STRAIGHT-ELEMENT GRID ANALYSIS OF HORIZONTALLY CURVED BEAM SYSTEMS

A COMPUTER METHOD OF ANALYSIS IS PRESENTED USING THE STATICALLY INDETERMINATE ANALYSIS OF PLAIN GRID SYSTEMS WITH STRAIGHT ELEMENTS FOR ANALYSIS OF HORIZONTALLY CURVED BEAM SYSTEMS. STRESS IS THE MOST POPULAR COMPUTER PROGRAM FOR THE ANALYSIS OF INDETERMINATE STRUCTURES, AND REFERENCE IS MADE TO A COMPUTER PROGRAM WHICH AIDS IN THE PREPARATION OF INPUT DATA FOR STRESS. HORIZONTALLY CURVED HIGHWAY BRIDGES DEVIATE FROM A TRUE GRID SYSTEM IN THE FOLLOWING WAYS: (1) DIAPHRAGMS CONSIST MOSTLY OF TRUSSED (AXIALLY LOADED) MEMBERS FRAMING INTO THE FLANGES OF THE CURVED BEAMS, (2) THE I-BEAM CROSS-SECTION WARPS UNDER TORSIONAL LOADS INTRODUCING ADDITIONAL DEGREES OF FREEDOM, AND (3) THE CONCRETE SLAB IS A CONTINUOUS MEMBER (NOT DISCRETE) AND ITS ELASTIC LINE IS OFFSET FROM THAT OF THE BEAMS. IN ORDER TO USE CONVENTIONAL INDETERMINATE ANALYSIS AND COMPUTER PROGRAMS, IT IS NECESSARY TO REPLACE CURVED SECTIONS OF THE BEAMS BY STRAIGHT LINES. THE BUILDING BLOCKS ARE PRESENTED OF STRAIGHT LINE SEGMENTS WHICH CAN BE USED TO MODEL A CURVED BEAM. IN ORDER TO INCORPORATE A TRUSSED DISPHRAGM INTO GRID SYSTEM, EQUIVALENT BEAM PROPERTIES MUST BE FOUND FOR IT. BECAUSE THERE ARE A RELATIVELY LARGE NUMBER OF JOINTS AND MEMBERS IN THE STRAIGHT-GRID ANALYSIS OF CURVED BEAMS, A LARGE PART OF THE INPUT DECK FOR STRESS WILL CONSIST OF DATA DESCRIBING THE JOINT COORDINATES AND THE MEMBER INCIDENCES. A COMPUTER CAN COMPUTE ALL THE JOINT COORDINATES AND THE MEMEBER INCIDENCES AND CAN PUNCH THE RESULTS ON CARDS FOR USE DIRECTLY IN THE STRESS PROGRAM. A PROGRAM IS PRESENTED FOR RADIAL SUPPORTS. A TWO BEAM, TWO SPAN CONTINUOUS STRUCTURE IS ANALYZED USING TWO MODELS AND THEN COMPARED WITH A MORE RIGOROUS CURVED GIRDER ANALYSIS. THE RESULTS FOR SHEAR AND BENDING MOMENTS ARE VERY CLOSE TO THOSE OF THE RIGOROUS ANALYSIS. THE TORSIONAL VALUES FOR BOTH MODELS ARE NOT IN AS CLOSE AGREEMENT WITH THE RIGOROUS ANALYSIS AS ARE THE VALUES FOR BENDING MOMENT AND SHEAR. HOWEVER, THE VALUES FOR THE MODEL B ARE IN BETTER AGREEMENT AND CAN BE USED TO ADEQUATELY SIMULATE A HORIZONTALLY CURVED BEAM SYSTEM.

  • Supplemental Notes:
    • Vol 7, No 2, PP 41-49, 13 FIG, 4 TAB, 7 REF
  • Authors:
    • Weissman, H A
  • Publication Date: 1970-4

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  • Accession Number: 00209233
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 17 1970 12:00AM