Computational Principle Of Finite Eelement And Program Development For Arch Bridges

Arch bridge has a long history in our country.It has a traditional bridge structure with the virtue of economy and ever lasting. Masonry arch bridges are widely used for they can bear high pressure, have less bending moment and shear force. Although arch bridge inferior to suspension bridge and staged-cable bridge in span. As a structure of modern bridge, arch bridge is a chiose when the bridge has a span of 200 to 600 meters. When the bridge has middle or small span, building arch bridge is an easy task when civilian craftsmen are available. Masonry arch bridges will be the first choice for its characteristic.In the past, people calculated arch bridge with the help of manual. It is a complicated work, sometimes approximate calculation is needed and the result is not precise. Recently, many kinds of software to compute bridge are available at home and abroad such as Doctor Bridge, Midas and Anysis and so on. These softwares can be applied to various of bridge structures including arch bridge, but these softwares cost people much time to model the bridge structure and inconvenience those who are not familiar with computer.Further more, they can caculate more than one kind of bridge sturcture and are not concise to people who use the software named Qiaoliangtong . In this paper, combining computer and finite element methode, the Stiffness matrix of cell, the Force of Equivalent Node matrix of cell by the force of volume and surface, the Force of Equivalent Node matrix of cell by changed temperature, feet of the arch change and the compression line departure are derived. According to the compute principle and process of finite element, the paper provides program of counting internal force for many kinds of arch axes. At the same time, subprogram of optimizing arch axes using least squares method was programmed which is convenient to design arches axes. Meanwhile, partition cell infect to frame internal force according to the program result was analyzed. Couputed result and theoretical result are also compared. At last, the changes of variable action in new criterion and old criterion are also explained.The program was developed by Delphi as a part of the program of QiaoLiangTong which have the characteristic of convenience.