Simulation of thermal load distribution in portal frame bridges

Gottsäter, Erik; Ivanov, Oskar Larsson; Molnár, Miklós; Crocetti, Roberto; Nilenius, Filip; Plos, Mario

doi:10.1016/j.engstruct.2017.04.012

Cited by 15 publications

(10 citation statements)

References 15 publications

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“…For this reason, in addition to the 1 year reference period, calculations with 3 day seasonal periods were also made, meaning that the data were divided into 3 day periods, and only periods within April-September were considered for positive temperature differences, while periods within October-March were considered for negative differences. Three-day seasonal reference periods have previously been used for determination of temperature gradients in the Eurocode, 4 thus showing that this is a reasonable assumption. Each set of extreme values was plotted as a cumulative distribution function (cdf), and the GEV distribution was then fitted to the values using the MATLAB ® function gevfit.…”

Section: Characteristic Load Valuesmentioning

confidence: 99%

“…Also, a thin asphalt layer leads to larger temperature differences. 4 Based on this information, a relatively small bridge geometry was chosen for this study (Fig. 1).…”

Section: Model For Thermal Simulationmentioning

confidence: 99%

“…In addition, previous studies indicate that although a characteristic value of 15°C may be reasonable, a quasi-permanent value would be likely to be significantly lower. 4,5 In the design of portal frame bridges, the thermal loads are applied in combination with other loads such as selfweight and traffic to obtain the required amount of reinforcement. Previously, the transverse direction was not considered in the design of portal frame bridges in Sweden, as two-dimensional (2D) frame models were used.…”

Section: Introductionmentioning

confidence: 99%

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Spatial Temperature Differences in Portal Frame Bridges

Gottsäter

Ivanov

2019

Structural Engineering International

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Thermal actions are considered in the design of bridges, as temperature variations can lead to restraint stresses and subsequent cracking. However, load descriptions are in some cases oversimplified or incompatible with modern applications, and background studies are limited. This paper therefore aims to develop a more detailed load description for the load case describing temperature differences between structural parts in bridges, focusing on portal frame bridges. The temperature in portal frame bridges is investigated by performing long-term thermal simulations using weather data from several locations in Sweden, and thereafter performing statistical analyses of the resulting temperature variations over time. The study gives suggestions of both characteristic and quasi-permanent values to be used in design based on the statistical analyses, and also notes a gradual change in temperature between structural parts, which could be considered in the design. The resulting quasi-permanent values are significantly lower than the values given in the Eurocode for temperature differences between structural parts, which, in turn, will lead to smaller and more realistic stress values in bridge design.

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Section: Characteristic Load Valuesmentioning

confidence: 99%

“…Also, a thin asphalt layer leads to larger temperature differences. 4 Based on this information, a relatively small bridge geometry was chosen for this study (Fig. 1).…”

Section: Model For Thermal Simulationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spatial Temperature Differences in Portal Frame Bridges

Gottsäter

Ivanov

2019

Structural Engineering International

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“…1 Thermal condition: Direct solar radiation, scatting radiation, reflection, and air temperature. 2 Direct solar radiation (7:00-9:00), scatting radiation, reflection, and air temperature. 3 Scatting radiation, reflection, and air temperature.…”

Section: The Variation Of Temperature Differencementioning

confidence: 99%

“…On the surfaces of an object, heat is transferred from the surrounding medium mainly in three ways as heat convection, heat conduction, and radiation. This heat transfer of the concrete bridge in the natural environment is related to solar radiation, air temperature, wind speed, material properties, and other factors [1,2]. The amount of solar radiation on the surfaces of the box girder mainly varies with seasons, time, weather, air quality, and other factors; it is also closely related to the geographical location, topography, and orientation of different surfaces of the girder [3].…”

Section: Introductionmentioning

confidence: 99%

Study on Solar Radiation and the Extreme Thermal Effect on Concrete Box Girder Bridges

Wang

et al. 2021

Applied Sciences

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Thermal effect is an essential factor in the durability and safety of concrete bridges. Therefore, this paper mainly studied the concrete bridge box girder temperature distribution and thermal effect under solar radiation and the thermal load. With a concrete rigid frame bridge as the engineering background, the temperature distribution of the box girder on a clear summer day was observed. Then, according to the solar physics and heat transfer theory, the different surfaces of the box girder cross-section are classified based on the heat transfer conditions, and the variation of solar radiation on different surfaces is investigated. The temperature field of the box girder is simulated by ANSYS. To obtain the extreme thermal condition, the meteorological data of the bridge site from 1990 to 2020 are collected. The data are fitted by generalized extreme value distribution to obtain the extreme temperature and average wind factors in the bridge design lifetime. Combined with the solar radiation, temperature, and wind factors, the extreme thermal condition of the concrete box girder is obtained. Lastly, the thermal effect of the box girder under the extreme condition is analyzed, and the thermal stress is compared with the allowable stress in the design code. The results show that the girder temperature difference is closely related to the solar radiation intensity and heat transfer conditions, and the solar radiation intensity is the more critical factor. The tensile stress caused by the extreme thermal load is more significant than the design strength value in the girder cross-section. The results also provide a method to obtain the extreme thermal condition and evaluate the impact of the thermal effect on concrete box girder bridges.

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