concreteproperties

The concreteproperties library provides computational tools for structural analysis of reinforced and composite concrete elements. It supports the following analysis types:

• Reinforced Concrete
• Steel-Concrete Composite
• Prestressed Concrete

Key capabilities include material modeling (concrete, steel, and strand), calculation of gross section properties, serviceability analysis (cracking, moment-curvature), ultimate strength analysis (bending capacity, squash load, M-N curves), and stress analysis for both uncracked and cracked states. The library includes design code modules for AS3600 and NZS3101 & NZSEE C5 Assessment Guidelines.

concreteproperties is a Python package designed to calculate the section properties of arbitrary reinforced concrete sections.

Key capabilities include:

• Calculating gross, cracked, and ultimate properties.
• Performing moment-curvature analyses.
• Generating moment interaction and biaxial bending diagrams.
• Generating stress plots.

Steel profiles are used to model the behavior of reinforcement. Unlike concrete, a single profile is used for both service and ultimate analyses.

Available Profiles:

• SteelProfile: A generic profile using manual strains and stresses arrays. Requires yield_strength, elastic_modulus, and fracture_strain.
• SteelElasticPlastic: A standard elastic-plastic model.
• SteelHardening: An elastic-plastic model that includes strain hardening (requires ultimate_strength).

from concreteproperties import SteelHardening

# Example of an elastic-plastic hardening steel profile
profile = SteelHardening(
    yield_strength=500,
    elastic_modulus=200e3,
    fracture_strain=0.05,
    ultimate_strength=600,
)
profile.plot_stress_strain()

The library provides tools for both serviceability and ultimate strength assessments:

Service Analysis

• Cracking moment calculation.
• Cracked area properties.
• Moment-curvature diagrams.

Ultimate Analysis

• Ultimate bending capacity.
• Squash load and Tensile load.
• Moment interaction diagrams: Including M-N curves and Biaxial bending curves.

Stress Analysis

• Calculation of Uncracked, Cracked, Service, and Ultimate stresses.

The design_codes module enables the use of concreteproperties within the context of specific reinforced concrete design standards. Currently, the library supports the following design codes:

• AS 3600 (Australian Standard for Concrete Structures)
• NZS 3101 (New Zealand Standard for Concrete Structures)

The concreteproperties library uses stress-strain profiles to model how materials behave under load.

For Concrete objects, you must provide two distinct profiles:

1. Service profile: Used for area properties, moment-curvature analysis, and elastic/service stress analysis.
2. Ultimate profile: Used for ultimate bending capacity, moment interaction diagrams, biaxial bending diagrams, and ultimate stress analysis.

All other material types (like steel or strands) only require a single profile, which is used for both service and ultimate analyses.

Interpolation and Extrapolation:

• Stress values are interpolated from the supplied points.
• If a requested strain is outside the profile's range, the stress is extrapolated using the two closest points in the profile.

The library provides specialized classes for different structural components. Choosing the correct class ensures proper meshing behavior and performance:

• Concrete: Used for concrete components. Meshing is enabled by default to capture strain variation.
• Steel: Used for large structural steel sections (e.g., in composite sections). Meshing is enabled by default.
• SteelBar: Used for reinforcement. Meshing is disabled by default (treats area as constant strain with lumped mass) to increase analysis performance.
• SteelStrand: Used for prestressing strands. Meshing is disabled by default.
• Material: A generic class that can be used to describe the behavior of any other material type.

Note on Meshing: You can manually toggle meshing for any geometry by setting the meshed=False attribute.

Strand profiles model the behavior of prestressing strands.

Available Profiles:

• StrandProfile: A generic profile using manual strains and stresses arrays.
• StrandHardening: An elastic-plastic hardening model for strands.
• StrandPCI1992: A specific strand profile based on the PCI Journal (1992).

from concreteproperties import StrandPCI1992

# Example of a PCI 1992 strand profile
profile = StrandPCI1992(
    yield_strength=1500,
    elastic_modulus=195e3,
    fracture_strain=0.035,
    breaking_strength=1830,
)
profile.plot_stress_strain()

When performing analyses or interpreting results in concreteproperties, follow these sign conventions:

• Stresses: Compressive stresses are positive (+), and tensile stresses are negative (-).
• Angles: Measured in radians, with positive values representing counter-clockwise rotation from the positive x axis.

In concreteproperties, material behavior follows a specific sign convention for forces, stresses, and strains:

• Positive (+): Compressive forces, stresses, and strains.
• Negative (-): Tensile forces, stresses, and strains.