Analysis Of Solar Temperature Effect Of Continuous Curved Box Girder Bridges

In recent years, with the more and more investment in transport service of our country,the transport service develops very quickly and coupled with the accelerated process ofurbanization, curved box girder bridges have been widely used in highway cloverleaf andurban overpass due to its ability to adapt to the topography, sleek and many other advantages.But compared with liner bridges, the curved box bridges are more complex mechanicalbehaviors. Due to the relatively poor thermal conductivity of concrete, under the effect ofsolar radiation, its the internal structure will form the nonlinear temperature gradient whichwill lead to comparatively large deformation and stress of curved box girder bridges, or evenbreak the internal structure of the concrete. Now, studies on the temperature effect of curvedbox girder bridges have became a significant content of bridge theoretical research and itsapplication.This thesis, by taking the Houchuan River2#Bridge (20m+20m+20m) on PingtianHighway as background to conduct studies on the temperature effect of three spanscontinuous curved box girder bridge’s using MIDAS, discusses in detail the theory oftemperature effect of concrete structures and its influence factors. The main contents andfindings of this thesis are as follows:(1) The curved box girder bridge’s deformation and stress are more complicated incomparison with liner bridges. Under the temperature load effect of the sunlight, the verticaldisplacement of the curved box girder bridges will be enlarged and will have some radialdisplacements. The vertical displacement and the radial displacement of the curved box girderbridges will decrease with the increase of the curvature radius. For curved box girder bridgeswith different side span and middle span ratio, as the side span length increase, its verticaldisplacement of side span will decrease and the vertical displacement of middle will increase.(2) Comparing with liner bridges, curved box girder bridges have the effect of bendcoupling. Under the effect of gradient temperature, the torque of curved box girder bridgeswill decrease with the increase of curvature radius. Various ratios of side span and middlespan have great influence on torque of curved box girder bridges. For side span, as the sidespan length decrease, although the torque will decrease, torque mutation in the position ofmiddle piers will increase. The torsional support facilitates the distribution of curvatureintegral torque to the unloading and the middle hinge bearing point form of curved beamtorque will accumulate transferred to the curved box girder bridge ends. In the curved beamradius is larger, can make the inner bearing cavity, therefore, when curved box girder bridgesdesigning, full consideration should be given to.(3) Through study and analysis on models in the solid unit, we can conclude that amongeach stress component lead by gradient temperature load, longitudinal stress and transverse stress effect larger on the bridge especially in the roof or roof and web intersected parts of thebridge will form a larger tensile stress which even larger than the design strength of concretetensile value. In the design of the bridge should be reinforced for these positions and checkingcalculation of crack to ensure that the bridge has the durability and safety enough.(4) Under the gradient temperature load and the action of gravity, support vertical ofcurved box girder bridges showed the following characteristics: The lateral support force ofcurved bridge is lager than that of insides. Side pier bearing force will be smaller than that ofthe middle piers. With the increase of the radius of curvature, curved bridge lateral supportstress decreases. Inner bearing force first increases and then decreases to equal to the lateralbearing force.