  Here is the Python code that performs the tasks you specified using the TACS library:
```
import numpy as np
import os
from mpi4py import MPI
from tacs import TACS, BDF, MeshLoader, Element, Assembler, Function, Variables, AnalysisFunction, OutputViewer

# Import necessary libraries

# Load a structural mesh from a BDF file
mesh = BDF.load_mesh('mesh.bdf')

# Set constitutive properties
density = 1.0
elastic_modulus = 100.0
poisson_ratio = 0.3
shear_correction_factor = 1.0
yield_stress = 100.0
thickness = 0.1

# Loop over components of the mesh, creating stiffness and element object for each
for comp in mesh.components:
    stiffness = Element.Stiffness(comp.num_nodes, comp.num_elements, comp.num_vars)
    element = Element.Element(comp.num_nodes, comp.num_elements, comp.num_vars, stiffness)
    element.set_density(density)
    element.set_elastic_modulus(elastic_modulus)
    element.set_poisson_ratio(poisson_ratio)
    element.set_shear_correction_factor(shear_correction_factor)
    element.set_yield_stress(yield_stress)
    element.set_thickness(thickness)
    comp.set_element(element)

# Create a TACS assembler object from the mesh loader
assembler = Assembler.createTACSAssembler(mesh)

# Create a KS function and get the design variable values
ks_function = Function.createTACSFunction(assembler)
design_vars = ks_function.getDesignVars()

# Get the node locations and create the forces
node_locations = assembler.getNodeLocations()
forces = assembler.getForces()

# Set up and solve the analysis problem by creating vectors, assembling the Jacobian, factoring, and solving the linear system
variables = Variables.createTACSVariables(assembler)
analysis_function = AnalysisFunction.createTACSAnalysisFunction(assembler)
analysis_function.setDesignVars(design_vars)
analysis_function.setNodeLocations(node_locations)
analysis_function.setForces(forces)
analysis_function.setUp()
analysis_function.solve()

# Evaluate the function and solve for the adjoint variables
function_value = analysis_function.evaluate()
adjoint_variables = analysis_function.getAdjointVariables()

# Compute the total derivative with respect to material design variables and nodal locations
total_derivative = analysis_function.compute_partials()

# Create a random direction along which to perturb the nodes and compute the total derivative with respect to nodal locations
perturb_direction = np.random.rand(3)
perturbed_solution = analysis_function.perturb(perturb_direction)
perturbed_function_value = analysis_function.evaluate()
perturbed_total_derivative = analysis_function.compute_partials()

# Set the complex step and compute the perturbed solution
complex_step = 1e-10
perturbed_solution = analysis_function.perturb(perturb_direction, complex_step)
perturbed_function_value = analysis_function.evaluate()
perturbed_total_derivative = analysis_function.compute_partials()

# Evaluate the function for the perturbed solution and compute the projected derivative
projected_derivative = analysis_function.project_derivative(perturbed_total_derivative)

# Output the results for visualization
output_viewer = OutputViewer.createTACSOutputViewer(assembler)
output_viewer.write_output('output.bdf')
```
Note that this code assumes that you have already installed the TACS library and have the necessary dependencies installed. Additionally, this code assumes that you have a BDF file named `mesh.bdf` in the same directory as the Python script.