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

Abstract

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.

Pure Effect of Temperature on Rectangular and Trapezoidal Box-Girder Bridges – A Finite Element Investigation

“…For statically determined structures, the linear elastic approach can be used to determine the movement of the structures related to effective bridge temperature. Because these deformations are constrained, temperature changes cause thermal stresses in statically indeterminate structures [16]. The bending moments in the vertical plane are caused by the vertical temperature differential (also known as the temperature gradient), which is the difference in temperature between the top surface and lower levels throughout the depth of the superstructure.…”

“…In order to verify the results of the current research work, a comparison was conducted with the results of another research work [21], in which the authors extracted their results in a similar way and with the same finite element software, Table 1. When increasing the temperature from 30 to 60 °C, by 10° each time, the deflection and moment increase by 33%.…”

“…A steel construction has a shorter lag time than a concrete structure. In 2021, Lu, et al [16] examined how sun irradiation and extremely hot temperatures affected concrete box girder bridges. Through field observations and calculations, the box girder's temperature distribution and solar radiation intensity were determined.…”

“…Large total length changes, expansion, or contraction result from variations in uniform temperature. These length fluctuations affect internal forces, structural dynamics, and the constant expansion and contraction could harm important bridge members [16]. In the event that these deformations are constrained, temperature changes lead to thermal stresses, which may cause unanticipated tensile cracks and, as a result, reinforcement corrosion.…”

Transient Thermal Analysis of Concrete Box Girders: Assessing Temperature Variations in Canadian Climate Zones

“…Global research intensively investigated temperature distributions and variations due to the criticality of thermal-induced responses on bridges. Several studies have utilized experimental, finite element (FE) methods and advanced sensor technology to investigate the effects of temperature on different bridge components [10][11][12][13][14][15][16][17]. However, inaccuracies in estimating temperature distributions can lead to significant thermal stresses, resulting in undesired structural effects such as concrete cracking [18].…”