TESTS EVALUATING PUNCHING SHEAR RESISTANCE OF PREFABRICATED COMPOSITE BRIDGE UNITS MADE WITH INVERTED STEEL T-BEAMS

DESIGN INFORMATION IS DEVELOPED FOR A SPECIAL TYPE OF PREFABRICATED COMPOSITE SUPERSTRUCTURE UNIT FOR BRIDGE SPANS IN THE 30- TO 70-FT RANGE. THESE STEEL AND CONCRETE UNITS CONSIST OF SPAN-LENGTH, 7-IN. THICK REINFORCED CONCRETE SLABS 6 TO 10 FT WIDE. THE WEBS OF A PAIR OF INVERTED T-SHAPED STEEL BEAMS ARE EMBEDDED IN EACH SLAB. HORIZONTAL STEEL STUDS WELDED AT INTERVALS TO THE BEAM WEBS ACT AS SHEAR CONNECTORS. TO EVALUATE THE RESISTANCE OF TWO PARTICULAR PREFABRICATED UNITS TO PUNCHING SHEAR AND TO DEVELOP GENERAL DESIGN INFORMATION FOR DETERMINING SAFE STUD SPACINGS, TESTS WERE CONDUCTED ON TWO 10-FT WIDE BY 5 1/2-FT LONG SPECIMENS REPRESENTING A SECTION OF A TYPICAL BRIDGE. THE STUDS WERE SPACED AT 4-IN. INTERVALS IN ONE SPECIMEN AND AT 10-IN. INTERVALS IN THE OTHER. BOTH SPECIMENS WERE SUPPORTED AND LOADED SO THAT THEY WOULD BE SUBJECTED TO PUNCHING SHEAR. BOTH SPECIMENS FAILED IN A SIMILAR MANNER AT LOADS THAT WERE ABOUT FIVE TIMES GREATER THAN THE MAXIMUM WHEEL LOAD /INCLUDING 30 PERCENT FOR IMPACT/ SPECIFIED BY AASHO FOR H20 OR H20-S16 TYPE TRUCKS. THE MODE OF FAILURE APPEARED TO BE A COMBINATION OF TENSION AND BOND FAILURE IN THE CONCRETE RATHER THAN A PUNCHING-TYPE FAILURE. A METHOD OF DETERMINING THE SAFE SPACING OF STUDS FOR RESISTING COMBINED PUNCHING AND HORIZONTAL SHEAR WAS DEVELOPED AND WAS BASED ON THE CONSERVATIVE ASSUMPTION THAT THE STUDS CARRY ALL THE PUNCHING SHEAR. IT WAS ALSO ASSUMED THAT THE INTENSITY OF THE PUNCHING SHEAR WAS PROPORTIONAL TO THE DEFLECTION OF THE SLAB NEAR THE WEB, AND THAT A CONSERVATIVE APPROXIMATION OF THIS RELATIONSHIP IS THAT THE SHEAR INTENSITY VARIES PARABOLICALLY--FROM ZERO TO MAXIMUM SHEARING STRESS TO ZERO--OVER AN 8-FT LENGTH. THIS PROCEDURE PERMITS THE MAXIMUM VERTICAL SHEAR PER STUDY TO BE CALCULATED AND THEREBY MAKES IT POSSIBLE TO USE CONVENTIONAL PROCEDURES IN DESIGNING THESE PREFABRICATED SUPERSTRUCTURE UNITS.

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrr/1965/103/103-005.pdf
• Supplemental Notes:
  • Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
• Authors:
  • McDermott, J F
• Publication Date: 1965

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: pp 41-52
• Monograph Title: Bridges and structures
• Serial:
  • Highway Research Record
  • Issue Number: 103
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Bridge superstructures; Calculation; Composite construction; Deflection; Design; Evaluation; Fasteners; Load tests; Prefabricated structures; Puncture resistance; Reinforced concrete; Shear rate; Shear reinforcement; Shear strength; Shear stress; Slabs; Spacing; Studs; T beams
• Uncontrolled Terms: Bridge spans; Computation; Punching shear; Shear connectors
• Old TRIS Terms: Design information; Vertical shear
• Subject Areas: Bridges and other structures; Design; Highways;

Filing Info

• Accession Number: 00207713
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Apr 1 1994 12:00AM