| Today,aesthetics in the long-span cable-stayed bridge design receives more and more attention,bridge towers develop to special-shaped orientation and diversification.For the special-shaped section of bridge tower,if it use concrete,the tensile stress can not be overcome at the junction of the tower and the rod.The stress concentration in the cross section can be met.Although it can satisfy the requirements of the specification,the structural safety surplus is too small,the durability and reliability are slightly worse.If it use steel,although the self-weight is light and the structure is safe and reliable,the high investment,low rigidity,large workload in late maintenance,the worse stability of the wind are its defect.Steel-concrete composite bridge tower combine the advantages of concrete towers and steel towers,receiving more and more attention.The special-shaped bridge tower consists of steel and concrete,the temperature changes in the structure will be more obviously.Because the integrated heat transfer coefficient,heat conduction coefficient,elastic modulus and linear expansion coefficient between two kinds of material are different,and the thermal conductivity of the concrete is poor,the steel is sensitive to temperature changes.Under the influence of natural factors in interior of the tower,it can form the adverse temperature field,deformation and great temperature stress.Therefore,the analysis of special-shaped steel-concrete pylon’s temperature field and temperature effect is quite practical.In this paper,with Yuejiang Bridge in Zhaoqing city as the engineering background,the tower is built by ANSYS entity model.The temperature field and temperature effect of steel-concrete tower of long span cable-stayed bridge are studied.Draw the following conclusions.Specific content as follows:(1)The basic theory of temperature field and temperature effect analysis of bridge tower is introduced,the relevant boundary conditions of temperature field and the calculation method of various parameters are discussed.(2)The changes of outside air temperature and solar radiation intensity under the most unfavorable sunshine conditions in summer are analyzed.The temperature field distribution and the temperature effect of the whole and local parts of the pylon underthe most unfavorable sunshine,via three-dimensional model of steel bridge and the two-dimensional model of steel-concrete cross-section of cable-stayed bridge.(3)By comparing of the theoretical value of the top displacement of the bridge tower under the sunshine effect and the measured displacement of the bridge tower in the monitoring of the cable-stayed bridge,the influence of sunshine on the displacement of bridge tower was analyzed.(4)With the analysis of the cold tide to the temporary external temperature changes,the temperature field distribution and the temperature effect of the whole and local steel bridge are obtained under the sudden cooling condition.(5)The local three-dimensional solid model of the mixed section of the bridge is established by ANSYS.The distribution of temperature field in the pouring of steel and concrete is simulated with comparing of construction monitoring values.In the most unfavorable sunshine effect,the tower’s appearance is under pressure and the internal tension.The tensile stress of concrete in steel-concrete section is the largest.It is most likely to form cracks.In the opposite direction of sunshine,cold waves will make the tower’s surface tensioned and internal stressful.The maximum tension zone of the bridge tower is on the outer surface of the steel section,but the outer surface of the bottom of the bridge is most likely to form cracks.Under the sunshine,the free-standing tower is more prone to deformation in the horizontal direction of the bridge.Bridge tower’s steel box section should be lifted in the evening when the temperature is low.Before pouring the concrete that in steel-concrete part,the estimated calculation of the hydration heat temperature can be carried out in order to better guide the construction. |
