Investigation Of The Temperature Field In Composite Box-girders With Corrugated Steel Webs Under Solar Radiation

The bridge structures are exposed to the complicated natural environment and are directly subjected to the fluctuations of air temperature and solar radiation.The impact of surrounding environmental factors will bring about a significantly non-uniform temperature distribution in the structures.The thermal stresses and deformations induced by the temperature gradient may deteriorate the structural safety and durability of bridges.The composite box-girder with corrugated steel webs has attracted the attention of researchers because of its excellent mechanical properties and has been widely applied in the bridge engineering.The corrugated steel web composite box-girder has a complicated geometric construction and the thermal properties of steel and concrete are significantly different.Thus,the temperature field of the composite box-girder with corrugated steel webs is more complicated and non-uniform when it compared with the conventional concrete box-girder.However,the investigation on the thermal behavior of the composite boxgirder with corrugated steel webs is insufficient.There is no effective and accurate method to consider the thermal impact of surrounding environment conditions on the composite box-girder.In this paper,the temperature field of the composite box-girder with corrugated steel webs has been experimentally and numerically investigated,which can provide some contributions for the structural design regarding the composite boxgirder with corrugated steel webs.The main results and achievements of the research are summarized as follows:(1)A composite box-girder specimen with corrugated steel webs has been constructed to evaluate the impact of exposure to the thermal loads on composite box-girders with corrugated steel webs in the current study.The time history and spatial distribution characteristics of the composite box-girder with corrugated steel webs have been investigated.According to the experimental results,four patterns have been proposed to describe the temperature distribution in the composite box-girder.(2)The numerical simulation method of the composite box-girder with corrugated steel webs has been developed and validated by the experimental data.The simulated results fit well with the measured temperatures,which verifies the accuracy and reliability of the numerical simulation model.(3)Based on the plane-section assumption,the temperature action indexes of any two-dimensional temperature field have been derived.The temperature field of a corrugated web composite box-girder in actual engineering has been simulated on basis of the validated numerical simulation model.Moreover,parametric studies have been conducted to reveal the effects of material parameters and geometric parameters on the on the temperature distribution and temperature action indexes of the composite box-girder.(4)The temperature fields of the corrugated steel web composite boxgirder,the ordinary steel-concrete composite box-girder,and the concrete box-girder have been numerically analyzed.The differences among three box-girders regarding the negative temperature distribution,the positive temperature distribution and the horizontal temperature distribution have been obtained.(5)China has been divided into seven climatic regions and the representative city for each region has been chosen.Based on the long-term climatic data of selected cities,the continuous numerical simulations have been conducted to obtain the temperature data of composite box-girders in different regions.According to the extreme value analysis,the design standard values of thermal loads in different regions have been determined.