CBFEM Base Plate

3D Shell FEM with Column Stub

Plate Geometry▼

Length X (in) ?Base plate dimension in the X direction (parallel to column web for W-shapes).

Length Z (in) ?Base plate dimension in the Z direction (parallel to column flanges for W-shapes).

Thickness (in) ?Plate thickness. Thicker plates distribute loads more evenly but add weight and cost. The analysis models this as shell elements with this thickness.

Fy (ksi) ?Plate steel yield strength. ASTM A36 = 36 ksi, A572 Gr50 = 50 ksi. Used for plate stress utilization check.

Column▼

Type

Stub Height ?Height of the column stub modeled above the base plate. This captures the local stiffness effects at the column-to-plate interface. 6" is typically sufficient.

Depth (in) ?Column depth (d) - the dimension parallel to the web. For W8×31: d = 8.0"

Width (in) ?Column flange width (bf). For W8×31: bf = 8.0"

Flange t ?Column flange thickness (tf). For W8×31: tf = 0.435"

Web t ?Column web thickness (tw). For W8×31: tw = 0.285"

Stiffeners▼

Stiffener Fins ?Outside-flange stiffener plates welded to column flanges. Reduces prying action and plate bending under heavy moment loading.

Height (in) ?Vertical extent of stiffener fins above the base plate.

Thickness (in) ?Plate thickness of stiffener fins.

Extension (in)

Applied Loads▼

Axial P (kip) ?Axial load at column top. Positive = compression (pushing down). Applied at the centroid of the column stub top.

+ = compression

Mx (k-in) ?Moment about the X-axis (causes rotation about X, bending in the Y-Z plane). Right-hand rule applies.

Mz (k-in) ?Moment about the Z-axis (causes rotation about Z, bending in the X-Y plane). This is the primary overturning moment for most designs.

My (k-in) ?Torsion about the Y-axis. Distributes shear to bolts via elastic bolt group analysis. Used in bolt shear + interaction checks.

Vx (kip) ?Shear force in the X direction. Distributed to bolts via elastic bolt group analysis.

Vz (kip) ?Shear force in the Z direction. Distributed to bolts via elastic bolt group analysis.

Bolts & Concrete▼

Bolt Pattern ?Select a preset pattern or choose Custom to define bolt positions manually.

Offset X (in) ?Horizontal distance from plate center to bolt columns.

Offset Z (in) ?Vertical distance from plate center to outermost bolt rows.

#	X (in)	Z (in)

Bolt Dia. ?Anchor bolt diameter. Used to calculate bolt stiffness: k = E·A / L where A = π·d²/4.

Bolt Length ?Effective length of anchor bolt (embedment + stretch length). Affects bolt stiffness - longer bolts are more flexible.

Bolt Grade ?Anchor bolt material grade. Affects bolt E, Fy, Fu, and nominal shear/tension strengths for capacity checks.

f'c (ksi) ?Concrete compressive strength. Used to calculate the modulus of subgrade reaction: ks = Ec / effective_depth, where Ec = 57000·√(f'c psi).

Custom ks (ksi/in)

ks (ksi/in) ?Override the automatic subgrade modulus calculated from f'c. Useful for specific soil/foundation conditions.

Mesh Density ?Number of elements along each plate edge. Higher values give more accurate results but slower analysis. 8-12 is typically sufficient.

Mesh Type ?Uniform: equal-sized elements everywhere. Graded: smaller elements near column flanges and bolts for better accuracy in critical regions.

Growth Ratio ?Element size ratio between adjacent zones. 1.0 = uniform, 2.0 = double size per zone. Controls mesh grading intensity.

Min Subdivisions ?Minimum number of element subdivisions per gap between features. Higher values ensure adequate resolution near bolts and flanges.

Parameter Sweep▼

Parameter

Start

End

Count

How It Works Disclaimer

CBFEM Base Plate

Results

Bolt Forces

CBFEM Base Plate

Results

Bolt Forces

Analysis Log

Important Disclaimer & Limitations

DEMONSTRATION SOFTWARE ONLY

NO WARRANTY OR GUARANTEE

NOT FOR PROFESSIONAL USE

LIMITATION OF LIABILITY

USER RESPONSIBILITY

How This Analysis Works

Overview

Finite Element Model

Contact & Nonlinearity

Results