DISCUSSION OF DESIGN AND TESTING OF CONE AND HYPAR FOOTINGS

THE WRITERS ARE CONDUCTING SOME RESEARCH IN THE FIELD OF HYPERBOLIC PARABOLOIDICAL SHELL FOUNDATIONS AND CONGRATULATE THE AUTHORS FOR THEIR ANALYTICAL AND EXPERIMENTAL STUDIES ON THE CONE AND HYPAR FOOTINGS. THEY OFFER THE FOLLOWING COMMENTS: (1) AN OPTIMUM DESIGN OF A SHELL FOOTING IS ONE IN WHICH BOTH THE FOOTING AND THE SUPPORTING SOIL FAIL SIMULTANEOUSLY, HOWEVER, A BETTER DESIGN WOULD BE ONE WHERE THE SAME FRACTION OF THE ULTIMATE CAPACITY OF THE OPTIMUM SYSTEM IS UTILIZED IN EITHER COMPONENT, AT THE WORKING LOAD, (2) THE ARCHING ACTION REPORTED IN THE CASE OF THE HYPAR FOOTING IS PREDOMINANT AT LOADS NEAR THE BEARING CAPACITY OF THE SOIL, BUT THE WRITERS HAVE COMPLETED A BENDING ANALYSIS OF AN INDIVIDUAL HYPERBOLIC PARABOLOIDICAL SHELL FOOTING BY THE METHOD OF FINITE DIFFERENCES AND HAVE DEVELOPED A HYPOTHESIS FOR AN UPPER-BOUND ON THE ULTIMATE STRUCTURAL STRENGTH OF THE SHELL FOOTING BY THE WORK METHOD, BASED ON A MECHANISM OF FAILURE OBSERVED FROM TESTS, (3) NO MENTION IS MADE OF THE BASIS ON WHICH THE HYPAR FOOTING MODEL WAS PROPORTIONED, (4) EVEN THOUGH IT IS MENTIONED THAT DEFLECTIONS WERE MEASURED, NO RESULTS ARE PRESENTED, (5) THE WRITERS HAVE OBSERVED THAT BEARING CAPACITY AS WELL AS SETTLEMENT GOVERN THE DESIGN OF FOOTING ON SAND, (6) A COST ANALYSIS OF THE HYPAR FOOTING, WHICH MIGHT SHOW THE MOST ECONOMIC RISE TO SPAN RATIO, SIMILAR TO THE ONE PRESENTED FOR CONE FOOTING, WOULD HAVE BEEN USEFUL, AND (7) THE ADMIRABLE PERFORMANCE OF SHELL FOOTINGS THEY HAVE OBSERVED IN SOME FIELD TESTS CONDUCTED IN MADRAS WHERE THE PROTOTYPES OF AN INDIVIDUAL HYPAR FOOTING WAS LOADED TO DESTRUCTION AND A COMBINED HYPAR FOOTING SUPPORTING TWO COLUMNS WAS LOADED TO ONE AND A HALF TIMES THE WORKING LOAD. REFERENCES: DESIGN AND TESTING OF CONE AND HYPAR FOOTINGS, ROBERT L. NICHOLLS AND MOHAMMAD V. IZADI, ASCE (PROC. PAPER 5732), JANUARY, 1968.

  • Supplemental Notes:
    • Vol 95, No SMI, PP 415-416, 2 REF, 1 APP
  • Authors:
    • Ninan, P K
    • Varghese, P C
  • Publication Date: 1969-1

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  • Accession Number: 00235503
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 29 1994 12:00AM