An Exact Method Research For Computing Internal Force Evelops Of Bridge Space

Prof. Yuan Si put forward to a new way to solve skeletal structures internalforce envelopes accurately in his paper an Exact Method for Computing InternalForce Envelopes of Skeletal Structures under Moving Loads. His student, LinSida, mentioned in his master’s thesis that the accurate solution for skeletalstructures internal forces envelope value was limited to planar skeletal structures.The bridge deck structure is usually been simplified as fishbone-typed beam asregard to the global analysis of large-span bridge. The influence of the movingloads on deck structure related not only to the section lengthwise position alongthe deck structure beams, but also to the transverse position of the beam sectionthat the loads acts on. In order to calculate internal forces envelope value inthree-dimensional space skeletal structures, the theory of Prof. Yuan need to beexpanded.Based on the theory of Prof. Yuan, this paper gave a research on specialskeletal structures bearing vertical loads, and mainly deduced the relationalexpression of units’ section internal forces, position of the loads(((x_p)|-),((y_p)|-))andsection position((x_a)|-), which was named as structure internal impact function. Afterderivation, the extreme point of the structure internal impact function was got.Compared with internal forces on the endpoint that the lads acts on, internalenvelop values of units axial forces, shear forces, twisting moment and flexuralmoment were got. A MATLAB program was given according to the theorydeduced ahead. Once basic information and loads information was given, thisprogram can accurately and automatically solve the internal forces envelop valueof the structure units, and the position that loads acts on when internal forces isequal to envelop value.A rigid frame bridge was analyzed using methods that this paper put forward.In this case, internal force impact, internal envelop graphic were analyzed, andthe rigid frame bridge mechanical characteristic was given. The methods that thispaper raised can also be used in the whole bridge mechanical analyze of largespan arch bridge, suspension bridge, and cable-stayed bridge bearing moving loads. Internal force envelop value of other special skeletal structure can also besolved using this method.