Options and errors#

LoadTracer options#

lt = LoadTracer(
    geometry_graph=graph,
    occupancies=occupancies,
    on_error="collect",
    missing_reactions="ignore",
    joist_loads="distributed",
)

on_error: "raise" (default) stops at the first member that cannot be analysed. "collect" records the error in lt.errors and continues. The members that the failed member bears on then have missing reactions (see below).
missing_reactions: What to do when a member receives load from a member that has no reactions, because it failed, was excluded, or has no support at that transfer_reaction_index. "raise" (default) raises a ReactionNotFoundError. "ignore" records the source in lt.ignored_reactions and continues without that load.
joist_loads: "distributed" (default) or "point". See Joist loads.
joist_profile_rel_tol, joist_variability_ratio: How joist reactions are classified when they are converted. See Joist loads.
show_progress: Not used yet; to show a progress bar, pass progress=True to execute_analyses.

Rundown options#

lt.execute_analyses(
    artifacts_dir="artifacts",
    exclude_members=["J1.0", "FB2.3"],
    linear_wall_spread_angle=45,
    linear_wall_minimum_point_spread=1,
    progress=True,
)

artifacts_dir: Write models.json and reaction_forces.json here (see Results).
exclude_members: Skip these members. Loads that they would transfer to the members below are dropped. Excluding a joist array (e.g. "J1.0") excludes all of its joists.
linear_wall_spread_angle: Spread loads down walls at this angle, in degrees (default 0). A non-zero angle needs the wall height: add a numeric height to each wall’s annotation in the drawing (papermodels reads it into user_defined).
linear_wall_minimum_point_spread: The minimum length that a point load on a wall spreads over (default 1, in drawing units).
progress: Show a progress bar while the members are analysed.

Load directions#

papermodels gives each load a direction: gravity, inplane or out_of_plane. Three mappings on LoadTracer set which analysis directions each of them becomes:

occupancy_distributed_load_direction_mapping = {"gravity": ["Fy"], "inplane": ["Fx"], "out_of_plane": ["Fz"]}
reaction_distributed_load_direction_mapping = {"gravity": ["FY"], "inplane": ["FX"], "out_of_plane": ["FZ"]}
reaction_point_load_direction_mapping = {"gravity": ["FY"], "inplane": ["FX"], "out_of_plane": ["FZ"]}

The reaction mappings list the reaction directions carried down to the member below. For example, {"gravity": ["FY", "MZ"]} would also carry moments. Only gravity loads are covered by the tests.

Errors#

Every error is a subclass of LoadTracerError, and names the member it concerns (Member FB2.0: ..., also in error.tag).

Error	Raised when
`InvalidPapermodelError`	A papermodel does not have the shape or values loadtracer needs, e.g. an occupancy with no pressures, or a member with no length
`UnstableMemberError`	A beam’s supports cannot make it stable, e.g. a beam with one support
`ReactionNotFoundError`	A member receives load from a member whose reactions are not available
`AnalysisError`	Any other failure while building or solving a model. The original exception is its `__cause__`

With on_error="collect", these are gathered in lt.errors instead of raised:

lt = LoadTracer(geometry_graph=graph, occupancies=occupancies, on_error="collect")
lt.execute_analyses()
for tag, error in lt.errors.items():
    print(error)

Warnings#

All warnings are subclasses of LoadTracerWarning:

LoadTracerWarning: once per rundown, when lt.issues is not empty
JoistLoadVariabilityWarning: joist reactions that vary a lot were converted to a uniform load
JoistTribWidthWarning: a trib width in converted_joist_loads() is approximate

Note

LoadTracer(elevations=..., vertical_element_heights=...) is deprecated. Heights and elevations are design data, and are ignored with a DeprecationWarning. Wall heights, when a spread angle needs them, come from the wall’s annotation.