Solar Radiation Parameters for Assessing Temperature Distributions on Bridge Cross-Sections

Abstract

Solar radiation is one of the most important factors influencing the temperature distribution on bridge girder cross-sections. The bridge temperature distribution can be estimated using estimation models that incorporate solar radiation data; however, such data could be cost-or time-prohibitive to obtain. A review of literature was carried out on estimation models for solar radiation parameters, including the global solar radiation, beam solar radiation and diffuse solar radiation. Solar radiation data from eight cities in Fujian Province in southeastern China were obtained on site. Solar radiation models applicable to Fujian, China were proposed and verified using the measured data. The linear Ångström-Page model (based on sunshine duration) can be used to estimate the daily global solar radiation. The Collares-Pereira and Rabl model and the Hottel model can be used to estimate the hourly global solar radiation and the beam solar radiation, respectively. Three bridges were chosen as case study, for which the temperature distribution on girder cross-sections were monitored on site. Finite element models (FEM) of cross-sections of bridge girders were implemented using the Midas program. The temperature-time curves obtained from FEM showed very close agreement with the measured values for summertime. Ignoring the solar radiation effect would result in lower and delayed temperature peaks. However, the influence of solar radiation on the temperature distribution in winter is negligible.

Research on the Internal Thermal Boundary Conditions of Concrete Closed Girder Cross-Sections under Historically Extreme Temperature Conditions

“…">IntroductionClosed girder cross-sections, such as box girders, small box girders, and adjacent box girders, are typically used worldwide for concrete bridges [1][2][3][4][5][6][7][8][9][10][11][12][13]. Numerous cases of recorded bridge damages, such as severe cracking, deterioration, or even failure, particularly in bridges with closed girder cross-sections, were caused by temperature-induced stresses and deformations [14][15][16][17][18][19][20][21][22][23][24][25][26]. Therefore, it is particularly important to accurately predict the temperature distributions on closed girder cross-sections.…”

“…For the external thermal boundary condition, the temperatures associated with solar radiation, convection, irradiation, and the temperature of the surrounding fluid medium, as well as the overall heat transfer coefficient (which is the combination of the convection heat transfer coefficient and the radiation heat transfer coefficient), should be taken into account [7,[13][14][15][16][17]22,23,25,36,[39][40][41][42][43][44][45][46]. The internal thermal boundary condition is affected by the temperatures inside the cavities and the convection heat transfer coefficient because it is not influenced by solar radiation [7,[13][14][15][16][17]22,23,25,36,39,40,[42][43][44][45][46].The ambient air temperature can be measured by a meteorological station. The temperature variation inside the cavity is usually less than that of the ambient air temperature and has a time delay [42,43] because there is no solar radiation inside the cavity and the thermal conductivity of concrete is low.…”

“…In order to accurately simulate the internal thermal boundary conditions for concrete closed girder cross-sections, researchers have proposed different methods. Temperature sensors were installed inside the cavities by some researchers during the girder construction process to measure the temperature variation curve inside the cavity (hereafter referred to as the Measured Temperature Method) [17,23,25,39,44]. The Measured Temperature Method can reflect the actual temperature inside the cavity, but measurements on site are cost-and time-prohibitive.…”

“…The temperature inside the cavity that is obtained or calculated by using the Measured Temperature Method, Ambient Temperature Method, or Mean Temperature Method can be input as the internal thermal boundary condition in the FEM. In addition, a method that established air elements in the FEM of the closed girder cross-sections was adopted by some researchers to simulate the heat conduction inside the cavity as the internal thermal boundary condition (hereafter referred to as the Air Element Method) [7,13,25,36,39]. When there is no measurement on site to obtain the temperature inside the cavity, the Ambient Temperature Method, Mean Temperature Method, or Air Element Method can be used as alternative methods.…”

“…It can be observed from the field test data that the differences between the temperatures inside the cavities and the ambient air temperature were large in the summer because of high solar radiation, while the temperature differences were small in the winter. The daily measured temperature responses obtained at different times of year have been used by researchers to analyze the temperature distributions on cross-sections [13,22,24,25,39]. Due to space limitations, the data from 13 August 2017 in summer, which is a sunny day with the highest ambient air temperature during the monitoring period, as well as high solar radiation and low wind speed, were selected for analysis.…”