WAREHOUSE SLAB ON BAD GROUND

MESSRS WHITE & CO LTD OF PORTSMOUTH DECIDED TO BUILD A WAREHOUSE ON EXCEPTIONALLY POOR GROUND. TO OVERCOME THE NECESSITY OF GROUND STABILIZATION, HAVING ENCOUNTERED RATHER POOR BUT NOT ALTOGETHER HOPELESS CONDITIONS, POST-TENSIONED CAST ON SOLID SLAB WAS USED AS A WAREHOUSE FLOOR. THE GROUND WAS JUDGED TO BE CAPABLE OF SUSTAINING PRESSURE OF AN ORDER OF 1/4-TON/SQ FT WHILE THE SLAB HAD TO BE CAPABLE OF SUPPORTING INCIDENTAL POINT LOADS OF 4 TONS AT ANY PART OF THE FLOOR. AS FORKLIFT TRUCKS WITH RATHER SMALL WHEELS WERE TO BE USED IN THE WAREHOUSE, CONSTRUCTION JOINTS HAD TO BE ELIMINATED. EXPERIENCE INDICATED THAT IN A NORMAL TYPE OF CONSTRUCTION THE EDGES OF CONSTRUCTION JOINTS TENDED TO BE ERODED, FORMING IN TIME, CHANNELS, AND ALSO INCREASING THE PROBLEM OF DUSTING. MANY METHODS OF GROUND STABILIZATION WERE INVESTIGATED BUT ALL WERE FOUND TO BE TOO COSTLY WITH RESPECT TO THE BUDGET SET BY THE CLIENT. SIX-INCH PRESTRESSED CONCRETE SLAB MONOLYTHIC WITH 3/4 IN GRANO- FINISH AND POST-TENSIONED WITH 1/2 IN DIA STRANDS AND CCL ANCHORAGES PROVIDED THE ONLY SUITABLE SOLUTION WITHIN THE TARGET COST. THE STRANDS WERE LOCATED AT THE CENTERS OF THE SLAB AT 18 IN CENTERS AND IN BOTH DIRECTIONS. THE MAGNITUDE OF INITIAL STRESS BEING IN THE ORDER OF 240 LB/SQ IN BOTH WAYS. THE FOUNDATION BASES TO STANCHIONS SUPPORTING THE ROOF WERE CONSTRUCTED BY THE CONTRACTORS WITH SUITABLE CONSTRUCTION JOINTS SURROUNDING EACH COLUMN IN ORDER TO MAKE THE GROUND FLOOR SLAB TOTALLY INDEPENDENT OF THE SUPERSTRUCTURE. THIS PARTICULAR WORK WAS CARRIED OUT SOME FOUR YEARS AGO BEFORE DEBONDED STRANDS WERE COMMERCIALLY AVAILABLE IN THE UK. THEREFORE 1-1/2 IN METAL SHEETING AND SUBSEQUENT GROUTING WERE NECESSARY. WITH UNBONDED TENDON NOW AVAILABLE THIS PARTICULAR FORM OF CONSTRUCTION WOULD SHOW FURTHER ADVANTAGES. TO PREVENT CRACKING AROUND THE EDGES STANDARD FABRIC WAS USED ALONG THE PERIMETER. GROUTING HOLES WERE PROVIDED AT SUITABLE INTERVALS. THE SPECIFIED CUBE STRENGTH WAS 4500 LB/SQ IN AT 28 DAYS. NO COMPLAINTS HAVE BEEN RECORDED DURING THE FOUR YEARS SINCE COMMISSIONING OF THE WAREHOUSE. THERE APPEARS TO BE NO DOUBT THAT PRESTRESSED SLABS OF THIS NATURE ARE INFINITELY SUPERIOR AND MORE ECONOMICAL THAN MORE TRADITIONAL TYPES OF REINFORCED SLAB ON SOLID MATERIAL AND THESE ARE ALSO COMPETITIVE EVEN IN CASES WHERE MUCH BETTER STRATA ARE AVAILABLE. /AUTHOR/

  • Supplemental Notes:
    • Vol 66, No 782, P 973, 975
  • Authors:
    • Bobrowski, A F
  • Publication Date: 1971-9

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  • Accession Number: 00236249
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 8 1972 12:00AM