Research On The Effect Of Different Width-span Ratio On The Structural Performance Of Wide Box Girder Bridge

With the continuous development of China's economy,bridge construction technology has also been gradually improved,and a large number of new bridge structure forms have emerged.The transverse width of bridge is also increasing.Therefore,higher requirements are put forward for engineering design.The large-span wide single-box girder section with multi-chamber cross is widely used in urban bridges,especially in urban expressways.It has the characteristics of large web spacing,wide transverse flange,thin box-wall and so on.It is necessary to analyze and study the structural performance of the bridge because of its complex force in structural design.In order to know how do different width-span ratios affect the structural performance of wide-width box girder bridges,taking a wide box girder construction as an example,five different width span ratio grillage simulation model were set up using MIDAS Civil,based on the basic theory of grillage method.The variation laws of load transverse distribution coefficient for wide box girder bridges with different width-span ratios and the change rule of structural vibration mode were calculated and analyzed.The results show that:(1)Under the action of design load,the transverse distribution coefficient of the deflection of central beam at 0.4L(S1)of the side span and 0.5L(S3)of the wide box girder bridge with different width-span ratios are the largest.The transverse distribution coefficient of deflection of the beam on both sides is small,and it is distributed in a parabolic shape.And with the increase of width span ratio,the transverse distribution of each beam is more and more uniform.(2)As the width-span ratio increases,the first-order vertical frequency of the bridge also increases correspondingly.It indicates that the overall stiffness of the structure increases with the increase of the width-span ratio of the bridge,which conforms to the basic theoretical analysis of the bridge.Moreover,the functional relationship between different width-span ratios B/L and first-order vertical natural frequency is also regression,and its correlation factor R=0.898.The results can be used as a reference for engineers to analyze the forces of such wide bridges.