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Structural Engineering and Mechanics
  Volume 83, Number 5, September10 2022 , pages 645-654

Experimental analysis of thermal gradient in concrete box girder bridges and effects of polyurethane insulation in thermal loads reduction
Farzad Raeesi, Sajad Heydari and Hedayat Veladi

    Environmental thermal loads such as vertical and lateral temperature gradients are significant factors that must be taken into account when designing the bridge. Different models have been developed and used by countries for simulating thermal gradients in bridge codes. In most of the codes only vertical temperature gradients are considered, such as Iranian Standard Loads for Bridge code (ISLB), which only considers the vertical gradient for bridge design proposes. On the other hand, the vertical gradient profile specified in ISLB, has many lacks due to the diversity of climate in Iran, and only one vertical gradient profile is defined for whole Iran. This paper aims to get the both vertical and lateral gradient loads for the concrete box girder using experimental analysis in the capital of Iran, Tehran. To fulfill this aim, thermocouples are installed in experimental concrete segment and temperatures in different location of the segment are recorded. A three dimensional finite element model of concrete box-girder bridge is constructed to study the effects of thermal loads. Results of investigation proved that the effects of thermal loads are not negligible, and must be considered in design processes. Moreover, a solution for reducing the negative effects of thermal gradients in bridges is proposed. Results of the simulation show that using one layer polyurethane insulation can significantly reduce the thermal gradients and thermal stresses.
Key Words
    concrete box girder; experimental test; lateral gradient; thermal loads; vertical gradient
Farzad Raeesi: Department of Civil Engineering, University of Tabriz, Tabriz, Iran
Sajad Heydari: School of Civil Engineering, College of Engineering, University of Tehran, Tehran, Iran
Hedayat Veladi: Department of Civil Engineering, University of Tabriz, Tabriz, Iran

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