WASM API Reference

A narrative guide to the 57 WASM exports it covers, out of the 167 the Rust boundary exposes.
Each function takes a JSON string argument and returns a JSON string.
Units are SI throughout (m, N, Pa, N·m) unless explicitly noted.

This page is a guide, not the whole boundary. The complete reference is WASM exports: every one of the 167 exports, its signature, and the fields of the JSON it reads and returns, with each type on WASM types. Those pages are generated from the Rust source and its types by npm run docs:wasm and checked in CI, so they cannot fall behind the code; this page is written by hand and can. Where the two disagree, the generated pages are right. Both numbers above are checked against the manifest by scripts/gen_wasm_manifest.mjs.

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Table of Contents

• Units & Conventions
• Common Types
  • WasmModel
  • WasmResults
  • Other Shared Types
• Solver / Analysis
  • solve_model
  • solve_model_pdelta
  • solve_model_tc
  • solve_model_buckling
  • solve_model_modal
  • member_capacities_only
• Results / Reports
  • analysis_report
• Steel Design (AS 4100)
  • as4100_phi_ms
  • as4100_phi_nc
  • as4100_phi_mbx
  • as4100_phi_vv
  • as4100_alpha_b
  • as4100_alpha_m
  • as4100_combined
• Steel Design (AS 5100)
  • as5100_member_check
  • as5100_combined
• Steel Design (AISC 360)
  • aisc360_member_check
• Steel Design (Eurocode 3)
  • ec3_member_check
• Steel Design (AS 4600)
  • as4600_capacity
• Timber (AS 1720)
  • as1720_timber_check
• Concrete (AS 3600)
  • as3600_rc_member_check
  • as3600_rc_beam_moment
  • as3600_rc_beam_shear
  • as3600_rc_column_capacity
  • as3600_rc_column_interaction_curve
  • rc_shear_torsion_combined
• Concrete Slabs (AS 3600)
  • as3600_slab_check
  • as3600_slab_strip_moment
  • as3600_slab_punching_shear
  • as3600_slab_deflection
• Composite (AS 2327)
  • composite_beam_check
• Pad Footing
  • pad_footing_design
• Retaining Wall
  • retaining_wall_design
• Seismic
  • distribute_seismic_forces
  • response_spectrum_analysis
• Time History
  • modal_time_history_analysis
• Influence Lines
  • influence_line
  • moving_load_effect
  • influence_line_continuous
• Load Generation
  • generate_load_combinations
  • as1170_wind_pressure
  • as1170_snow_load
  • as1170_seismic_base_shear
  • as4100_notional_force
• Connections
  • bolt_capacity
  • weld_capacity
  • base_plate_check
  • fin_plate_check
  • end_plate_check
  • weld_group_check
  • eccentric_bolt_group_check
• Section Properties
  • section_properties
• Import / Export
  • import_sg_model
  • list_sg_entries
• Merge (Phase 4)
  • merge_snapshots

---

Units & Conventions

Quantity	Unit	Notes
Length	m	Some concrete/steel design modules convert to mm internally.
Force	N
Stress	Pa	Concrete design modules convert to MPa internally.
Moment	N·m
Area	m²
Mass	kg	Node mass field.
Angle	rad	beta, rotations.
Time	s	Modal / time-history only.

Internal scaling notes:

• pad_footing_design: b/d/h in m → mm internally, fPrimeC Pa → MPa internally.
• retaining_wall_design: gammaSoil/gammaConc in N/m³, qAllowable in Pa. Core converts footing dimensions m→mm, fPrimeC Pa→MPa.
• rc_shear_torsion_combined: vStar [N], tStar [N·m] (converted to N·mm internally), b/d/h [m], fPrimeC [Pa], aSt [m²].
• Concrete beam/column/slab exports: dimensions m→mm, stress Pa→MPa, steel area m²→mm²; moments returned in N·m.
• Connection exports (fin_plate_check, end_plate_check, base_plate_check): lengths m→mm, stresses Pa→MPa internally; capacities returned as forces (N) or moments (N·m).
• aisc360_member_check & ec3_member_check: SI inputs converted to mm/MPa internally; capacities returned in N / N·m.
• as5100_member_check: section geometry in mm, material in MPa, effective lengths in m; capacities returned in N / N·m.

---

Common Types

Many exports share the following input/output structs.

WasmModel

Standard FEM model definition used by solver exports.

{
  "nodes": [WasmNode],
  "members": [WasmMember],
  "materials": [WasmMaterial],
  "sections": [WasmSection],
  "load_cases": [WasmLoadCase],
  "nodal_loads": [WasmNodalLoad],
  "member_loads": [WasmMemberLoad],
  "plates": [WasmPlate],
  "plate_loads": [WasmPlateLoad],
  "load_combinations": [WasmLoadCombination]
}

Field	Type	Description
nodes	[WasmNode]	Structural nodes.
members	[WasmMember]	1D members (beams / trusses).
materials	[WasmMaterial]	Linear-elastic material definitions.
sections	[WasmSection]	Cross-section properties.
load_cases	[WasmLoadCase]	Load case definitions.
nodal_loads	[WasmNodalLoad]	Concentrated nodal loads.
member_loads	[WasmMemberLoad]	Distributed / point member loads.
plates	[WasmPlate]	Quad shell elements (optional).
plate_loads	[WasmPlateLoad]	Pressure loads on plates (optional).
load_combinations	[WasmLoadCombination]	Linear combination definitions (optional).

WasmNode

{
  "id": 1,
  "x": 0.0,
  "y": 0.0,
  "z": 0.0,
  "restraint_flags": 63,
  "mass": 0.0,
  "spring_stiffness": [0.0, 0.0, 0.0, 0.0, 0.0, 0.0],
  "settlement": [0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
}

Field	Type	Description
id	i32	Unique node identifier.
x / y / z	f64	Global coordinates (m).
restraint_flags	u32	Bit mask: Tx(1) Ty(2) Tz(4) Rx(8) Ry(16) Rz(32).
mass	f64	Lumped nodal mass (kg). Default 0.
spring_stiffness	[f64; 6]	Ground spring stiffness per DOF (N/m or N·m/rad). Default all 0.
settlement	[f64; 6]	Prescribed support settlement per DOF. Default all 0.

WasmMember

{
  "id": 1,
  "node_a": 1,
  "node_b": 2,
  "material_id": 1,
  "section_id": 1,
  "member_type": 0,
  "beta": 0.0,
  "fixity_a": 0,
  "fixity_b": 0,
  "offset_a": [0.0, 0.0, 0.0],
  "offset_b": [0.0, 0.0, 0.0],
  "ke_x": 1.0,
  "ke_y": 1.0
}

Field	Type	Description
id	i32	Unique member identifier.
node_a / node_b	i32	End-node IDs.
material_id	i32	Reference to WasmMaterial.id.
section_id	i32	Reference to WasmSection.id.
member_type	i32	0=Beam, 1=Truss, 4=TensionOnly, 5=CompressionOnly.
beta	f64	Roll angle about local x-axis (rad).
fixity_a / fixity_b	u32	End-release bit mask (same bits as restraint_flags). Default 0.
offset_a / offset_b	[f64; 3]	Rigid end offsets in global coordinates (m). Default all 0.
ke_x	f64	Effective-length factor for major-axis buckling / LTB. Default 1.0.
ke_y	f64	Effective-length factor for minor-axis compression buckling. Default 1.0.

WasmMaterial

{
  "id": 1,
  "name": "Steel",
  "e": 200e9,
  "g": 80e9,
  "nu": 0.3,
  "rho": 7850.0,
  "alpha": 1.2e-5,
  "fy": 250e6,
  "fu": 400e6
}

Field	Type	Description
id	i32	Unique material identifier.
name	String	Human-readable name. Default "".
e	f64	Young's modulus (Pa).
g	f64	Shear modulus (Pa).
nu	f64	Poisson's ratio. Default 0.3.
rho	f64	Density (kg/m³). Default 7850.
alpha	f64	Thermal expansion coefficient (/°C). Default 1.2e-5.
fy	f64	Yield strength (Pa). Default 250e6.
fu	f64	Ultimate strength (Pa). Default 400e6.

WasmSection

{
  "id": 1,
  "a": 0.01,
  "iyy": 1e-4,
  "izz": 1e-4,
  "j": 2e-4,
  "zyy": 0.0,
  "zzz": 0.0,
  "syy": 0.0,
  "szz": 0.0,
  "d": 0.0,
  "bf": 0.0,
  "tf": 0.0,
  "tw": 0.0,
  "fy": 0.0,
  "name": ""
}

Field	Type	Description
id	i32	Unique section identifier.
a	f64	Cross-sectional area (m²).
iyy	f64	Minor-axis second moment of area (m⁴).
izz	f64	Major-axis second moment of area (m⁴).
j	f64	Torsion constant (m⁴).
zyy / zzz	f64	Elastic section moduli (m³). Default 0.
syy / szz	f64	Plastic section moduli (m³). Default 0.
d / bf / tf / tw	f64	Section geometry for steel design (m). Default 0.
fy	f64	Section-specific yield strength override (Pa). Default 0 (use material).
name	String	Section name. Default "".

WasmLoadCase

{
  "id": 1,
  "name": "Dead",
  "self_weight_factor": 0.0,
  "load_case_type": 0
}

Field	Type	Description
id	i32	Unique load-case identifier.
name	String	Human-readable name.
self_weight_factor	f64	Self-weight multiplier. Default 0.
load_case_type	i32	0=Dead, 1=Live, 2=Wind, 3=Seismic, 4=Snow, 5=Other, 6=WindUltimate, 7=WindServiceability, 8=SeismicServiceability. Default 0.

WasmNodalLoad

{
  "node_id": 1,
  "load_case_id": 1,
  "fx": 0.0,
  "fy": 0.0,
  "fz": -1000.0,
  "mx": 0.0,
  "my": 0.0,
  "mz": 0.0
}

Field	Type	Description
node_id	i32	Target node.
load_case_id	i32	Load case.
fx / fy / fz	f64	Force components (N).
mx / my / mz	f64	Moment components (N·m). Default 0.

WasmMemberLoad

{
  "member_id": 1,
  "load_case_id": 1,
  "load_type": 0,
  "qx": 0.0,
  "qy": 0.0,
  "qz": -5000.0,
  "qx2": 0.0,
  "qy2": 0.0,
  "qz2": 0.0,
  "start_ratio": 0.0,
  "end_ratio": 1.0
}

Field	Type	Description
member_id	i32	Target member.
load_case_id	i32	Load case.
load_type	i32	0=UniformDistributed, 1=PointLoad, 2=Trapezoidal. Default 0.
qx / qy / qz	f64	Start / uniform load intensities (N/m).
qx2 / qy2 / qz2	f64	End load intensities for trapezoidal (N/m). Default 0.
start_ratio	f64	Normalised start position along member [0, 1]. Default 0.
end_ratio	f64	Normalised end position. For UDL, if <= start_ratio it defaults to 1.0 (whole member). Default 0.

WasmPlate

{
  "id": 1,
  "node_ids": [1, 2, 3, 4],
  "material_id": 1,
  "thickness": 0.01
}

Field	Type	Description
id	i32	Unique plate identifier.
node_ids	[i32; 4]	Corner node IDs (quad only).
material_id	i32	Reference to WasmMaterial.id.
thickness	f64	Plate thickness (m).

WasmPlateLoad

{
  "plate_id": 1,
  "load_case_id": 1,
  "pressure": -5000.0
}

Field	Type	Description
plate_id	i32	Target plate.
load_case_id	i32	Load case.
pressure	f64	Normal pressure (Pa, positive = toward plate local -Z).

WasmLoadCombination

{
  "id": 101,
  "name": "1.2D+1.5L",
  "terms": [
    { "load_case_id": 1, "factor": 1.2 },
    { "load_case_id": 2, "factor": 1.5 }
  ]
}

Field	Type	Description
id	i32	Unique combination identifier.
name	String	Human-readable name.
terms	[WasmComboTerm]	Constituent load cases and factors.

WasmComboTerm

Field	Type	Description
load_case_id	i32	Load case to factor.
factor	f64	Load factor.

---

WasmResults

Top-level results returned by solve_model and related solver exports.

{
  "load_cases": [WasmLoadCaseResults],
  "combinations": [WasmCombinationResults],
  "envelope": WasmEnvelopeResults | null
}

Field	Type	Description
load_cases	[WasmLoadCaseResults]	Per load-case results.
combinations	[WasmCombinationResults]	Per combination results (empty if none defined).
envelope	WasmEnvelopeResults | null	Max/min envelopes over combinations (null if none).

WasmLoadCaseResults

{
  "load_case_id": 1,
  "displacements": [WasmNodeDisplacement],
  "member_forces": [WasmMemberForce],
  "reactions": [WasmReaction],
  "plate_results": [WasmPlateResult],
  "member_station_forces": [WasmMemberStationForces],
  "member_capacities": [WasmMemberCapacity]
}

Field	Type	Description
load_case_id	i32	Echo of load case ID.
displacements	[WasmNodeDisplacement]	Nodal displacements.
member_forces	[WasmMemberForce]	End forces for each member.
reactions	[WasmReaction]	Support reactions.
plate_results	[WasmPlateResult]	Plate stress / moment results.
member_station_forces	[WasmMemberStationForces]	Internal forces at stations along each member.
member_capacities	[WasmMemberCapacity]	AS 4100 capacity check results (populated when steel design is enabled).

WasmNodeDisplacement

Field	Type	Description
node_id	i32	Node identifier.
ux / uy / uz	f64	Translations (m).
rx / ry / rz	f64	Rotations (rad).

WasmMemberForce

Field	Type	Description
member_id	i32	Member identifier.
fx1 / fy1 / fz1	f64	Force at end A (N).
mx1 / my1 / mz1	f64	Moment at end A (N·m).
fx2 / fy2 / fz2	f64	Force at end B (N).
mx2 / my2 / mz2	f64	Moment at end B (N·m).

WasmReaction

Field	Type	Description
node_id	i32	Restrained node.
rx / ry / rz	f64	Reaction forces (N).
mx / my / mz	f64	Reaction moments (N·m).

WasmPlateResult

Field	Type	Description
plate_id	i32	Plate identifier.
sx / sy / txy	f64	Membrane stresses at centroid (Pa).
mx / my / mxy	f64	Bending / twisting moments per unit width (N·m/m).
mx_star_bottom / my_star_bottom	f64	Design moments at bottom face (N·m/m).
mx_star_top / my_star_top	f64	Design moments at top face (N·m/m).
vonMises	f64	von Mises stress (Pa).
bucklingFactor	f64 | null	Critical buckling load factor (if computed).
sxTop / syTop / sxBottom / syBottom	f64	Membrane stresses at top / bottom faces (Pa).
sigma1Top / sigma2Top / thetaPTop	f64	Principal stresses & angle at top face (Pa, rad).
sigma1Bottom / sigma2Bottom / thetaPBottom	f64	Principal stresses & angle at bottom face (Pa, rad).

WasmMemberStationForces

Field	Type	Description
member_id	i32	Member identifier.
stations	[WasmStationForce]	Internal forces at evaluation points.

WasmStationForce

Field	Type	Description
s_norm	f64	Normalised position [0, 1] along member.
s	f64	Absolute distance from end A (m).
n	f64	Axial force (N).
vy / vz	f64	Shear forces (N).
mx / my / mz	f64	Moments (N·m).
dy / dz	f64	Local deflections (m).

WasmMemberCapacity

{
  "member_id": 1,
  "fy": 300e6,
  "phi": 0.9,
  "axis_x": WasmAxisCapacity,
  "axis_y": WasmAxisCapacity,
  "compression": WasmCompressionCapacity,
  "phiNt": 1200e3,
  "phiVv": 450e3,
  "utilBiaxialSection": 0.42,
  "utilBiaxialMember": 0.38,
  "utilMax": 0.42,
  "assumptions": WasmCapacityAssumptions
}

Field	Type	Description
member_id	i32	Member identifier.
fy	f64	Yield strength used (Pa).
phi	f64	Capacity reduction factor.
axis_x / axis_y	WasmAxisCapacity	Major / minor axis capacities.
compression	WasmCompressionCapacity	Compression buckling capacity.
phiNt	f64	Tension capacity φNt (N).
phiVv	f64	Shear capacity φVv (N).
utilBiaxialSection	f64	Section-level biaxial utilisation.
utilBiaxialMember	f64	Member-level biaxial utilisation.
utilMax	f64	Maximum utilisation across all checks.
assumptions	WasmCapacityAssumptions	Assumptions used (Le, kt, kl, kr, αm, αs, αb).

WasmAxisCapacity

Field	Type	Description
compactness	WasmAxisCompactness	Section compactness classification.
Ze	f64	Effective section modulus (m³).
phiMs	f64	Section moment capacity φMs (N·m).
phiMb	f64	Member moment capacity φMb (N·m).

WasmAxisCompactness

Field	Type	Description
flange / web	WasmPlateCompactness	Slenderness limits.
class	String	"compact", "non-compact", "slender".

WasmPlateCompactness

Field	Type	Description
lambda_e	f64	Element slenderness.
lambda_ep	f64	Plastic limit.
lambda_ey	f64	Yield limit.

WasmCompressionCapacity

Field	Type	Description
kf	f64	Form factor.
Ns	f64	Squash capacity (N).
phiNcx / phiNcy	f64	Compression capacities about x / y (N).
lambda_n	f64	Modified slenderness.
alpha_c	f64	Member slenderness reduction factor.

WasmCapacityAssumptions

Field	Type	Description
le_x / le_y	f64	Effective lengths (m).
kt / kl / kr	f64	Twist / load / rotation restraint factors.
alpha_m / alpha_s / alpha_b	f64	Moment modification, slenderness reduction, and residual-stress factors.

WasmCombinationResults

Same fields as WasmLoadCaseResults but with combination_id and name instead of load_case_id.

Field	Type	Description
combination_id	i32	Combination identifier.
name	String	Combination name.
displacements	[WasmNodeDisplacement]	Combined displacements.
member_forces	[WasmMemberForce]	Combined member end forces.
reactions	[WasmReaction]	Combined reactions.

WasmEnvelopeResults

Field	Type	Description
displacements_max / displacements_min	[WasmNodeDisplacement]	Envelope extremes.
member_forces_max / member_forces_min	[WasmMemberForce]	Envelope extremes.
reactions_max / reactions_min	[WasmReaction]	Envelope extremes.

WasmBucklingResults / WasmBucklingMode

{
  "modes": [
    { "index": 1, "load_factor": 15.3, "mode_shape": [WasmNodeDisplacement] }
  ]
}

Field	Type	Description
index	usize	Mode number (1-based).
load_factor	f64	Buckling load factor.
mode_shape	[WasmNodeDisplacement]	Normalised buckled shape.

WasmModalResults / WasmModalMode

{
  "modes": [
    { "index": 1, "frequency_hz": 3.45, "eigenvalue": 21.7, "mode_shape": [WasmNodeDisplacement] }
  ]
}

Field	Type	Description
index	usize	Mode number (1-based).
frequency_hz	f64	Natural frequency (Hz).
eigenvalue	f64	Eigenvalue (rad/s).
mode_shape	[WasmNodeDisplacement]	Normalised mode shape.

---

Other Shared Types

WasmStoreyDefinition

Field	Type	Description
elevation	f64	Storey height above datum (m).
nodeIds	[i32]	Node IDs whose tributary mass contributes to this storey.

WasmStoreyForce

Field	Type	Description
elevation	f64	Storey elevation (m).
weight	f64	Lumped storey weight (N).
force	f64	Lateral force assigned to this storey (N).
cv	f64	Distribution coefficient w·h^k / Σ(w·h^k).

---

Solver / Analysis

solve_model

Performs a full linear static analysis for all load cases in the model.

Input: WasmModel JSON

Output: WasmResults JSON (see Common Types).

Notes:

• Automatically subdivides physical members at intermediate nodes before solving.
• If load_combinations are provided, they are solved and an envelope is computed.
• Returns {"error": "..."} on parse or solve failure.

---

solve_model_pdelta

Iterative P-Delta (geometric stiffness) analysis for the first load case.

Input: WasmModel JSON + extra arguments:

{
  "model": { ... },
  "max_iterations": 10,
  "tolerance": 1e-6
}

Wait - the actual WASM signature is solve_model_pdelta(json_input: &str, max_iterations: usize, tolerance: f64).
The caller must pass the JSON string as arg 0 and the two scalars as separate JS arguments.

Output: WasmResults JSON (single load case only).

Notes:

• P-Delta is applied to the first load case only.
• Uses fem_core::solver::solve_load_case_pdelta internally.

---

solve_model_tc

Tension/compression-only member analysis for the first load case (iterative removal of members that go into tension or compression depending on their type).

Input: WasmModel JSON + extra argument:

Signature: solve_model_tc(json_input: &str, max_iterations: usize)

Output: WasmResults JSON (single load case only).

Notes:

• Members with member_type: 4 (TensionOnly) or 5 (CompressionOnly) are iteratively removed when they develop the wrong sign of axial force.
• max_iterations caps the iteration count.

---

solve_model_buckling

Linear buckling (eigenvalue) analysis.

Signature: solve_model_buckling(json_input: &str, load_case_id: i32, n_modes: usize)

Input: WasmModel JSON

Output: WasmBucklingResults JSON

{
  "modes": [
    { "index": 1, "load_factor": 15.3, "mode_shape": [WasmNodeDisplacement] }
  ]
}

Notes:

• Applies the specified load_case_id as the reference load vector.
• load_factor is the multiplier at which buckling occurs under that reference load.

---

solve_model_modal

Undamped free-vibration (modal) analysis.

Signature: solve_model_modal(json_input: &str, n_modes: usize)

Input: WasmModel JSON

Output: WasmModalResults JSON

{
  "modes": [
    { "index": 1, "frequency_hz": 3.45, "eigenvalue": 21.7, "mode_shape": [WasmNodeDisplacement] }
  ]
}

Notes:

• Consistent mass matrix built from nodal masses and material density.
• Physical members are auto-subdivided before solving (same as solve_model).

---

member_capacities_only

Compute AS 4100 member capacities without running a full FEM solve. Fast path for auto-sizing.

Input: WasmMemberCapacitiesInput JSON

{
  "model": { ... },
  "member_forces": [WasmMemberForce]
}

Field	Type	Description
model	WasmModel	Model definition (geometry, sections, materials).
member_forces	[WasmMemberForce]	Optional solved end forces for αm / utilisation update.

Output: WasmMemberCapacitiesOutput JSON

{
  "member_capacities": [WasmMemberCapacity]
}

Notes:

• If member_forces are empty, utilisations and alpha_m use default / uniform-moment assumptions.
• Catches panics internally and returns {"error": "Capacity computation panicked"}.

---

Results / Reports

analysis_report

Generates a concise JSON summary of a solved model: stats, extreme reactions / displacements, per-member utilisation, and a pass/fail rollup.

Signature: analysis_report(model_json: &str, results_json: &str) -> String

Input: Two JSON strings: the WasmModel and the WasmResults.

Output: AnalysisReport JSON

{
  "stats": {
    "nodeCount": 4,
    "memberCount": 3,
    "plateCount": 0,
    "loadCaseCount": 2,
    "combinationCount": 1,
    "hasEnvelope": true
  },
  "maxReactions": [
    { "component": "Ry", "value": 12000.0, "node_id": 1, "load_case_id": 1 }
  ],
  "maxDisplacements": [
    { "component": "uz", "value": 0.012, "node_id": 3, "load_case_id": 1 }
  ],
  "memberUtilisation": [
    { "member_id": 1, "utilMax": 0.42, "governing": "biaxial section", "pass": true }
  ],
  "passFailRollup": {
    "totalMembersChecked": 3,
    "passingMembers": 3,
    "failingMembers": 0,
    "maxUtilOverall": 0.42,
    "pass": true
  }
}

Field	Type	Description
stats	ModelStats	Model size and envelope presence.
maxReactions	[ReactionExtreme]	Peak reaction per component across all load cases.
maxDisplacements	[DisplacementExtreme]	Peak absolute displacement per component.
memberUtilisation	[MemberUtilSummary]	Governing utilisation per member (first load case with capacities).
passFailRollup	PassFailRollup	Overall pass/fail summary.

ReactionExtreme / DisplacementExtreme

Field	Type	Description
component	String	Component name (e.g. "Ry", "uz").
value	f64	Extreme value (N or m / rad).
node_id	i32	Node where extreme occurs.
load_case_id	i32	Load case where extreme occurs.

MemberUtilSummary

Field	Type	Description
member_id	i32	Member identifier.
utilMax	f64	Maximum utilisation.
governing	String	"biaxial section" or "biaxial member".
pass	bool	true if utilMax <= 1.0.

PassFailRollup

Field	Type	Description
totalMembersChecked	usize	Count of members with capacity data.
passingMembers	usize	Count with pass = true.
failingMembers	usize	Count with pass = false.
maxUtilOverall	f64	Maximum utilMax across all members.
pass	bool	true if failingMembers == 0.

---

Steel Design (AS 4100)

as4100_phi_ms

AS 4100 section moment capacity φMs for a doubly symmetric I-section.

Input: WasmAs4100SectionInput JSON

{
  "d": 0.248,
  "bf": 0.124,
  "tf": 0.008,
  "tw": 0.005,
  "z_x": 4.8e-6,
  "s_x": 5.5e-6,
  "fyf": 300e6,
  "fyw": 300e6
}

Field	Type	Description
d	f64	Overall depth (m).
bf	f64	Flange width (m).
tf	f64	Flange thickness (m).
tw	f64	Web thickness (m).
z_x	f64	Elastic section modulus (m³).
s_x	f64	Plastic section modulus (m³).
fyf / fyw	f64	Flange / web yield strength (Pa).

Output: WasmAs4100PhiMsResult JSON

{
  "section_class": "compact",
  "lambda_s": 8.2,
  "lambda_sp": 9.0,
  "lambda_sy": 15.0,
  "z_ex": 5.5e-6,
  "m_sx": 1650.0,
  "phi_m_sx": 1485.0
}

Field	Type	Description
section_class	String	"compact", "non-compact", "slender".
lambda_s	f64	Section slenderness.
lambda_sp / lambda_sy	f64	Plastic / yield slenderness limits.
z_ex	f64	Effective section modulus (m³).
m_sx	f64	Nominal moment capacity (N·m).
phi_m_sx	f64	Design moment capacity φMs (N·m).

---

as4100_phi_nc

AS 4100 member compression capacity φNc.

Input: WasmAs4100PhiNcInput JSON

{
  "area": 3.25e-3,
  "r": 0.038,
  "fy": 300e6,
  "kf": 1.0,
  "alpha_b": 0.0,
  "le_mm": 5000.0,
  "phi": 0.9
}

Field	Type	Description
area	f64	Cross-sectional area (m²).
r	f64	Radius of gyration (m).
fy	f64	Yield strength (Pa).
kf	f64	Form factor. Default 1.0.
alpha_b	f64	Residual-stress parameter. Default 0.
le_mm	f64	Effective length (mm) - note: mm, not m.
phi	f64	Capacity reduction factor. Default 0.9.

Output: WasmAs4100PhiNcResult JSON

{
  "lambda_n": 0.85,
  "alpha_c": 0.92,
  "n_s": 975e3,
  "n_c": 897e3,
  "phi_n_c": 807e3
}

Field	Type	Description
lambda_n	f64	Modified slenderness.
alpha_c	f64	Member slenderness reduction factor.
n_s	f64	Squash capacity (N).
n_c	f64	Nominal member capacity (N).
phi_n_c	f64	Design capacity φNc (N).

---

as4100_phi_mbx

AS 4100 member moment capacity φMbx (LTB check).

Input: WasmAs4100PhiMbxInput JSON

{
  "d": 0.248,
  "bf": 0.124,
  "tf": 0.008,
  "tw": 0.005,
  "z_x": 4.8e-6,
  "s_x": 5.5e-6,
  "fyf": 300e6,
  "fyw": 300e6,
  "i_y": 3.5e-5,
  "j": 1.5e-7,
  "i_w": 0.0,
  "e": 200000.0,
  "g": 80000.0,
  "le_mm": 5000.0,
  "alpha_m_case": 0,
  "beta_m": 0.0,
  "phi": 0.9
}

Field	Type	Description
(section fields)		Same as WasmAs4100SectionInput (all in m, Pa).
i_y	f64	Minor-axis second moment of area (m⁴).
j	f64	Torsion constant (m⁴).
i_w	f64	Warping constant (m⁶). Default 0.
e	f64	Young's modulus (MPa). Default 200_000.
g	f64	Shear modulus (MPa). Default 80_000.
le_mm	f64	Effective length (mm).
alpha_m_case	i32	0=UniformMoment, 1=SimplySupportedUdl, 2=SimplySupportedPointLoad, 3=EndMoments, 4=CantileverUdl.
beta_m	f64	End-moment ratio for alpha_m_case: 3. Default 0.
phi	f64	Capacity reduction factor. Default 0.9.

Output: WasmAs4100PhiMbxResult JSON

{
  "m_sx": 1650.0,
  "m_o": 4500.0,
  "alpha_s": 0.55,
  "alpha_m": 1.0,
  "phi_m_bx": 817.0
}

Field	Type	Description
m_sx	f64	Section capacity (N·m).
m_o	f64	Elastic buckling moment (N·m).
alpha_s	f64	Slenderness reduction factor.
alpha_m	f64	Moment modification factor.
phi_m_bx	f64	Design capacity φMbx (N·m).

---

as4100_phi_vv

AS 4100 web shear capacity φVv.

Input: WasmAs4100PhiVvInput JSON

{
  "d": 0.248,
  "tw": 0.005,
  "tf": 0.008,
  "fy": 300e6,
  "section_name": "250UB25.7"
}

Field	Type	Description
d	f64	Overall depth (m).
tw	f64	Web thickness (m).
tf	f64	Flange thickness (m).
fy	f64	Yield strength (Pa).
section_name	String	Section name (used for special-case tables).

Output: WasmAs4100PhiVvResult JSON

{ "phi_vv": 280e3 }

Field	Type	Description
phi_vv	f64	Design shear capacity φVv (N).

---

as4100_alpha_b

Returns the AS 4100 residual-stress factor αb for a given section name.

Signature: as4100_alpha_b(section_name: &str) -> f64

Input: Plain string (not JSON). Example: "250UB25.7"

Output: f64 - the αb value (e.g. 0.0 for hot-rolled I sections).

---

as4100_alpha_m

Computes the AS 4100 moment-modification factor αm from end moments.

Input: WasmAs4100AlphaMInput JSON

{ "my1": 50e3, "my2": -30e3 }

Field	Type	Description
my1 / my2	f64	End moments (N·m).

Output: WasmAs4100AlphaMResult JSON

{ "alpha_m": 1.35 }

Field	Type	Description
alpha_m	f64	Moment modification factor.

---

as4100_combined

AS 4100 combined axial + biaxial bending capacity check (Section 8).

Input: WasmAs4100CombinedInput JSON

{
  "m_star_x": 80e3,
  "m_star_y": 20e3,
  "n_star": -500e3,
  "phi_msx": 120e3,
  "phi_msy": 45e3,
  "phi_mbx": 100e3,
  "phi_mby": 45e3,
  "phi_ncx": 600e3,
  "phi_ncy": 250e3,
  "phi_nt": 800e3,
  "ns": 975e3,
  "section_class": "compact",
  "kf": 1.0
}

Field	Type	Description
m_star_x / m_star_y	f64	Design moments (N·m). Default m_star_y = 0.
n_star	f64	Design axial force (N, negative = compression).
phi_msx / phi_msy	f64	Section moment capacities (N·m). Default phi_msy = 0.
phi_mbx / phi_mby	f64	Member moment capacities (N·m). Default phi_mby = 0.
phi_ncx / phi_ncy	f64	Compression capacities (N).
phi_nt	f64	Tension capacity (N).
ns	f64	Squash capacity (N).
section_class	String	"compact", "non-compact", "slender".
kf	f64	Form factor. Default 1.0.

Output: WasmAs4100CombinedResult JSON

{
  "phi_m_rx": 120e3,
  "phi_m_ry": 45e3,
  "phi_m_ox": 100e3,
  "phi_m_oy": 45e3,
  "section_util_x": 0.67,
  "section_util_y": 0.44,
  "member_util_x": 0.80,
  "member_util_y": 0.44,
  "axial_util": 0.83,
  "util_biaxial_section": 0.89,
  "util_biaxial_member": 0.94,
  "util_max": 0.94
}

Field	Type	Description
phi_m_rx / phi_m_ry	f64	Reduced section moment capacities (N·m).
phi_m_ox / phi_m_oy	f64	Reduced member moment capacities (N·m).
section_util_x / section_util_y	f64	Section-level utilisations.
member_util_x / member_util_y	f64	Member-level utilisations.
axial_util	f64	Axial force utilisation.
util_biaxial_section	f64	Combined section utilisation.
util_biaxial_member	f64	Combined member utilisation.
util_max	f64	Maximum of all utilisations.

---

Steel Design (AS 5100)

as5100_member_check

Full AS 5100.6 bridge steel member check: section classification, moment, compression, tension, shear, and combined.

Input: WasmAs5100MemberInput JSON

{
  "d": 248.0,
  "bf": 124.0,
  "tf": 8.0,
  "tw": 5.0,
  "a": 3250.0,
  "iyy": 3.5e7,
  "izz": 4.8e8,
  "j": 1.5e5,
  "zzz": 0.0,
  "szz": 0.0,
  "zyy": 0.0,
  "syy": 0.0,
  "fy": 300.0,
  "fu": 440.0,
  "e": 200000.0,
  "leMajor": 5.0,
  "leMinor": 2.5,
  "alphaMCase": 1,
  "beta_m": 0.0,
  "nStar": -300e3,
  "mxStar": 80e3,
  "myStar": 10e3,
  "vxStar": 50e3
}

Field	Type	Description
d / bf / tf / tw	f64	Section geometry in mm.
a	f64	Area mm².
iyy / izz / j	f64	Second moments mm⁴.
zzz / szz / zyy / syy	f64	Section moduli mm³ (auto-computed if 0).
fy / fu / e	f64	Material MPa. Default e = 200_000.
leMajor / leMinor	f64	Effective lengths m.
alphaMCase	i32	Same cases as AS 4100.
beta_m	f64	End-moment ratio. Default 0.
nStar / mxStar / myStar / vxStar	f64	Applied forces N / N·m.

Output: WasmAs5100MemberResult JSON

{
  "phiMsx": 120e3,
  "phiMsy": 45e3,
  "phiMbx": 100e3,
  "phiMby": 45e3,
  "phiNcx": 600e3,
  "phiNcy": 250e3,
  "phiNt": 800e3,
  "phiVv": 280e3,
  "section_class": "compact",
  "utilAxial": 0.50,
  "utilFlexX": 0.80,
  "utilFlexY": 0.22,
  "utilShear": 0.18,
  "utilCombined": 0.94,
  "utilMax": 0.94,
  "governing": "OK",
  "assumptions": { "leMajor": 5.0, "leMinor": 2.5, "alpha_m": 1.13, "alpha_s": 0.55, "section_class": "compact" }
}

Field	Type	Description
phiMsx / phiMsy	f64	Section moment capacities (N·m).
phiMbx / phiMby	f64	Member moment capacities (N·m).
phiNcx / phiNcy	f64	Compression capacities (N).
phiNt	f64	Tension capacity (N).
phiVv	f64	Shear capacity (N).
section_class	String	Compactness classification.
utilAxial / utilFlexX / utilFlexY / utilShear / utilCombined / utilMax	f64	Utilisations.
governing	String	"OK" or "OVER".
assumptions	WasmAs5100Assumptions	Effective lengths and factors used.

Notes:

• Invalid geometry (zero or negative) returns a result with all zeros and governing: "invalid input".
• Minor-axis LTB is not reduced (φMby = φMsy per AS 5100 Cl 5.3.1).

---

as5100_combined

AS 5100.6 combined capacity check (same interaction equations as AS 4100 Section 8 but with AS 5100 factors).

Input: WasmAs5100CombinedInput JSON - same fields as WasmAs4100CombinedInput but with camelCase keys (mStarX, phiMsx, etc.).

Output: WasmAs5100CombinedResult JSON - same utilisations as AS 4100 combined but with camelCase keys (phiMRx, sectionUtilX, utilBiaxialMember, etc.).

---

Steel Design (AISC 360)

aisc360_member_check

Full AISC 360-16 member check: tension, compression, flexure, shear, and interaction.

Input: WasmAisc360MemberInput JSON

{
  "d": 0.248,
  "bf": 0.124,
  "tf": 0.008,
  "tw": 0.005,
  "a": 3.25e-3,
  "iyy": 3.5e-5,
  "izz": 4.8e-6,
  "j": 1.5e-7,
  "zzz": 0.0,
  "szz": 0.0,
  "fy": 300e6,
  "fu": 450e6,
  "e": 200e9,
  "leMajor": 5.0,
  "leMinor": 2.5,
  "lb": 5.0,
  "cb": 1.0,
  "nStar": -300e3,
  "mxStar": 80e3,
  "myStar": 10e3,
  "vxStar": 50e3
}

Field	Type	Description
d / bf / tf / tw	f64	Section geometry m.
a	f64	Area m².
iyy / izz / j	f64	Second moments m⁴.
zzz / szz	f64	Section moduli m³ (auto-computed if 0).
fy / fu / e	f64	Material Pa. Default e = 200e9.
leMajor / leMinor	f64	Effective lengths m.
lb	f64	LTB unbraced length m.
cb	f64	Lateral-torsional buckling modification factor. Default 1.0.
nStar / mxStar / myStar / vxStar	f64	Applied forces N / N·m.

Output: WasmAisc360MemberResult JSON

{
  "phiPn": 900e3,
  "phiPnComp": 700e3,
  "phiMnx": 120e3,
  "phiMny": 35e3,
  "phiVn": 280e3,
  "section_class": "compact",
  "utilAxial": 0.43,
  "utilFlexX": 0.67,
  "utilFlexY": 0.29,
  "utilShear": 0.18,
  "utilCombined": 0.88,
  "utilMax": 0.88,
  "governing": "H1-1a",
  "assumptions": { "leMajor": 5.0, "leMinor": 2.5, "lb": 5.0, "cb": 1.0 }
}

Field	Type	Description
phiPn	f64	Tension capacity (N).
phiPnComp	f64	Compression capacity (N).
phiMnx / phiMny	f64	Major / minor axis moment capacities (N·m).
phiVn	f64	Shear capacity (N).
section_class	String	"compact", "non-compact", "slender".
utilAxial / utilFlexX / utilFlexY / utilShear / utilCombined / utilMax	f64	Utilisations.
governing	String	Interaction equation ("H1-1a", "H1-1b", "none").
assumptions	WasmAisc360Assumptions	Effective lengths and cb used.

Notes:

• Invalid geometry returns zeros with governing: "invalid input".
• Minor-axis flexure is estimated as 0.9·Fy·Zy where Zy = Iyy / (bf/2).

---

Steel Design (Eurocode 3)

ec3_member_check

Full EN 1993-1-1 member check: cross-section resistances, flexural buckling, LTB, shear, and simplified M-N interaction.

Input: WasmEc3MemberInput JSON

{
  "d": 0.248,
  "bf": 0.124,
  "tf": 0.008,
  "tw": 0.005,
  "a": 3.25e-3,
  "iyy": 3.5e-5,
  "izz": 4.8e-6,
  "j": 1.5e-7,
  "zzz": 0.0,
  "szz": 0.0,
  "w_pl_y": 0.0,
  "w_el_y": 0.0,
  "fy": 300e6,
  "e": 200e9,
  "lcrY": 5.0,
  "lcrZ": 2.5,
  "lcrLT": 5.0,
  "c1": 1.0,
  "nStar": -300e3,
  "myStar": 80e3,
  "mzStar": 10e3,
  "vyStar": 50e3
}

Field	Type	Description
d / bf / tf / tw	f64	Section geometry m.
a	f64	Area m².
iyy / izz / j	f64	Second moments m⁴.
zzz / szz	f64	Major-axis moduli m³ (auto if 0).
w_pl_y / w_el_y	f64	Plastic / elastic modulus m³ (auto if 0).
fy / e	f64	Material Pa. Default e = 200e9.
lcrY / lcrZ / lcrLT	f64	Buckling lengths m.
c1	f64	LTB equivalent uniform moment factor. Default 1.0.
nStar / myStar / mzStar / vyStar	f64	Applied forces N / N·m.

Output: WasmEc3MemberResult JSON

{
  "NtRd": 900e3,
  "NcRd": 975e3,
  "NbYRd": 700e3,
  "NbZRd": 300e3,
  "MyRd": 135e3,
  "MzRd": 30e3,
  "MbRd": 110e3,
  "VplRd": 280e3,
  "section_class": "class 1",
  "utilAxial": 0.43,
  "utilFlexY": 0.59,
  "utilFlexZ": 0.33,
  "utilShear": 0.18,
  "utilCombined": 0.95,
  "utilMax": 0.95,
  "governing": "EC3 6.3.3",
  "assumptions": { "lcrY": 5.0, "lcrZ": 2.5, "lcrLT": 5.0, "c1": 1.0, "curveY": "a", "curveZ": "b", "curveLT": "a" }
}

Field	Type	Description
NtRd	f64	Tension resistance (N).
NcRd	f64	Compression resistance (N).
NbYRd / NbZRd	f64	Flexural buckling resistances (N).
MyRd / MzRd	f64	Major / minor axis moment resistances (N·m).
MbRd	f64	LTB resistance (N·m).
VplRd	f64	Shear resistance (N).
section_class	String	"class 1" … "class 4".
utilAxial / utilFlexY / utilFlexZ / utilShear / utilCombined / utilMax	f64	Utilisations.
governing	String	Interaction check reference.
assumptions	WasmEc3Assumptions	Buckling lengths, c1, and buckling curves used.

Notes:

• Invalid geometry returns zeros with governing: "invalid input".
• Interaction uses EC3 6.3.3 simplified M-N with ky = kz = kLT = 1.0.

---

Steel Design (AS 4600)

as4600_capacity

AS 4600 cold-formed steel section capacity (compression + bending).

Input: WasmAs4600Input JSON

{
  "section_type": "LippedC",
  "d": 0.15,
  "b": 0.075,
  "t": 0.0015,
  "r": 0.003,
  "f_y": 450e6,
  "e": 200e9,
  "lip": 0.02
}

Field	Type	Description
section_type	String	"PlainC", "LippedC", "Z", "SHS", "RHS".
d	f64	Depth (m).
b	f64	Width (m).
t	f64	Thickness (m).
r	f64	Internal corner radius (m). Default 0.
f_y	f64	Yield strength (Pa).
e	f64	Young's modulus (Pa). Default 200e9.
lip	f64	Lip length for lipped C-sections (m). Default 0.

Output: WasmAs4600Result JSON

{
  "phiNc": 85e3,
  "phiMs": 12e3,
  "aGross": 4.5e-4,
  "aEff": 3.8e-4,
  "zGross": 1.2e-5,
  "zEff": 9.5e-6,
  "governing": "compression"
}

Field	Type	Description
phiNc	f64	Design compression capacity (N).
phiMs	f64	Design moment capacity (N·m).
aGross / aEff	f64	Gross / effective area (m²).
zGross / zEff	f64	Gross / effective section modulus (m³).
governing	String	Governing limit state.

---

Timber (AS 1720)

as1720_timber_check

AS 1720.1 timber member check for a rectangular sawn, MGP or glulam section: bending, compression about each axis, tension and shear. φ, k4, k6, k9 and k12 are derived from the inputs; k1 is given. Cross-checked against timberas and the SA HB 108 worked examples, not yet verified against the standard (see docs/reference/as1720_validation.md).

Units: millimetres, N and N·mm (unlike most exports, which are SI base).

Input: WasmAs1720Input JSON

{
  "grade": "MGP10",
  "species": "softwood",
  "seasoned": true,
  "category": 2,
  "b": 35,
  "d": 190,
  "length": 2800,
  "la_y": 0,
  "restraint_edge": "compression",
  "g13x": 1.0,
  "g13y": 1.0,
  "k1": 1.0,
  "m_star": 5e6,
  "n_star": 2e3,
  "nt_star": 0,
  "v_star": 10e3
}

Field	Type	Description
grade	String	"F4"…"F34", "MGP10"/"MGP12"/"MGP15", "GL8"…"GL18". Anything else is an error.
species	String	"softwood" (default) or "hardwood"; an F-grade's f't depends on it.
seasoned	bool	Default true; selects the ρb / ρc expressions of Appendix E2.
category	u8	Application category 1-3 (Table 2.1), sets φ. Default 2.
b / d	f64	Breadth of one board and depth (mm).
n_boards	u32	Boards fixed side by side (default 1).
length	f64	Member length L (mm): column length and span for k9. Absent -> no stability check.
la_y	f64	Lateral restraint spacing (mm) for S1 and S4. Defaults to length.
la_phi	f64	Torsional restraint spacing (mm), for restraint_edge: "tension_and_torsional".
restraint_edge	String	"compression" (default), "tension" or "tension_and_torsional".
g13x / g13y	f64	Effective length factors (Table 3.2). Default 1.0.
r	f64	Temporary / total action ratio for ρb, ρc. Default 0.25.
n_members / spacing	u32 / f64	Parallel system for k9 (members, spacing mm). Default 1 / 0.
partial_seasoning / high_temp	bool	Table 2.5 k4 for unseasoned timber; k6 = 0.9 regions.
a_t	f64	Net tension area (mm²). Defaults to the gross area.
k1	f64	Load duration factor. Default 1.0.
k4 / k6 / k9 / k12 / k12c	f64	Optional overrides of the derived factors.
m_star / n_star / nt_star / v_star	f64	Design actions (N·mm / N). Default 0.
le_bending / le_compression	f64	Legacy: read as la_y / length when those are absent.

Output: WasmAs1720Result JSON

{
  "phiM": 1300000, "phiN": 2855, "phiNcx": 66560, "phiNcy": 2855, "phiNt": 33050, "phiV": 7758,
  "phi": 0.7, "k1": 1, "k4": 1, "k6": 1, "k9": 1,
  "k12": 0.5514, "k12x": 0.7943, "k12y": 0.03407, "k12c": 0.03407,
  "rhoB": 0.7283, "rhoC": 0.9577, "S1": 26.05, "S3": 14.74, "S4": 80,
  "continuousRestraint": false, "stabilityAssessed": true,
  "fB": 16, "fT": 7.1, "fS": 2.5, "fC": 18, "E": 10000,
  "utilM": 3.845, "utilN": 0.7006, "utilNt": 0, "utilV": 1.289, "utilMax": 3.845,
  "governing": "bending"
}

(The input above, run through the export, rounded to four figures. The 2.8 m stud is unrestrained about its minor axis, so k12y is 0.034 and bending governs at 3.8.)

Field	Type	Description
phiM / phiNt / phiV	f64	Capacities (N·mm / N).
phiN	f64	Compression capacity, the smaller of phiNcx and phiNcy (N).
phi, k1, k4, k6, k9	f64	Factors used.
k12 / k12x / k12y / k12c	f64	Stability factors: bending, compression about x and y, governing compression.
rhoB / rhoC / S1 / S3 / S4	f64	Material constants and slenderness coefficients behind k12.
continuousRestraint	bool	Whether la_y is within L_CLR (Eq 3.2(6)).
stabilityAssessed	bool	false when no length was given: k12 is then 1 and stability was not checked.
fB / fT / fS / fC / E	f64	Characteristic values after the size notes (MPa).
utilM / utilN / utilNt / utilV / utilMax	f64	Utilisations.
governing	String	Governing check.

---

Concrete (AS 3600)

as3600_rc_member_check

Combined RC beam/column check: bending, axial, and shear.

Input: WasmRcMemberInput JSON

{
  "b": 0.4,
  "d_section": 0.6,
  "d": 0.55,
  "d_sc": 0.05,
  "f_prime_c": 32e6,
  "f_sy": 500e6,
  "a_st": 0.0025,
  "a_sc": 0.0,
  "n_star": 500e3,
  "m_star": 200e3,
  "v_star": 180e3
}

Field	Type	Description
b	f64	Section width (m).
d_section	f64	Overall depth (m).
d	f64	Effective depth to tension steel (m).
d_sc	f64	Cover to compression steel (m). Default 0.
f_prime_c	f64	Concrete strength (Pa).
f_sy	f64	Steel yield strength (Pa).
a_st / a_sc	f64	Tension / compression steel area (m²). Default a_sc = 0.
n_star / m_star / v_star	f64	Design actions (N / N·m / N).

Output: WasmRcMemberResult JSON

{
  "phiMu": 320e3,
  "phiNuo": 4500e3,
  "phiMN": 280e3,
  "phiVuc": 210e3,
  "util_bending": 0.63,
  "util_axial": 0.11,
  "util_interaction": 0.71,
  "util_shear": 0.86,
  "util_max": 0.86,
  "governing": "shear"
}

Field	Type	Description
phiMu	f64	Bending capacity (N·m).
phiNuo	f64	Axial-only capacity (N).
phiMN	f64	Axial-bending combined capacity (N·m).
phiVuc	f64	Concrete shear capacity (N).
util_bending / util_axial / util_interaction / util_shear / util_max	f64	Utilisations.
governing	String	Governing check ("bending", "axial", "shear", etc.).

Notes:

• Dimensions converted m→mm, stresses Pa→MPa, m_star N·m→N·mm internally.
• Returned moments are converted back to N·m.

---

as3600_rc_beam_moment

RC beam moment capacity (singly or doubly reinforced).

Input: WasmRcBeamInput JSON

{
  "b": 0.4,
  "d": 0.55,
  "d_sc": 0.05,
  "f_prime_c": 32e6,
  "f_sy": 500e6,
  "a_st": 0.0025,
  "a_sc": 0.0
}

Field	Type	Description
b / d	f64	Width and effective depth (m).
d_sc	f64	Compression steel cover (m). Default 0.
f_prime_c / f_sy	f64	Concrete and steel strengths (Pa).
a_st / a_sc	f64	Steel areas (m²). Default a_sc = 0.

Output: WasmRcBeamResult JSON

{
  "phiMu": 320e3,
  "kU": 0.28,
  "a": 0.154,
  "phi": 0.8,
  "overReinforced": false
}

Field	Type	Description
phiMu	f64	Moment capacity (N·m).
kU	f64	Neutral-axis depth ratio k_u = d_n / d.
a	f64	Equivalent rectangular stress-block depth (m).
phi	f64	Strength-reduction factor.
overReinforced	bool	true if concrete crushes before steel yields.

---

as3600_rc_beam_shear

RC beam concrete shear capacity φVuc per AS 3600.

Input: WasmRcShearInput JSON

{
  "b": 0.4,
  "d": 0.55,
  "f_prime_c": 32e6,
  "a_st": 0.0025
}

Field	Type	Description
b / d	f64	Width and effective depth (m).
f_prime_c	f64	Concrete strength (Pa).
a_st	f64	Tensile steel area (m²).

Output: WasmRcShearResult JSON

{
  "phiVuc": 210e3,
  "vUc": 280e3,
  "rhoW": 0.005,
  "phi": 0.7
}

Field	Type	Description
phiVuc	f64	Design shear capacity (N).
vUc	f64	Nominal shear capacity (N).
rhoW	f64	Steel ratio A_st / (b·d).
phi	f64	Strength-reduction factor.

---

as3600_rc_column_capacity

RC column capacity check including interaction curve.

Input: WasmRcColumnInput JSON

{
  "b": 0.4,
  "d_section": 0.6,
  "d": 0.55,
  "d_sc": 0.05,
  "f_prime_c": 32e6,
  "f_sy": 500e6,
  "a_st": 0.0025,
  "a_sc": 0.0,
  "n_star": 2000e3,
  "m_star": 300e3
}

Field	Type	Description
b / d_section / d / d_sc	f64	Dimensions (m).
f_prime_c / f_sy	f64	Strengths (Pa).
a_st / a_sc	f64	Steel areas (m²).
n_star / m_star	f64	Design actions (N / N·m).

Output: WasmRcColumnResult JSON

{
  "phiNuo": 4500e3,
  "phiMu": 420e3,
  "phiMN": 380e3,
  "util_n": 0.44,
  "util_m": 0.71,
  "util_interaction": 0.76,
  "util_max": 0.76,
  "curve": { ... }
}

Field	Type	Description
phiNuo	f64	Axial-only capacity (N).
phiMu	f64	Pure bending capacity (N·m).
phiMN	f64	Combined capacity at n_star (N·m).
util_n / util_m / util_interaction / util_max	f64	Utilisations.
curve	WasmRcColumnCurveResult	Full N-M interaction curve points.

WasmRcColumnCurveResult

{
  "points": [
    { "c": 0.0, "n": 4500e3, "m": 0.0, "phi": 0.6, "phiN": 4500e3, "phiM": 0.0, "label": "pure_compression" }
  ],
  "phiNuo": 4500e3,
  "phiMu": 420e3,
  "nBalanced": 2200e3,
  "mBalanced": 380e3
}

Field	Type	Description
points	[WasmRcColumnCurvePoint]	Interaction curve vertices.
phiNuo	f64	Pure compression capacity (N).
phiMu	f64	Pure moment capacity (N·m).
nBalanced / mBalanced	f64	Balanced point (N / N·m).

WasmRcColumnCurvePoint

Field	Type	Description
c	f64	Neutral-axis depth fraction.
n / m	f64	Nominal N and M at this point.
phi	f64	Strength-reduction factor.
phiN / phiM	f64	Factored capacities.
label	String	Point label.

---

as3600_rc_column_interaction_curve

Returns the full N-M interaction curve for an RC column without checking a specific demand.

Input: WasmRcColumnInput JSON (same as as3600_rc_column_capacity, but n_star and m_star are ignored).

Output: WasmRcColumnCurveResult JSON (same curve object as above).

---

rc_shear_torsion_combined

AS 3600 combined shear + torsion capacity check.

Input: WasmShearTorsionInput JSON

{
  "vStar": 180e3,
  "tStar": 45e3,
  "b": 0.4,
  "d": 0.55,
  "h": 0.6,
  "fPrimeC": 32e6,
  "aSt": 0.0025
}

Field	Type	Description
vStar	f64	Design shear force (N).
tStar	f64	Design torsion (N·m).
b / d / h	f64	Section dimensions (m).
fPrimeC	f64	Concrete strength (Pa).
aSt	f64	Longitudinal tensile steel area (m²).

Output: WasmShearTorsionResult JSON

{
  "phiVUc": 210e3,
  "phiTUc": 68e3,
  "utilV": 0.86,
  "utilT": 0.66,
  "utilCombined": 0.94,
  "utilMax": 0.94,
  "governing": "combined"
}

Field	Type	Description
phiVUc	f64	Concrete shear capacity φVuc (N).
phiTUc	f64	Torsion capacity φTuc (N·m).
utilV / utilT / utilCombined / utilMax	f64	Utilisations.
governing	String	"shear", "torsion", or "combined".

Notes:

• tStar is converted N·m → N·mm internally.
• Dimensions converted m → mm, fPrimeC Pa → MPa, aSt m² → mm².

---

Concrete Slabs (AS 3600)

as3600_slab_check

Combined slab check: moment capacity, minimum steel, punching shear, and deflection.

Input: WasmSlabInput JSON

{
  "d": 0.25,
  "cover": 0.03,
  "f_prime_c": 32e6,
  "f_sy": 500e6,
  "a_st_per_m": 0.001,
  "m_star": 50e3,
  "col_a": 0.4,
  "col_b": 0.4,
  "n_star": 1000e3,
  "span": 6.0,
  "support_type": 0
}

Field	Type	Description
d	f64	Overall slab thickness (m).
cover	f64	Concrete cover (m).
f_prime_c / f_sy	f64	Strengths (Pa).
a_st_per_m	f64	Tensile steel area per unit width (m²/m).
m_star	f64	Design moment per unit width (N·m/m).
col_a / col_b	f64	Column dimensions for punching check (m).
n_star	f64	Design axial load for punching (N).
span	f64	Slab span for deflection check (m).
support_type	i32	0=SimplySupported, 1=Continuous, 2=Cantilever. Default 0.

Output: WasmSlabResult JSON

{
  "phiMu": 85e3,
  "a_st_provided": 0.001,
  "a_st_min": 8e-4,
  "util_min_steel": 0.80,
  "util_moment": 0.59,
  "phiVUo": 1200e3,
  "util_punching": 0.83,
  "lOverDActual": 24.0,
  "lOverDLimit": 32.0,
  "util_deflection": 0.75,
  "util_max": 0.83,
  "governing": "punching"
}

Field	Type	Description
phiMu	f64	Moment capacity (N·m/m).
a_st_provided / a_st_min	f64	Steel areas (m²/m).
util_min_steel / util_moment	f64	Utilisations.
phiVUo	f64	Punching shear capacity (N).
util_punching	f64	Punching utilisation.
lOverDActual / lOverDLimit	f64	Span/depth ratios.
util_deflection	f64	Deflection utilisation (actual / limit).
util_max	f64	Maximum utilisation.
governing	String	Governing check.

---

as3600_slab_strip_moment

Slab strip moment capacity and minimum steel check.

Input: WasmSlabStripInput JSON

{
  "d": 0.25,
  "cover": 0.03,
  "f_prime_c": 32e6,
  "f_sy": 500e6,
  "a_st_per_m": 0.001,
  "m_star": 50e3
}

Field	Type	Description
d / cover	f64	Thickness and cover (m).
f_prime_c / f_sy	f64	Strengths (Pa).
a_st_per_m	f64	Steel area per unit width (m²/m).
m_star	f64	Design moment (N·m/m).

Output: WasmSlabStripResult JSON

{
  "phiMu": 85e3,
  "a_st_provided": 0.001,
  "a_st_min": 8e-4,
  "util_min_steel": 0.80,
  "util_moment": 0.59
}

Field	Type	Description
phiMu	f64	Moment capacity (N·m/m).
a_st_provided / a_st_min	f64	Steel areas (m²/m).
util_min_steel / util_moment	f64	Utilisations.

---

as3600_slab_punching_shear

AS 3600 slab punching shear capacity at a column.

Input: WasmSlabPunchingInput JSON

{
  "d": 0.25,
  "cover": 0.03,
  "f_prime_c": 32e6,
  "col_a": 0.4,
  "col_b": 0.4,
  "n_star": 1000e3
}

Field	Type	Description
d / cover	f64	Thickness and cover (m).
f_prime_c	f64	Concrete strength (Pa).
col_a / col_b	f64	Column dimensions (m).
n_star	f64	Design axial load (N).

Output: WasmSlabPunchingResult JSON

{
  "d": 0.22,
  "u": 2.4,
  "f_cv": 1.8,
  "vUo": 1200e3,
  "phiVUo": 950e3,
  "util_punching": 0.83
}

Field	Type	Description
d	f64	Effective depth (m).
u	f64	Critical perimeter (m).
f_cv	f64	Concrete shear stress factor.
vUo	f64	Design punching shear force (N).
phiVUo	f64	Punching shear capacity (N).
util_punching	f64	Utilisation.

---

as3600_slab_deflection

AS 3600 simplified slab deflection span/depth check.

Input: WasmSlabDeflectionInput JSON

{
  "span": 6.0,
  "d": 0.25,
  "f_sy": 500e6,
  "support_type": 0
}

Field	Type	Description
span	f64	Span (m).
d	f64	Effective depth (m).
f_sy	f64	Steel yield strength (Pa).
support_type	i32	0=SimplySupported, 1=Continuous, 2=Cantilever. Default 0.

Output: WasmSlabDeflectionResult JSON

{
  "lOverDActual": 24.0,
  "lOverDLimit": 32.0,
  "util_deflection": 0.75
}

Field	Type	Description
lOverDActual	f64	Actual span/depth ratio.
lOverDLimit	f64	AS 3600 limit.
util_deflection	f64	actual / limit.

---

Composite (AS 2327)

composite_beam_check

Simply-supported composite steel-concrete beam capacity check.

Input: WasmCompositeBeamInput JSON

{
  "span": 10.0,
  "beam_spacing": 3.0,
  "d": 0.5,
  "b_f": 0.19,
  "t_f": 0.014,
  "t_w": 0.009,
  "f_y": 300e6,
  "z_e": 1.2e-3,
  "d_s": 0.12,
  "f_prime_c": 32e6,
  "n_studs": 20,
  "d_stud": 0.019,
  "f_u_stud": 450e6,
  "m_star": 500e3
}

Field	Type	Description
span	f64	Beam span (m).
beam_spacing	f64	Tributary width (m).
d / b_f / t_f / t_w	f64	Steel section geometry (m).
f_y	f64	Steel yield strength (Pa).
z_e	f64	Elastic section modulus (m³).
d_s	f64	Slab thickness above deck (m).
f_prime_c	f64	Concrete strength (Pa).
n_studs	i32	Number of shear studs.
d_stud	f64	Stud diameter (m).
f_u_stud	f64	Stud ultimate strength (Pa).
m_star	f64	Design moment (N·m).

Output: WasmCompositeBeamResult JSON

{
  "bEff": 2.5,
  "fCc": 3200e3,
  "fSt": 2800e3,
  "mFull": 650e3,
  "mBare": 420e3,
  "phiMbv": 585e3,
  "eta": 0.88,
  "pnaInSlab": true,
  "phiNQ": 2500e3,
  "nStudsReq": 17.6,
  "util_stud": 0.88,
  "util_moment": 0.85,
  "util_max": 0.88
}

Field	Type	Description
bEff	f64	Effective slab width (m).
fCc	f64	Concrete compression force (N).
fSt	f64	Steel tension force (N).
mFull	f64	Full-interaction moment capacity (N·m).
mBare	f64	Bare steel moment capacity (N·m).
phiMbv	f64	Design composite moment capacity (N·m).
eta	f64	Degree of shear connection.
pnaInSlab	bool	true if plastic neutral axis is in the slab.
phiNQ	f64	Stud shear capacity (N).
nStudsReq	f64	Required number of studs.
util_stud / util_moment / util_max	f64	Utilisations.

---

Pad Footing

pad_footing_design

AS 3600 / AS 2870 pad footing design: bearing, moment, one-way shear, and punching.

Input: WasmPadFootingInput JSON

{
  "columnBx": 0.4,
  "columnBy": 0.4,
  "footingBx": 2.5,
  "footingBy": 2.5,
  "footingH": 0.6,
  "cover": 0.05,
  "fPrimeC": 32e6,
  "fSy": 500e6,
  "qUlt": 400e3,
  "nStar": 2500e3,
  "mxStar": 800e3,
  "myStar": 600e3,
  "selfWeight": 0.0
}

Field	Type	Description
columnBx / columnBy	f64	Column dimensions (m).
footingBx / footingBy / footingH	f64	Footing plan dimensions and thickness (m).
cover	f64	Concrete cover to reinforcement (m).
fPrimeC	f64	Concrete compressive strength (Pa).
fSy	f64	Reinforcement yield strength (Pa).
qUlt	f64	Ultimate soil bearing pressure (Pa).
nStar	f64	Design axial load (N, positive compression).
mxStar / myStar	f64	Design moments (N·m).
selfWeight	f64	Optional self-weight of footing (N). Default 0.

Output: WasmPadFootingResult JSON

{
  "cornerPressures": [320e3, 280e3, 260e3, 220e3],
  "qMax": 320e3,
  "qAllowable": 400e3,
  "utilBearing": 0.80,
  "dEff": 0.525,
  "mXDesign": 450e3,
  "mYDesign": 380e3,
  "aStXReq": 0.0025,
  "aStYReq": 0.0021,
  "aStMin": 0.0018,
  "aStXProvided": 0.0028,
  "aStYProvided": 0.0024,
  "utilMomentX": 0.89,
  "utilMomentY": 0.88,
  "vX": 520e3,
  "vY": 480e3,
  "phiVUc": 650e3,
  "utilShear": 0.80,
  "punchingPerimeter": 4.2,
  "vPunch": 1800e3,
  "phiVPunch": 2200e3,
  "utilPunching": 0.82,
  "utilMax": 0.89,
  "governing": "moment_x"
}

Field	Type	Description
cornerPressures	[f64; 4]	Soil pressure at four corners (Pa).
qMax	f64	Maximum corner pressure (Pa).
qAllowable	f64	Echo of qUlt (Pa).
utilBearing	f64	qMax / qAllowable.
dEff	f64	Effective depth to tensile reinforcement (m).
mXDesign / mYDesign	f64	Design bending moments per unit width (N·m/m).
aStXReq / aStYReq	f64	Required steel area per unit width (m²/m).
aStMin	f64	Minimum reinforcement area per unit width (m²/m).
aStXProvided / aStYProvided	f64	Provided steel area (currently set equal to required + min).
utilMomentX / utilMomentY	f64	Moment utilisations.
vX / vY	f64	Design one-way shear forces (N).
phiVUc	f64	Concrete shear capacity (N).
utilShear	f64	Max one-way shear utilisation.
punchingPerimeter	f64	Critical punching perimeter at dEff/2 from column face (m).
vPunch	f64	Design punching shear force (N).
phiVPunch	f64	Punching shear capacity (N).
utilPunching	f64	Punching utilisation.
utilMax	f64	Highest utilisation.
governing	String	Governing check.

Notes:

• If invalid inputs cause NaN utilisation, returns {"error": "..."} where the message is the governing string from the core.

---

Retaining Wall

retaining_wall_design

Cantilever retaining wall check: sliding, overturning, bearing, stem bending, and heel bending.

Input: WasmRetainingWallInput JSON

{
  "wallHeight": 3.0,
  "stemThicknessBase": 0.35,
  "stemThicknessTop": 0.2,
  "baseWidth": 2.5,
  "baseThickness": 0.4,
  "toeLength": 0.6,
  "gammaSoil": 18e3,
  "ka": 0.33,
  "gammaConc": 24e3,
  "fPrimeC": 32e6,
  "fSy": 500e6,
  "cover": 0.05,
  "phiBaseDeg": 30.0,
  "qAllowable": 200e3
}

Field	Type	Description
wallHeight	f64	Stem height above base (m).
stemThicknessBase / stemThicknessTop	f64	Stem thickness at base / top (m).
baseWidth / baseThickness	f64	Base slab dimensions (m).
toeLength	f64	Toe length in front of stem (m).
gammaSoil	f64	Unit weight of retained soil (N/m³).
ka	f64	Active earth-pressure coefficient.
gammaConc	f64	Unit weight of concrete (N/m³). Default 24e3.
fPrimeC	f64	Concrete strength (Pa).
fSy	f64	Steel yield strength (Pa).
cover	f64	Concrete cover (m).
phiBaseDeg	f64	Base friction angle (°). Default 30.
qAllowable	f64	Allowable soil bearing pressure (Pa).

Output: WasmRetainingWallResult JSON

{
  "pa": 89.1e3,
  "paHeight": 1.7,
  "slidingResistance": 110e3,
  "utilSliding": 0.81,
  "restoringMoment": 420e3,
  "overturningMoment": 151e3,
  "utilOverturning": 0.36,
  "resultantX": 1.34,
  "eccentricity": 0.21,
  "qMax": 185e3,
  "qMin": 45e3,
  "utilBearing": 0.92,
  "stemMoment": 95e3,
  "stemAst": 0.0012,
  "utilStem": 0.78,
  "heelMoment": 62e3,
  "heelAst": 0.0009,
  "utilHeel": 0.65,
  "utilMax": 0.92,
  "governing": "bearing"
}

Field	Type	Description
pa	f64	Total active thrust per metre length (N/m).
paHeight	f64	Height of resultant active thrust above base (m).
slidingResistance	f64	Resisting force from base friction (N/m).
utilSliding	f64	pa / slidingResistance.
restoringMoment / overturningMoment	f64	Moments about toe (N·m/m).
utilOverturning	f64	overturningMoment / restoringMoment.
resultantX	f64	Position of vertical resultant from toe (m).
eccentricity	f64	Eccentricity from base centre (m).
qMax / qMin	f64	Max/min soil bearing pressure (Pa).
utilBearing	f64	qMax / qAllowable.
stemMoment / heelMoment	f64	Design moments (N·m/m).
stemAst / heelAst	f64	Required steel area per unit width (m²/m).
utilStem / utilHeel	f64	Moment utilisations.
utilMax	f64	Maximum utilisation.
governing	String	Governing check ("sliding", "overturning", "bearing", "stem", "heel").

---

Seismic

distribute_seismic_forces

Distributes a total seismic base shear to storey nodes per AS 1170.4 equivalent-static method.

Input: WasmSeismicDistributionInput JSON

{
  "model": { ... },
  "baseShear": 500e3,
  "period": 0.8,
  "direction": [1.0, 0.0, 0.0],
  "storeys": [
    { "elevation": 0.0, "nodeIds": [1, 2] },
    { "elevation": 3.5, "nodeIds": [3, 4] }
  ],
  "loadCaseId": 99,
  "verticalAxis": null
}

Field	Type	Description
model	WasmModel	Model for mass extraction.
baseShear	f64	Total seismic base shear (N).
period	f64	Building period (s).
direction	[f64; 3]	Horizontal direction vector.
storeys	[WasmStoreyDefinition]	Storey elevations and node IDs.
loadCaseId	i32	Load case to attach generated nodal loads.
verticalAxis	String | null	Optional axis name ("Z", "Y", etc.).

Output: WasmSeismicDistributionResult JSON

{
  "nodalLoads": [WasmNodalLoad],
  "storeyForces": [WasmStoreyForce],
  "totalBaseShear": 500e3,
  "sumForces": 500e3,
  "k": 1.5
}

Field	Type	Description
nodalLoads	[WasmNodalLoad]	Nodal forces to inject into the model.
storeyForces	[WasmStoreyForce]	Per-storey lateral force, weight, and coefficient.
totalBaseShear	f64	Echo of input (N).
sumForces	f64	Sum of storey forces (should equal totalBaseShear).
k	f64	Vertical distribution exponent (1.0 for T <= 0.5 s; 2.0 for T >= 2.5 s; linear in between).

---

response_spectrum_analysis

Modal response-spectrum analysis using SRSS or CQC combination.

Input: WasmResponseSpectrumInput JSON

{
  "model": { ... },
  "spectrum_points": [[0.0, 0.5], [0.5, 1.0], [1.0, 0.8]],
  "direction": "X",
  "n_modes": 10,
  "damping_ratio": 0.05,
  "combination_method": "SRSS"
}

Field	Type	Description
model	WasmModel	Standard FEM model.
spectrum_points	[[f64, f64]]	Spectrum pairs [period_s, accel_m_s2].
direction	String	"X", "Y", or "Z".
n_modes	usize	Number of modes. Default 10.
damping_ratio	f64	Damping ratio. Default 0.05.
combination_method	String	"SRSS" or "CQC". Default "SRSS".

Output: WasmResponseSpectrumResult JSON

{
  "direction": "X",
  "combination_method": "SRSS",
  "damping_ratio": 0.05,
  "total_mass": 15000.0,
  "total_effective_mass": 14500.0,
  "combined_base_shear": 420e3,
  "mode_responses": [
    { "modeIndex": 1, "periodS": 0.85, "frequencyHz": 1.18, "spectralAccel": 0.45, "participationFactor": 1.2, "effectiveMass": 8000.0, "baseShear": 250e3 }
  ],
  "combined_displacements": [WasmNodeDisplacement]
}

Field	Type	Description
direction / combination_method / damping_ratio		Echoes of inputs.
total_mass	f64	Total lumped mass (kg).
total_effective_mass	f64	Sum of effective modal masses (kg).
combined_base_shear	f64	Combined base shear (N).
mode_responses	[WasmModeResponse]	Per-mode contribution.
combined_displacements	[WasmNodeDisplacement]	SRSS/CQC combined peak displacements.

WasmModeResponse

Field	Type	Description
mode_index	usize	Mode number.
period_s / frequency_hz	f64	Period and frequency.
spectralAccel	f64	Spectral acceleration (m/s²).
participationFactor	f64	Modal participation factor.
effectiveMass	f64	Effective modal mass (kg).
baseShear	f64	Modal base shear (N).

---

Time History

modal_time_history_analysis

Modal superposition time-history analysis using a ground-motion record.

Input: WasmTimeHistoryInput JSON

{
  "model": { ... },
  "record": [[0.0, 0.0], [0.01, 0.05], [0.02, -0.03]],
  "direction": [1.0, 0.0, 0.0],
  "damping_ratio": 0.05,
  "n_modes": 6
}

Field	Type	Description
model	WasmModel	Standard FEM model.
record	[[f64, f64]]	Ground-motion pairs [time_s, acceleration_m_s2].
direction	[f64; 3]	Ground-motion direction vector. Default [1, 0, 0].
damping_ratio	f64	Modal damping ratio. Default 0.05.
n_modes	usize	Number of modes. Default 6.

Output: WasmTimeHistoryResult JSON

{
  "peak_displacements": [WasmNodeDisplacement],
  "peakBaseShearX": 45000.0,
  "peakBaseShearY": 1200.0,
  "peakBaseShearZ": 0.0,
  "n_modes": 6,
  "n_steps": 200,
  "dt": 0.01
}

Field	Type	Description
peak_displacements	[WasmNodeDisplacement]	Peak absolute displacement per node.
peakBaseShearX / peakBaseShearY / peakBaseShearZ	f64	Peak global base shear (N).
n_modes	usize	Modes actually used.
n_steps	usize	Time steps analysed.
dt	f64	Average time step (s).

Notes:

• Base shear computed by summing support reactions at restrained nodes.
• If the record has fewer than 2 points or mismatched lengths, returns {"error": "Invalid ground motion record"}.

---

Influence Lines

influence_line

Returns influence-line ordinates for a single-span idealised beam.

Input: WasmInfluenceLineInput JSON

{
  "span": 10.0,
  "support_type": "SimplySupported",
  "action": "moment",
  "station": 0.5,
  "n_points": 101
}

Field	Type	Description
span	f64	Beam span (m).
support_type	String	"SimplySupported", "Cantilever", "FixedFixed", "FixedPinned".
action	String	"moment", "shear", "reaction".
station	f64	Normalised position [0, 1] where action is measured.
n_points	usize	Number of sample points. Default 101.

Output: WasmInfluenceLineResult JSON

{
  "action": "moment",
  "station": 0.5,
  "span": 10.0,
  "support": "SimplySupported",
  "positions": [0.0, 0.1, ..., 10.0],
  "ordinates": [0.0, 0.09, ..., 0.0]
}

Field	Type	Description
action	String	Echo of requested action.
station	f64	Normalised station.
span	f64	Echo of span.
support	String	Echo of support type.
positions	[f64]	Absolute x positions (m).
ordinates	[f64]	Influence ordinates (dimensionless).

Notes:

• For "reaction", station < 0.5 returns left-hand reaction line; otherwise right-hand.
• Ordinates are signed; positive when a unit load increases the measured action.

---

moving_load_effect

Maximum and minimum effect of a vehicle crossing a span using the relevant influence line.

Input: WasmMovingLoadInput JSON

{
  "span": 10.0,
  "support_type": "SimplySupported",
  "action": "moment",
  "station": 0.5,
  "n_points": 101,
  "vehicle": {
    "axle_weights": [10000.0, 10000.0],
    "axle_spacings": [0.0, 4.0]
  }
}

Field	Type	Description
(span, support_type, action, station, n_points)		Same as influence_line.
vehicle.axle_weights	[f64]	Axle forces (N).
vehicle.axle_spacings	[f64]	Axle positions relative to first axle (m).

Output: WasmMovingLoadResult JSON

{
  "max_value": 125000.0,
  "min_value": -25000.0,
  "critical_position_max": 5.0,
  "critical_position_min": 0.0
}

Field	Type	Description
max_value / min_value	f64	Maximum / minimum effect (N or N·m).
critical_position_max / critical_position_min	f64	First-axle position when extreme occurs (m).

Notes:

• Vehicle is stepped across the span in increments determined by n_points.

---

influence_line_continuous

Builds an influence line for a specific action in a continuous beam / frame by direct simulation (unit load stepping).

Input: WasmContinuousInfluenceLineInput JSON

{
  "model": { ... },
  "member_ids": [1, 2, 3],
  "action": "moment",
  "station_member": 2,
  "station_local_x": 0.5,
  "support_node": 0,
  "n_points": 101
}

Field	Type	Description
model	WasmModel	Standard FEM model.
member_ids	[i32]	Ordered member IDs forming the continuous load path.
action	String	"moment", "shear", "reaction".
station_member	i32	Member ID where ordinates are evaluated.
station_local_x	f64	Normalised position [0, 1] along station_member.
support_node	i32	Node ID for reaction actions. Default 0 (ignored).
n_points	usize	Resolution along the total path. Default 101.

Output: WasmContinuousInfluenceLineResult JSON

{
  "action": "moment",
  "station_member": 2,
  "station_local_x": 0.5,
  "total_length": 12.0,
  "positions": [0.0, 0.12, ..., 12.0],
  "ordinates": [0.0, 0.05, ...],
  "support_reaction_node": null
}

Field	Type	Description
action	String	Echo of action.
station_member	i32	Evaluation member.
station_local_x	f64	Evaluation position.
total_length	f64	Total path length (m).
positions	[f64]	Load positions along path (m from start).
ordinates	[f64]	Influence ordinates.
support_reaction_node	i32 | null	Populated only for reaction actions.

Notes:

• Runs a full static solve at every load position; keep n_points modest for large models.
• Unit load is applied vertically in global -Z.

---

Load Generation

generate_load_combinations

Generates factored load combinations from a set of load cases per AS/NZS 1170.

Input: WasmComboGenInput JSON

{
  "load_cases": [WasmLoadCase],
  "psi_l": 0.4,
  "psi_c": 0.4,
  "psi_s": 0.7
}

Field	Type	Description
load_cases	[WasmLoadCase]	Load cases to combine.
psi_l	f64	Live load combination factor. Default 0.4.
psi_c	f64	Companion action factor. Default 0.4.
psi_s	f64	Snow load combination factor. Default 0.7.

Output: WasmComboGenOutput JSON

{
  "combinations": [WasmLoadCombination]
}

---

as1170_wind_pressure

AS/NZS 1170.2 site wind pressure calculator.

Input: WasmWindInput JSON

{
  "region": "B",
  "terrain": "TC2",
  "height": 10.0,
  "return_period_factor": 1.0
}

Field	Type	Description
region	String	"A", "B", "C", "D", "WN", "WO", "WP", "WS".
terrain	String	"TC1", "TC2", "TC2.5", "TC3", "TC4" (or numeric equivalents).
height	f64	Structure height (m).
return_period_factor	f64	Return period multiplier. Default 1.0.

Output: WasmWindResult JSON

{
  "vR": 45.0,
  "mZcat": 0.83,
  "mC": 1.0,
  "vDes": 37.4,
  "q": 0.84e3,
  "p": 0.84e3
}

Field	Type	Description
vR	f64	Regional wind speed (m/s).
mZcat	f64	Terrain/height multiplier.
mC	f64	Climate change multiplier (AS/NZS 1170.2 Table 3.3).
vDes	f64	Design wind speed (m/s).
q	f64	Dynamic pressure (Pa).
p	f64	Design wind pressure (Pa).

---

as1170_snow_load

AS/NZS 1170.3 roof snow load calculator.

Input: WasmSnowInput JSON

{
  "region": "Alpine",
  "roof_pitch_deg": 15.0
}

Field	Type	Description
region	String	Snow region name.
roof_pitch_deg	f64	Roof pitch (°). Default 0.

Output: WasmSnowResult JSON

{
  "s_0": 1.5e3,
  "muI": 0.8,
  "s": 1.2e3
}

Field	Type	Description
s_0	f64	Ground snow load (Pa).
muI	f64	Roof shape coefficient.
s	f64	Design snow load (Pa).

---

as1170_seismic_base_shear

AS 1170.4 seismic base shear calculator.

Input: WasmSeismicInput JSON

{
  "zone": "II",
  "soil": "C",
  "period": 0.8,
  "r_u": 1.0,
  "s_p": 0.77,
  "weight": 5000e3
}

Field	Type	Description
zone	String	Seismic zone.
soil	String	Soil class "A"-"E".
period	f64	Building period (s).
r_u	f64	Ductility-related factor. Default 1.0.
s_p	f64	Structural performance factor. Default 0.77.
weight	f64	Seismic weight (N).

Output: WasmSeismicResult JSON

{
  "c": 0.12,
  "v": 600e3
}

Field	Type	Description
c	f64	Seismic coefficient V / W.
v	f64	Base shear (N).

---

as4100_notional_force

AS 4100:2020 Cl 3.2.4 notional horizontal force at one floor level: 0.002 times the total design vertical load applied at that level, for multi-storey buildings only. It acts with the design dead and live loads only, for strength and serviceability, not for the stability limit state.

Input: WasmNotionalInput JSON

{
  "total_gravity_load": 5000e3,
  "multi_storey": true
}

Field	Type	Description
total_gravity_load	f64	Total design vertical load at the floor level (N).
multi_storey	bool	Default true. false returns 0: the clause does not apply.
adequately_braced	bool	Legacy, ignored (the 2020 edition has one factor).

Output: WasmNotionalResult JSON

{ "force": 10e3 }

Field	Type	Description
force	f64	Notional horizontal force (N).

---

Connections

shear_plate_check

Flexible end plate ("kind": "fep", ASI Design Guide 4) or web side plate / fin plate ("kind": "wsp", the default; ASI Design Guide 3) shear connection, each component to AS 4100:2020: weld, bolt group with ply bearing and tear-out, plate shear, plate block shear, beam web shear at the plate, beam shear, and for a web side plate the eccentric weld and bolt groups and plate bending; coped beams add cope bending and block shear. Cross-checked component by component against steelas over 416 ASI standard details (rust_solver/fem-core/tests/asi_shear_connection_differential.rs). SI units: lengths m, stresses Pa, forces N.

Input: WasmShearPlateInput JSON (main fields)

Field	Type	Description
kind	String	"wsp" (default) or "fep".
v_star	f64	Design shear (N).
beam or beam_d / beam_bf / beam_tf / beam_tw / beam_fy / beam_fu	object / f64	The supported beam, nested or flat.
bolt_diameter, bolt_grade, threads_included		Bolts (default 8.8, threads included).
rows or bolt_count, cols, pitch, gauge		Bolt grid.
plate_b, plate_t, plate_fy, plate_fu	f64	Plate.
weld_leg, weld_fuw	f64	Fillet weld.
a_ev	f64	Plate edge distance to the end bolts.
s_g1, a_eh_beam, a	f64	WSP: weld line to first bolt column, beam end distance, beam top to top bolt.

Output: components (each with capacity, utilisation and clause), govUtil, govComponent, status, notes, phiVDes (least component capacity, N), governing, d_i and e (m).

ridge_tie_cleat_check

Ridge tie cleat: a plate hung under the rafter soffit with the longitudinal tie bolted through its web in a run going down the plate. Checked for the tie's axial force n_star (in the plate's plane, at the bolts' depth, so in-plane bending N e at the weld) and shear v_star, to AS 4100:2020: bolt shear (Cl 9.2.2.1), bearing and tear-out on the plate and the tie web (Cl 9.2.2.4), the plate at the weld in bending, shear and axial (Cl 5.2, 5.11.3, 9.1.9) and the fillets (Cl 9.6.3.10). SI in (m, Pa, N): bolt_diameter, bolt_grade, n_bolts, plate_b (the run along the soffit), plate_t, plate_fy, plate_fu, e (weld line to the bolt centroid), tie_tw, tie_fu, tie_end, weld_leg, weld_fuw. Out: util_bolt_shear, util_plate_bearing, util_tie_bearing, util_plate_bending, util_plate_shear, util_plate_axial, util_weld, util_max, governing.

bolt_capacity

AS 4100 Section 9 bolt and ply bearing capacity.

Input: WasmBoltInput JSON

{
  "bolt_diameter": 0.02,
  "bolt_grade": "8.8/S",
  "shear_planes_threads_intercepted": 1,
  "shear_planes_threads_excluded": 0,
  "kr": 1.0,
  "ply_thickness": 0.008,
  "ply_fu": 450e6
}

Field	Type	Description
bolt_diameter	f64	Bolt diameter (m).
bolt_grade	String	Grade string (e.g. "8.8/S").
shear_planes_threads_intercepted	i32	Shear planes with threads in shear.
shear_planes_threads_excluded	i32	Shear planes with threads excluded.
kr	f64	Reduction factor. Default 1.0.
ply_thickness	f64	Ply thickness (m).
ply_fu	f64	Ply tensile strength (Pa).

Output: WasmBoltResult JSON

{
  "phiVf": 180e3,
  "phiNtf": 250e3,
  "phiVb": 120e3
}

Field	Type	Description
phiVf	f64	Design shear capacity per bolt (N).
phiNtf	f64	Design tension capacity per bolt (N).
phiVb	f64	Ply bearing capacity per bolt (N).

---

weld_capacity

AS 4100 fillet weld shear capacity.

Input: WasmWeldInput JSON

{
  "leg_size": 0.008,
  "length": 0.15,
  "fuw": 480.0,
  "kr": 1.0
}

Field	Type	Description
leg_size	f64	Fillet weld leg size (m).
length	f64	Weld length (m).
fuw	f64	Weld metal ultimate strength (MPa). Default 480.
kr	f64	Reduction factor. Default 1.0.

Output: WasmWeldResult JSON

{ "phiVw": 95e3 }

Field	Type	Description
phiVw	f64	Design weld shear capacity (N).

---

base_plate_check

Base plate bearing and bending check.

Input: WasmBasePlateInput JSON

{
  "n_star": 800e3,
  "column_d": 0.25,
  "column_bf": 0.15,
  "plate_b": 0.4,
  "plate_d": 0.5,
  "plate_t": 0.02,
  "concrete_fc": 32e6,
  "plate_fy": 300e6,
  "bolt_count": 4,
  "bolt_diameter": 0.02,
  "bolt_grade": "8.8/S"
}

Field	Type	Description
n_star	f64	Axial load (N).
column_d / column_bf	f64	Column depth and flange width (m).
plate_b / plate_d / plate_t	f64	Plate dimensions (m).
concrete_fc	f64	Concrete strength (Pa).
plate_fy	f64	Plate yield strength (Pa).
bolt_count	i32	Number of anchor bolts. Default 0.
bolt_diameter	f64	Bolt diameter (m). Default 0.
bolt_grade	String	Bolt grade. Default "".

Output: WasmBasePlateResult JSON

{
  "n_star": 800e3,
  "phiNcConc": 1200e3,
  "bearing_pressure": 4e6,
  "confinement": 1.2,
  "phiPlateBending": 150e3,
  "t_req": 0.018,
  "util_bearing": 0.67,
  "util_plate": 0.80,
  "util_bolts": 0.0,
  "util_max": 0.80,
  "cantilever_d": 0.125,
  "cantilever_b": 0.075,
  "assumptions": { "phi_concrete": 0.6, "phi_steel": 0.9, "method": "bearing" }
}

Field	Type	Description
n_star	f64	Echo of axial load (N).
phiNcConc	f64	Concrete bearing capacity (N).
bearing_pressure	f64	Actual bearing pressure (Pa).
confinement	f64	Confinement factor.
phiPlateBending	f64	Plate bending capacity (N·m/m).
t_req	f64	Required plate thickness (m).
util_bearing / util_plate / util_bolts / util_max	f64	Utilisations.
cantilever_d / cantilever_b	f64	Cantilever overhangs from column face (m).
assumptions	WasmBasePlateAssumptions	Factors and method used.

Notes:

• Bolt diameter is converted m → mm internally for the core lookup tables.

---

fin_plate_check

Fin-plate connection shear capacity check (bolts + plate + weld).

Input: WasmFinPlateInput JSON

{
  "v_star": 150e3,
  "bolt_diameter": 0.02,
  "bolt_grade": "8.8/S",
  "bolt_count": 4,
  "plate_depth": 0.3,
  "plate_thickness": 0.01,
  "plate_fy": 300e6,
  "plate_fu": 450e6,
  "weld_leg_size": 0.006,
  "weld_length": 0.3,
  "weld_fuw": 480.0,
  "end_distance": 0.04
}

Field	Type	Description
v_star	f64	Design shear (N).
bolt_diameter	f64	Bolt diameter (m).
bolt_grade	String	Bolt grade.
bolt_count	i32	Number of bolts.
plate_depth / plate_thickness	f64	Plate dimensions (m).
plate_fy / plate_fu	f64	Plate yield / ultimate strengths (Pa).
weld_leg_size / weld_length	f64	Weld dimensions (m).
weld_fuw	f64	Weld metal strength (MPa). Default 480.
end_distance	f64	Bolt end distance (m). Default 0.

Output: WasmFinPlateResult JSON

{
  "v_star": 150e3,
  "phiBolts": 720e3,
  "phiPlateShear": 400e3,
  "phiPlateBearing": 600e3,
  "phiPlateTearout": 500e3,
  "phiWeld": 380e3,
  "phiVDes": 380e3,
  "util_bolts": 0.21,
  "util_plate_shear": 0.38,
  "util_plate_bearing": 0.25,
  "util_plate_tearout": 0.30,
  "util_weld": 0.39,
  "util_max": 0.39
}

Field	Type	Description
v_star	f64	Echo of design shear (N).
phiBolts	f64	Bolt group shear capacity (N).
phiPlateShear	f64	Plate shear capacity (N).
phiPlateBearing	f64	Plate bearing capacity (N).
phiPlateTearout	f64	Plate tear-out capacity (N).
phiWeld	f64	Weld capacity (N).
phiVDes	f64	Minimum of all capacities = design capacity (N).
util_* / util_max	f64	Utilisations.

Notes:

• Lengths converted m→mm, stresses Pa→MPa internally.
• Capacities returned as forces (N).

---

end_plate_check

End-plate connection moment capacity check (bolts in tension + plate bending).

Input: WasmEndPlateInput JSON

{
  "m_star": 80e3,
  "beam_d": 0.5,
  "beam_tf": 0.014,
  "bolt_diameter": 0.024,
  "bolt_grade": "8.8/S",
  "bolt_count_tension": 4,
  "plate_thickness": 0.02,
  "plate_fy": 300e6
}

Field	Type	Description
m_star	f64	Design moment (N·m).
beam_d / beam_tf	f64	Beam depth and flange thickness (m).
bolt_diameter	f64	Bolt diameter (m).
bolt_grade	String	Bolt grade.
bolt_count_tension	i32	Number of bolts in tension.
plate_thickness	f64	Plate thickness (m).
plate_fy	f64	Plate yield strength (Pa).

Output: WasmEndPlateResult JSON

{
  "m_star": 80e3,
  "d_eff": 0.486,
  "tStar": 165e3,
  "phiBoltsTension": 720e3,
  "phiPlateBending": 95e3,
  "phiMDes": 85e3,
  "util_bolts": 0.11,
  "util_plate": 0.84,
  "util_max": 0.84
}

Field	Type	Description
m_star	f64	Echo of design moment (N·m).
d_eff	f64	Effective lever arm (m).
tStar	f64	Tension force in bolt group (N).
phiBoltsTension	f64	Bolt tension capacity (N).
phiPlateBending	f64	Plate bending capacity (N·m).
phiMDes	f64	Design moment capacity (N·m).
util_bolts / util_plate / util_max	f64	Utilisations.

Notes:

• m_star converted N·m → N·mm internally; returned values converted back to N·m.
• d_eff uses (beam_d - beam_tf) with a 1 mm floor in mm units, so inputs must be in m.

---

weld_group_check

Eccentric weld group capacity by instantaneous centre of rotation method.

Input: WasmWeldGroupInput JSON

{
  "segments": [
    { "x1": 0.0, "y1": 0.0, "x2": 0.0, "y2": 0.3, "legSize": 0.006 },
    { "x1": 0.0, "y1": 0.3, "x2": 0.2, "y2": 0.3, "legSize": 0.006 }
  ],
  "fuw": 480.0,
  "kr": 1.0,
  "vx": 50e3,
  "vy": 0.0,
  "mz": 15e3
}

Field	Type	Description
segments	[WasmWeldSegmentInput]	Weld segments in local coordinates (m).
fuw	f64	Weld metal strength (MPa).
kr	f64	Reduction factor.
vx / vy	f64	Applied shear forces (N).
mz	f64	Applied torsional moment (N·m).

WasmWeldSegmentInput

Field	Type	Description
x1 / y1 / x2 / y2	f64	Segment end coordinates (m).
legSize	f64	Fillet weld leg size (m).

Output: WasmWeldGroupResult JSON

{
  "phiVtotal": 180e3,
  "util_max": 0.83,
  "governingSegment": 1,
  "vPerMmGov": 350.0,
  "phiVperMmGov": 420.0
}

Field	Type	Description
phiVtotal	f64	Total weld group capacity (N).
util_max	f64	Maximum segment utilisation.
governingSegment	usize	0-based index of critical segment.
vPerMmGov	f64	Resultant force per mm on governing segment (N/mm).
phiVperMmGov	f64	Capacity per mm on governing segment (N/mm).

---

eccentric_bolt_group_check

Eccentric bolt group capacity by instantaneous centre of rotation method.

Input: WasmBoltGroupInput JSON

{
  "bolts": [
    { "x": 0.0, "y": 0.0 },
    { "x": 0.1, "y": 0.0 }
  ],
  "boltDiameter": 0.02,
  "boltGrade": "8.8/S",
  "nN": 1,
  "nX": 1,
  "kr": 1.0,
  "vx": 50e3,
  "vy": 0.0,
  "mz": 15e3
}

Field	Type	Description
bolts	[WasmBoltPositionInput]	Bolt positions in local coordinates (m).
boltDiameter	f64	Bolt diameter (m).
boltGrade	String	Bolt grade.
nN	i32	Shear planes threads intercepted.
nX	i32	Shear planes threads excluded.
kr	f64	Reduction factor.
vx / vy	f64	Applied shear forces (N).
mz	f64	Applied torsional moment (N·m).

WasmBoltPositionInput

Field	Type	Description
x / y	f64	Bolt position (m).

Output: WasmBoltGroupResult JSON

{
  "phiVtotal": 320e3,
  "util_max": 0.78,
  "governingBolt": 1,
  "vResultantGov": 90e3,
  "phiVbolt": 115e3
}

Field	Type	Description
phiVtotal	f64	Total bolt group capacity (N).
util_max	f64	Maximum bolt utilisation.
governingBolt	usize	0-based index of critical bolt.
vResultantGov	f64	Resultant shear on governing bolt (N).
phiVbolt	f64	Single-bolt shear capacity (N).

---

Section Properties

section_properties

Polygon section property calculator from arbitrary closed loops.

Input: WasmSectionBuilderInput JSON

{
  "loops": [
    [
      { "x": 0.0, "y": 0.0 },
      { "x": 0.1, "y": 0.0 },
      { "x": 0.1, "y": 0.2 },
      { "x": 0.0, "y": 0.2 }
    ]
  ]
}

Field	Type	Description
loops	[[WasmPoint2]]	List of closed polygons (counter-clockwise = positive area).

WasmPoint2

Field	Type	Description
x / y	f64	Vertex coordinates (m).

Output: WasmSectionBuilderResult JSON

{
  "area": 0.02,
  "cx": 0.05,
  "cy": 0.1,
  "Ixx": 6.67e-5,
  "Iyy": 1.67e-5,
  "Ixy": 0.0,
  "I1": 6.67e-5,
  "I2": 1.67e-5,
  "thetaP": 0.0,
  "Ip": 8.33e-5,
  "Japprox": 3.33e-5,
  "Jopen": 0.0,
  "Zxapprox": 6.67e-4,
  "Zyapprox": 3.33e-4,
  "Sx": 0.0,
  "Sy": 0.0,
  "Asx": 0.0167,
  "Asy": 0.0083,
  "Iw": 0.0,
  "rx": 0.0577,
  "ry": 0.0289
}

Field	Type	Description
area	f64	Cross-sectional area (m²).
cx / cy	f64	Centroid (m).
Ixx / Iyy	f64	Second moments about centroidal axes (m⁴).
Ixy	f64	Product of inertia (m⁴).
I1 / I2	f64	Principal moments of inertia (m⁴).
thetaP	f64	Principal angle (rad).
Ip	f64	Polar moment of inertia (m⁴).
Japprox / Jopen	f64	Approximate torsion constants (m⁴).
Zxapprox / Zyapprox	f64	Approximate elastic moduli (m³).
Sx / Sy	f64	Plastic moduli (m³).
Asx / Asy	f64	Shear areas (m²).
Iw	f64	Warping constant (m⁶).
rx / ry	f64	Radii of gyration (m).

---

Import / Export

import_sg_model

Parses a legacy SpaceGass binary model file (.sg or .sgw) and returns a WasmModel JSON.

Signature: import_sg_model(bytes: &[u8]) -> String

Input: Raw binary byte array (not JSON).

Output: WasmModel JSON or {"error": "..."}.

Notes:

• Best-effort conversion: not all legacy features are supported.
• May lose plate data, advanced releases, or non-linear properties.

---

list_sg_entries

Lists the named entries (models / data sets) inside a SpaceGass binary file without fully parsing them.

Signature: list_sg_entries(bytes: &[u8]) -> String

Input: Raw binary byte array (not JSON).

Output: JSON array of entry descriptors or {"error": "..."}.

---

Merge (Phase 4)

merge_snapshots

Structural 3-way merge for collaborative editing. Merges two divergent model snapshots against a common base.

Signature: merge_snapshots(base_json: &str, ours_json: &str, theirs_json: &str) -> String

Input: Three JSON strings representing WasmModel-like snapshots.

Output: Merge result JSON

{
  "merged": { ... },
  "conflicts": [
    { "kind": "field", "entity": "nodes", "id": "n1", "field": "x", "base": 0, "ours": 5, "theirs": 10 }
  ],
  "stats": {
    "merged_clean": 42,
    "conflicts": 1
  }
}

Field	Type	Description
merged	object	The merged model snapshot.
conflicts	[object]	List of unresolvable conflicts with base/ours/theirs values.
stats	object	Count of clean merges vs conflicts.

Notes:

• When a conflict occurs, the merged output keeps the base value.
• Arrays of entities (nodes, members, etc.) are matched by id field.

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Document generated from source: rust_solver/fem-wasm/src/lib.rs + report_exports.rsTotal documented exports: 55