Calculation Of Transverse Load Distribution Of Skew Bridge And Its Experimental Study

Chinese highway bridges boom fast during the past decades,in order to adapt to the river and the road better,the application of skew bridge is much more than ever before.Especially in the city overpass,it is a common form of structure and is widely used.Compared with the right bridge,the spatial stress characteristic and mechanism of skew bridge are much more complex.Mechanics characteristic of the skew bridge mainly include that the bending torsional coupling effect,the distribution of counter force is not uniform and moment of mid-span decrease and so on.In actual design,the spatial problem is simplified to plane problem,and cites the concept of load transverse distribution coefficient.Because there are many factors influence the skew bridge,such as the skew angle,width span ratio,flexural stiffness,torsional stiffness,support condition and loading form and some others,the calculation of the transverse distribution coefficient of right bridge is simple,but in skew bridge is not so easy.In view of this,research on the calculation method of load transverse distribution coefficient o the skew bridge is very important.In this paper,the simplified calculation method of the load transverse distribution coefficient of the skew bridge is studied based on the research object of Tianzhu interchange A bridge on Guizhou Sansui highway in Liping Province,the main works are as follows:⑴ This paper started from the calculation method of load transverse distribution coefficient and summed up their application conditions as well as advantages and disadvantages.Then the calculation method of load transverse distribution coefficient for skew bridge was summarized,and the application focused on the space grillage method in skew bridge.⑵ Proposed a new method to calculate the load transverse distribution coefficient of the skew bridge,that is the modal flexibility method and the feasibility of this method will be analyzed theoretically.The principle of the method is derived from the mathematics,and the expression of the mass normalized mode shapes was obtained,at the same time,two examples were used to verify,it provided theoretical support for the following theory and practical calculation.⑶ According to the proposed simplified calculation method,a space grillage model based on finite element analysis software ANSYS was built to compute.At the same time,a space grillage model based on finite element analysis software Midas/civil was built,the grillage theory was used to solve the load transverse distribution coefficient.The calculation results of grillage method and modal flexibility method were compared,and the error of the two was calculated.⑷ Combined with the load test of the skew bridge,actual results were calculated through the relevant data.The calculation results were compared with the results of modal flexibility method and the grillage method,the relative variation rule of the three was obtained,which verified the accuracy and precision of this simple method.⑸ Based on the ANSYS model of original bridge,parameters influencing transverse load distribution were discussed.The influence of various oblique angles,different span values,different numbers of beams and density of concrete were studied and gave the simplified calculation formula of load transverse distribution coefficient on skew hollow slab bridge with 5 to 9 beams.