Design and Experiment of an Automatic Temperature Control Device of Composite Shape-Stabilized Phase Change Material for Concrete Box Bridges

Abstract

To solve the problem of bridge surface cracking caused by an uneven temperature field inside and outside the web of a concrete box structure, an automatic temperature control device applied to the beam surface of a concrete box bridge in the daytime is developed. The device, hanging on the surface of the box girder webs, consists of a radiation cooling coating and a composite shape-stabilized phase change material. With reference to a bridge in Guizhou Province, finite element analysis, short-term temperature monitoring and temperature-drop monitoring are carried out using the device. The result shows that the automatic temperature control device works well continuously. For a box girder without an automatic temperature control device, the inside and outside of the web demonstrate different sensitivities to the temperature of the external environment, with a high temperature fluctuation and a relatively high temperature stress. For a box girder with an automatic temperature control device, as the cooling coating reflects part of the solar radiation and the phase transformation of the composite shape-stabilized phase change material releases or absorbs part of the latent heat to or from the external environment, the temperature fluctuation and temperature stress of the inside and outside of the web are relatively small. When the temperature suddenly drops, the automatic temperature control device works better than under conventional weather conditions because it can reduce the external temperature by approximately 50% on the outer surface of the box girder webs.