ETL 1110-2-536
31 Dec 94
APPENDIX A: NONLINEAR INCREMENTAL STRUCTURAL
ANALYSIS OF ZINTEL CANYON DAM
A-1. Introduction
b. Scope. This work is limited to the NISA
evaluation of Zintel Canyon Dam. The analyses
a. Purpose.
performed for the project are not intended to be com-
prehensive evaluations as described in the ETL, but
(1) The U.S. Army Corps of Engineers, Civil
abbreviated evaluations, more appropriate for a struc-
Works, has been developing guidelines and proce-
ture of this type and function. There are two reasons
dures for determining thermally generated stresses
for this abbreviation. The structure is a simple
resulting in construction of massive concrete struc-
gravity design, containing no contraction joints and
tures. The original product of the research and devel-
impounding no permanent reservoir. Since transverse
opment was documented in ETL 1110-2-324, Special
cracking of the structure poses no threat to the safety
Design Provisions for Massive Concrete Structures
of the structure or to the public and does not impact
and has since been superseded by ETL 1110-2-365,
the function of the project, a relatively simple analy-
Nonlinear Incremental Structural Analysis of Massive
sis is sufficient. Secondly, the level of funding for
Concrete Structures.
this study was not sufficient to perform extensive
analyses. Funding only permitted simple modeling
(2) The Walla Walla District was commissioned
and limited evaluations. However, the extent of
to perform a thermal stress analysis of Zintel Canyon
analysis was sufficient to evaluate the thermal stress
Dam. The goals in performing this study are to:
performance, to provide recommendations on district
implementation of the NISA, and to evaluate the
(a) Perform a nonlinear, incremental, structural
guidelines specified in the ETL.
analysis (NISA) to evaluate the effects of tempera-
ture, Roller Compacted Concrete (RCC) material
c. Report. This report is organized to specifi-
properties, and the subsequent volume changes on the
cally address the study goals. Section 2 provides
cracking potential of Zintel Canyon Dam. The pur-
background on the development of finite element
pose of such an analysis is to evaluate costs and
analyses for mass concrete structures which led to the
performance so that appropriate design features and
development of the current procedures for performing
requirements may be established. Obviously, since
thermal stress evaluations and Corps guidance on the
the dam is complete, no design modifications will be
subject. The NISA evaluation for Zintel Canyon
done. However, some observations of the effective-
Dam, which includes the details of performing the
ness of such an evaluation can be made.
evaluation and the project specific results, conclu-
sions, and recommendations, is contained in Section 3
(b) Demonstrate the implementation of the NISA
and the referenced appendices. Recommendations are
process for an RCC structure and compare analytical
provided, in Section 4, on implementing a NISA
performance with observed performance of the struc-
evaluation. Finally, recommendations for modifica-
ture. In the process, evaluate the NISA method to
tion of the guidance, to make it more useful in appli-
provide recommendations on what measures may be
cation of the NISA process, are contained in
implemented to make the process more serviceable.
Section 5.
By performing a NISA of a current project at the
District level, valuable insight would be gained on
whether this analytical method is a suitable tool for
A-2. Background
designers and implementable at the district level.
a.
Development of the NISA process.
(c) Evaluate the suitability of the Corps of Engi-
neers' guidance in performing nonlinear, incremental
(1) Mass concrete structures are different from
structural analyses for Zintel Canyon Dam. At the
many concrete structures in that material properties
time the NISA was performed, the guidance was
have a significant effect on the state of stress in the
contained in ETL 1110-2-324. A new document,
structure. These material properties are not only
ETL 1110-2-265, has been published, but most of the
dependent on the type and quantity of material, but
procedures for performing a NISA remain the same.
on the age of the concrete, temperature of the
A-1
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