Composite Bridge Model Research Articles

Numerical and experimental validation of the static performance of a full-scale flax fiber-polyester composite bridge model to support the design of an innovative footbridge

This paper deals with the numerical and experimental analysis of a large-scale footbridge model made of flax fiber-reinforced polyester composite. The goal of this work was to support the design of the 15 m span flax-polyester footbridge installed at the Floriade Expo 2022 in Almere, the Netherlands. The model stacking sequence, thicknesses, material, and vacuum infusion technology are identical to those of the footbridge. For the numerical analysis, a multi-layered laminate was modeled using ABAQUS with a composite layup and continuous shell elements. The model was equipped with 16 embedded fiber-optic Bragg grating (FBG) sensors for strain sensing and mechanical evaluation. The specimen was subjected to monotonic loading and unloading. Numerical results were compared with those obtained from the load test. The good agreement revealed the correctness of the assumptions. This study provides a design methodology based on numerical and experimental investigation, to overcome uncertainties derived from the application of this innovative material for load-bearing applications in footbridges.

Basic static behaviours of an arch-cable composite bridge

To improve the material utilisation efficiency, a new type of arch-cable composite bridge was proposed based on the tied-arch bridge and beam string structure. Then, the stress mechanism of this system, as well as its deformation and stress under vertical loading, were analysed. Arch-cable composite bridges use arch ribs and main cables as their main load-bearing components. The main cable anchors are fixed to the arch springing in place of the tie rods employed in tied-arch bridges. The main cable is not only used to balance the thrust of arch springing but also directly bears dead and live loads. Theoretical analyses show that, in arch-cable composite systems, when the bending moment of the vault is zero, the ratio of dead load carried by the arch and the cable equals the ratio of the rise of the arch to the cable sag. In light of this situation, a simplified mechanical model of the arch-cable composite bridge was established to derive the analytical equations for the vertical deformation of the structure, as well as the bending moment of the arch rib and the horizontal force of the main cable under the impact of concentrated load and full-span uniform load. Subsequently, a finite element model (FEM) of the arch-cable composite bridge was established to verify the theoretical equations. The finite element simulation results are consistent with the theoretical values. Furthermore, a tied-arch model with the same span was established to compare and analyse the stress differences between its main members and those of the arch-cable composite bridge model. Results show that, compared with the tied-arch bridge, the arch-cable composite bridge bears fewer stresses on the arch rib, main cable and hangers, showing greater structural stiffness and excellent structural performance.

A Novel Slip Sensory System for Interfacial Condition Monitoring of Steel-Concrete Composite Bridges

Steel-concrete composite (SCC) beams are widely employed in bridge decks. The interfacial shear transfer between the top concrete slab and the supporting steel beams significantly affects the overall load carrying capacity and performance of a bridge deck. The inaccessibility of the connection system makes the visual inspection difficult, and the traditional vibration-based methods are insensitive to this type of local damage. In this study, a novel interlayer slip monitoring system has been developed for interfacial condition assessment of SCC beams. The monitoring system is mainly based on the Ultra-flat Industrial Potentiometer Membrane (UIPM). The sensor film that is glued on a steel base is mounted on the concrete slab, and the wiper is installed on the steel beam. The interlayer slip between the concrete slab and steel beam is monitored by the relative displacement between the sensor film and the wiper. An experimental study has been carried out on a 6-m long composite bridge model in the laboratory. In the model, the concrete slab and the steel beams are bolt-connected, and the bolts could be loosened to simulate the defects in the shear connection system. Seven slip sensors are evenly installed along the bridge model. The sensors are calibrated using the testing machine before they are installed on the bridge model. Three damage scenarios are simulated by loosening bolts at different locations. Different loadings are also applied on the bridge to simulate the operational conditions. Undamaged and damaged scenarios have been considered within load increments, and data are collected and interpreted to find out how the slip changes. The results show that this system is reliable and efficient to monitor the interlayer slip for assessing the interface condition of composite structures.

Analysis Of Steel-Rcc Composite Deck Bridge

: In the literature, provisions for analysis and design of steel-RCC composite deck type truss and cable-stayed bridges do not exist. A composite deck type truss bridge model is analyzed using STAAD Pro V8i software and a model with the same dimensions is tested in the laboratory. The experimental test results are used to validate the STAAD analysis results.
 Bottom chord strain and mid-span deflection of the composite bridge model as found from the STAAD analysis and the laboratory experiment closely tally with each other. This validates the standard STAAD analysis results. However, in the top chord member, due to shrinkage cracks in the deck slab concrete, the experimentally recorded strain is higher by about 100% than the STAAD analysis result. 
 Shear force in studs is considerably large near supports and joints as compared to the midsection. Therefore, the design of shear studs may be carried out based on the shear forces in the studs found from the STAAD analysis. 
 Thus it is recommended that STAAD or any other standard finite element analysis software can be used for analysis and design of the composite bridges.

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.

Damage detection in steel-concrete composite bridge using vibration characteristics and artificial neural network

This paper develops and applies a procedure for detecting damage in a composite slab-on-girder bridge structure comprising of a reinforced concrete slab and three steel I beams, using vibration characteristics and Artificial Neural Network (ANN). ANN is used in conjunction with modal strain energy-based damage index for locating and quantifying damage in the steel beams which are the main load bearing elements of the bridge, while the relative modal flexibility change is used to locate and quantify damage in the bridge deck. Research is carried out using dynamic computer simulations supported by experimental testing. The design and construction of the experimental composite bridge model is based on a 1:10 ratio of a typical multiple girder composite bridge, which is commonly used as a highway bridge. The procedure is applied across a range of damage scenarios and the results confirm its feasibility to detect and quantify damage in composite concrete slab on steel girder bridges.

Modeling the shape memory and strength properties of fiber-reinforced shape memory polymer composite laminates

Shape memory polymer composites (SMPCs) are one of the promising material candidates applied in the fields of aerospace and biomedicine. The shape memory and strength properties of SMPCs are very important in engineering structures based on the material. In the paper, an efficient generalized Maxwell model is developed to describe the constitutive relations of the pure shape memory polymers under small deformation at first, and then extended to predict the thermomechanical properties of the SMPCs based on the bridge micromechanics model. The simulation results show that the SMPCs possess remarkable shape memory performance and enhanced mechanical properties. Thereafter, the strength properties of the matrix and the composites, as well as the effects of fiber contents, temperatures and loading angles, are studied in detail based on the polymer strength theory, the composite bridge model and the Tsai-Hill criterion. The present micromechanical model provides an efficient method for designing and optimizing SMPCs.

Using multi-type sensor measurements for damage detection of shear connectors in composite bridges under moving loads

This paper proposes using the multi-type sensor vibration measurements, such as from a relative displacement sensors and a traditional accelerometer for the damage detection of shear connectors in composite bridge under moving loads. Hilbert-Huang Transform (HHT) spectra of these responses will be fused with a data fusion approach i.e., Dempster-Shafer method, to detect the damage of shear connectors. Experimental studies on a composite bridge model in the laboratory are conducted to demonstrate the effectiveness and performance of using the proposed approach in detecting the damage of shear connectors in composite bridges. Both undamaged and damaged scenarios are considered. The detection results with the data fusion of multi-type sensor measurements show a more reliable and robust performance and accuracy, avoiding the false identifications.

Seismic fragility of a typical bridge using extrapolated experimental damage limit states

This paper improves seismic fragility of a typical steel-concrete composite bridge with the deck-to-pier connection joint configuration at the concrete crossbeam (CCB). Based on the quasi-static test on a typical steel-concrete composite bridge model under the SEQBRI project, the damage states for both of the critical components, the CCB and the pier, are identified. The finite element model is developed, and calibrated using the experimental data to model the damage states of the CCB and the bridge pier as observed from the experiment of the test specimen. Then the component fragility curves for both of the CCB and the pier are derived and combined to develop the system fragility curves of the bridge. The uncertainty associated with the mean system fragility has been discussed and quantified. The study reveals that the CCB is more vulnerable than the pier for certain damage states and the typical steel-concrete composite bridge with CCB exhibits desirable seismic performance.

Investigation of free vibration and ultimate behavior of composite twin-box girder bridges

Multi spine composite concrete-deck steel-box girder bridges became a very popular choice in highway bridges due to their high torsional and wraping stiffness as well as for economic and aesthetic reasons. This study presents an experimental investigation on both elastic and ultimate behavior of composite box girder bridges in order to study the effect of internal cross bracing between box girders along with the curvature effect at different loading stages. Three composite concrete deck-steel simply-supported twin-box bridge models, two curved and one straight, were fabricated, and tested. First, the response of each model was monitored under free-vibration excitation, then an eccentric loading was applied and the corresponding deflections were recorded in the elastic range. Finally, the bridge models were tested up to collapse. The structural behavior of the three bridge models was compared at the three loading stages. It was noticed that the presence of an external cross bracing system between the steel boxes had an insignificant effect on the developed deflection and the fundamental natural frequency in the elastic range of loading. On the other hand, these external bracings assisted in decreasing the developed deflection approaching failure and in increasing the load carrying capacity by about 8.9%. In addition, the external bracing ensured a better distribution of the stresses under ultimate loading conditions. Moreover, the experimental findings were verified numerically using finite element modeling. A good agreement was noticed to exist between the experimental findings and the numerical results.

Damage detection in bridge structures under moving loads with phase trajectory change of multi-type vibration measurements

This paper presents a non-model based damage detection approach for bridge structures under moving loads based on the phase trajectory change of multi-type vibration measurements. A brief theoretical background on the vibration of a simply-supported bridge with a crack under moving load is described. The phase trajectories of multi-type dynamic responses are obtained and a damage index is defined as the separated distance between the trajectories of undamaged and damaged structures to indicate the damage location. Numerical studies on a simply-supported beam structure are conducted to investigate the sensitivity and robustness of the proposed approach to accurately identify the damage location. Experimental studies demonstrate that the proposed approach can be used to successfully identify the shear connection failure in a composite bridge model subjected to moving loads.

Damage detection of shear connectors under moving loads with relative displacement measurements

This paper investigates the use of relative displacement measurements from the newly developed relative displacement sensors to identify the damage of shear connectors in composite bridges. Continuous Wavelet Transform and Hilbert–Huang Transform are applied to analyze the measured dynamic responses and to identify the damage of shear connectors in the composite bridge model under moving loads. Comparative studies by using the relative displacement, acceleration and displacement measurements respectively for the damage detection are conducted. A comparative study of using relative displacements and acceleration responses of the bridge under ambient excitations to monitor the shear connector conditions is also conducted. Numerical and experimental studies demonstrate that both relative displacement and acceleration measurements can identify the location and the instant of damage occurrence in shear connectors when the bridge is under moving loads. The results demonstrate that relative displacement is a better response quantity for structural health monitoring of composite bridges.

Development and application of a relative displacement sensor for structural health monitoring of composite bridges

Summary This paper proposes a relative displacement sensor developed to measure directly the relative slip between slab and girder in composite bridges for assessing the health condition of shear connections. The structure, design principle, features, and calibration of the developed relative displacement sensor are presented. The design of the sensor ensures that there are no voltage outputs for the tension, compression, bending, and torsion effects, but only for the relative displacement between the two connecting pads of the sensor. The accuracy of the developed sensor in measuring the relative displacement response and using it for monitoring the conditions of shear connectors was tested on a composite bridge model in the laboratory. Shear connection condition was monitored under ambient vibrations, then static load tests were conducted to introduce cracks into the composite bridge. Both the vertical deflections and relative displacements were used for the crack detection. Experimental studies demonstrate that the developed sensor is very sensitive to the relative displacement and has a decent performance for the structural health monitoring of composite bridges. Copyright © 2014 John Wiley & Sons, Ltd.

A comparative study on static and dynamic responses of FRP composite and steel suspension bridges

Fiber reinforced polymer (FRP) composites offer many attractive and unique features for existing and new bridges. Among these features are light weight, high stiffness-to-weight and strength-to-weight ratios, damping capabilities, and high resistance to environmental degradation when properly designed and installed. This article presents a pilot numerical study aiming at evaluating the feasibility of using FRP composites in suspension bridge applications. This was accomplished by comparing the response of two identical long-span suspension bridges, one constructed from FRP composite and the other made of steel under static and dynamic loadings using FEM. The numerical results indicated that the responses of the two bridges are different and that the response values obtained for the steel bridge are relatively large compared to the composite bridge. Despite different mode sequences of the two bridge models, the dynamic analysis results indicated that both bridge models have similar mode shapes. As a result of lower self-weight of the FRP composite bridge model, the frequencies of the FRP composite bridge model are larger than those of the steel bridge model.

Investigation of Ultimate Strength of Deck Slabs in Steel-Concrete Bridges

Many bridges are composite structures with reinforced concrete decks supported by longitudinal steel beams. The presence of the longitudinal steel beams and the unloaded area of concrete slab cause the loaded deck slabs to be restrained against lateral expansion. This creates a compressive membrane (or arching) action. This study uses experimental tests to investigate the effects of structural variables on the load capacity of the deck slabs of the composite bridges. A practical design approach is presented to assess the restraint stiffness that exists in the composite bridge deck and thereby the strength enhancement due to arching action. A series of one-third scale steel-concrete composite bridge models were built with several varying structural parameters, including concrete compressive strength, reinforcement percentage, and the size of steel supporting beams. After comparing the results of different models, the influence of these structural parameters on the amount of compressive membrane action in the deck slab was evaluated. Experimental results showed that compressive membrane action is influenced by concrete compressive strength and lateral restraint stiffness. The proposed method provided accurate, consistent but slightly conservative predictions for the strength of a wide range of deck slabs.

Flexural Behavior of Continuous Composite Bridges with Precast Concrete Decks

For the construction of open-topped steel box girder bridges, prefabricated concrete slab could offer several advantages over cast-in-situ deck including good quality control, fast construction, and elimination of the formwork for concrete slab casting. However, precast decks without reinforcements at transverse joints between precast slabs should be designed to prevent the initiation of cracking at the joints, because the performance of the joint is especially crucial for the integrity of a structural system. Several prestressing methods are available to introduce proper compression at the joints, such as internal tendons, external tendons and support lowering after shear connection. In this paper, experimental results from a continuous composite bridge model with precast decks are presented. Internal tendons and external tendons were used to prevent cracking at the joints. Judging from the tests, precast decks in negative moment regions have the whole contribution to the flexural stiffness of composite section under service loads if appropriate prestressing is introduced. The validity of the calculation of a cracking load fur serviceability was presented by comparing an observed cracking load and the calculated value. Flexural behavior of the continuous composite beam with external prestressing before and after cracking was discussed by using the deflection and strain data.

Nonlinear analysis of plate–truss composite steel girders

An efficient approach to the nonlinear analysis of plate–truss composite steel girders is presented in this paper. Using finite strip elements in transverse direction, a spatial displacement field in consideration of local buckling of a plate–truss composite structure is constructed. The updated Lagrangian formulation of the finite strip element is introduced based on the incremental virtual work principle of the three-dimensional continuum, and the effect of large deformation is taken into account with the Euler coordinate transformation. The effect of material nonlinear behavior is considered with inner-force plastic coefficients of cross section. As an illustrating example of the application of the presented approach, the nonlinear behavior of a plate–truss composite steel bridge model is studied, and the computational results are verified with test data.

Simply Supported Curved Cellular Bridges: Simplified Design Method

The use of curved composite bridges in interchanges of modern highway systems has become increasingly popular for economic and aesthetic considerations. Bridges with a concrete deck composite with a steel multicell section can adequately resist torsional and warping effects induced by high curvature. Although current design practices in North America recommend few analytical methods for the design of curved multicell box girder bridges, economical requirements in the design process point to a need for a simplified design method. This paper summarizes the results from an extensive parametric study, using the finite-element method, in which simply supported curved composite multicell bridge prototypes are analyzed to evaluate the moment and deflection distributions between girders, as well as the axial forces expected in the bracing system, due to truck loading as well as dead load. Results from tests on four, 1/12 linear-scale, simply supported curved composite concrete deck-steel multicell bridge models are used to substantiate and verify the analytical modeling. The parameters considered in the study are cross-bracing system, aspect ratio, number of lanes, number of cells, and degree of curvature. Based on the data generated from the parametric study, expressions for moment and deflection distribution factors are deduced. Expressions for the maximum axial force in bracing members are also derived. An illustrative design example is presented.

Shear Distribution in Simply-Supported Curved Composite Cellular Bridges

Composite steel-concrete multicell box girder bridges are quite often used in modern bridge superstructures with curved alignments. They provide excellent torsional resistance as well as elegant appearance. While current design practices in North America recommend few analytical methods for the design of curved multicell box bridges, practical requirements in the design process require a need for a simplified design method. This paper summarizes the results from an extensive parametric study, using a finite-element model, in which 120 simply-supported curved bridge prototypes are analyzed to evaluate the shear distribution in the webs due to truck loading as well as dead load. Results from tests on four 1/12 linear-scale simply-supported curved composite concrete deck-steel three-cell bridge models are used to substantiate the analytical modeling. The parameters considered in the study are: cross-bracing system, aspect ratio, number of lanes, number of cells, and degree of curvature. Based on the data generated from the parametric study, expressions for the shear distribution factors for truck loadings as well as dead load are deduced. An illustrative design example is presented.

Vibrations of horizontally curved continuous composite cellular bridges

The use of cellular-shaped cross sections for highway bridges, especially on curved alignments, is an economical solution because of the high flexural and torsional strength of such sections. This paper summarizes the dynamic characteristics of curved composite multi-cell (contiguous boxes) bridges, continuous over two and three spans. An extensive parametric study, using the finite-element method, was conducted to evaluate the key parameters that may affect the natural frequencies and the corresponding mode shapes for this type of bridge. These parameters are end-diaphragm thickness, number of cross-bracings, aspect ratio, span-to-depth ratio, degree of curvature, number of cells, and span-to-span ratio. The effect of cracking of the concrete deck slab in the vicinity of interior supports is also investigated. Results obtained from tests on a 1/12 scale two-span continuous curved composite three-cell bridge model are used to substantiate the analytical modelling. Based on the data generated from the parametric study, empirical formulas for the dominant frequency are deduced. An illustrated design example is presented. A study is also conducted to determine the dynamic deflections caused by a moving truck over the bridge with a view to improve human discomfort and perception to vibration.Key words: box girder, bridges, cellular, curved, composite, continuous, dynamic analysis, experimental, finite-element.