EP 1110-2-12
30 Sep 95
1-5.
Design Philosophy
Chapter 1
Introduction
a. Response spectrum analysis. The nonlinear-
ities associated with concrete behavior under seismic
loading are difficult to assess and beyond practical
1-1.
General
analyzing capabilities of most design offices.
Procedures which permit the use of a linear-elastic
Roller compacted concrete (RCC) dams are designed
type of dynamic analysis adjusted to provide a
in accordance with EM 1110-2-2200. The
reasonable but conservative approximation of the
proportions of the RCC dam are derived by stability
nonlinear behavior are adequate in almost all design
analysis in a manner identical to that for a
situations. The philosophy of design followed in this
conventional concrete gravity dam and are governed
EP will be to establish the procedures applicable to
by the static forces to be resisted and not by the
the majority of design situations. This consists of
dynamic forces generated during seismic activity.
providing in some detail the requirements for
After the geometric proportions are determined based
performing the linear-elastic response spectrum
on the static loads a dynamic analysis is conducted.
analysis and the criteria for evaluating the results.
Zones requiring superior RCC mixes are established,
and vibratory compaction methods and joint
b. Refined analyses. For the few occasions
preparation methods which affect the RCC tensile
where this approach does not produce a satisfactory
strength are also established based on the criteria
design or where an existing dam does not satisfy
provided in this engineer pamphlet (EP).
criteria, the designer is then advised to pursue the
more refined analysis methods. Should the even
more complex nonlinear analysis become necessary, it
1-2.
References
should be performed under the guidance of a
recognized expert in this specialized field and should
Required and related publications are listed in
only be undertaken with approval of CECW-ED.
Appendix A.
1-6.
Design Earthquakes
1-3.
Explanation of Terms
The linear-elastic response spectrum method of
Abbreviations, symbols, and notations used
analysis is the simplest dynamic analysis method and
throughout this EP are explained in the glossary.
provides adequate results for most designs. The
ground motion is usually defined by design response
spectra scaled to peak ground accelerations (PGA) for
1-4.
Background
the two design earthquakes described below.
Basic criteria and guidance for the design of RCC
a. Operating basis earthquake. The operating
dams are provided in EM 1110-2-2200. ER 1110-2-
basis earthquake (OBE) is defined as the earthquake
1806 provides guidance on analysis methods and
producing the greatest level of ground motion that is
procedures for new designs and an investigative
likely to occur at the site during the economic life of
program for existing dams. ETL 1110-2-301 gives
the dam.
additional information on specifying earthquake
ground motions for a particular site. ETL 1110-2-303
b. Maximum credible earthquake. The
provides guidance on finite element dynamic analysis
maximum credible earthquake (MCE) is defined as
methods and on evaluating the severity of cracking
the earthquake which produces the greatest level of
based on tensile stresses from the linear analysis.
ground motion at the site as a result of the largest
EM 1110-2-2006 provides guidance concerning RCC
magnitude earthquake that could reasonably occur
usage and mix design.
along the recognized faults or within a particular
seismic source.
1-1
Previous Page
