Composite Cable-stayed Bridge Research Articles

Experiment and numerical study on the static and fatigue behavior of a novel deck joint

To increase the prestressing efficiency and alleviate the longitudinal cracking in the concrete slab of composite cable-stayed bridges, a novel deck joint was proposed. The joint is composed of epoxy joint and concrete wet joint, which allows to introduce the prestress before the precast deck slabs are connected to the steel girder, therefore significantly increases the prestressing efficiency. Full-scale test models were fabricated and tested under repeated negative bending load, with the main variables being prestress level and fatigue load amplitude, and the evolutions of displacement, strain, crack width and moment distribution were investigated. A numerical study was conducted to investigate the effects of joint geometries and prestress level on the joint strength, the moment distribution and the neutral axes. The failure mechanism of the joint was revealed and a calculation method was recommended. Results show that the failure modes of the test models are rebar fracture in the tension zone, and the prestress has significant benefits on the joint behavior. The moment distribution between the precast and the post-cast sections is affected by the prestress level and the width ratio of epoxy and wet joints. The recommended method can predict the static flexural resistance of the joint with accuracy.

A theoretical model for investigating shear lag in composite cable-stayed bridges

A theoretical model for investigating shear lag in composite cable-stayed bridges

COMPARATIVE STUDY ON THE GIRDER ERECTION SCHEME FOR THE CHIBI YANGTZE RIVER HIGHWAY BRIDGE

The construction process of composite cable-stayed bridges varies, and it closely affects the finished bridge. This study takes the Chibi Yangtze River Highway Bridge, which is the world's largest-span composite cable-stayed bridge, as an example in determining the optimal scheme of girder erection during the construction of the composite cable-stayed bridge. Six girder construction schemes were proposed for comparison and analysis. On the basis of satisfying the objective principles of the finished bridge, the stress safety principle, and the economic principle, qualitative and quantitative methods were used to analyze the girder erection schemes. The refined model of the composite girder segment was established by the finite element software ABAQUS to examine the local stress of the bridge. Subsequently, the optimal scheme of girder erection was determined. Then, the key calculation results of the optimal scheme of girder erection during the construction stages and for the finished bridge were given, which proved the feasibility, safety, economy, and controllability of the proposed optimal scheme. Results show that the measured data of the girder line shapes and the cable forces of the finished bridge agree well with the theoretical values. This agreement verifies the correctness of the determination and demonstration of the proposed optimal scheme. This study provides a certain reference for the determination of the girder erection scheme of composite cable-stayed bridges. Keywords: Composite girder; cable-stayed bridge; steel girder erection; single segment one cycle; two segments one cycle; construction process;

Shear lag effect of composite cable-stayed bridges under dead and live loads

The modern composite cable-stayed bridge always has a wider deck, and the slab has an obvious shear lag effect. At the operation stage, internal forces distribution of the composite girder under live loads differs from that under dead loads only. It is essential to investigate the shear lag of the main beam under dead and live loads. Then, in-situ tests under truck loads were carried out on Xia Zhang Bridge. Considering the superposition of axial forces, a simplified method is proposed to evaluate the effective width. The finite element models (FEMs) of the full bridge using solid shell elements under dead and live loads were established. The longitudinal distribution of the effective widths for concrete slabs under different loading positions and loading forms was obtained. Furthermore, the full-scale variable parameter analysis considering the effects of span lengths and deck widths was conducted by FEMs. The numerical results show that the composite girder segments at the location of the bridge tower and the loading position need to be concerned for shear lag analysis. A generalised verification for a cable-stayed bridge was made, and compared results show that simplified methods can calculate the normal stresses in slabs more accurately than Eurocode 4.

Shear lag effect of composite girders in cable-stayed bridges under dead loads

The shear lag effect is a common phenomenon among civil infrastructures, which is also a critical issue for composite girders. For composite girders in large-span cable-stayed bridges, there is a large proportion of internal forces caused by dead loads, and the shear lag effect of the concrete slab under dead loads is significant. To investigate the normal stress distribution at the construction and service stages, systematic in-situ stress monitoring of composite girders was performed on a cable-stayed bridge under dead loads. Then, the finite element models were built for numerical modeling. The theoretical analysis model was proposed to evaluate the shear lag effect of composite cable-stayed bridges under dead load. Then the law of the stress ratio and the shear lag effect was analyzed by contrasting the test data and simulation results. Meanwhile, the calibrated FE models were used to do the full-scale parametric analysis of the factors including span length, slab width, and cable spacing. The results show that the main girder segment near the bridge tower and the mid-span are critical sections at the construction and service stages for analyzing the shear lag effect. The cable spacing and slab width are the main factors affecting the shear lag effect under dead loads. The effective width coefficients are positively correlated with the stress ratio.

Real-Time Tracking of Time-Varying Cable Frequency Based on a Time-Domain Signal Processing Method

In this paper, a time-domain signal processing method is proposed to extract the real-time time-varying cable frequency. The proposed conjugate-pair decomposition (CPD) method uses empirical mode decomposition (EMD) to obtain intrinsic mode functions (IMFs), and then the instantaneous frequency can be extracted by post-processing the conjugate-pair of IMFs. Several numerical simulations and a composite cable-stayed bridge experiment are used to validate the accuracy and capability of the proposed method for tracking time-varying cable frequency. Moreover, the proposed method may be further used to assess cable fatigue damage.

Seismic Damage Identification of Composite Cable-Stayed Bridges Using Support Vector Machines and Wavelet Networks

A seismic damage identification method for composite cable-stayed bridges has been developed. The proposed method is based on a Support Vector Machine (SVM) and Wavelet Network (WN). A shaking table test of a composite cable-stayed bridge is employed to verify the identification accuracy of the WNSVM method; the test results show that the nonlinear Finite Element Model (FEM) can correctly simulate the single-tower cable-stayed bridge, and the learning samples of WNSVM can be produced based on the nonlinear FEM. The structural damage results identified by the WNSVM method are in good agreement with those obtained by the shaking table test, and the maximum error is less than 8%. Therefore, the WNSVM method can be used for the seismic damage identification of composite cable-stayed bridges.

Danjiangkou Reservoir Bridge, China: a new record for earth-anchored cable-stayed bridges

Danjiangkou Reservoir Bridge, the world’s longest earth-anchored composite cable-stayed bridge, connects the highway networks of Hubei and Henan provinces in China. With a main span of 760 m, the 2022 structure is also the first of its kind to use a non-axial-force connection at mid-span and a steel and ultra-high performance concrete lightweight composite construction for the main-span girder. This paper describes the configuration of the non-axial-force connection, the arrangement of the composite girder and a new steel–concrete deck joint. It also explains how construction challenges were innovatively resolved by new closure and segmental precast erection methods.

Dynamic Performance Analysis of a Curved Cable-Stayed Bridge Based on the Direct Method and the Sensitivity-Based Iterative Method

Curved cable-stayed bridges have been regularly accepted due to their ability to cross long spans, and a number of studies have been conducted to investigate the mechanical or dynamic performance of them. Meanwhile, currently just a few studies focus on the curved composite cable-stayed bridges. In this study, an operational modal testing and finite element model updating of a conventional straight bridge with the steel-concrete composite girder were conducted to investigate the performance of the potential methods for the model updating, which included the direct method and the sensitivity-based iterative method. Then, dynamic tests were performed for one typical curved steel-concrete composite cable-stayed bridge as the key case study. A highly refined finite element model of the bridge was developed and then calibrated based on the aforementioned methods in reference to the experimental results. Finally, the dynamic behavior of the curved steel-concrete composite cable-stayed bridge was studied based on the model. It is found that the solution accuracy of the finite element model can be improved significantly by employing the structural health monitoring technique. Moreover, by using the iterative method, the solutions of the updating parameters are generally more accurate compared with the solutions of the direct method. Nevertheless, when the appropriate choices are made for the algorithmic parameters, both methods can lead to the updated models with satisfactory numerical analysis results as compared to the experimental data.

Experimental and numerical investigation on mechanical performance of continuous steel-UHPC composite slabs

Ultra-high-performance concrete (UHPC) has recently gained popularity for use in bridge constructions. Innovative steel-UHPC composite slabs (SUCS) with perfobond rib shear connectors were utilized as the deck slabs of the Fulong Xijiang Bridge (a composite cable-stayed bridge with span length of 580 m) in Foshan, China. The SUCS functions as multi-span continuous slabs supported on the transverse diaphragms of the girder. Two full-scale experiments were conducted to explore key mechanical performance aspects of continuous SUCS, including the load-deflection response, strain development, cracking behavior, moment redistribution and interface slipping behavior. The specimens experienced ductile flexural failure, and significant moment redistribution occurred with the formation of three plastic hinges. A detailed finite element model (FEM) was established to simulate the tested continuous slabs and also simply supported SUCS reported in the literature. A new constitutive model is proposed to describe the strain-hardening behavior of UHPC. Fasteners based on the shear stiffness formula and load-slip relationship reported in the literature modeled perfobond rib shear connectors and studs, respectively. The predicted results of deflection, interface slip and failure mode correspond well with experimental results, indicating that the FEM accurately simulates SUCS. In addition, comprehensive parametric studies performed using the validated FEM revealed the influences of different parameters on mechanical performance of continuous SUCS.

Full-scale experimental study on continuous UHPC slabs of steel-UHPC composite deck system

The heavy self-weight and the cracking of normal strength concrete (NSC) deck slabs hindered the application of steel-concrete composite girders in long-span bridges. These problems can be solved by using ultra-high performance concrete (UHPC) deck slabs instead of the NSC deck slabs. Based on Yellow River Bridge of Zhanhua-Linzi Highway, a steel-UHPC composite cable-stayed bridge with span length of 442 m, full-scale tests on seven continuous UHPC (NSC) deck slabs were conducted. The studied parameters were sagging-to-hogging reinforcement ratio, concrete type, yield strength of steel bars and wet joints. The static properties of continuous UHPC (NSC) deck slabs were investigated in detail, including failure modes, load-deflection response, cracking behavior, strain development and moment redistribution. Discussions were made on the effect of different parameters according to the experimental data. Results showed that the use of UHPC can avoid shear failure, which was the case for the continuous NSC slab. Reducing the sagging-to-hogging reinforcement ratio from 1.00 to 0.63, the failure mode changed due to the altered formation order of plastic hinges. The ultimate capacity was decreased while the ductility and moment redistribution were improved by decreasing the yield strength of steel bars. The existence of wet joints significantly weakened the deck slabs. Strengthening the wet joints with steel plates can effectively compensate for this effect and even achieve better mechanical properties compared with integrally cast slabs. Furthermore, placing a comb-shaped wet joint at the intermediate support of continuous slab will result in a certain decrease of ultimate capacity and stiffness, which is acceptable for the transverse direction with relatively small internal forces. It is suggested that wet joints should be avoided at the supports of continuous deck slabs along the longitudinal direction.

Shear lag effect of twin I-shaped composite girders in cable-stayed bridges

The five loading cases for experimental models were designed to investigate the shear lag effects in composite girders of a cable-stayed bridge at the action of the positive or negative moment combined with axial and shear forces. The governing differential equations were established for the composite girder in cable-stayed bridges. The finite segment model considering the slip effect was developed using the differential equations solutions as displacement patterns. And the applicability of the finite segment model was calibrated with experimental results. The key influencing factors of effective width were analyzed by the full-scale parametric study. The slab width and cable spacing are the key factors controlling the effective slab width in composite cable-stayed bridges.

Numerical simulation and simplified calculation of the effective slab width for composite cable-stayed bridges

With the advent of progressively large and complex structures, the simultaneous presence of axial forces and bending on bridge decks is emerging as a recurring and increasingly concerning phenomenon. In the design of steel–concrete composite cable-stayed bridges, the combination of the axial force, mainly induced by the inclination of the cables, and bending is being increasingly considered to realize long spans that can bear the weight of the structure while ensuring a high rigidity of the deck. Despite its importance, this aspect is not sufficiently treated in the design codes, e.g., Eurocode specifications do not consider the axial force and its shear lag effects; therefore, the design rules are specified exclusively for the case of bending. From a practical standpoint, this deficiency can entail design complications due to the use of complicated FE models (shell and brick elements), which incur significant computational loads and design effort. In this study, a simple methodology for the design and verification of a girder composite deck subjected to combined compression and bending is developed. The methodology is based on a parametric study performed using finite element (FE) models that are valid for a generic girder composite deck. The stress distribution on the composite deck can be assessed while accounting for the axial force and bending moments associated with the deck by considering the results obtained using universal beam models. The proposed methodology is applied to an existing cable-stayed bridge.

Flexural behavior of wet joints in steel-UHPC composite deck slabs under hogging moment

A new type of steel-UHPC composite slabs (SUCS) with PBL shear connectors are used as bridge decks in an ultra-long-span composite cable-stayed bridge under construction in China. SUCS can be prefabricated in the factory and then transported to the construction site for assembly. The steel parts of the adjacent SUCS shall be welded together and UHPC wet joints, which are the weak parts of the bridge deck, shall be cast in-situ to finish the assembly. Full-scale tests of three SUCS with dovetail-shaped wet joint or newly-proposed construction-friendly rectangular wet joint were conducted to investigate the flexural behavior under hogging moment. Flexural failure of the interface section occurred in all specimens. The ultimate capacity and crack resistance of rectangular wet joints can be close to the dovetail-shaped wet joints with the same notch length. The phenomenon that tenons were pulled out from the rectangular notch appeared in rectangular wet joints during loading, which was especially prominent when the notch length was short, and the ultimate capacity and crack resistance would be reduced. Experimental results showed significant differences between cracking behavior of the interface and the non-interface, revealing the importance influence of wet joints on durability. The ultimate capacity was analyzed theoretically, and discussions were made on the reduction of ultimate capacity caused by wet joints. In addition, a crack width prediction model was obtained by modifying the model in GB50010-2010, which was based on the comprehensive analysis method combining bond-slip method and non-slip method. The modified model can give satisfactory prediction results of crack width for both interfacial and non-interfacial cracks.

Dynamic characteristics of a curved steel–concrete composite cable-stayed bridge and effects of different design choices

The paper presents and discusses the dynamic response of a curved cable-stayed bridge in Venice (Italy). Two distinct experimental campaigns in 2010 and 2011 led to identifying the bridge dynamic characteristics in operational conditions. The dynamic identification included the characterization of both the deck and cables response. The authors developed a highly refined finite element (FE) model of the bridge, mirroring up to twelve experimental modes. An updating procedure drove the estimate of the optimum parameters associated with the lowest discrepancy with the experimental modal parameters. The calibrated model was the base of a parametric analysis on the effects of the deck curvature, cables arrangement and tower cross-section inertia on the bridge dynamics. Specifically, the authors developed fourteen FE models of the bridge distinguished by the lack and different arrangement of the stay cables, the increasing value of the deck curvature and the tower cross-section inertia. The analysis intends to quantify the impact of the design choices of cable-stayed bridges on the modal parameters.

Nonuniform wind characteristics and buffeting response of a composite cable-stayed bridge in a trumpet-shaped mountain pass

Due to the spatial differences in wind fields in mountainous areas, it is an urgent problem to accurately estimate the buffeting response of long-span bridges in mountainous areas. In this paper, the spanwise variations in the mean and fluctuating wind characteristics of a bridge site are obtained based on a terrain wind tunnel test of a trumpet-shaped mountain pass. Additionally, the aerodynamic admittance function of a Π-shaped composite girder under different wind attack angles is measured in the wind tunnel. The buffeting response calculation theory considering the spanwise variations in the mean wind and fluctuating wind characteristics along the main girder is established. The influence of the nonuniform wind characteristics on the buffeting response of the main girder is analyzed. The results show that the spanwise variation in wind characteristics at the bridge site is affected by the direction of inflow and can be described by a quadratic polynomial. Nonuniform wind parameters have obvious effects on the buffeting response, and a nonuniform wind attack angle is a key factor affecting the buffeting response. It may not be appropriate to predict the buffeting response by using the single-point wind field observation results in mountainous areas.

EXPERIMENTAL AND NUMERICAL INVESTIGATIONS ON THE FLEXURAL BEHAVIOR OF STEEL-UHPC COMPOSITE SLABS WITH PERFOBOND RIB SHEAR CONNECTORS

A new type of steel-ultra-high performance concrete (UHPC) composite slab with perfobond rib shear connectors (PBL shear connectors) is studied, which can be used as large-span bridge decks and floors in buildings. According to the deck system of an ultra-long-span composite cable-stayed bridge, full-scale tests on three steel-UHPC composite slabs (SUCS) and a steel-C60 composite slab (SCCS) were conducted. The influence of the number and type of shear connectors were investigated. The experimental results demonstrate that, subjected to concentrated load, typical flexural failure of SUCS occurred while punching failure of SCCS occurred; that the SUCS possessed much higher ultimate capacity, rigidity and ductility than the SCCS with the same thickness did; that the specimen with sufficient perfobond rib shear connectors exhibited the best mechanical performance among the three SUCSs. Elaborate finite element models of the SUCSs were established in ABAQUS, which can reproduce the load-deflection curves obtained from the tests. Parametric study is conducted adopting the established finite element models.

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.

Research of Thermal Effect of Cable-Stayed Bridge with a Separated Side-Box Steel-Concrete Composite Girder under Solar Radiation

At present, there are few studies on the thermal effect of solar radiation on a separated double-sided box steel-concrete composite girder cable-stayed bridge. In this paper, the beam element and mixed element models are combined with the theory of transient heat transfer analysis and meteorology; this approach is adopted to carry out a thermodynamic analysis of a related bridge project. The calculation results of the thermal field and structural thermodynamic analysis of bridge sections show that, in terms of a separated double-sided box steel-concrete composite girder cable-stayed bridge, the thermal field distributions of the main girder and the pylons are extremely complex under conditions of solar radiation. Therefore, the real thermal field cannot be accurately described as a one-dimensional temperature gradient. The traditional beam element model cannot accurately simulate the temperature effect, and it will underestimate its thermal effect. The calculated temperature stress values of the mixed element model are quite different from those of the of beam element model. The mixed element model can precisely reflect the local thermal effect of each component in this system under solar radiation. Compared with the calculation results of the beam element model, the maximum temperature stress of the bridge deck in each section of the main girder is generally 20% larger; the maximum temperature stress levels of the steel-beam top and bottom plates are 14.7 MPa and 15.9 MPa larger, respectively. The maximum shear stress of the steel-concrete interface is 0.2 MPa larger. The research results of the temperature effect calculated by the mixed element have an important guiding significance for the design and maintenance of bridges.

Design feasibility of long-span composite bridge with corrugated steel webs

A partial cable-stayed composite girder bridge with prestressed concrete flanges and corrugated steel webs (CSWs) is a beneficial new type of bridge structure that provides lower structural weight, reduced structural depth, increased span and lower seismic response. The structural responses and cost of four bridge types (a partial stayed-cable composite bridge with CSWs, a partial stayed-cable concrete bridge, a cable-stayed composite bridge with CSWs and a continuous rigid-frame composite bridge with CSWs) were compared and analysed. The results showed that the structural form and response of the main girder of a partial cable-stayed composite bridge are between those of a continuous rigid-frame composite bridge and a composite cable-stayed bridge. Compared with a concrete cable-stayed bridge of the same span, the self-weight of a partial cable-stayed composite bridge with CSWs is lighter, the main beam is lighter and the overall cost is less.