Study Of Temperature Effect On Long-span Suspension Bridges

Suspension bridge is a type of flexible structure with high degree of statical indeterminacy and composite by different components (main cable, suspender cable and pylon) with different stiffness. Its structural deformation presents obvious nonlinear geometry and this feature makes it sensitive to temperature changing. In order to make the actuarial state under construction stage and completed stage be close to the most reasonable state, as a sensitive factor, temperature must be monitored and modified in real-time.The Sidu River Bridge in national highway of HuBei Province is set as the engineering background,to develop the Study of Temperature Effect on Long-span Suspension Bridges. Main research work are as follows:1. First, the basic theory of temperature field is illustrated, then, embark on resolving the structural temperature field on the theory basis. And finally, pertinencial studies on several aspects influencing temperature action are carried out.2. According to the temperature monitoring plan, through 24 hours non interrupted displacement monitoring of pylon, variable regularity of pylon under temperature action is found by comparison of theory values and measured values. Moreover, the pylon's initial coordinate can be ascertained which provide referrence for the later displacement monitoring. The temperature action deviation from the tower and the moment changes can be calculated from the model in the bridge state , which provide the reference for the safety using of the bridge.3.Based on two different calculation method, catenary curve nonlinear calculation method and parabolic curve linear calculation method, the variation quantity of bearing rope is calculated under the most disadvantageous temperature load. It is found that the approximate formula also can meet the engineering demand. The elevation height of the bearing rope and datum strands are measured under different stage. The theory elevation height and measured elevation height under different cable temperature are given out, and provide reference for catwalk construction and lineshape control4.Based on nonlinear iterative method and finite element method, the main cable's sag are calculated under different temperature. Through comparison calculation, it is found that the pylon's temperature changing also make some effects on main cable's sag. Thereafter, the main cable's sag modified values are calculated by theory method and utilized for adjusting the main cable's lineshape. Meantime compared the theory and the measured of the elevation height of datum strands at mid-span, and of which can be referenced for its adjustment.5.Bridge in the state, consider±25°C temperature load, calculated the changes of the elevation height of the main cable in mid-span and the displacement of main beam in mid-span, Provided reference for the final phase of the bridge cable shape and the future safety using.