Projects

Dr. B. R. Ambedkar Institute of Technology
B.Tech · Civil Engineering

Dr. B. R. Ambedkar Institute of Technology

Port Blair, Andaman & Nicobar Islands · 2011–2015
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Condition Assessment of an RC Building using NDT
B.Tech ProjectNon-Destructive TestingRebound HammerUPVSTAAD.ProRetrofitting

My undergraduate project was a full field condition assessment of a G+2 residential RC building at Brichgunj Military Station, built in 1991 and no longer serviceable — with no structural drawings and no record of the as-built material properties. We began with a visual condition survey, colour-coding every column and beam on all three floors for corrosion, cracking and spalling of cover, which showed corrosion concentrated in the exposed external columns where stirrups were in places completely lost. In-situ material properties were then recovered non-destructively: rebound hammer readings and ultrasonic pulse velocity at 101 member locations, combined to estimate compressive strengths ranging from roughly 8 to 23 N/mm². Those measured strengths — rather than assumed design values — were fed into a linear analysis in STAAD.Pro, and member demand was checked against capacity per IS 456:2000 for every beam and column. The exercise identified the specific members failing in flexure and led to a recommended repair scheme, including an RCC jacketing procedure for the distressed columns and beams.

The assessed G+2 residential building at Brichgunj Military Station

The assessed building — a G+2 residential block at Brichgunj Military Station, built in 1991.

Rebound hammer and ultrasonic pulse velocity instruments used on site
The field kit: Schmidt rebound hammer and the ultrasonic pulse velocity tester.
Calibration curves relating compressive strength to rebound number and to UPV
Calibration curves built from cube tests, used to convert the field readings into in-situ compressive strength.
Ground floor plan with every beam and column numbered
Every beam and column was numbered floor by floor so survey observations, NDT readings and analysis results could be tied to one member.
STAAD.Pro model highlighting beams and columns whose demand exceeds capacity
The outcome: members whose demand exceeds capacity, marked in red on the STAAD.Pro model.
TKM College of Engineering
M.Tech · Structural Engineering & Construction Management

TKM College of Engineering

Kollam, Kerala · 2016–2018
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Seismic Response of Vertically Irregular Buildings
M.Tech ThesisSAP2000Response SpectrumIS 1893Earthquake Engineering

My M.Tech thesis at TKM College of Engineering (APJ Abdul Kalam Technological University, 2018), supervised by Dr. Sajeeb R., asked how much vertical geometric irregularity actually changes the seismic demand on a building. Stepped frames and buildings on sloping ground are common in modern urban construction, but IS 1893 only prescribes limits on irregularity — it says little about how the design forces should change once those limits are crossed. I modelled 16 stepped frames and 16 sloping-ground frames in SAP2000 alongside their regular counterparts, and compared fundamental time period, modal participation, base shear and overturning moment across the set. From that comparison I proposed an Irregularity Index — built on overturning moment, which showed the lowest RMS error against the time-period ratio — to grade how irregular a frame really is, and a magnification factor expressed as a function of the number of storeys that corrects the code-based seismic force. The IS code method was found to consistently underestimate both the fundamental period and the seismic demand of irregular frames; the magnified estimate agreed with the full finite-element response to within about 3–17% across the four demonstration frames.

Stepped building frame modelled in SAP2000 — 3D view and elevation

Stepped frame (5 bays, 12 storeys) modelled in SAP2000 — 3D view and elevation.

Building frame on sloping ground modelled in SAP2000
The second irregularity type: a frame founded on sloping ground.
Fundamental time period from FE modal analysis versus the IS code formula
The IS code formula underestimates the fundamental period badly, and the gap widens with height.
Overturning moment ratio versus number of storeys for sloping-ground and stepped frames
Overturning-moment ratio against storey count for every bay configuration; the dashed average is what the magnification factor fits — MF = 0.27n + 2.462 for sloping ground, MF = 1.187n − 3.183 for stepped frames.

Publications

  • U. M. Krishnan and R. Sajeeb. Performance assessment of irregular buildings under earthquake excitation — a state of the art review. International Conference on Advances in Construction Materials and Structures (ACMS-2018), IIT Roorkee, 2018.
Indian Institute of Technology Roorkee
Ph.D. · Civil Engineering (Computational Mechanics)

Indian Institute of Technology Roorkee

Roorkee, Uttarakhand · 2019–2024
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Phase Field Fracture
FEniCSPETScPythonHPCMesh Adaptivity
Fracture in Functionally Graded Materials
FGMPhase FieldCohesive ZoneFEniCS

Functionally graded materials have spatially varying properties — for example, transitioning from ceramic to metal across a component — making them ideal for high-temperature and structural applications, but challenging to model for fracture. I extended the phase-field cohesive zone framework to FGMs, where material parameters vary continuously as a function of spatial coordinates. The adaptive implementation captures complex crack paths and mixed-mode failure with adaptive meshing, offering a robust tool for fracture design in graded structures.

FGM Fracture
Topology Optimization
SIMPPhase Field3D PrintingMPIFEniCS

Topology optimization finds the optimal distribution of material within a design domain to maximize structural performance under given constraints. My work scaled this to large 3D problems using FEniCS and MPI-based parallel computing. The resulting geometries are fabricated using 3D printing, bridging computational design with physical manufacturing.

Topology Optimization
Auxetic Metamaterials Design
Topology Opt.HomogenizationFGM3D Printing

Auxetic materials exhibit a negative Poisson's ratio — they expand laterally when stretched — a counter-intuitive behaviour that leads to enhanced indentation resistance, energy absorption, and acoustic damping. Using topology optimization, I designed microstructures using FGMs that achieve auxetic responses through tailored geometry rather than intrinsic material properties and the designs were validated through 3D-printed physical samples.

Auxetic Metamaterial
Johns Hopkins University
Postdoctoral Research Fellow

Johns Hopkins University

Baltimore, Maryland, USA · 2025–present
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Evolutionary Deep Neural Networks
EDNNPINNMulti-physicsScientific ML

Evolutionary Deep Neural Networks (EDNN) are a mesh-free, physics-informed approach that evolves the solution of PDEs in time by training a neural network to satisfy the governing equations and boundary conditions. My current research at Johns Hopkins applies EDNN to coupled physics problems in solid mechanics — working toward efficient solvers that generalise across geometries and loading conditions without requiring labeled simulation data.

Fracture-Bench: Benchmarking Neural-Operator Surrogates
Neural OperatorsFNODeepONetDiffusion ModelsBenchmark DatasetsScientific ML

Machine-learning surrogates for fracture are usually reported on the authors' own data, with their own preprocessing and their own training budget — which makes it almost impossible to tell whether one architecture is genuinely better than another. Fracture-Bench, my ongoing work at Johns Hopkins, is an attempt to fix that. It evaluates five CNN- and neural-operator-based surrogates — UNet, FNO, DeepONet, Latent DeepONet, and a conditional denoising diffusion model — for phase-field fracture under identical preprocessing, loss functions, and training budgets, across two high-fidelity datasets that differ in formulation, material heterogeneity, and prediction task. Beyond raw accuracy it measures computational cost and, more tellingly, generalisation: how each model holds up on withheld load steps and on parameter configurations it never saw during training. The datasets, evaluation protocols, and model code are all released openly, so the comparison can be reproduced and extended rather than taken on trust.

Producing that comparison meant first producing the ground truth. Both benchmark datasets below were generated with adaptive phase-field simulations and published through the Johns Hopkins Research Data Repository, with documented preprocessing and evaluation splits so other groups can train against exactly the same data.

Crack paths at four traction magnitudes, from a single straight crack to repeated branching

Dynamic dataset — raising the applied traction takes the same notched plate from steady propagation (σ* = 1.0) through to repeated branching and coalescence (σ* = 3.0). Left: initial notch. Right: final damage field.

Displacement, initial and final phase field, and the graded material property field for one FGM realisation

FGM dataset — each realisation stores the displacement field, the initial and final phase-field damage, and the underlying stiffness map. The crack visibly deflects around the stiff inclusion.

Problem setup: 100 by 40 mm plate under step tensile traction, with sampled crack-tip positions
The setup that generates the variation: a 100 × 40 mm plate under a step tensile traction, with the initial notch tip sampled across the domain in both directions.
Animation of a crack propagating through a functionally graded plate
A crack advancing through the graded plate over the 31 load steps — the trajectory a surrogate has to reproduce.