RELATIVE VARIABLE MOMENT OF INERTIA AND INFLUENCE LINES FOR ONE-SHOT ANALYSIS OF THREE-SPAN CONTINUOUS HIGHWAY-BRIDGE STEEL GIRDERS IN CENTER-SPAN RANGE OF 300 TO 450 FEET

ANALYSIS AND DESIGN OF A THREE-SPAN CONTINUOUS BRIDGE GIRDER ARE REDUCED TO A ONE-STEP PROCEDURE, SAVING MUCH TIME AND REPETITION OF WORK ESPECIALLY WHEN LONG SPANS ARE INVOLVED. THE CONVENTIONAL APPROACH IS TO ASSUME A SET OF VALUES FOR THE MOMENTS OF INERTIA, WORK UP THE INFLUENCE LINES, AND MAKE A PRELIMINARY DESIGN. THIS DESIGN RESULTS IN A NEW SET OF VALUES, AND THE PROCESS MUST BE REPEATED UNTIL FINAL AND INITIAL VALUES COME INTO AGREEMENT. THIS REPORT DEVELOPS A PROCEDURE WHICH YIELDS A ONE-SHOT ANALYSIS AND DESIGN THROUGH THE USE OF DATA FROM PREVIOUSLY DESIGNED BRIDGES OF THIS TYPE. THE DEPTHS AND RELATIVE I VALUES /RATIO OF I AT A POINT TO THE I AT THE CENTER/ AT 10TH OR 20TH POINTS ALONG THE EXISTING BRIDGES ARE FIRST ADJUSTED TO THE LENGTH OF THE BRIDGE UNDER CONSIDERATION. A SET OF RELATIVE I VALUES AND DEPTHS TO BE USED FOR ANALYSIS AND DESIGN IS OBTAINED BY ASSIGNING A WEIGHT TO EACH KNOWN SET ACCORDING TO COMMON CHARACTERISTICS AND COMPUTING THE WEIGHTED MEAN VALUES. THIS PROCEDURE WAS USED FOR EACH OF THREE BRIDGES WITH CENTER SPAN LENGTHS OF 300 FEET, AND 450 FEET RESULTING IN THE NEED FOR ONLY ANALYSIS AND DESIGN FOR EACH CASE. THREE-MOMENT EQUATION FOR VARIABLE I IS DERIVED BY THE MATRIX ENERGY APPROACH. INFLUENCE TABLES AND CURVES ARE PRESENTED. TENTATIVE EMPIRICAL FORMULAE ARE PRESENTED FOR ESTIMATING CONSTANT AND VARIABLE DEAD LOADS ALONG THE VARIABLE-DEPTH GIRDER SPANS.

• Supplemental Notes:
  • Hps-hpr 1/26, STATE RES PROJ?617 , SEPT64
• Corporate Authors:

  South Dakota School of Mines and Technology, Rapid City

  501 East St Joseph Street
  Rapid City, SD  United States  57701
• Authors:
  • Li, S T
• Publication Date: 1964-9

Subject/Index Terms

• TRT Terms: Analysis; Beams; Bridge design; Bridge members; Bridges; Continuous structures; Equations; Estimating; Girders; Highway bridges; Influence lines; Length; Measures of central tendency; Methodology; Shape; Static loads; Steel structures; Structural design; Structural steel
• Uncontrolled Terms: Bridge spans; Center; Continuous beams; Data; Long
• Old TRIS Terms: Empirical equations; Influence tables; One-shot; One-step; Previously designed; Relative variable moment of inertia; Three-span; Variable-depth
• Subject Areas: Bridges and other structures; Highways;

Filing Info

• Accession Number: 00207747
• Record Type: Publication
• Files: TRIS
• Created Date: Oct 1 1994 12:00AM