Two Wide Flange Beams Stitch Welded as Column, Torsion Properties
Two Wide Flange Beams Stitch Welded as Column, Torsion Properties
(OP)
In my industry, fairly tall columns (~50ft) are required with no possibility of bracing and a common style is two wide flange beams stitch welded in a "T" formation as shown below. Required corrosion allowance renders some of these column elements slender as well. It seems that using ASIC 360-16 E7 and E4(b) is correct. A few questions:
Is J = the sum of (b*t^3)/3 accurate with this open built-up section? (Per AICS Design Guide 9)
How do I calculate Cw of the built-up section?
Is there an easy way to calculate the location of the shear center?
Is J = the sum of (b*t^3)/3 accurate with this open built-up section? (Per AICS Design Guide 9)
How do I calculate Cw of the built-up section?
Is there an easy way to calculate the location of the shear center?
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RE: Two Wide Flange Beams Stitch Welded as Column, Torsion Properties
https://sectionproperties.readthedocs.io/en/latest...#
I forget who is the expert around here tho. I'm sure they'll show up.
Best of luck!
RE: Two Wide Flange Beams Stitch Welded as Column, Torsion Properties
I believe that it would be as accurate as in many other situations. It's always an approximation I think. I wouldn't sweat getting too accurate with this as warping stiffness will probably dominate your twist resistance.
I'd pretend that the section is nothing more than the three flanges shown in the first sketch below to get a reasonable, lower bound estimate. Use that to estimate a center of rotation and then the twist stiffness offered by each flange flexed about its own strong axis. Kinda like shear wall analysis in short buildings.
For many purposes, I'd deem it sufficient to plop the SC right along the two strongest lines of flexural resistance in each direction. This one's a bit tricky though in that, depending on what your doing with the shear center, different estimates may be lower bound for different things. Some judgment is required.
With stuff like this, I try not to get too lost in the weeds of mathematical complexity. How you introduce the load to the member at the top and exit the load at the bottom may wall muddy up some of the results of our spiffy math and FEM munching anyhow.
RE: Two Wide Flange Beams Stitch Welded as Column, Torsion Properties
RE: Two Wide Flange Beams Stitch Welded as Column, Torsion Properties
RE: Two Wide Flange Beams Stitch Welded as Column, Torsion Properties
I literally just started a series of posts on my personal blog on built up section properties because the subject always seems to pop up here. You might find it of interest.
Here is a script for running with the sectionproperties python package that does exactly what you are after. Just change the inputs to suit.
CODE --> python
import copy import sectionproperties.pre.sections as sections from sectionproperties.analysis.cross_section import CrossSection # ------------------------------------------------------------- # Inputs # ------------------------------------------------------------- top_flg = False d = 612 # I-section depth b_f = 229 # I-section flange width t_f = 19.6 # I-section flange thickness t_w = 11.9 # I-section web thickness r_1 = 14 # I-section root radii d_1 = 612 # strengthening I-Section depth b_f1 = 229 # strengthening I-Section flange width t_f1 = 19.6 # strenghtening I-Section flange thickness t_w1 = 11.9 # strengthening I-Section web thickness r_2 = 14 # strengthening I-Section root radii gap = 0.3 # gap between I-Sections weld_size = 10 # weld size n_r = 20 # number of points considered around root radii mesh_area = 10 # max mesh size # ------------------------------------------------------------- # Calculations # ------------------------------------------------------------- # create constituent geometry # weld base geometry weld = sections.CustomSection( points=[[0, 0], [weld_size, 0], [0, weld_size]], facets=[[0, 1], [1, 2], [2, 0]], holes=[], control_points=[[weld_size / 3, weld_size / 3]] ) if d_1 > b_f and not gap == 0: weld_vert_move = -gap else: weld_vert_move = 0 # I-Section beam geometry1 = sections.ISection(d=d, b=b_f, t_f=t_f, t_w=t_w, r=r_1, n_r=n_r, shift=[-b_f / 2, -d / 2]) # strengthening I-Section if top_flg: geometry2 = sections.ISection(d=d_1, b=b_f1, t_f=t_f1, t_w=t_w1, r=r_2, n_r=n_r, shift=[-b_f1 / 2, d / 2 - d_1 / 2 + gap + t_w1 / 2]) geometry2.rotate_section(angle=-90, rot_point=[0, d / 2 + gap + t_w1 / 2]) else: geometry2 = sections.ISection(d=d_1, b=b_f1, t_f=t_f1, t_w=t_w1, r=r_2, n_r=n_r, shift=[-b_f1 / 2, -d / 2 - d_1 / 2 - gap - t_w1 / 2]) geometry2.rotate_section(angle=-90, rot_point=[0, -d / 2 - gap - t_w1 / 2]) # weld 1 & 2 geometry3 = copy.deepcopy(weld) if b_f > d_1: geometry3.mirror_section(axis='x', mirror_point=[0, 0]) geometry3.shift = [min(d_1 / 2, b_f / 2), -d / 2 + weld_vert_move] geometry3.shift_section() geometry4 = copy.deepcopy(geometry3) geometry4.mirror_section(axis='y', mirror_point=[0, 0]) if top_flg: geometry3.mirror_section(axis='x', mirror_point=[0, 0]) geometry4.mirror_section(axis='x', mirror_point=[0, 0]) # total number of individual geometry elements geo_number = 4 # assemble geometry list geo_list = [globals()[f'geometry{i}'] for i in range(1, geo_number + 1)] # create merged section geometry = sections.MergedSection(geo_list) # add holes for gaps between I-Section and strengthening tee if not gap == 0: if top_flg: geometry.add_hole([0, d / 2 + gap / 2]) else: geometry.add_hole([0, -d / 2 - gap / 2]) # clean geometry geometry.clean_geometry(verbose=True) # create mesh mesh = geometry.create_mesh(mesh_sizes=[mesh_area] * geo_number) # create section section = CrossSection(geometry, mesh) # calculate results section.calculate_geometric_properties() section.calculate_plastic_properties() section.calculate_warping_properties() # ------------------------------------------------------------- # Display results # ------------------------------------------------------------- # plot results section.plot_mesh() section.plot_centroids() # display all results # check https://sectionproperties.readthedocs.io/en/latest/rst/post.html for definitions section.display_results(fmt='.3f')https://engineervsheep.com
RE: Two Wide Flange Beams Stitch Welded as Column, Torsion Properties
https://engineervsheep.com
RE: Two Wide Flange Beams Stitch Welded as Column, Torsion Properties