Abstract
Thermal energy exchange induces non-uniform temperature distribution on the concrete bridge structures, leading to variation of static and dynamic properties of structural systems. The finite element method can facilitate thermal simulation and predict the structural temperature distribution based on heat flow theories. Previous studies mainly focused on the daytime with sunny weather, and the effects of solar shadow distribution were not fully considered or even ignored. In this paper, a systematic all-weather thermal simulation method was proposed to investigate the temperature distributions of concrete maglev bridges. The solar shadow distribution on the bridge surface could be accurately simulated to determine the solar radiation-imposed range. A meteorological station and some thermocouples were installed on a real concrete maglev bridge to obtain the real-time structural temperatures and environmental conditions. Its temperature distribution is also simulated using the proposed method within the 27 monitoring days in Summer. Results show that the simulated structural temperature matches well with the measured results under various weather conditions, except that of the east structural surface. Moreover, the simulation method acquired a higher accuracy under overcast or rainy weather due to weaker solar radiation effects. Both the numerical results and experimental records illustrated that direct solar radiation dominates the thermal energy exchange under sunny or cloudy conditions. The proposed methodology for temperature field simulation is oriented by all-weather prediction of structural temperature, which is reliable for concrete bridge structures with the help of accurate measurement of real-time solar radiation.
Highlights
Concrete bridges are generally constructed in open areas and exposed to the environment, and the structural temperature fields are heavily affected by the energy exchanged between bridge structures and surrounding environments [1,2]
A great number of structural health monitoring (SHM) systems with temperature monitoring functions have been installed on some constructed bridges in the world [7,8,9], which provides an effective approach to investigate the temperature field of real bridge structures based on monitored data [10]
A large experimental model of a box-girder arch was established by Wang et al [14] to evaluate the effect of nonlinear temperature gradients on arch structure; the finite element simulation was verified by 1-day experimental measurements data
Summary
Concrete bridges are generally constructed in open areas and exposed to the environment, and the structural temperature fields are heavily affected by the energy exchanged between bridge structures and surrounding environments [1,2]. Focusing on thermal effects on structural temperature distribution, this paper carried out an all-weather numerical simulation methodology of the structural temperature field, Sensors 2021, 21, 5789 based on the real-time meteorological monitoring data of the bridge site and a simulation algorithm of real-time solar shadow, to predict the structural temperature distribution of concrete bridges. The logic of the paper is as follows: (i) the experimental setup of a maglev bridge in service is introduced, in which thermocouples were instrumented on the structural surfaces, and a meteorological station was established at the bridge site; (ii) the theory of thermal boundary conditions for the three-dimensional transient heat analysis is elaborated with a simulation method of solar shadow; (iii) overall framework of all-weather thermal numerical simulation is presented and applied to extensive analysis of the experimental structure, in which initial temperature values and equivalent boundary conditions were adopted; and (iv) the numerical results and measured records of structural temperature are presented and discussed to demonstrate the proposed methodology, especially for considering the weather conditions during 27 days.
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