diff --git a/src/domains/beams/api.jl b/src/domains/beams/api.jl
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--- a/src/domains/beams/api.jl
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-# This file is a part of JuliaFEM.
-# License is MIT: see https://github.com/JuliaFEM/JuliaFEM.jl/blob/master/LICENSE.md
-
-"""
-Beam formulation API definitions.
-
-This file defines beam-specific abstract types and formulation theories.
-Must be included after core api.jl.
-"""
-
-# ============================================================================
-# BEAM FORMULATION THEORIES
-# ============================================================================
-
-"""
-    AbstractBeamTheory
-
-Abstract type for beam theory variants.
-
-Beam theories differ in how they model shear deformation and cross-section kinematics.
-
-# Concrete Theories
-- `EulerBernoulli`: Classical beam theory (no shear deformation)
-- `Timoshenko`: Includes shear deformation (thick beams)
-
-# See Also
-- [`BeamFormulation`](@ref)
-"""
-abstract type AbstractBeamTheory end
-
-"""
-    EulerBernoulli <: AbstractBeamTheory
-
-Euler-Bernoulli beam theory (classical, no shear deformation).
-
-Assumptions:
-- Plane sections remain plane and perpendicular to neutral axis
-- No transverse shear deformation
-- Valid for slender beams (L/h > 10)
-
-# Usage
-```julia
-formulation = BeamFormulation{EulerBernoulli}()
-physics = Physics(
-    formulation=formulation,
-    field=DisplacementRotation{3}(),
-    mesh=beam_mesh,
-    material=steel
-)
-```
-"""
-struct EulerBernoulli <: AbstractBeamTheory end
-
-"""
-    Timoshenko <: AbstractBeamTheory
-
-Timoshenko beam theory (includes shear deformation).
-
-Assumptions:
-- Plane sections remain plane but NOT perpendicular to neutral axis
-- Transverse shear deformation included
-- Valid for thick beams and higher frequencies
-
-# Usage
-```julia
-formulation = BeamFormulation{Timoshenko}()
-physics = Physics(
-    formulation=formulation,
-    field=DisplacementRotation{3}(),
-    mesh=beam_mesh,
-    material=steel
-)
-```
-"""
-struct Timoshenko <: AbstractBeamTheory end
-
-"""
-    BeamFormulation{Theory<:AbstractBeamTheory} <: AbstractFormulation
-
-Beam element formulation with theory variant.
-
-# Type Parameter
-- `Theory`: Beam theory type (EulerBernoulli or Timoshenko)
-
-# Examples
-```julia
-# Slender beam (classical theory)
-BeamFormulation{EulerBernoulli}()
-
-# Thick beam (includes shear)
-BeamFormulation{Timoshenko}()
-```
-
-# Fields per Node
-Typically 6 DOFs in 3D: (ux, uy, uz, θx, θy, θz)
-Use with `DisplacementRotation{3}` field type.
-"""
-struct BeamFormulation{Theory<:AbstractBeamTheory} <: AbstractFormulation end