Gravity-type cellular cofferdams are widely used as waterfront retaining structures. Static design of these structures is generally performed by considering several modes of static failure. The experience gained from post-construction observation of cofferdam behavoir has greatly enhanced the prostulation of admissible failure mechanisms that should be considered in design. Because static methods of cofferdam design have become somewhat standardized and have been verified through observations of performance, a promising approach to the seismic design of such structures is centered about the development of consistent pseudo-static failure mechanisms. This paper illustrates such extensions of the static design techniques, and compares the factors of safety obtained from static and pseudo -static (seismic) analyses. Certain design criteria, which have been modified to account for dynamic action, are explained. Local soil, rock and hydrostatic conditions, as well as liquefaction potential and hydrodynamic forces, are considered. The method of analysis admits various assumptions that are based on the static failure modes of the analytical models; for example, the postulated sliding failure condition assumes an inflexible rigid body-type of behaviour, while the Cumming's method of horizontal shear considers the structure to be flexible and the soil to be capable of developing failure planes. By extending these postualted failure modes for the dynamic analysis, the same modeling assumptions are admitted for the pseudo-static case. the methodology proposed is suggested as a means of conservatively performing design checks, using simplified procedures, and not as a replacement for a dynamic, state-of-stress response analysis. /Author/

Media Info

  • Features: Figures; References;
  • Pagination: p. 325-341

Subject/Index Terms

Filing Info

  • Accession Number: 00179753
  • Record Type: Publication
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Oct 12 1978 12:00AM