Tammam Bakeer Dr.-Ing. habil.

Research

Research

Mechanics-consistent, uncertainty-aware computation with data assimilation, and the question of when the available information is sufficient to support a structural decision.

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Research profile

My work concerns the path from an existing structure to a decision about it: how the structure is modelled, what measurements reveal about it, how reliable the resulting prediction is, and when the evidence is sufficient to act. It connects nonlinear computational mechanics, inverse problems, structural reliability and scientific machine learning, and it is meant to remain practical for real structures.

Existing structures, such as bridges, dams and heritage buildings, are assessed, not designed anew, and part of the evidence comes from measurements. This raises questions of identifiability and information: which observations add knowledge, what remains unidentifiable however long we measure, and how much uncertainty survives once the data are in. My work on sensor informativeness and identifiability (2026) examines these questions on a full-scale research bridge. Monitoring and digital twins carry the same questions into continuous assessment.

Predictions then have to support safety decisions. Classical safety formats assume a well-behaved limit state. In nonlinear systems, the failure domain is curved and often non-convex, several failure modes compete, and a factor applied to a material property no longer corresponds to a defined probability. My general partial safety factor theory (2023) extends the classical format to such systems through a notion of homogeneity, so that engineers can keep a format they already know how to apply.

All of this rests on the mechanics: nonlinear finite element and finite–discrete element formulations, constitutive and fracture models, and the numerical methods needed to follow a structure beyond its peak load. I use demanding systems from real infrastructure as benchmarks, because they show where algorithms fail.

Scientific machine learning and high-performance computing make these methods usable at scale: surrogate models and learned material laws that stay physically admissible, and computations fast enough for reliability analysis and monitoring.

The motivation is practical: scientific insight that holds up on a real structure and becomes a method that can be used in an engineering office, in an assessment or in a design code. Work at the university, in engineering practice and in standardization has made this possible, because each setting tests a method in a different way.

Earlier in my career, many of these methods were developed through work on masonry and heritage structures and carried into European standardization. These remain important fields of application within a broader research agenda.

Stiffness identified from two tilt sensors on a simply supported beamA simply supported beam with two tilt sensors near the supports and a moving load. The identified bending stiffness with its 95 percent credible band recovers a local stiffness loss at mid-span with a narrow band, while the band stays wide near the supports. Below, the information carried by the tilt data along the span, which vanishes at the supports where bending moments vanish.θ₁θ₂Pmoving loaddamagedidentified stiffness EI / EI₀mean and 95 % band0.511.5stiffness loss identifiedwide nearsupportstrue EI dashedinformation in the tilt data01234position along the span [m]
Stiffness identified from two tilt sensors: the local loss is found, the stiffness near the supports stays uncertainθ₁θ₂moving loaddamagedidentified stiffness0.511.5loss identifiedwide near supportsinformation in the tilt data02 m4 m
Two tilt sensors and a moving load on a simply supported beam: the local stiffness loss is identified with a narrow credible band, while near the supports the band stays wide. Bending moments vanish there, and so does the information the tilt data carry, however close a sensor is. Synthetic study from Bakeer, Herbers and Marx (2026), tilt noise 0.005 mm/m.
A nonlinear, non-convex limit state in standard normal space, with two competing design points and the linearised surface that misses part of the failure domainβ₁β₂u₁u₂g(u) = 0failure domainlinearised at β₁
A curved limit state with two design points and a linearisation that misses part of the failure domainfailure domainlinearised at β₁β₁β₂g(u) = 0standard normal space
Why nonlinear reliability is not a corollary of the linear case: a curved, non-convex limit state with two competing design points, and the linearisation at the nearer one, which misses part of the failure domain entirely.
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Fields

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Nonlinear computational structural mechanics

Finite element and finite–discrete element formulations, constitutive and interface models, fracture, stability, damage and collapse. The numerical machinery needed to follow a structure past its peak load, and the computational capability needed to apply these methods at the scale of real structures.

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Structural reliability and safety concepts

Reliability of nonlinear systems, where the failure domain is curved and several modes compete. The general partial safety factor theory that extends the classical format to them, together with robustness, quality control, conformity assessment and code calibration.

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Information, identifiability and inverse problems

What observations actually reveal about a structure: Bayesian inversion, sensor informativeness, spatially distributed parameter fields, and decision identifiability, which asks when the available evidence already settles the decision that has to be made.

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Monitoring, digital twins and predictive assessment

Coupling measurements with calibrated models so that the estimated condition of a structure is updated continuously: data assimilation, deterioration and early warning, inspection planning, service-life prediction and the case for extending service life on the basis of evidence, not assumption.

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Scientific machine learning and complexity

Mechanics-informed operator learning, learned material models and structure-preserving surrogates: fast, mesh-independent solvers that stay physically admissible. Measures of complexity for systems too large to reason about one member at a time.

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Engineering practice and standardization

Where the methods are tested: assessment of existing structures and infrastructure, earthquake resilience and retrofitting, and the translation of research into European and German design rules, the point at which a method’s practical value is established.

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Current directions

A learned operator maps a material field to the structural response on any meshLeft, a spatially varying material field. Centre, a learned operator constrained by mechanics. Right, the predicted response evaluated on a coarse mesh and on a fine mesh. Conceptual illustration.Gθlearned,mechanics-constrainedmaterial fieldcoarse meshfine meshone operator, same response, any meshinputpredicted response
A learned operator maps a material field to the response on a coarse and a fine meshmaterial fieldGθlearned,mechanics-constrainedsame response, any meshcoarse meshfine mesh
Mechanics-informed operator learning: one learned operator maps a material field to the structural response and can be evaluated on any mesh, while respecting equilibrium. Conceptual illustration.
  • Information sufficiency for reliability decisions. When the available observations are sufficient to settle a structural decision, and what further evidence would change it.
  • Identifiability of spatially distributed parameters. Bayesian random-field formulations and multiscale identifiability measures that separate what can be resolved from what cannot, under sparse observations and in the presence of model discrepancy.
  • Information-driven experimental design. Planning sensors and tests around the decision that has to be made.
  • Mechanics-informed operator learning. Embedding equilibrium, material objectivity and thermodynamic consistency into deep operator learning, to obtain mesh-independent surrogate solvers for families of nonlinear boundary-value problems that stay physically admissible.
  • Structure-preserving surrogates for reliability. Reduced-order models that preserve energy balance and passivity, so that very small failure probabilities can be estimated without brute-force Monte Carlo and without losing the physics.

This research programme is under active development. Several parts are still in preparation, and I am glad to discuss any of them with people working on the same questions.

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Standardization and transfer

Research becomes useful in practice when it reaches the rulebook. I have worked in European and German standardization since 2013, with my principal contribution being the safety format for numerical methods in EN 1990.

European standardization · CEN

  • CEN/TC 250/SC 10/WG 3 — Safety formats and FEM applications
    Co-author of the new Annex X of EN 1990, which governs design assistance by numerical methods.
  • CEN/TC 250/WG 7 T1 — EN 1990 — Basis of structural design
    Safety of nonlinear structural systems.
  • CEN/TC 250/SC 6 PT T1 — EN 1996-1-1 — Design of masonry structures
    Developed and advanced the adopted safety-verification method for the buckling of masonry members.
  • AhG Reliability, CEN/TC 250/SC 10 — Reliability of the Eurocodes
    Preparatory work for the background report of prEN 1990.

German standardization · DIN

  • DIN NA 005-06-37 AA — Earthquake safety of masonry structures
  • DIN NA 005-51 FBR-01 SO — “GruSiBau” — fundamental safety requirements for building structures

Memberships

  • JCSS — Joint Committee on Structural Safety
  • GAMM — International Association of Applied Mathematics and Mechanics