Steel-Concrete Composite Section Meshing

This example demonstrates how to create a mesh for a steel-concrete composite section.

import opstool as opst

The following materials are intended for the purpose of calculating section properties and are not related to OpenSeesPy.

Ec = 3.45e7
Es = 2.0e8
Nus = 0.3
Nuc = 0.2
pho_c = 2.55
pho_s = 7.86
steel_mat = opst.pre.section.create_material(name="steel", elastic_modulus=Es, poissons_ratio=Nus, density=pho_s)
conc_mat = opst.pre.section.create_material(name="conc", elastic_modulus=Ec, poissons_ratio=Nuc, density=pho_c)

outlines = [[0, 0], [2, 0], [2, 2], [0, 2]]
coverlines = opst.pre.section.offset(outlines, d=0.05)
cover_geo = opst.pre.section.create_polygon_patch(outlines, holes=[coverlines], material=conc_mat)
bonelines = [
    [0.5, 0.5],
    [1.5, 0.5],
    [1.5, 0.7],
    [1.1, 0.7],
    [1.1, 1.3],
    [1.5, 1.3],
    [1.5, 1.5],
    [0.5, 1.5],
    [0.5, 1.3],
    [0.9, 1.3],
    [0.9, 0.7],
    [0.5, 0.7],
    [0.5, 0.5],
]

core_geo = opst.pre.section.create_polygon_patch(coverlines, holes=[bonelines], material=conc_mat)

bone_geo = opst.pre.section.create_polygon_patch(bonelines, material=steel_mat)

SEC_MESH = opst.pre.section.FiberSecMesh()
SEC_MESH.add_patch_group(dict(cover=cover_geo, core=core_geo, bone=bone_geo))
SEC_MESH.set_mesh_size(dict(cover=0.1, core=0.2, bone=0.1))
SEC_MESH.set_mesh_color(dict(cover="gray", core="#b84592", bone="#ffc168"))
SEC_MESH.set_ops_mat_tag(dict(cover=1, core=2, bone=4))
SEC_MESH.mesh()

OPSTOOL™ :: The section My Section has been successfully meshed!

add rebars

rebar_lines1 = opst.pre.section.offset(outlines, d=0.05 + 0.032 / 2)
SEC_MESH.add_rebar_line(points=rebar_lines1, dia=0.032, gap=0.1, color="black", ops_mat_tag=3)

Since it is a composite section, we use the elastic modulus of concrete as the reference modulus to obtain equivalent properties based on concrete material.

SEC_MESH.centring()
props = SEC_MESH.get_sec_props(Eref=Ec, display_results=True)

                              Section Properties
┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ Symbol    ┃ Value                  ┃ Definition                             ┃
┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ A         │ 6.494E+00              │ Cross-sectional area                   │
│ Asy       │ 5.357E+00              │ Shear area y-axis                      │
│ Asz       │ 4.557E+00              │ Shear area z-axis                      │
│ centroid  │ (0.000E+00, 0.000E+00) │ Elastic centroid                       │
│ Iy        │ 1.664E+00              │ Moment of inertia y-axis               │
│ Iz        │ 1.495E+00              │ Moment of inertia z-axis               │
│ Iyz       │ 4.319E-15              │ Product of inertia                     │
│ Wyt       │ 1.664E+00              │ Section moduli of top fibres y-axis    │
│ Wyb       │ 1.664E+00              │ Section moduli of bottom fibres y-axis │
│ Wzt       │ 1.495E+00              │ Section moduli of top fibres z-axis    │
│ Wzb       │ 1.495E+00              │ Section moduli of bottom fibres z-axis │
│ J         │ 2.482E+00              │ Torsion constant                       │
│ phi       │ 0.000E+00              │ Principal axis angle                   │
│ mass      │ 1.296E+01              │ Section mass                           │
│ rho_rebar │ 1.548E-02              │ Ratio of reinforcement                 │
└───────────┴────────────────────────┴────────────────────────────────────────┘

Or use the faster property calculation method for frame elements

frame_props = props = SEC_MESH.get_frame_props(Eref=Ec, display_results=True)

                           Frame Section Properties
┏━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃ Symbol    ┃ Value                  ┃ Definition                             ┃
┡━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│ A         │ 6.494E+00              │ Cross-sectional area                   │
│ centroid  │ (0.000E+00, 0.000E+00) │ Elastic centroid                       │
│ Iy        │ 1.664E+00              │ Moment of inertia y-axis               │
│ Iz        │ 1.495E+00              │ Moment of inertia z-axis               │
│ Iyz       │ 1.490E-07              │ Product of inertia                     │
│ Wyt       │ 1.664E+00              │ Section moduli of top fibres y-axis    │
│ Wyb       │ 1.664E+00              │ Section moduli of bottom fibres y-axis │
│ Wzt       │ 1.495E+00              │ Section moduli of top fibres z-axis    │
│ Wzb       │ 1.495E+00              │ Section moduli of bottom fibres z-axis │
│ J         │ 2.482E+00              │ Torsion constant                       │
│ phi       │ 0.000E+00              │ Principal axis angle                   │
│ rho_rebar │ 1.548E-02              │ Ratio of reinforcement                 │
└───────────┴────────────────────────┴────────────────────────────────────────┘

SEC_MESH.view(fill=True, show_legend=True)