few studies have been conducted to study the mechanical performance of composite beams subjected to combined hogging (negative) bending and torsion. The purpose of the present study is to investigate the effects of curvatures on both elastic and inelastic behaviours of curved continuous steel-concrete composite beams in the interior support regions. Based on the experimental observations in a straight composite beam, a three-dimensional FE model capable of analysing the composite beams subjected to negative bending moment is built. Further numerical studies on curved composite beams with different curvatures are performed in this study. Strength and load carrying capacity, sectional strain distribution and movement of composite neutral axis before and after cracking, as well as the strain results of longitudinal reinforcing bars are investigated. Besides, the interaction equation for ultimate bending and torsional moments is proposed.

Study of Arch and Beam Rigidity of Long-Span V-Shaped Rigid Frame Composite Arch Bridges

AbstractAt first, we proposed the concept of nominal rigidity of a long-span V-shaped rigid frame composite arch bridge, analyzed the effects of structural parameters on nominal rigidity, and derived a theoretical nominal rigidity equation. In addition, we also discussed the selection of the arch-to-beam rigidity ratio and its effect on the distribution of internal forces, and analyzed the influence of the ratio on the internal forces. Then, we determined the delimitation value between rigid arch-flexible beam and flexible arch-rigid beam. At last, we summarized the nominal rigidity and arch to beam rigidity ratios of existing bridges. The results show that (1) rigid arch-flexible beam and flexible arch-rigid beam can be defined by the arch-to-beam rigidity ratio; (2) nominal rigidities have no obvious differences among the continuous rigid frame composite arch bridge, V-shaped rigid frame bridge, and arch bridge, which shows that nominal rigidity can reflect the global stiffness of a structure.