Tubular Arch Bridge Research Articles

Damage Identification of Concrete-filled Steel Tubular Arch Bridge using Data Fusion Based on Information Allocation Theory

It is proposed in this paper a novel damage identification method of concrete-filled steel tubular arch bridge using data fusion based on information allocation theory. This method is actually a data fusion process, in which the statistic characteristics of the measured data, such as mean, standard deviation are calculated firstly, and then the bad points are excluded by the Grubbs Guidelines from the data set. After that, the measured data satisfied to certain precision are sent to a data fusion centre where the fusion computation is performed by employing a weighted average algorithm, and the damage location of a CFST arch bridge is determined by the peak value method finally. The efficiency and feasibility of the method proposed is validated by detecting both single- and multi-damage patterns of a two-span CFST arch bridge, and the effect of environmental on identification results is studied simultaneously. The results show that the proposed method is capable of detecting damage and has a good robustness.

State of the art of creep of concrete filled steel tubular arches

The state of the art of creep of Concrete Filled Steel Tubular (CFST) arch bridges including CFST members is presented in this paper. It is delineated that researches on creep of CFST is not mature and need much study compare to creep of plain concrete and reinforced concrete. In comparison with the plain concrete members, creep magnitude in CFST is relatively low but, the duration is longer. Creep has much influence on the deformation, stress redistribution between steel tube and core concrete and to reduce the buckling strength of CFST arches; how to implement the research results on actual arch bridge design is necessary part of research in pending. A good creep prediction model is the urgent essence of today’s design works with CFST element.

Seismic Testing of a Long-Span Concrete Filled Steel Tubular Arch Bridge

Long-span bridges are always a multi-support structural system, and seismic ground motion can vary significantly over distances comparable to the length of such kind of bridges, so it’s difficult to carry out shaking table tests because of the restriction of the dimension and amount of shaking tables. This paper discusses the multiple sub-table cordwood system is used to conduct a study on the seismic testing of a three-span irregular Concrete filled steel tubular (CFST) arch bridge with the objective of investigating the dynamic performance of the bridge under spatial earthquake motions. The development and testing of the bridge model and selected experimental results are discussed then. The seismic response and response characteristics of acceleration, displacement, internal force, and strain of the structure under earthquake excitations are gained, which can provide test data and basis to evaluate the seismic performance of this CFST arch bridge or other similar structural system design.

Reliability Estimating of Existing Bridge Using Dynamic Monte-Carlo Method

Based on time-dependent reliability theory, intermediate working state is considered, combining with current specifications, concrete filled steel tubular (CFST) arch bridge is discussed as a case, determination principle of three-stage mode is given. The direct correspondence from reliability indices to working states is made clear consequently. Introducing state variables, dynamic Monte-carlo method is presented. Basic formulas of failure probability and damage probability are derived by variable time increment method. The bridge is an CFST arch bridge with 83.6 meter-span, which operated for 10 years. According to test result, dynamic Monte-carlo method is used to estimate the reliability of this bridge. The analysis result shows that, in the tenth year, both damage reliability index and failure reliability index are above target reliability index. The example bridge is in safe working state at present. This conclusion is consistent with the facts.

Experimental Study on Temperature Fields of Dumbbell-Shape Section of CFST Arch Rib and its Effects

Based on the investigation of a constructing dumbbell-shaped concrete-filled steel arch bridge in Nanning, Guangxi, continuous on-site experimental researches on temperature field and its effects were carried out under the influence of hydration heat of concrete in the molding process of concrete-filled dumb-bell steel tubular arch bridge. On the basis of measured data, analysis on time-history law of temperature field and its effect under the impact of hydration heat of concrete of composite structure of concrete-filled steel tubes is made. The results reveal that temperature variation of hydration heat of the concrete within the steel tube is showed as follows: “Temperature up-continuous high temperature-temperature down-balance”. The structural temperature field, generated under the effect of hydration hea in the process of molding arch rib, is nonlinear temperature field. Concrete hydration temperature effect of crown section basically changes with temperature field simultaneously, while the residual strain of arch foot section is relatively large; hydration temperature effect of L/4 Section emerges peak fluctuations in concrete pouring process and finally levels off. Hydration temperature field of concrete has a great effect on crown section, which makes the steel tube continuously withstand the tension and compression alternatively, while the influence on the arch foot steel tube is not obvious. Surface strains of L/8, L/4, 3L/8 sections of steel tube transit from single-wave peak to dual-wave peak and finally turn into a single wave peak.

Intelligent Data-Fusion Model Using Correlation Fractal Dimension for Structural Damage Identification

To extract effectively features and improve damage identification precision, this study proposed an intelligent data-fusion model by integrating fractal theory, probabilistic neural network (PNN) and data fusion. A two-span concrete-filled steel tubular arch bridge in service was used to validate the intelligent model by identifying both single- and multi-damage patterns. The results show that the intelligent model proposed can not only reliably identify damage with different noise levels, but also have an excellent anti-noise capability and robustness.

Static Characteristics and Nonlinear Seismic Response of Concrete-Filled Tubular Arch Bridge with Half-Through Deck

Static Characteristics and Nonlinear Seismic Response of Concrete-Filled Tubular Arch Bridge with Half-Through Deck

Time-Dependent Behavior of Concrete-Filled Steel Tubular Arch Bridge

This paper develops a simplified method using a summation procedure and a related computer program to calculate the time-dependent behavior of a concrete filled steel tubular (CFST) arch bridge based on the geometric compatibility principle, a step-by-step time incremental process, and self-equilibrium equations. An experimental test on a scaled (1:5) segmental model of the main arch ribs of the Maocaojie Bridge was used to confirm the effectiveness of the proposed calculation method for evaluating the long-term behavior of CFST arch bridge under sustained load. It is concluded that: (1) the numerical results were in good agreement with the experimental results, demonstrating that the proposed analytical model is capable of predicting long-term effects for CFST arch bridges; (2) the stresses in the steel tubes increased, and the compressive stresses in the concrete decreased due to the effects of concrete creep and shrinkage. The maximum relaxation of the compressive stress in concrete due to concrete creep was 52.7% of the initial concrete stress, and the maximum increase of stress in the steel tubes was 27.3%; and (3) more than 90% of the total creep of the concrete took place in the first year. Subsequent creep of the concrete was limited because of the lack of water exchange between the structure and atmosphere and the reduction of compressive stress in the concrete.

Effects of Arch Rib Crossbars on Dynamic and Stabilization Characteristics of Concrete Filled Steel Tubular Arch Bridge

AbstractConsidering the influence of crossbars of arch rib of CFST arch bridge on vertical bending rigidity and torsional rigidity of the whole bridge system, the space finite element calculating m...

Approach for analyzing the ultimate strength of concrete filled steel tubular arch bridges with stiffening girder

A convenient approach is proposed for analyzing the ultimate load carrying capacity of concrete filled steel tubular (CFST) arch bridge with stiffening girders. A fiber model beam element is specially used to simulate the stiffening girder and CFST arch rib. The geometric nonlinearity, material nonlinearity, influence of the construction process and the contribution of prestressing reinforcement are all taken into consideration. The accuracy of this method is validated by comparing its results with experimental results. Finally, the ultimate strength of an abnormal CFST arch bridge with stiffening girders is investigated and the effect of construction method is discussed. It is concluded that the construction process has little effect on the ultimate strength of the bridge.

Finite element model updating of concrete-filled steel tubular arch bridge under operational condition using modal flexibility

This paper presents finite element (FE) model updating method for real bridge structure under operational condition using modal flexibility. The theoretical background of the updating procedure is presented. The case study of a simulated simply supported beam demonstrates an effectiveness of modal flexibility in objective function. This objective function is then implemented in case study of a real concrete-filled tubular arch bridge. The bridge was tested under operational condition. Followed by the three-dimensional FE modeling of the bridge, an eigenvalue sensitivity study is carried out to select the most sensitive parameters to the concerned modes. Guyan technique is used to the mass normalization of the mode shapes extracted from ambient modal test to calculate the modal flexibility. The updated FE model of the bridge is able to produce a sufficient improvement on modal parameters of the concerned modes, which is in close agreement with the experiment results and updated parameters still preserve the physical meaning in practice.

Computation and Analysis of the Creep Effect of Long-span Concrete-filled Steel Tubular Arch Bridge

There are a number of factors that influence the creep of concrete-filled steel tubular arch bridges, while the related research theory lags behind the state of practice. Based on the computing formula of creep coefficient in the code, the creep function is formulated. The computing method of creep in structural analysis is deduced, using the integral concepts of stress and time. Combined with the calculation of Meixi River Bridge it is noted out that creep affects the displacement of CFST arch bridge prominently, which will lead to redistribution of internal force. This should be recognized in related engineering circles.

Data processing in subspace identification and modal parameter identification of an arch bridge

A data-processing method concerning subspace identification is presented to improve the identification of modal parameters from measured response data only. The identification procedure of this method consists of two phases, first estimating frequencies and damping ratios and then extracting mode shapes. Elements of Hankel matrices are specially rearranged to enhance the identifiability of weak characteristics and the robustness to noise contamination. Furthermore, an alternative stabilisation diagram in combination with component energy index is adopted to effectively separate spurious and physical modes. On the basis of identified frequencies, mode shapes are extracted from the signals obtained by filtering measured data with a series of band-pass filters. The proposed method was tested with a concrete-filled steel tubular arch bridge, which was subjected to ambient excitation. Gabor representation was also employed to process measured signals before conducting parameter identification. Identified results show that the proposed method can give a reliable separation of spurious and physical modes as well as accurate estimates of weak modes only from response signals.

Nonlinear seismic properties of the Second Saikai Bridge: A concrete filled tubular (CFT) arch bridge

The technology of concrete filled tube (CFT) arch bridges has developed rapidly in China since 1990. More than one hundred CFT arch bridges have been built or are now under construction. However, since the weight of a CFT arch rib is greater than that of a steel rib and the arch action is not effective in the out-of-plane direction, the seismic safety of CFT bridges should be evaluated. This paper examines nonlinear seismic responses of the Second Saikai Bridge, which is the first highway bridge in Japan to be a CFT arch bridge. This bridge has a main span length of 240 m. The natural vibration characteristics of this bridge are discussed using a three-dimensional FE model. A nonlinear seismic analysis is performed using the strong ground motions observed in the Hyogo-ken Nanbu Earthquake of Japan. The nonlinear seismic characteristics and seismic safety of this bridge are examined in detail by subjecting the bridge to earthquakes in the out-of-plane direction, longitudinal direction and combined out-of-plane and longitudinal directions. It is found that the analysis should consider the combined out-of-plane and longitudinal excitations.

Numerical analysis of ultimate strength of concrete filled steel tubular arch bridges

The calculation of ultimate bearing capacity is a significant issue in the design of Concrete Filled Steel Tubular (CFST) arch bridges. Based on the space beam theory, this paper provides a calculation method for determining the ultimate strength of CFST structures. The accuracy of this method and the applicability of the stress-strain relationships were validated by comparing different existing confined concrete uniaxial constitutive relationships and experimental results. Comparison of these results indicated that this method using the confined concrete uniaxial stress-strain relationships can be used to calculate the ultimate strength and CFST behavior with satisfactory accuracy. The calculation results are stable and seldom affected by concrete con- stitutive relationships. The method is therefore valuable in the practice of engineering design. Finally, the ultimate strength of an arch bridge with span of 330 m was investigated by the proposed method and the nonlinear behavior was discussed.

Vibration analysis of the Second Saikai Bridge—a concrete filled tubular (CFT) arch bridge

Concrete-filled steel tubular (CFT) arch bridges have been rapidly developing in China since 1990. Research has focused on the static behavior, thermal stress and erection technique, however, and there has been very little research of natural vibrations and dynamic responses of these bridges. Japan's first CFT arch bridge in highway bridges, the Second Saikai Bridge, is now under construction in Nagasaki Prefecture. Furthermore, this bridge has a pedestrian bridge that is suspended under the girder, which is rare. Therefore, the natural vibration properties are examined, and the influence of pedestrian bridge structure on the natural vibration of main bridge is discussed first. Response analysis under a moving vehicle and pedestrian is carried out, and the response characteristics and response level are clarified. The natural vibrations and responses are compared to those of CFT arch bridges that have been constructed in China. Results show the fine performance of both main bridge and pedestrian bridge of the Second Saikai Bridge.

Structural Finite Element Model Updating Using Ambient Vibration Test Results

This paper presents a practical and user-friendly finite element (FE) model updating technique for real structures using ambient vibration test results. The first case study of a simulated simply supported beam demonstrates a comparative study of the influence of different possible residuals in objective function. Frequency residual only, mode shape related function only, modal flexibility residual only, and their combinations are studied independently. In view of tuning as well as damage localization, full objective function that considers all three residuals is the best for FE updating. This objective function is implemented in a second case study of a real concrete-filled steel tubular arch bridge. The bridge was tested by ambient vibration measurements. Followed by the three-dimensional FE modeling of the bridge, an eigenvalue sensitivity study is carried out to see the most sensitive parameters to the concerned modes. FE model mass matrix obtained from Guyan reduction technique is used to the mass normalization of the mode shapes extracted from ambient modal test to calculate the modal flexibility. The updated FE model of the bridge is able to produce a sufficient improvement on modal parameters of the concerned modes which is in close agreement with the experimental results still preserving the physical meaning of updated parameters.

Dynamic analysis of a half-through concrete-filled steel tubular arch bridge

This paper presents the analytical and experimental dynamic analysis of a concrete-filled steel tubular (CFST) half-through arch bridge, with a span of 90 m, located at the center of Xining City, Qinghai Province, China. A three-dimensional finite element (FE) model is developed and an analytical modal analysis is carried out to obtain natural frequencies and mode shapes. Dynamic field testing under ambient excitations was conducted before the opening of the bridge to traffic. Three independent but complementary output-only modal identification techniques are used for system identification. They are a modified single-degree-of-freedom identification (SDOFI) method and a peak picking (PP) method in the frequency domain and the stochastic subspace identification (SSI) method in the time domain. There is a good correlation among the modal parameters identified from the three independent identification techniques. The initial FE model is then corrected with the help of measured natural frequencies and mode shapes by varying some influential parameters of the bridge making use of engineering intuition. The model thus obtained can be treated as the baseline FE model and is suitable for long term monitoring and safety evaluation of the bridge in different severe circumstances such as earthquakes and wind loading.

Output-only modal parameter identification of civil engineering structures

The ambient vibration measurement is a kind of output data-only dynamic testing where the traffics and winds are used as agents responsible for natural or environmental excitation. Therefore an experimental modal analysis procedure for ambient vibration testing will need to base itself on output-only data. The modal analysis involving output-only measurements presents a challenge that requires the use of special modal identification technique, which can deal with very small magnitude of ambient vibration contaminated by noise. Two complementary modal analysis methods are implemented. They are rather simple peak picking (PP) method in frequency domain and more advanced stochastic subspace identification (SSI) method in time domain. This paper presents the application of ambient vibration testing and experimental modal analysis on large civil engineering structures. A 15 storey reinforced concrete shear core building and a concrete filled steel tubular arch bridge have been chosen as two case studies. The results have shown that both techniques can identify the frequencies effectively. The stochastic subspace identification technique can detect frequencies that may possibly be missed by the peak picking method and gives a more reasonable mode shapes in most cases.

Design and construction of Tongwamen Bridge, China

Tongwamen bridge is a half-through, concrete-filled steel tubular (CFST) X-type arch bridge with deck width to span ratio of 1/23·8. It is the first time that arch ribs of the plane truss type have been used in the construction of a long-span CFST bridge in China. The rationality of the design for this type of large-span, narrow bridge is justified using a description and discussion of some key issues related to the bridge design and construction, The paper provides an example of the design of a long-span, narrow, CFST arch bridge.