The Design Parameters Analysis Of The Double X-arch Bridge

Along with the fast development of bridge industry,people's request to landscape of bridge is also more and more high. Double X-arch bridge is a beauty with novel strueture, the model is distinct and it has a line of beauty,so it is usually to be the best scheme of the landscape bridge in our country. Because the strueture is made up of two vertical arch ribs and two inclined arch ribs, the stress and the structure are complex,the space effect is obvious. Besides, the quantity of the double X-arch bridge constructed is little, and the research outcome about the double X-arch bridge has only a few in our country and overseas,which limited the development of this new kind of bridge. Therefore, making research on the design parameters of the double X-arch bridge has important theories meaning and practical value.According to the structure characteristies of the double X-arch bridge,this text takes Yangmei Bridge with 100m span as an example. The space model of the double X-arch bridge is established by finite element procedure MIDAS/Civil. The influences of the main design parameters (the ratio of rise to span, the distance between the suspenders, the rake angle of inclined arch, the number and location of transverse) to the structural internal force, structural dynamic characteristics and stability are discussed. The main work and results of this text are as follows:1. This thesis intorduces the development of arch bridges,the characteristics of combinat -orial bridge with beam and arch and several double X-arch bridges having been built.2. The project background of the Yangmei Bridge is introduced. According to the finite element principle, the space model of the bridge is established by finite element procedure MIDAS/Civil.3. Under three kind of different working conditions, the influence of the main design parameters to the structural internal force of the double X-arch bridge is discussed. When the ratio of rise to span is changed from 1/5 to 1/6, all the internal forces are suddenly changed, and the increase is the biggest. The enlargement of the distance between the suspenders and the reduction of the number of transverse are unfavorable to the internal forces of the inclined arch. The reduction of the rake angle of inclined arch and the change of the location of transverse are unfavorable to the internal forces of the the main arch, the main beam and the inclined arch, but the influence is not too big.4. The influence of the main design parameters to the first ten step base frequency of the double X-arch bridge is discussed. The base frequency increases along with the distance between the suspenders reduces, but the change rule to the ratio of rise to span and the rake angle of inclined arch is not obvious. When the of the number of transverse is reduced or the different locations of transverse are removed, the frequencies reduce except individual frequencies are invariable.5. The influence of the main design parameters to the first step structural stability of the double X-arch bridge is discussed. The ratio of rise to span, as well as the rake angle of inclined arch and the number of transverse is proportional to the the stable safety factor. Along with the distance between the suspenders is increased, the stable safety factor increases, but its actual critical load reduces. The position of transverse is more approaches the skewback, the contribution to enhances the stable is bigger.