The Key Technology Research Of Preprocessing And Postprocessing In Simulation Of Masonry Arch Bridge Collapse Process

In the recent years, it happens many bridge collapse accidents because ofthe reasons of design、construction and operating environment est. Therefore, itis very important to research the bridge collapse mechanism and understand thereasons of collapse. Three dimensional computer simulation technique developsquickly, and it becomes an economic、practical and feasible studying method tosimulate the process of bridge collapse. So, this paper explores the computeradded key technologies in the simulation of bridge collapse. And the studyingmainly contains two parts.The first Part: the modeling of masonry arch bridge is cockamamie, elapse-timed and non-repeatable. Therefore, this paper provides a three-dimensionalfinite element modeling method, and it mainly contains three key technologies.1) Section Stretching, which means that stretching the defined sectionsalong the defined direction and length to build the bridge entities.2) The three-dimensional entity algorithm of intersection and union, whichmeans that the three-dimensional entities intersect and union basing on thecomputer graphics theory to build the Geometries in need.3) Designing the interface form of model output to build the Finite Elementmodel which can be calculated by OpenSEES.The second part: Basing on the OpenGL graphics library and selecting thedevelopment language C#which is object oriented, this paper systematically develops an post processing of system of bridge collapse finite element analysis,which mainly contains six key technology.1) The visualization of the output of the finite element static analysis,which means that the system displays the stress and displacement cloud atlas bybuilding a series of classes and geometry algorithms.2) The visualization of the all process of bridge collapse, which means thatthis paper designs an algorithm about entity movable updating and deleting, byuse of the element life and death simulation technology.3) The spacing Strategy and the stress extraction algorithm of observationpoint, which means that it firstly quickly lookups the related points by bubblesort algorithm, and then calculates the stress of observation point by the knownpoint stress in triangular element, with the interpolated calculation of shapefunction.4) The realization of the dissection algorithm of solid elements, this papertakes the example of hexahedron element, basing on the intersection algorithmbetween lines and planes, to calculate the intersection surfaces between planesand solid elements.5)The realization and verification of the internal force integral algorithm ofkey section, which means that this paper makes triangulation of the key sectionbasing on the theory of section internal force equivalent integral.The input algorithm of capacious file, which this paper inputs thecalculated results by reading the stacks in step, and displaying the dynamic computation result simultaneously.6)Lastly, this paper takes the example of Ti XiTuo Masonry arch Bridge,and builds an analysis system of the all collapse process of the masonry archbridge with the partners in the project group, which contains pre-processing、FEA and post processing.This paper indicates that: firstly, it could simulate vividly the all process ofbridge collapse, basing on the OpenGL graphics library with C#; secondly, itprovides internal force data familiar by engineers in the bridge collapseall-process analysis, according to building a dependable key section internalforce integral algorithm, and it also provides a valid technology in the analysisof bridge collapse mechanism; lastly, it provides a dependable method in quicklythree-dimensional modeling.