Node

Node#

The Node class is a fundamental component in the Mento library. It represents a node in a structural model, associating a Section object with one or more Forces objects. This allows you to apply and manage forces on a specific section of your structure.

A Node connects a Section (e.g., a rectangular concrete beam or column) with the forces acting on it. You can:

  • Add one or more forces to the node.

  • Retrieve the list of forces applied to the node.

  • Clear all forces from the node.

  • Check for shear or flexure.

  • Design for shear or flexure.

This guide will walk you through how to use the Node class effectively. A Section could be a Beam, Slab or Column object since it just connects the section with the forces.

1. Attributes#

The Node class has the following attributes:

  • section: The Section object associated with this node. For now, a RectangularConcreteBeam is available.

  • forces: A list of Forces objects applied to this node.

To create a Node you must define the concrete and steel materials, the concrete section based on those materials and the forces object.

from mento import Concrete_ACI_318_19, SteelBar, Forces, RectangularBeam, Node
from mento import mm, cm, kN, MPa, kNm

# Defines materials and beam section
conc  = Concrete_ACI_318_19(name="C25",f_c=25*MPa)
steel = SteelBar(name="ADN 420", f_y=420*MPa)
beam  = RectangularBeam(label="101",concrete=conc,steel_bar=steel,width=20*cm, height=60*cm, c_c=2.5*cm)

# Define forces
f1 = Forces(label='1.4D', V_z=50*kN, M_y=90*kNm)
f2 = Forces(label='1.2D+1.6L', V_z=55*kN, M_y=-80*kNm)
# Assign transverse and longitudinal reinforcement
beam.set_transverse_rebar(n_stirrups=1, d_b=10*mm, s_l=20*cm)
beam.set_longitudinal_rebar_bot(n1=3,d_b1=16*mm)
beam.set_longitudinal_rebar_top(n1=3,d_b1=12*mm)

# Create node and assign beam section and list of forces
node_1 = Node(section=beam, forces=[f1, f2])

# Plot the beam section
beam.plot()

2. Performing Checks#

The Node class provides the following methods for checking, designing and printing results. They all apply for beams and columns. Once the Section is defined and forces are assigned in a Node object, you can perform checks for shear and flexure.

Mento will apply corresponding design code formulas depending on the type of Concrete object created for all the forces assigned and store the limiting case for shear and top and bottom bending moment.

  • Shear Check: Use check_shear().

# Perform shear checks and show DataFrame with results
shear_results = node_1.check_shear()
shear_results

  • Flexure Check: Use check_flexure().

# Perform flexure checks and show DataFrame with results
flexure_results = node_1.check_flexure()
flexure_results

Each method will return a Pandas DataFrame with all the check results for each Load Case in the Force object assigned to the Node, both for shear and flexure analysis.

3. Jupyter Notebook Results#

After performing the checks, you can view the results in a formatted way in a Notebook.

When you run node.results:

beam.results

The output includes for a Beam object:

  • Top and bottom longitudinal reinforcement.

  • Shear reinforcement.

  • Applied moments and shear forces.

  • Design capacity ratios (DCR).

  • Warnings (if any).

The output is formatted using LaTeX math notation for clarity and precision. See the Beam section for more information on how to display results. The results are presented in a user-friendly format, with color-coded Demand-Capacity Ratios (DCR) for quick assessment.

4. Design the section#

If you don’t assign transverse or longitudinal rebar, you can ask Mento to design for shear and flexure. Mento will apply corresponding design code formulas depending on the type of Concrete object created for all the forces assigned and store the limiting case for shear and top and bottom bending moment.

After performing the numerical design, Mento will assign the optimal rebar combination of stirrups and longitudinal reinforcement, considering all the longitudinal positions in the beam. This optimizations takes into account the default settings for longitudinal rebar limitation (vibrator size, maximum rebar diameter difference) and engineering criteria to suggest the best rebar configuration balancing the amount of rebars, layers and different diameters.

Mento will also create a Pandas DataFrame with all the check results for each Load Case in the Force object assigned to the Node, both for shear and flexure analysis. You can print those results from the previous method.

  • Shear Design: Use design_shear().

# Perform shear design and show DataFrame with results
node_1.design_shear()
shear_results

  • Flexure Design: Use design_flexure().

You can see the best rebar configuration designed by Mento when you print beam.results un a Jupyter Notebook.

beam.results

5. Detailed Results#

For more detailed results, you can use the following methods:

  • Shear Results: Use shear_results_detailed().

  • Flexure Results: Use flexure_results_detailed().

These methods provide a comprehensive breakdown of the calculations, which can be useful for reporting or further analysis. This results will print in the Terminal or in a Jupyter Notebook the same way.

# View detailed shear results
node_1.shear_results_detailed()
# View detailed flexure results
node_1.flexure_results_detailed()

You can also print the detailed results for the analysis of a specific force if you pass it as an input:

# Print detailed results for shear, for specific force
node_1.shear_results_detailed(f1)
# Print detailed results for flexure, for specific force
node_1.flexure_results_detailed(f1)

If you want to save the detailed results as a report in Microsoft Word, just run the following methods instead:

# View detailed shear results
node_1.shear_results_detailed_doc()
# View detailed flexure results
node_1.flexure_results_detailed_doc()

6. Force methods#

The Node class provides the following methods for changing the Forces assigned to it:

  • Add a force: Use add_forces(forces).

  • Get list of forces: Use get_forces_list().

  • Clear forces: Use clear_forces().

# Add a single force
force1 = Forces(label='D', V_z=10*kN)
node_1.add_forces(force1)
# Add multiple forces
force2 = Forces(label='L', V_z=20*kN)
force3 = Forces(label='W', V_z=30*kN)
node_1.add_forces([force2, force3])
# Get forces list.
forces_list = node_1.get_forces_list()
# Print each force item in the list
for force in forces_list:
    print(f"Label: {force.label}, N_x: {force._N_x}, V_z: {force._V_z}, M_y: {force._M_y}")
# Remove forces from the node
node_1.clear_forces()