Design a Wood Column to CSA O86 - Calcs.com Documentation

CanadaCSA O86:19NBCC 2015Wood Design Manual 2017

Wood Column

The Calcs.com timber column calculator to CSA O86 enables the fast and accurate design of wood columns and studs to Canadian standards. With support for dynamic load linking between beams and columns, easily design accurate and quality engineered columns.

The Calcs.com Timber Generic Concentrically Loaded Column Calculator allows users to design timber columns by specifying the desired load cases and dimensions of the column assuming concentric loading. In this article, a worked example comes first, followed by an explanation of each section of the calculator. The Timber Column Calculator has 4 main sections

Key Properties
Loads
Design Conditions
Summary and Graphs

Worked example

Example 1: concentrically loaded column

A 3 m timber column with blocking every 1 m carries an axial load at the top. The steps below use the conditions in the image.

Example Column #1, concentrically loaded: a 3000 mm column with a roller support at the top and a fixed base, with blocking along the weak axis every 1000 mm, under axial line loads G of 14 kN/m and Q of 15 kN/m. Conditions listed: 3 m height with blockings along the weak axis every 1 m, Douglas Fir No1/No2, fixed base and a roller support at the top, axial line loads with 0.6 m stud spacing, zero eccentricity, self-weight included, dry service conditions, untreated with no load sharing.

The conditions are:

3 m in height with blockings (along the weak axis) every 1 m
Member type: Douglas Fir, No1/No2
Supports: fixed base and a roller support at the top
Axial line loads: dead load G = 14 kN/m and live load Q = 15 kN/m, with 0.6 m stud spacing
Assume zero eccentricity
Include self-weight
Assume dry service conditions, untreated with no load sharing

Open the Generic Concentrically-Loaded Column preset

In your project, choose Add New Calculation, select CA, choose Wood Column under Columns, then choose Generic Concentrically-Loaded Column.

Add a new calculation window for Canada with Wood Column selected under Columns and its six presets listed below, starting with Generic Concentrically-Loaded Column.

Choose the member

Select Select… under Size and Grade, type 2x8 in the search box, and choose 2x8 [38x184] D.Fir-L No.1/No.2.

Size and Grade dialog with 2x8 typed in the search box, listing twelve 2x8 [38x184] sections with the D.Fir-L No.1/No.2 row highlighted and a badge for each check.

Check the height and the bracing

Number of Plies stays at 1 and Column Height stays at 3000 mm. The three continuous bracing choices stay at No.

Key Properties section with a 2x8 [38x184] D.Fir-L No.1/No.2 section, one ply, a Column Height of 3000 millimeters, and Continuous Bracing for Strong Axis Buckling, Weak Axis Buckling and Lateral Torsional Buckling all set to No.

Set the supports

In the Position of Supports & Braces from Bottom table, set the first support to Fixed (Base) at 0 mm and the second to Roller (Axial Free) at 3000 mm. For the blocking every 1 m, add two rows: Weak Axis Brace at 1000 mm and Weak Axis Brace at 2000 mm.

Position of Supports & Braces from Bottom table with a Fixed (Base) support at 0 millimeters, a Roller (Axial Free) support at 3000 millimeters, and two Weak Axis Brace rows at 1000 and 2000 millimeters.

Set the axial load

The load on one stud is the line load times the stud spacing: 14 kN/m × 0.6 m = 8.4 kN of dead load and 15 kN/m × 0.6 m = 9 kN of live load. In the Axial, Lateral & Moment Loads about X-axis table, select Edit… on the Floor Load row at 3000 mm. In the Load Magnitudes window, enter 8.4 kN for the (D) Dead Load and 9 kN for the (L) Live Load under Y-Direction Axial Load. The X-Direction Lateral Load and the Moment Load stay at 0.

Load Magnitudes window for an axial load with the Dead Load at 0 kilonewtons lateral, 8.4 kilonewtons axial and 0 moment, and the Live Load at 0 kilonewtons lateral, 9 kilonewtons axial and 0 moment.

Check the rest of the loads

The load diagram shows the floor load at the top of the column, the self-weight and the two weak axis braces. The Default Load Eccentricity for Bending about X-axis stays at 0 mm, the Lateral Distributed Loads table stays empty, and Include Self-weight stays Yes.

Loads section with a load diagram of the 3 meter column showing the floor load at the top, the self-weight and two weak axis braces, a Default Load Eccentricity for Bending about X-axis of 0, the axial load row at 3000 millimeters, an empty Lateral Distributed Loads table, and Include Self-weight set to Yes.

Check the design conditions

The preset already has Dry for Service Condition, Untreated for Treatment, and No system factor. Storage Live Load is No, the deflection limits are 20 mm absolute, 240 for live and short-term, and 360 for long-term, and Check Bottom Plate Bearing is No. Leave them as they are.

Design Conditions section with Service Condition set to Dry, Treatment set to Untreated, System Factor set to No system factor, Storage Live Load set to No, an absolute deflection limit of 20 millimeters, deflection ratio limits of 240 and 360, and Check Bottom Plate Bearing set to No.

Read the results

The Summary lists the factored compressive load and the factored compressive resistance, with a utilization badge, and the governing load combination. Below it, the graph shows the axial load along the column, and the diagram shows the axial load and the reaction at the base. The badges at the top of the sheet show the compression and governing checks.

Summary section listing the factored compressive load parallel to grain, the factored compressive resistance with a utilization badge, the governing load combination and a Graphed Load Combination dropdown, with a graph of the axial load along the column and a diagram of the column showing the axial load and the reaction at its base.

Look at the effective length

Open Compressive Resistance Parallel to Grain (CSA O86:19 Section 6.5.5). The effective length table has three span rows. The X length is 3000 mm in the first span and the Y length is 1000 mm in each span, because the weak axis braces split the weak axis into three spans. The panel then gives a resistance for each axis, and the lower one is the factored compressive resistance.

Compressive Resistance Parallel to Grain panel with the load-duration and size factors, an effective length table with three spans, the slenderness ratios and factors for the X and Y axes, and the factored compressive resistance for each axis.

Inputs, Calcs.com output and a hand check

Inputs

Section2x8 [38x184]

Species and gradeD.Fir-L No.1/No.2

Number of plies1

Column height L3000 mm

Continuous bracingNone

Base supportFixed, 0 mm

Top supportRoller, 3000 mm

Weak axis braces1000 mm, 2000 mm

Dead line load G14 kN/m

Live line load Q15 kN/m

Stud spacing0.6 m

Axial load at 3000 mm, D8.4 kN

Axial load at 3000 mm, L9 kN

Eccentricity0

Self-weightIncluded (D 0.0336 kN/m)

Service conditionDry

TreatmentUntreated

System factorNone

Calcs.com output

Factored compressive load

P_f

24.1 kN

Factored compressive resistance

P_r

43.3 kN (56%)

Resistance, X-axis

P_{rx}

69.1 kN

Resistance, Y-axis

P_{ry}

43.3 kN

Slenderness ratio, X-axis

C_{cx}

16.3

Slenderness ratio, Y-axis

C_{cy}

26.3

Slenderness factor, X-axis

K_{cx}

0.781

Slenderness factor, Y-axis

K_{cy}

0.425

Governing load combination1.25D + 1.5L

Governing badge56%

Reaction at the base24.1 kN

Hand check

Load on one stud: 14(0.6) = 8.4 kN dead and 15(0.6) = 9 kN live

Dead load with self-weight: 8.4 + 0.0336(3) = 8.50 kN

P_f = 1.25(8.50) + 1.5(9) =

24.1 kN, which matches the sheet’s

P_f

and the reaction at the base

Slenderness ratios:

L_{ex} / d = 3000 / 184 =

16.3 and

L_{ey} / b = 1000 / 38 =

26.3

Utilization:

P_f / P_r = 24.1 / 43.3 =

0.56

This is a sanity check on the factored load, the reaction and the slenderness ratios only. It uses the 1.25D + 1.5L load combination shown in the Summary. Calculator version 24, Generic Concentrically-Loaded Column preset.

Method & scope

Property	Detail
Design standards	CSA O86:19, NBCC 2015, Wood Design Manual 2017, American Wood Council Technical Report 14
Regions	Canada
Presets	Generic Concentrically-Loaded Column, Interior Isolated Column, Exposed Outdoor Isolated Column, Interior Stud Wall, Exterior Stud Wall, Jack Stud
What it checks	Structural model and load combinations, Axial compressive resistance (CSA O86:19 Cl.6.5.5.2.4), Bending moment resistance (CSA O86:19 Cl.6.5.3.1 and Cl.7.5.6.5.1), Combined bending and axial interaction (CSA O86:19 Cl.7.5.12), Shear resistance (CSA O86:19 Cl.6.5.4.3), Bearing perpendicular to grain (CSA O86:19 Cl.6.5.6.2)
Key assumptions	As listed in the calculator’s Sheet Details: 1. Members are straight, prismatic (not-tapered) and not notched. 2. In built-up columns where the number of plies causes the depth to be greater than the width, strong and weak axes refer to the axes for individual plies. 3. Bearing is not considered at point loads. 4. Individual members of built-up columns are fastened together per CSA O86 requirements. 5. For glulam, the CSA O86 simplified shear resistance method is used. 6. The special bearing provisions for loads near supports are not considered. 7. ClearCalcs [Now Calcs.com] doesn’t apply importance factors to load combinations. 8. The X axis corresponds to the member major axis. In multi-ply members, this refers to the individual plies’ major axis.

See the exact clause

Every check in this calculator links back to its governing clause in CSA O86. Open the Formula Reference panel on any result and select the clause reference to read it. See Viewing Clauses from Inside a Calculator.

Symbols

These are the symbols used on this page. The names for the sheet’s inputs and results are the labels the calculator shows; the others are as described in the sections below and in the calculator’s explanations.

Symbol	Meaning
$n_{plies}$	Number of Plies
$L$	Column Height
$b$	Width of the section
$d$	Depth of the section
$e_x$	Default Load Eccentricity for Bending about X-axis
$e_y$	Default Load Eccentricity for Bending about Y-axis
$P_x$	X-Direction Lateral Load
$N_y$	Y-Direction Axial Load
$M$	Moment Load
$P_f$	Factored Compressive Load Parallel to Grain
$P_r$	Factored Compressive Resistance Parallel to Grain, the minimum of $P_{rx}$ and $P_{ry}$
$P_{rx}$ , $P_{ry}$	Factored Compressive Resistance Parallel to Grain for the X-axis and the Y-axis
$LC_{gov}$	Governing Load Combination
$L_x$ , $L_y$	X and Y Unbraced Length
$K_{ex}$ , $K_{ey}$	Override X and Y Effective Length Factor
$L_{ex}$ , $L_{ey}$	X and Y Effective Length
$C_c$ , $C_{cx}$ , $C_{cy}$	Slenderness ratio, for each axis
$K_c$ , $K_{cx}$ , $K_{cy}$	Slenderness factor, derived from the slenderness ratio for each axis
$K_{Dc}$	Load-Duration Factor for Compression Parallel to Grain
$K_{Zcx}$ , $K_{Zcy}$	Size Factor for Compression Parallel to Grain, X-axis and Y-axis
$\Delta_{max}$	Absolute Deflection Limit
$(L/)_{ST}$ , $(L/)_{LT}$	Live / Short-term and Long Term Deflection Ratio Limit
$G$ , $Q$	Dead (permanent) and live (imposed) line load in the worked example
$P^*$	Factored axial load on the column in the hand check
$K_D$	Load-duration factor
$K_L$	Lateral stability factor
$F_c$	Characteristic compressive strength parallel to grain
$K_H$	System factor
$K_{Scp}$	Service-condition factor for compression
$K_T$	Treatment factor
$M_r$ , $M_{rx}$ , $M_{ry}$	Factored bending resistance, overall and for the X-axis and the Y-axis
$F_b$	Adjusted bending strength
$M_{fx}$ , $M_{fy}$	Factored bending moments about the strong and weak axes
$Q_{rp}$	Factored bearing resistance perpendicular to grain
$F_{cp}$	Characteristic compressive strength perpendicular to grain

Calculation method

Structural model and load combinations

The calculator models the wood column as a member under combined axial compression and biaxial bending. Loads are entered by type, dead (D), live (L), snow (S), wind (W), and the calculator generates all governing NBCC 2015 / CSA O86:19 strength load combinations. Bending moments can be entered directly or received via load linking from beam calculations above.

Axial compressive resistance (CSA O86:19 Cl.6.5.5.2.4)

Factored compressive resistance

P_r

is computed from the characteristic compressive strength

F_c

parallel to grain, adjusted by:

$K_H$ , system factor
$K_{Scp}$ , service-condition factor for compression
$K_T$ , treatment factor
$K_c$ , slenderness factor, derived from the slenderness ratio $C_c$ for each axis

The slenderness ratio $C_c$ is computed for both the X-axis and Y-axis independently per Cl.6.5.5.2.2. The governing (largest) ratio controls the slenderness factor

K_c

, reducing compressive resistance for slender members. For multi-ply columns, Cl.6.5.5.4 applies additional reduction factors based on the ply connection method. compression utilization

= P_f / P_r \le 1.0

Bending moment resistance (CSA O86:19 Cl.6.5.3.1 and Cl.7.5.6.5.1)

Factored bending resistance

M_r

is computed for both the X-axis and Y-axis using adjusted bending strength

F_b

. The lateral stability factor (Cl.7.5.6.5.1) accounts for buckling of the compression face and is applied independently for each axis.

Combined bending and axial interaction (CSA O86:19 Cl.7.5.12)

When both axial compression and bending moments are present, the calculator checks the biaxial interaction equation per CSA O86:19 Cl.7.5.12, using the formulation from AWC Technical Report 14: interaction utilization

= P_f / P_r + M_{fx} / M_{rx} + M_{fy} / M_{ry} \le 1.0

Where

M_{fx}

and

M_{fy}

are the factored bending moments about the strong and weak axes respectively. This single interaction check governs over the individual axial and bending utilizations when moments are present.

Shear resistance (CSA O86:19 Cl.6.5.4.3)

Shear resistance is checked independently for forces applied in each direction, using the same adjustment factors applied to the bending checks.

Bearing perpendicular to grain (CSA O86:19 Cl.6.5.6.2)

At the base of the column or wherever the member bears on a sill plate or other perpendicular-grain surface, factored bearing resistance

Q_{rp}

is computed from the characteristic compressive strength perpendicular to grain

F_{cp}

, adjusted for service condition and treatment.

Load linking

The column’s axial reaction at its base is exported as a linked output to connected footing calculations. Axial load at the top can be linked from beam reactions above, so the full load path, beam to column to footing, updates automatically when any upstream input changes.

How to use it

Key Properties

Size and GradeIn Calcs.com, you can select the size of the member you want from a list of industry-standard sized members by using the “Select” button. Using the corresponding filters, you can view available options based on the chosen type, species, grade, manufacturer, and nominal size of the column. You can also type in the search box at the top of the dialog, or set a maximum width and depth. Each row shows the member’s width, depth, species and grade, with a badge for each check. If the species or grade you need is not listed, use the link at the bottom of the dialog to let us know.

Size and Grade dialog with a search box, filters for type, manufacturer, species, nominal size and grade, maximum width and depth fields, and a list of 6x8 and 8x8 sections showing width, depth, species, grade and utilization badges for the X-axis bending, Y-axis bending, compression, interaction and governing checks.

Number of PliesThe number of timber laminates in the column. This quantity needs to be either equal to or greater than 1. Built-up columns are essentially limited to 5 plies by CSA O86:19. When there is more than one ply, a Built-up Member Fastener System dropdown appears. Choose the fastener type so that Calcs.com can factor in the appropriate built-up column strength reduction factor. If the number of plies makes the total width greater than the depth of one ply, the strong and weak axis designations stay aligned with the axes of the individual plies. Lateral-torsional buckling stability is not checked in the weak axis direction, so the strictest bracing requirements in CSA O86:19 are followed when loads are present in the weak axis direction.

Number of Plies set to 2, with a Built-up Member Fastener System dropdown below it set to Nails or spikes.

Column HeightThe total height of the column, in millimeters (mm) or feet (ft).Lateral Restraint ConditionsYou are prompted to specify whether the following conditions exist for the column that is being designed.

Continuous Bracing for Strong Axis Buckling: setting this to Yes sets the effective length equal to zero. It is conservative to assume that the column is not braced.
Continuous Bracing for Weak Axis Buckling: setting this to Yes sets the effective length equal to zero. This is often used for a sheathed stud wall. It is always conservative to assume that the column is not braced.
Continuous Bracing for Lateral Torsional Buckling: setting this to Yes disables all lateral stability checks in bending ( $K_L = 1$ ), as is often the case in stud walls. If the column is subject to both positive and negative bending, both sides are considered fully braced when this is Yes. It is conservative to assume that the column is not braced.

Discrete bracing conditions can be specified in the Position of Supports & Braces from Bottom table below. It is assumed that lateral bracing is provided at pinned, fixed, or roller connections.Position of Supports and Braces from BottomSelect the support type or bracing type from a drop-down menu and then specify the location of each support or brace in feet (ft) or millimeters (mm) as measured from the bottom of the column. The Support Type options are Pinned (Base), Fixed (Base), Roller (Axial Free), Weak Axis Brace, Strong Axis Brace and Lateral Brace (Bending). Base supports take all the axial loads above them and do not transmit them under. Rollers resist lateral loads only, serving as beam supports, and also brace against buckling in both axes, so they suit an intermediate support in a column. Weak axis braces and strong axis braces provide bracing for buckling in compression, while lateral braces provide bracing against lateral-torsional buckling.

Support Type dropdown open in the Position of Supports & Braces from Bottom table, listing Pinned (Base), Fixed (Base), Roller (Axial Free), Weak Axis Brace, Strong Axis Brace and Lateral Brace (Bending).

Loads

Load DiagramThe load diagram provides a live illustration of the column and the assigned loading.EccentricityGenerally, axial loads (i.e., loads acting vertically downwards) act through the center of a column. However, in some cases, the load can act off the center of the column and cause bending in addition to compression of the column. Axial load eccentricity refers to the horizontal distance between the center of the column and the line of action of the axial load.The default load eccentricity for bending about the X-axis is set to zero (i.e. no bending, pure compression is assumed). If you wish to change this, enter the new load eccentricity in inches (in) or millimeters (mm). Positive values bias the load to the right of the column, and negative values bias it to the left. Typically, many will consider using an eccentricity of 1/6th of the depth to accommodate for construction flexibility and connections, and this is recommended and usually required for SCL. You can override the eccentricity for individual loads in the table below, or enter the moment load manually and set the eccentricity to 0.Axial, Lateral and Moment Loads about the X-axisTo enter an axial, point or moment load, fill out the table. The first column refers to the name of the load, which you can decide. Then enter the location at which the load acts on the column, as measured from the bottom of the column (in feet or millimeters). The third column refers to the axial eccentricity of the load. By default, this is set to the Default Load Eccentricity above but can be changed. When you click the fourth column or the “Edit” text, the Load Magnitudes window appears.In this window, select the load type from the drop-down menu and specify the magnitude of the load in the X direction (lateral load) and the Y direction (axial load) in pounds (lb) or kilonewtons (kN), and enter any moment loads in pound-feet (lb-ft) or kilonewton-meters (kN-m). Additionally, the link button can be used to import the loads from another calculation or sheet.Enter the loads unfactored. The load combinations are then generated automatically in accordance with NBCC 2015, or as set in the custom defaults. Calcs.com does not automatically apply load importance factors to the entered loads, so apply them manually when entering the value (or using a custom formula) in the relevant input fields for snow, wind and earthquake loads. Uplift wind forces (Wu,up) should be positive. Each row of the table is a single location, and as many rows as you need can be added. Axial loads are added together with the axial loads entered in the equivalent table for Y-axis loads.

Load Magnitudes window for an axial load with a load type, an X-Direction Lateral Load in kilonewtons, a Y-Direction Axial Load in kilonewtons and a Moment Load in kilonewton-meters on each row, with the Dead Load and Live Load rows filled in.

Lateral Distributed LoadsThis table is for distributed loads that act in the X direction (i.e. perpendicular to the column), such as wind on a column. Like the axial loads table, the first column prompts you to name the load. Then specify the start and end location of the distributed load, as measured from the bottom of the column, in feet (ft) or millimeters (mm). Then enter the start and end width of the load in feet (ft) or millimeters (mm). A triangular load is entered by using a different load width at the start than at the end, and the tributary width must be greater than zero. When you select the fourth column or the “Edit” text, the Load Magnitudes window appears.Select the load type from the drop-down menu in the first column: Wind Down (Wu,dn) applies the load toward the left of the diagram, and Wind Up (Wu,up) applies it toward the right. Then specify the load magnitude per area in pounds per square foot (psf) or kilopascals (kPa). Additionally, the link button can be used to import the loads from another calculation or sheet.

Load Magnitudes window for a lateral distributed load with the load types (Wu,dn) ULS Wind Down and (Wu,up) ULS Wind Up, each with an empty magnitude per area in kilopascals.

Self-WeightYou can choose whether to include the self-weight of the column in your calculations. The calculator is set to include the self-weight by default unless you specify otherwise.Weak Axis LoadsThe weak axis is the weaker orientation of a column that results in a smaller moment of inertia when compared to the strong axis. The Weak Axis Loads section follows the same format as the strong axis loading. In this section, you only need to input the moment and lateral loads relevant to the weak axis. To set an eccentricity about the weak axis, use the Default Load Eccentricity for Bending about Y-axis at the top of the section.

Weak Axis Loads section with a load diagram of the column, the Default Load Eccentricity for Bending about Y-axis, the Lateral & Moment Loads about Y-axis table, and the Lateral Distributed Loads about Y-axis table.

Cross-section of a column with the x-x axis horizontal and the y-y axis vertical, labeled Strong Axis: x-x and Weak Axis: y-y.

Design Conditions

Design Code for Load Combinations: Shows the design code used for the load combinations, the National Building Code of Canada (2015). It may be changed in the Project Defaults sheet for the project, and it cannot be changed in an individual calculation.
Design Standard Edition Note: A note that the calculation is based on the 2019 edition of the CSA O86 wood design standard, while the NBCC 2015 specifies the 2014 edition.
Service Condition: You can select if the service condition is ‘dry’ or ‘wet.’ It is considered dry if the average equilibrium moisture content of the wood is 15% or less on average over a year without exceeding 19%. Wet service conditions are all other service conditions, and most often apply only to exterior use. Structural composite lumber (LVL, PSL, etc.) products are not to be used in wet conditions.
Treatment: Indicate if the wood column is untreated, or preservative-treated, and whether it is incised or non-incised. The options are Untreated, Preservative-treated non-incised and Preservative-treated incised. The treatment factor depends on the incising and treatment of the lumber, and appears as an adjustment factor in the Modulus of Elasticity, Bending Moment Resistance, Shear Resistance and Bearing sections.
System Factor: A system factor is considered if the member is part of a system where loads can be shared. It magnifies the design resistance based on the arrangement of members and the presence of sheathing, and appears in the Bending Moment Resistance and Shear Resistance sections as an adjustment factor. There are three options.
- No system factor: There are less than 3 columns spaced 610mm apart and/or are not mutually sharing loads
- Case 1: There are more than 3 columns spaced less than 610mm apart, mutually sharing loads
- Case 2: All the following conditions are met
  - There are more than 3 columns spaced less than 610mm apart
  - Members are sheathed with a minimum of 9.5mm OSB, waferboard, plywood or with min. 17mm lumber with panel coverings.
  - The sheathing is attached with sufficient stiffness and adequate spacing equal to 2 common nails at 150 mm on center at edges and 300 mm on center elsewhere.
Storage Live Load: A storage live load is a live load (loads due to occupancy use) that occurs for a long duration. An example of this is storage space items in an attic. If this is set to yes, an appropriate loading factor is assigned to accommodate for the storage live load. A long duration live load has a decreased load-duration factor of 0.65 ( $K_D$ ) for load combinations of dead load plus live load only.
Absolute Deflection Limit: The maximum allowable deflection for the column set by you in inches (in) or millimeters (mm), regardless of span length. The default is 20 mm. Normally, your local building code will dictate this.
Live/Short-term Deflection Ratio Limit: The maximum allowable deflection ratio for live and short loading, calculated independently for each span. The default is L/240 but you may indicate a preferred ratio.
Long Term Deflection Ratio Limit: The maximum allowable deflection ratio for long-term loading, calculated independently for each span. The default is L/360 but you may indicate a preferred ratio.
Check Bottom Plate Bearing? (Same Species & Grade): If this is set to yes, a bearing check will be performed assuming the column bears on a perpendicular member of the same grade.

Summary and Graphs

In the summary section, the key parameters of your calculation will be outlined: the factored compressive load, the factored compressive resistance with its utilization badge, and the governing load combination. In the graphs section, you can select the load combination that you would like to see in the graph. Along the top of the sheet, a row of badges shows the utilization for Compression and Governing.

Badges at the top of the sheet for the compression and governing checks.

Summary section listing the factored compressive load parallel to grain, the factored compressive resistance with a utilization badge and the governing load combination, a Graphed Load Combination dropdown with a graph of the axial load along the column, and a diagram of the column with its axial and lateral loads and its reaction.

Additionally, in the associated tabs, below design conditions, you can see the respective parameters used to derive the summary figures and calculations. These include the following.

Member Properties
Load Combination Analysis
Modulus of Elasticity (CSA O86:19 Section 6.3)
Compressive Resistance Parallel to Grain (CSA O86:19 Section 6.5.5)
Bending Moment Resistance (CSA O86:19 Section 6.5.3)
Shear Resistance (CSA O86:19 Section 6.5.4)

Should you want to enter a different unbraced length for the column, you can do so in the effective length table under Compressive Resistance Parallel to Grain.

Compressive Resistance Parallel to Grain panel with the load-duration and size factors, an effective length table with the unbraced lengths and the effective length factor overrides for each axis, the slenderness ratios and factors, and the factored compressive resistance for each axis.

Available presets

Each preset opens the calculator with a typical setup already entered.

Preset	Open in Calcs.com
Generic Concentrically-Loaded Column	Run with preset
Interior Isolated Column	Run with preset
Exposed Outdoor Isolated Column	Run with preset
Interior Stud Wall	Run with preset
Exterior Stud Wall	Run with preset
Jack Stud	Run with preset

Common questions

What design standard does this calculator use?

The calculator designs wood columns to CSA O86:19 (Limit States Design) with load combinations per NBCC 2015. Biaxial bending interaction follows CSA O86:19 Cl.7.5.12, which references American Wood Council Technical Report 14 for the combined bending-plus-axial interaction equations.

What are the key inputs?

Key inputs include the wood section (species, grade, and product type from the built-in database or a custom section), column height, number of plies, effective length factors for both axes, service condition (dry or wet), treatment, factored axial load, and bending moments about both axes from linked beam reactions or manually entered loads.

What checks and outputs does it produce?

The calculator checks factored compressive resistance parallel to grain (CSA O86:19 Cl.6.5.5.2.4), factored bending moment resistance about both axes (Cl.6.5.3.1 and Cl.7.5.6.5.1), combined bending-plus-axial interaction (Cl.7.5.12), shear in both planes (Cl.6.5.4.3), and bearing perpendicular to grain (Cl.6.5.6.2). Slenderness ratios for both axes are computed per Cl.6.5.5.2.2.

How does biaxial buckling work for multi-ply columns?

For multi-ply (built-up) columns, the calculator applies the multi-ply compressive resistance provisions of CSA O86:19 Cl.6.5.5.4, which reduce the effective compressive resistance based on how the plies are connected. Slenderness ratios are computed independently for the X-axis (bending the full built-up section) and Y-axis (buckling of individual plies), and the governing direction controls.

Can it handle combined bending and axial loading?

Yes. The combined bending-plus-axial check follows CSA O86:19 Cl.7.5.12 using the interaction equations from AWC Technical Report 14. Moments can be entered directly or linked from beam reactions above the column. Both strong-axis and weak-axis moments are included in the interaction equation simultaneously.

Does this calculator support load linking with beam and footing calculations?

Yes, axial load from beam reactions above links directly into the column, and the column reaction at its base links to connected footing calculations. Change a load or span in a beam above and the column and footing calculations below update automatically.

Next steps

Design a Wood Beam, Joist, and Girder to CSA O86

Design simple and continuous wood beams, joists and girders to CSA O86:19 with unlimited supports and loads. Checks moment, shear and deflection.

🇨🇦 Calculators for Canada

Complete list of Calcs.com design calculators available for Canadian projects (CSA O86, CSA S16, NBCC, and related standards).

Generalized Lateral Stability Calculation for Wood Beams

How the lateral stability factor KL for wood beams in bending is calculated to CSA O86:19, including effective lengths for common loading conditions.

​Worked example

​Example 1: concentrically loaded column

​Method & scope

​See the exact clause

​Symbols

​Calculation method

​Structural model and load combinations

​Axial compressive resistance (CSA O86:19 Cl.6.5.5.2.4)

​Bending moment resistance (CSA O86:19 Cl.6.5.3.1 and Cl.7.5.6.5.1)

​Combined bending and axial interaction (CSA O86:19 Cl.7.5.12)

​Shear resistance (CSA O86:19 Cl.6.5.4.3)

​Bearing perpendicular to grain (CSA O86:19 Cl.6.5.6.2)

​Load linking

​How to use it

​Available presets

​Common questions

​Next steps

Design a Wood Beam, Joist, and Girder to CSA O86

🇨🇦 Calculators for Canada

Generalized Lateral Stability Calculation for Wood Beams

Worked example

Example 1: concentrically loaded column

Method & scope

See the exact clause

Symbols

Calculation method

Structural model and load combinations

Axial compressive resistance (CSA O86:19 Cl.6.5.5.2.4)

Bending moment resistance (CSA O86:19 Cl.6.5.3.1 and Cl.7.5.6.5.1)

Combined bending and axial interaction (CSA O86:19 Cl.7.5.12)

Shear resistance (CSA O86:19 Cl.6.5.4.3)

Bearing perpendicular to grain (CSA O86:19 Cl.6.5.6.2)

Load linking

How to use it

Available presets

Common questions

Next steps