LIGHT WEIGHT-ON-STEEL COMPOSITE BEAMS

(1) COMPOSITE BEAMS WITH LIGHTWEIGHT CONCRETE CAN BE JUST AS EFFECTIVE AS THOSE WITH NORMAL WEIGHT CONCRETE, AND THEIR BEHAVIOR CAN BE PREDICTED WITH SATISFACTORY ACCURACY. (2) THE EFFECTS OF CREEP AND SHRINKAGE INCREASE THE DEFLECTIONS SUBSTANTIALLY. FOR DESIGN PURPOSES (WITH TIME DEPENDENT STRAINS IN THE RANGE OF 500-800 MICRO-INCHES), THE TIME DEPENDENT DEFLECTION MAY BE TAKEN EQUAL TO THE INSTANTANEOUS DEFLECTION FOR BOTH LIGHTWEIGHT AND NORMAL WEIGHT COMPOSITE BEAMS. (3) SHEAR CONNECTION OF LESS THAN 50 PERCENT SHOULD NOT BE PERMITTED. (4) IN SELECTING THE BEAM CROSS SECTION, THE DESIGN METHODS USED CURRENTLY FOR NORMAL WEIGHT CONCRETE MAY BE USED ALSO FOR LIGHTWEIGHT CONCRETE. ALL OTHER CALCULATIONS SHOULD BE BASED ON THE ACTUAL MODULAR RATIO FOR THE LIGHTWEIGHT CONCRETE. (5) THE CURRENT (AMERICAN INSTITUTE OF STEEL CONSTRUCTION (AISC) SPECIFICATION OVERESTIMATES THE BEAM STIFFNESS AND SECTION MODULUS AT 100 PERCENT CONNECTION BY 15 AND 5 PERCENT, RESPECTIVELY, BUT UNDERESTIMATES THE SECTION MODULUS AT 80 PERCENT CONNECTION AND LESS. (6) IN SOME CASES, THE CURRENT AISC FORMULA MAY NOT PROVIDE ENOUGH RESERVE TO AVOID YIELDING UNDER THE COMBINED EFFECTS OF FULL DESIGN LOADS, CREEP, SHRINKAGE, AND RESIDUAL STRESSES. /AUTHOR/

  • Supplemental Notes:
    • Vol 8, No 3, PP 90-98, 16 FIG, 7 REF
  • Authors:
    • Mcgarraugh, J B
    • Baldwin, J W
  • Publication Date: 1971-7

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Filing Info

  • Accession Number: 00209560
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Nov 8 1971 12:00AM