MASTER'S THESIS RESEARCH PLAN
Comprehensive Framework & Execution Roadmap
Focus Area: Seismic Safety, Progressive Evaluation & Advanced Numerical Modeling of Concrete Gravity Dams
1. THESIS TOPIC
Proposed Working Title
Progressive Seismic Risk Evaluation and Contact Non-Linearity Modeling of Concrete Gravity Dams Using
FEA: Benchmark Application to Koyna Dam
2. RESEARCH OBJECTIVES
The primary goal of this research is to evaluate the dynamic response and structural safety of concrete gravity dams
under strong seismic action through multi-tier progressive analysis and advanced numerical contact interface
formulations. The specific objectives are:
• Objective 1: To implement a tiered progressive seismic evaluation framework (Level 1: Pseudo-Static Analysis /
Linear Dynamic Time History Analysis vs. Level 2: Advanced Non-Linear Analysis) for concrete gravity dams.
• Objective 2: To validate a 2D finite element model of the Koyna Dam benchmark section against published historical
earthquake response data and benchmark numerical literature in MIDAS FEA / GTS NX.
• Objective 3: To model and evaluate geometric and interface contact non-linearities (lift joints, contraction joints, and
dam-foundation interface) under non-linear dynamic time history analysis (NLDTHA).
• Objective 4: To establish calibration recommendations and best-practice input parameters for contact formulations,
fluid-structure interaction (FSI), and boundary conditions in MIDAS solvers.
• Objective 5: To perform comparative data synthesis across evaluation tiers to quantify safety margins, sliding/opening
displacements, and structural stress redistribution.
3. NEED OF THE STUDY (LITERATURE GAP & CONTRIBUTION)
3.1 Previous Works
Extensive research has been conducted on the seismic performance of concrete gravity dams following major events
such as the 1967 Koyna Earthquake ($M_w 6.6$). Classical studies by Westergaard (1933) established simplified addedmass hydrodynamic formulations, while Chopra et al. (1970–2020) advanced linear and non-linear dynamic response
spectrum methods incorporating dam-reservoir-foundation interaction. Subsequent finite element investigations (Clough &
Zienkiewicz, 1982; Fenves & Chopra, 1987) established the role of concrete tensile cracking and joint opening during
intense shaking.
3.2 Identified Literature Gaps
• Gap 1 — Disconnect in Multi-Tier Codal Practice vs. Advanced FEA: Standard engineering codes (e.g., IS 6512 /
IS 1893 Part 3 and USACE guidelines) prescribe pseudo-static and response spectrum methods (Level 1), but lack
clear quantitative guidelines on when linear approximations become overly conservative or unsafe compared to Level
2 Non-Linear Dynamic Time History Analysis (NLDTHA).
• Gap 2 — Simplified Representation of Joint Contact Non-Linearities: Many practical numerical investigations
treat concrete gravity dams as monolithic continuous bodies or simplify joint interfaces, ignoring the transient
separation, sliding friction, and energy dissipation at lift joints and dam-foundation contacts.
• Gap 3 — Lack of Software Calibration Guidelines for Engineers: While advanced commercial solvers like MIDAS
FEA / GTS NX possess sophisticated gap and contact elements, concise documentation regarding parameter
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sensitivity (penalty stiffness, friction coefficients, mesh dependence, and absorbing boundary conditions) for dam
engineering applications remains sparse in academic literature.
3.3 How This Thesis Fills the Gaps
This thesis bridges these gaps by providing a standardized, comparative benchmark study on the Koyna Dam section. It
systematically transitions from Level 1 linear evaluation to Level 2 fully non-linear interface modeling in MIDAS,
quantifying the exact performance delta between linear and non-linear predictions. Furthermore, it delivers a practical
guideline table detailing recommended input parameters and numerical contact configurations for practicing dam
engineers.
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4. RESEARCH METHODOLOGY
4.1 Literature Review Framework
The literature review is organized across six core thematic modules to build the theoretical and regulatory foundation for
the numerical investigation:
LITERATURE MODULE
KEY CODES & STANDARDS
SEMINAL REFERENCES & CORE THEORY
1. Dam Portfolios & Risk
• CWC NRLD
• Wieland, M. (2012) Earthquake Safety of Large
Assessment
• USACE EM 1110-2-6053
Dams.
• FEMA P-1020
• Risk matrix ($Risk = Hazard imes Vulnerability
imes Consequence$) & RIDM framework.
2. PFMA & Progressive
• FERC Guidelines Ch. 11
• Hartford & Baecher (2004) Risk and Uncertainty
Evaluation
• USBR/FERC RIDM Module 3
in Dam Safety.
• USACE EM 1110-2-2200
• Event tree analysis; Tiered evaluation (Pseudostatic $ ightarrow$ Response Spectrum $
ightarrow$ NLDTHA).
3. Load Combinations &
• IS 6512: 1984
• Kramer, S. L. (1996) Geotechnical Earthquake
Input Motion
• IS 1893 (Part 3): 2014
Engineering.
• CWC Hazard Guidelines
• Probabilistic Seismic Hazard Analysis (PSHA),
Target Response Spectrum (TRS), Ground Motion
Selection.
4. Reservoir & Foundation
• ICOLD Bulletin 155
• Westergaard, H. M. (1933) Trans. ASCE.
• Chopra, A. K. (2020) Dynamics of Structures
Dynamics
(Ch. 20).
• Added-mass formulation, Eulerian FSI, radiation
damping boundaries.
5. Non-Linearity & Damage
• USACE ETL 1110-2-580
Mechanics
• Lubliner et al. (1989); Mazars (1986).
• Concrete Damaged Plasticity (CDP), joint
opening/sliding, Mohr-Coulomb friction criterion.
6. Numerical FEA
• USACE EM 1110-2-6051
• Bathe, K. J. (2006) Finite Element Procedures.
Formulations
• MIDAS Technical Manuals
• Zienkiewicz & Taylor (2005).
• Penalty vs. Lagrange contact algorithms, Lysmer
absorbing boundaries.
4.2 Case Study Implementation: Koyna Dam
4.2.1 Geometry Definition, Modeling Setup & Verification
• Software Orientation: Mastery of MIDAS FEA / GTS NX pre-processing, solver configuration, and postprocessing tools.
• Geometric Definition: Modeling the non-overflow and overflow key benchmark sections of Koyna Dam ($H = 103
ext{ m}$, base width $B = 70 ext{ m}$) including dam body, reservoir region, and foundation bedrock domain.
• Mesh Convergence Study: Systematic mesh refinement (coarse, medium, fine mesh) to ensure discretization
independence of stresses and fundamental frequency modal results.
• Benchmark Verification: Validation of natural frequencies, mode shapes, and static stress distribution against
standard published literature (e.g., Chopra & Chakrabarti, 1973).
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4.2.2 Progressive Seismic Analysis (Level 1 Analysis)
• Pseudo-Static Analysis (PSA): Application of equivalent seismic coefficients ($a_h, a_v$) as per IS 1893 (Part
3) / IS 6512 to determine baseline sliding factor of safety and overturning stability.
• Linear Dynamic Time History Analysis (LDTHA): Modal transient dynamic analysis subjecting the elastic dam
model to historical Koyna earthquake ground motion (1967 transverse and vertical accelerograms). Evaluation of
peak crest acceleration and elastic tensile stress concentrations at the neck change.
4.2.3 Non-Linear Interface Modeling
• Interface Formulation: Insertion of zero-thickness contact/gap elements along the dam-foundation joint and
critical lift joints (e.g., neck region elevation).
• Constitutive Properties: Assigning normal stiffness ($K_n$), tangential shear stiffness ($K_t$), cohesion ($c$),
friction angle ($\phi$), and tensile bond strength ($f_t$) based on Mohr-Coulomb shear behavior with tension cutoff.
4.2.4 Non-Linear Dynamic Time History Analysis (NLDTHA - Level 2 Analysis)
• Full Transient Integration: Execution of full non-linear dynamic time history integration using Newmark-$ eta$
implicit integration scheme.
• Dynamic Non-Linear Response: Simulating transient joint opening, closing, impact forces, and sliding
displacement during strong motion shaking.
4.2.5 Data Interpretation & Comparative Synthesis
• Comparative Analysis: Rigorous quantitative comparison between Level 1 (PSA, LDTHA) and Level 2
(NLDTHA) outputs regarding peak stresses, crest displacement, and stability factors.
• Performance Margins: Assessment of conservatism in Level 1 codal methods versus true energy dissipation
and stress relaxation in Level 2 contact modeling.
5. THESIS WRITING, DRAFTING & PUBLICATION ROADMAP
• Thesis Compilation: Structured drafting of Chapters 1 through 6 (Introduction, Literature Review, Methodology &
Verification, Level 1 Evaluation, Level 2 Non-Linear Analysis, Data Comparison & Conclusions).
• Manuscript Preparation: Preparation of a peer-reviewed journal paper targeting reputed hydraulic and structural
engineering publications (e.g., ASCE Journal of Performance of Constructed Facilities or Computers and Structures).
• Technical Presentation: Preparation of defense slides and seminar summaries for departmental review.
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6. KEY DELIVERABLES
Primary Research Outputs
1. Comprehensive Comparison Matrix: A structured quantitative comparison table detailing crest displacement,
tensile/compressive stress distributions, sliding factors, and computational time across PSA, LDTHA, and
NLDTHA.
2. Contact Non-Linearity Assessment Report: Detailed evaluation of joint opening behavior, interface sliding
residual displacements, and stress relief phenomena during strong earthquake ground motion.
3. MIDAS FEA / GTS NX Modeling Guideline & Input Parameter Matrix: A standardized user guide detailing
recommended normal/tangential contact stiffness values, fluid mesh parameters, damping settings, and boundary
conditions tailored for concrete gravity dam modeling in MIDAS software.
4. M.Tech Thesis Dissertation & Published Journal Manuscript.
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