Analysis Of Thermal Effect Of Rounded-Ended Hollow Pier Under Solar Radiation

Structural temperature is an important form of loading for bridges, particularly for hollow pier. The thermal stress caused by temperature difference will affect the safety and durability of hollow pier significantly. To study the temperature stress of the round-ended hollow pier, we must first study the temperature distribution. Nowadays, when designing the hollow pier, we use half experiential and half theoretical formula, which simplified the three-dimensional temperature field to be one-dimensional on every direction to simulate the temperature distribution under solar radiation. The precision of this method also needs basis of measured temperature value. However, due to the lack of the basis of measured temperature value among being one-dimensional, the precision of this method is low.Due to the climate changing diversely, randomly, and with uncertainty, the temperature distribution of round-ended hollow pier is a three-dimensional transient heat conduction problem with complex boundary conditions. In this case, we require a method based on developed temperature theory and measured temperature data to simulate the temperature distribution of round-ended hollow pier.In 1973 the German scholar Kehlbeck thoroughly studied the factors that affect the temperature distribution of bridge such as solar radiation, atmospheric radiation, surface reflection, convective heat exchange and temperature change. His studies allowed him to establish a more comprehensive boundary condition model for solving the temperature problem of concrete bridge structure. The Canadian scholar Elbadry simplified this model in 1983, and made it more applicable for engineering. However, due to the orientation of the wall of hollow pier and box girder is not the same, using the same simplified model is bound to produce errors.This paper aims to investigate temperature distribution of a round-ended hollow pier through field temperature distribution monitoring and numerical simulation. The temperature variation and distribution law of the pier is analyzed and summarized based on the measured data of one year. According to Kehlbeck's thermal analytical theory of bridge, combined with the temperature data, modifies the simplified model proposed by Elbadry to make it more applicable to the pier. Fine finite element model is built for thermal analysis of the hollow pier. The analytical results of temperature distribution are compared with those obtained from the long-term temperature monitoring system to test if the modified solar radiation model can predict the temperature variation of the bridge accurately.The temperature stress could be calculated by the thermal-structural coupling function of the finite element software ANSYS, using the calculated temperature field of the round-ended hollow pier.Due to the solar radiation intensity of every wall is related to the axis direction of the rounded-ended hollow pier, this paper studies the temperature and thermal distribution law of the hollow pier with four different directions of the axis.