Expansion joints are a crucial component of bridges, influencing not only the force state, service performance, and operational safety of the structures but also playing a substantial role in ensuring the comfort and safety of traffic on the bridge deck. This paper investigates the static mechanical responses of bridge modular expansion joints using a full-scale 3D solid finite element (FE) analysis method. Firstly, the working mechanism, force transmission path, and influencing factors of the modular expansion joint are analyzed. Secondly, a full-size 3D solid finite model of the modular expansion joint is established using ANSYS FE software and APDL parametric modeling. The model incorporates the actual structure, force transmission path, contact effects, and boundary conditions of the expansion joint. Then, the load size and action position of typical vehicles on the joint are analyzed to obtain adverse vehicle action. Finally, the force state of the modular expansion joint under vehicle load using the 3D solid FE model is calculated and discussed. This paper proposes a precise FE analysis method for the complex stress state calculation of bridge modular expansion joints, providing theoretical and technical support for damage identification, state evaluation, and safety assessment of such joints, and can also be learned and used for other types of bridge expansion joints.
KEYWORDS: Wind turbine technology, Temperature metrology, Thermal analysis, Air temperature, Finite element methods, Boundary conditions, Wind speed, Surface air temperature, Solar radiation, Bridges
Temperature is an important environmental load on offshore wind power systems. The harsh marine environment characterized by high temperatures and radiation, along with the slender and towering metal structure system, makes the temperature effects on offshore wind turbine support structures highly substantial and complex. However, the temperature load has not received sufficient attention and, in some cases, has been overlooked in the design and operation of wind turbine support structures. This paper focuses on the support tower structure of a wind power system, conducting finite element analysis and research on the temperature load of the support tower structure. First, the marine thermal environment of the wind turbine tower in service is analyzed to clarify the factors and mechanisms that affect the tower temperature. Secondly, based on the heat exchange and transfer process of the actual structure, a finite element calculation model for the temperature field of the wind turbine tower structure is established. Then, the finite element transient thermal analysis method is used to numerically calculate the temperature field of the wind turbine tower in service. Finally, the optimization of the finite element calculation model is carried out. The accurate finite element analysis of the temperature field of the wind turbine support tower structure is achieved, which provides the important theoretical foundation and technical support for the design of the wind turbine support structure considering the influence of the temperature effect, identification of the service state, and safety management of operation and maintenance.
Temperature has significant effects on the mechanical properties of bridge. This paper investigated the temperature effects on dynamic properties of a long-span suspension bridge with steel box girder. The correlation between the air temperature and the natural frequencies of the bridge is analyzed based on field measurements. The finite element (FE) models for thermal analysis and structural analysis are developed separately using ANSYS software. The structural temperatures of the bridge’s components are calculated. The calculated temperatures are applied to the structural FE model, and then the bridge’s natural frequencies are obtained using model analysis. The calculated structural temperatures and natural frequencies are compared with the field measurements to verify the reliability and accuracy of the numerical analysis method. The calculated temperatures have good agreement with the measurements. The value and variation of the low order natural frequencies of the suspension bridge can be properly simulated with acceptable reliability and accuracy.
In order to analyze the static and dynamic characteristics of an under-supported truss bridge, the laboratory truss bridge model is established, and the displacement and strain data are measured by the sensors laid on the bridge model. Then two different finite element model software are used to create the bridge element by nodes, and two finite element models of the under-supported truss bridge are established respectively. The static analysis of the model is carried out to obtain the internal force and deformation of the bridge model under different working conditions, and the stress of the bridge is understood. After comparing the finite element model with the laboratory model data, the static characteristics of the truss bridge are obtained, and the reliability of the finite element models simulated by different software is analyzed and verified. Finally, the dynamic characteristics of the model are analyzed by finite element analysis method.
Temperature has significantly negative effect on structural performance, this situation is sure to be even worse for support structure of offshore wind turbine (OWT) in harsh ocean environment. In this study, the daily temperature effects on a support structure of jacket-type OWT are investigated using numerical simulation. The basic theory and method of thermal analysis for structure are briefly introduced. The finite element (FE) models for thermal analysis of the support structure of an OWT are constructed. Then, the time-dependent thermal boundary conditions are determined using the meteorological parameters of a typical sunny day. Accordingly, the thermal boundary conditions are applied on the FE model. Subsequently, the transient heat-transfer analysis is performed for structural temperature calculation. At last, the time-dependent structural temperature variation and distribution of the support structure are discussed. The results show that the temperature effects are considerable and have obvious daily-cycle property. The solar radiation and air temperature are the major influential factors on the structural temperature behavior of the steel tube tower. The temperature effects should be seriously considered in the design and maintenance of the support structure of OWT.
The long-term adverse effect caused by environmental factors is one of the main causes for performance degradation of bridges. Accurately obtaining the environmental meteorological data on the bridge site can provide basis information for analyzing and assessing the negative effects of environments on bridges. To improve the efficiency and reduce the cost of meteorological data collection, this paper proposed a method to predict the meteorological data of bridge site based on the available shared date of weather station near the concerned bridge. Focusing on bridge temperature effects in this study, two major meteorological parameters, air temperature and wind speed, are investigated for data predication. Meanwhile, different geomorphologic conditions at different regionsin China are discussed. Four interpolation methods, inverse distance weighting, Kriging interpolation, radial basis function, and minimum curvature method, are investigated. Cross-validation has been used to evaluate the performance of these four methods. The results show that Kriging method has the best predication on air temperature, and the inverse distance weighted method and Kriging method are both good for wind speed, however, Kriging shows better performance as a whole. Spatial interpolation method is feasible to predicate the meteorological parameters of bridge site, which provides a higher efficiency and less cost approach to obtaining the on-site meteorological data for the bridge temperature effects analysis and assessment.
Temperature effect is one of the most significant and negative effects on bridges, even worse for long-span bridges. In this study, numerical method for temperature-induced structural strains analysis based on a long-span suspension bridge is investigated. The finite element (FE) models for transient thermal analysis and structural analysis of the long-span suspension bridge are developed, respectively. The variations and distributions of structural temperatures are calculated by applying the thermal boundary conditions on the thermal FE models. Then, structural temperatures are loaded on the structural FE models for structural analysis to obtain the structural strains. The temperature-induced strains of box girder, main cables and towers of the suspension bridge are calculated and analyzed. The results indicated that the temperature effects on the main components of suspension bridge are significant. The structural temperature variations exactly explicate the changes of environmental conditions. The strains of temperature effects not only caused by temperatures of itself, but also the impact of other components. This numerical method can conveniently and effectively calculate the structural temperatures and temperature-induced strains of suspension bridge.
Structural measurements for model updating are limited, and the global responses are usually not sensitive to the local and small damages. Therefore, it is full of challenge to identify small and local damages using global responses of structure. The updated parameters have different effects on the structural response. In the model updating, the large sensitivity parameters converge quickly and relatively small sensitivity parameters cannot be effectively corrected. In this study, the effects of structural measurements on the model updating results are investigated. The method to update the parameters with large difference in sensitivity based on response surface method is proposed. Firstly, the samples of small sensitivity parameter are adjusted to generate new samples according to the difference of sensitivities. Then, response surface models are constructed using the new samples and the original characteristic information. At last, model updating is carried out based on the new response surface models and the updated results inversely computed to get the final results. The numerical simulation of a space truss structure is adopted to verify the efficiency and feasibility of the method.
The main cables are key complements of the suspension bridge. The temperature properties of main cables have significant effects on the structural responses of entire bridge. This paper presents a numerical method for temperature analysis of main cable for suspension bridge. The finite element (FE) model of main cable section is developed as homogeneous material using Plan elements. The material parameters for thermal analysis are determined based on equivalent principle. The third type thermal boundary conditions of a sunny day are calculated and then applied on the FE model for transient thermal analysis. The numerical results are compared with the experimental measurements of a full scale main cable for validation of the thermal analysis method. The results present good agreement with respect to the measurements. The temperature variations exactly explicate the changes of environmental conditions such as solar radiation and ambient temperature of daily. This FE model-based thermal analysis can provide a high effective and precision method for analysis of temperature and induced structural responses of main cables and suspension bridge.
Harsh service environment degenerates the performance of bridges even leads to catastrophic collapse. Structural temperature has been widely recognized as one of the most negative environmental effects on bridges. The structural responses are deeply affected by the variation and distribution of temperatures on bridges. Therefore, identifying the correlations between them is a significant issue for structural safety assessment. In this study, the relationships between the temperature induced static response and the surrounding weather factors are investigated based on the long-term field measurements of a long-span suspension bridge. The correlations of the meteorological parameters between the bridge filed and the nearby weather station, and the relations of structural static responses to the air temperature, are investigated. The results indicate that relationships of meteorological parameters between nearby weather station and the bridge field can be predicted. The correlation between the static responses and the air temperature and is remarkable with high correlation coefficient. The conclusions are expected to provide reference for the design and evaluation of longspan suspension bridges.
Structural temperatures and their uneven distributions have significantly negative effects on bridges. It is very important to accurately calculate the structural temperatures. Structural temperatures are deeply affected by the surrounding weather conditions, and the environmental wind is a critical factor. In this study, the wind effects on the thermal analysis of bridges are investigated using numerical simulation. Frist, the traditional theory and method are briefly introduced to show the important effects of wind on structural heat transfer analysis. Then, a new approach is proposed to take account of the wind effects for temperature analysis of bridges. At last, numerical study based on the finite element transient heat transfer analysis of a box-girder bridge is carried out and discussed to verify the proposed method. The results indicate that the proposed method is more reasonable than the traditional methods. This method can be easily implemented in practice for temperature analysis of bridges.
Structural temperature has been widely recognized as one of the most negative environmental effect on bridge. In this study, the temperature distribution of a large rigid-continuous concrete box girder bridge is investigated combining the numerical simulation and the field measurements. A temperature sensor system has be installed on the bridge for field monitoring the structural temperature. For simulation study, the fine tow-dimensional finite element (FE) model of box girder section is first constructed. Then, the time-dependent thermal boundary conditions are determined to extensively take account of environmental factors resulting of thermal effects on bridge. At last, transient heat transfer analysis is implemented on FE model and corresponding time-dependent temperature distribution is obtained. The analytical results are compared with the measurements for validation of the thermal analysis method. The results have very good agreements with the measurements, and the temperature variations exactly explicate the changes of environmental conditions such as solar radiation and ambient temperature of daily. The temperature simulation provides a foundation for the structural analysis of temperature induced effects.
The field measurements of structures are very important to the structural finite element (FE) model updating because the
errors and uncertainties of a FE model are corrected directly through closing the discrepancies between the analytical
responses from FE model and the measurements from field testing of a structure. Usually, the accurate and reliable field
measurements are very limited. Therefore, it is very important to make full use of the limited and valuable field
measurements in structural model updating to achieve a best result with the lowest cost. In this paper, structural FE
model updating is investigated in the point of view of solving a mathematical problem, and different amount and
category of structural dynamic responses and static responses are considered as constraints to explore their effects on the
updated results of different degree and types of structural damages. The numerical studies are carried out on a space
truss. Accounting for the numerical results, some inherent phenomena and connections taking account of the updating
parameters, output responses and the updated results are revealed and discussed. Some useful and practicable
suggestions about using the field measurements for FE model updating are provided to achieve efficient and reliable
results.
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