부산대학교 도서관

Thermal gradient may have significant effect on the bending behavior of the composite girderwith trapezoidal profiled web. To quantify such an effect on the thermos-strain action,temperature elevation test and finite element modeling were carried out on the specimenswith the flange sensitive to bending and the web possessed adequate buckling resistance. Thecross-sectional thermal gradients for different location away from the middle of span weremeasured using thermocouples and correlated using Boltzmann sigmoid equations. Theapplicability of finite element model was validated against experiments in terms of thedistribution of thermal strain, deflections and axial strains. The axial strain distributions acrossthe flange width and along the longitudinal direction of girder were analyzed in details. Thetesting and finite element modeling results showed that, the deflections with applied loadsnear the middle of span subjected to maximum bending moment are notably influenced bythe increase of thermal gradient. The maximum axial strains at the upper surface and thelower surface of the bottom flange are obviously influenced by the temperature, especially forthe girders with relatively high span-depth ratios or thicker flanges. The thermal gradient at theupper surface of the bottom flange is relatively higher than that on lower surface for every10oC rise of temperature which meant that the upper surface of the bottom flange connectingtrapezoidal profiled webs is more sensitive to thermo-elastic action.