ANOTHER APPROACH TO SIMPLIFIED DESIGN OF A CURVED STEEL GIRDER

METHODS OF CONDUCTING AN APPROXIMATE ANALYSIS OF A CURVED GIRDER GRID SYSTEM ARE REVIEWED. THE PRINCIPAL ASSUMPTION OF ANALYSIS USED IN THE METHODS IS BASED ON THE WELL ESTABLISHED FACT THAT THE CHANGE IN TORQUE BETWEEN TWO POINTS OF A CURVED GIRDER SUBJECTED TO BENDING IS EQUAL TO THE AREA OF BENDING MOMENT DIAGRAM BETWEEN THESE POINTS, DIVIDED BY THE RADIUS OF CURVATURE OF THE GIRDER. ANALYSIS SHOWS THAT ADDITIONAL FORCES ARE CALCULATED AS SECONDARY FORCES CREATED BY MAIN TENSILE AND COMPRESSIVE STRESSES ACTING IN BEAM FLANGES DUE TO BENDING MOMENT. BEING A BY-PRODUCT OF BENDING MOMENTS, SECONDARY FORCES CAN BE EVALUATED FOR THE UNIFORMLY DISTRIBUTED AND CONCENTRATED LOADS, WHICH ARE THE MAIN SOURCES OF THE BENDING. THE DIRECT TORSIONAL MOMENTS, UNIFORMLY DISTRIBUTED OR CONCENTRATED, DO NOT INDUCE PRIMARY BENDING MOMENTS AND, THEREFORE, THEIR TORSIONAL EFFECT, WHICH ACTUALLY IS ESSENTIAL, CANNOT BE EVALUATED BY THE DESCRIBED METHODS. AN APPROXIMATE METHOD OF CALCULATION IS PROPOSED OF ADDITIONAL VERTICAL FORCES AT POINT OF DIAPHRAM CONNECTIONS OF CURVED STEEL FRAMING. THE METHOD IS SIMPLE IN CONCEPT AND EASY IN APPLICATION. FOR LOADING APPLIED ALONG THE CENTER LINE OF CURVED FRAMING, THIS METHOD PRODUCED RESULTS RELATIVELY CLOSE TO FIGURES OBTAINED BY THE U. S. STEEL DESIGN HANDBOOK FORMULA. HOWEVER, THIS METHOD PROVIDES THE POSSIBILITY OF REVEALING ADDITIONAL SECONDARY FORCES DUE TO DIRECTLY APPLIED MOMENTS WHICH CAN BE OF CONSIDERABLE VALUE AND SHOULD NOT BE DISREGARDED.

• Supplemental Notes:
  • Vol 6, No 4, PP 116-123, 12 FIG, 2 TAB, 5 REF
• Authors:
  • Ketchek, K
• Publication Date: 1969-10

Media Info

• Serial:
  • Engineering J, Am Inst Steel Constr

Subject/Index Terms

• TRT Terms: Bending moments; Compressive strength; Curvature; Curves (Geometry); Framed structures; Frames; Girders; Radius; Structural analysis; Tension; Torque
• Uncontrolled Terms: Tensile stress
• Old TRIS Terms: Curved steel girders; Framing; Radius of curvature
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00209111
• Record Type: Publication
• Files: TRIS
• Created Date: Feb 24 1970 12:00AM