Free Column Splice Calculator | AISC 360-22 Bolted & Welded Design
The Column Splice Calculator is a free structural engineering tool that helps engineers and designers quickly design and verify steel column splices according to the latest AISC 360-22 specifications.
Whether you're using bolted flange plates, welded connections, bearing splices, or hybrid details, this calculator handles axial compression/tension, strong- and weak-axis moments, and shear forces. It provides clear demand-to-capacity ratios, limit state checks, bolt and weld capacities, a detailed step-by-step report, and an interactive diagram — all in both Imperial and Metric units.
Perfect for multi-story buildings, moment frames, and gravity columns. Results should always be reviewed by a licensed professional engineer.
Column Splice Calculator
Design & verify steel column splice connections — bolted, welded, or bearing. AISC 360-22 LRFD/ASD code compliance with step-by-step results.
1. Flange Force (Moment Transfer)
Flange Force
$$P_f = \frac{M_u}{d - t_f}$$
where $M_u$ = factored moment (kip-in), $d$ = column depth (in), $t_f$ = flange thickness (in).
AISC 360-22 Commentary to Chapter J
2. Axial Strength Checks — Splice Plates
Tensile Yielding (Gross Section)
$$\phi R_n = \phi F_y A_g \quad (\phi = 0.90)$$
AISC 360-22 §J4.1(a)
Tensile Rupture (Net Section)
$$\phi R_n = \phi F_u A_e = \phi F_u U A_n \quad (\phi = 0.75)$$
$U$ = shear lag factor; $A_n$ = net area.
AISC 360-22 §J4.1(b)
Compression Yielding (Bearing Splice)
$$\phi R_n = \phi \cdot 1.8 F_y A_{pb} \quad (\phi = 0.75)$$
$A_{pb}$ = projected bearing area.
AISC 360-22 §J7
3. Block Shear Rupture
Block Shear Strength
$$\phi R_n = \phi \left[ 0.6 F_u A_{nv} + U_{bs} F_u A_{nt} \right] \leq \phi \left[ 0.6 F_y A_{gv} + U_{bs} F_u A_{nt} \right]$$
$A_{nv}$ = net shear area; $A_{nt}$ = net tension area; $U_{bs}$ = 1.0 (uniform stress).
AISC 360-22 §J4.3
4. Bolt Strength Checks
Bolt Shear Strength
$$\phi R_n = \phi F_{nv} A_b \quad (\phi = 0.75)$$
$F_{nv}$ = nominal bolt shear stress; $A_b$ = bolt cross-sectional area.
A325-N: $F_{nv}$ = 54 ksi; A325-X: $F_{nv}$ = 68 ksi; A490-N: $F_{nv}$ = 68 ksi.
AISC 360-22 §J3.6, Table J3.2
Bolt Bearing / Tearout
$$\phi R_n = \phi \cdot 2.4 F_u d_b t \quad \text{(bearing)}$$
$$\phi R_n = \phi \cdot 1.2 L_c t F_u \quad \text{(tearout)}$$
$d_b$ = bolt diameter; $t$ = plate thickness; $L_c$ = clear distance.
AISC 360-22 §J3.10
5. Weld Strength
Fillet Weld Strength per Unit Length
$$\phi R_n = \phi \cdot 0.6 F_{EXX} \cdot (0.707 \, a) \cdot L_w \quad (\phi = 0.75)$$
$a$ = weld leg size (in); $L_w$ = weld length (in); $F_{EXX}$ = electrode strength (ksi).
AISC 360-22 §J2.4
Directional Strength Increase
$$\phi R_n = \phi \cdot 0.6 F_{EXX} (1.0 + 0.5 \sin^{1.5}\theta) \cdot A_w$$
$\theta$ = angle of loading to weld axis ($\theta = 90°$ for transverse welds gives 1.5× increase).
AISC 360-22 §J2.4(b)
6. Column Stability (Euler Buckling)
Critical Buckling Load
$$P_{cr} = \frac{\pi^2 E I}{(KL)^2}$$
$K$ = effective length factor; $L$ = unbraced length; $I$ = moment of inertia; $E$ = elastic modulus.
AISC 360-22 §E3
7. Demand/Capacity Ratio
Utilization (D/C Ratio)
$$DCR = \frac{\text{Demand}}{\phi R_n} \leq 1.0 \quad \text{(PASS)}$$
Values > 1.0 indicate overstress (FAIL). Values 0.90–1.00 are shown as WARNING.
8. AISC J1.4 Minimum Splice Strength
LFRS Column Minimum (50% Rule)
$$P_{splice,min} = \max\left(P_u, \; 0.50 \cdot \phi P_n\right)$$
For LFRS columns, the splice must resist at least 50% of the full member capacity, even if demand is lower.
AISC 360-22 §J1.4(b)
Bolted Flange Plate Splice: Flange plates bolted to each flange face transfer moment forces; web plates transfer shear. Most common type for multi-story buildings. Suitable for both gravity and LFRS columns.
Welded Splice: CJP or PJP groove welds at the flanges and fillet welds on the web. Used in seismic moment frames where full moment transfer and ductility are required. More expensive and requires field welding inspection.
Column Splice Calculator
Complete User Guide
Step-by-step instructions, all formulas explained with worked examples, AISC 360-22 code references, and answers to the most common column splice design questions.
1 What Is a Steel Column Splice? A Structural Engineer's Definition
A column splice is a structural connection that joins two steel column segments end-to-end in a vertical line. It is one of the most critical connections in multi-story steel construction because it must reliably transfer axial compression, axial tension, bending moments, and shear forces between column segments to maintain full structural continuity up the height of a building.
Column splices become necessary for several practical reasons: full-height columns are too long to fabricate in a single piece, too heavy to transport, or too large to erect safely with available cranes. In practice, columns are typically fabricated in two-story lengths (roughly 30–40 ft), and the splice joins them at an intermediate level.
- Fabrication limits: Standard mill lengths max out at ~60 ft; shop handling limits are often lower
- Transport constraints: Highway clearances restrict pieces to roughly 40 ft for truckload delivery
- Erection practicality: Crane hook heights and lift capacities require manageable piece weights
- Section changes: Column sections often reduce in size at upper floors as loads decrease
- Seismic design: Splices must be located and detailed to avoid the protected zone in moment frames
- Height: Typically located 2–4 ft above the finished floor level
- Position within story: Should be in the lower quarter of the story height where moments are smallest
- AISC guidance: Not within the "protected zone" for seismic moment frames (AISC 341)
- Erection clearance: Must allow adequate bolt access and welding clearance around connection
- Inspection access: CJP weld splices require ultrasonic testing (UT) access post-installation
2 Key User Pain Points — And How This Column Splice Calculator Solves Them
Engineers, detailers, and fabricators searching for a column splice design calculator typically face a recurring set of frustrations with manual methods and existing software. Here is exactly what this tool solves.
3 Column Splice Types Explained — Bearing, Bolted, Welded, Hybrid
The calculator supports four splice types. Selecting the correct type is the first and most important design decision, as it determines which structural checks are performed, which inputs are required, and which limit states govern.
| Splice Type | Primary Load Path | Best For | Typical Cost | Inspection | Code References |
|---|---|---|---|---|---|
| Bearing Splice | Direct end bearing (compression only) | Gravity-only columns; no net tension under any load combo | $ Lowest | Visual + mill cert | AISC 360-22 §J7; AISC 14th Ed. Table 14-3 |
| Bolted Flange Plate | Bolt shear + plate yielding/rupture | Most multi-story buildings; gravity + LFRS columns | $$ Moderate | Visual + torque check | AISC 360-22 §J3, §J4; J1.4 |
| Welded Splice | Groove weld throat + fillet weld shear | Seismic moment frames (SMF/IMF); full moment transfer | $$$ Highest | UT + visual (CJP) | AISC 360-22 §J2; AISC 341 §D2.5 |
| Hybrid Splice | Bolted web + welded flanges | IMF; balance of ductility, cost, and inspection | $$ Moderate | Visual + torque + UT (flanges) | AISC 360-22 §J2, §J3; AISC 341 |
Table 1 — Column splice type comparison. SMF = Special Moment Frame; IMF = Intermediate Moment Frame; UT = Ultrasonic Testing.
4 Column Splice Connection Diagram — Components & Force Flow
Understanding the anatomy of a column splice is essential before entering inputs. The diagram below shows a standard bolted flange plate splice on a wide-flange (W-shape) column, which is the most common splice type in multi-story steel construction. All force paths are shown with arrows indicating how loads transfer through each element.
Figure 1 — Bolted flange plate column splice anatomy. Forces P (axial), M (moment), and V (shear) flow from the upper column through the flange plates, bolts, and web plates to the lower column. All checks in the calculator reference this load path.
Splice Component Functions
| Component | Primary Function | Load Transferred | Key Design Check |
|---|---|---|---|
| Flange Splice Plates | Carry flange force from moment + share of axial | P𝑧 = M𝑢 / (d - t𝑓) | Yielding, rupture, block shear |
| Flange Bolts | Transfer flange forces by shear into plates | Compression or tension flange force | Bolt shear, bearing, tearout |
| Web Splice Plates | Carry shear + residual web moment fraction | V𝑢, residual bending | Plate shear yielding, block shear |
| Web Bolts | Transfer shear from web plate to column web | V𝑢 (vertical shear) | Bolt shear, bearing, tearout |
| Bearing Surface | (Bearing splice only) Direct compression transfer | Compressive P𝑢 | Contact pressure per AISC §J7 |
| Filler Plate | Fill gap when upper/lower flanges differ in thickness | Transfers load across offset | Developed vs undeveloped per AISC §J5 |
5 Step-by-Step Input Guide — What to Enter & Why
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1Select Splice TypeChoose from Bolted Flange Plate, Welded, Bearing, or Hybrid. This controls which input panels appear and which limit states are checked. If you are unsure, Bolted Flange Plate is the most common choice for new multi-story building columns.⚠ Common mistake: Selecting Bearing splice when the column carries uplift under wind or seismic combinations. Bearing only handles compression — the calculator will flag net tension if detected.
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2Enter Column Sections & MaterialInput the upper and lower column geometry. For a standard W14×82: d = 14.3 in, bⁱ = 10.1 in, tⁱ = 0.855 in, t˧ = 0.510 in, Aɡ = 24.1 in². If upper and lower columns differ in size, enter each separately — the calculator will flag when a filler plate is needed based on the flange thickness difference.⚠ Common mistake: Entering web thickness instead of flange thickness (or vice versa). The flange thickness tⁱ is always the horizontal plate at top and bottom; t˧ is the vertical web plate. Double-check the AISC Steel Construction Manual or manufacturer data.
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3Enter Factored Applied LoadsEnter loads in LRFD (factored) or ASD (unfactored) format based on your code selection. Axial load convention: compression is positive (+), tension is negative (−). Moment M𝑢ₓ is the strong-axis (major) bending moment at the splice location. Shear V𝑢ₓ is the horizontal shear transferred across the joint.⚠ Common mistake: Using unfactored service loads with the LRFD setting. LRFD requires factored loads per ASCE 7-22 combinations (e.g., 1.2D + 1.6L). Using service loads will severely underestimate demand and produce unconservative results.
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4Define Splice PlatesEnter flange plate and web plate dimensions. For the flange plate: thickness t𝐍 should be at least equal to the column flange thickness; width b𝐍 should match or slightly exceed flange width; length L𝐍 should accommodate the required bolt pattern plus minimum edge distances. Select the number of flange plates: 2 (one on each side of the flange) is standard for a standard W-shape bolted splice.⚠ Common mistake: Using only 1 flange plate (outer plate only) when moment transfer is required. Single-plate flange splices cannot efficiently develop the full moment unless carefully checked for eccentricity — always use 2 plates (one each side) for moment-resisting splices.
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5Configure Bolt PatternSelect bolt grade (A325 or A490), diameter, and hole type. Then enter the rows, columns, pitch spacing, and edge distance. The minimum bolt pitch is 2⅔ d𝐋 (2.67 times bolt diameter); preferred is 3d𝐋. Minimum edge distance from center of hole to plate edge per AISC Table J3.4 ranges from 1 in (¾ in bolt) to 1¾ in (1¼ in bolt) depending on hole type.⚠ Common mistake: Entering bolt rows as the number along the flange width direction instead of the length direction. In this calculator, rows = bolts along the length of the plate (load direction); columns = bolts across the plate width (gage direction). This is consistent with AISC bolt group notation.
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6Configure Weld Parameters (Welded or Hybrid Splices)This panel appears when you select Welded or Hybrid splice type. Enter weld leg size
a(fillet leg size in inches or mm), electrode classification (E70XX is standard for structural steel), and weld length. The calculator uses the effective throat of 0.707a for fillet welds per AISC §J2.2b. For CJP groove welds, the effective area equals the full cross-section, and the nominal strength equals the lesser of the base metal or weld metal.⚠ Common mistake: Entering the weld throat instead of the weld leg size. The AISC calculator and this tool use the leg size (a) as input — the effective throat is then computed as 0.707a automatically. Entering the throat value as the leg will underestimate weld strength by 29%.
6 All Formulas & Calculations Explained — AISC 360-22 Column Splice Design
The Column Splice Calculator performs up to 8 simultaneous limit state checks. Every formula is listed below with its AISC 360-22 section reference, variable definitions, and the units used. All intermediate values appear in the step-by-step report output.
6.1 Flange Force Calculation — Moment Transfer to Splice Plates
The most critical first step in any moment splice design is converting the bending moment into an equivalent force at the flanges. This is done by treating the moment as a couple acting through the flange centroids.
$P_f$ = flange force (kip) — tension in one flange, compression in the other
$M_u$ = factored bending moment at the splice (kip⋅in) — convert kip⋅ft to kip⋅in by multiplying by 12
$d$ = column depth (in)
$t_f$ = column flange thickness (in)
$P_{f,comp}$ = compression flange demand (kip) — this governs if both terms are additive
$P_{f,tens}$ = tension flange demand (kip) — becomes governing tension demand when $P_f > P_u/2$
$P_u$ = factored axial load, positive for compression (kip)
6.2 Splice Plate Strength Checks — Yielding, Rupture & Block Shear
$A_g$ = gross cross-sectional area of plate = $t_p \times b_p$ (in²)
$\phi$ = resistance factor = 0.90 for yielding limit state
$A_n$ = net area = $(b_p - n_{bolts} \cdot d_h) \times t_p$ (in²) where $d_h$ = hole diameter = $d_b + \frac{1}{16}$ in
$U$ = shear lag reduction factor = 0.90 for 3+ bolt rows, 0.75 for 2 or fewer rows
$\phi$ = 0.75 for rupture limit state
$A_{nv}$ = net area in shear = $(L_{gv} - n_{rows} \times d_h) \times t_p$ (accounting for hole deductions)
$A_{nt}$ = net area in tension = $(b_p - n_{cols} \times d_h) \times t_p$
$U_{bs}$ = 1.0 for uniform tension stress (typical splice plates)
Two terms inside the min(): first governs when rupture in both shear and tension; second when shear yields before rupture
6.3 Bolt Strength Checks — Shear, Bearing, Tearout & Spacing
$A_b$ = bolt cross-sectional area = $\frac{\pi d_b^2}{4}$ (in²) e.g., 1-in bolt: A𝐋 = 0.785 in²
N = threads included in shear plane; X = threads excluded (stronger)
$d_b$ = bolt diameter (in)
$t$ = thickness of the connected plate at the bolt location (in)
This formula applies to inner bolts; end bolts may be governed by tearout
For end bolt: $L_c = L_e - \frac{d_h}{2}$ where $L_e$ = edge distance
For inner bolt: $L_c = s - d_h$ where $s$ = bolt pitch spacing
Governing bolt shear = min(bearing, tearout) per bolt
6.4 Weld Strength Checks — Fillet, CJP & PJP Groove Welds
$t_e$ = effective throat of fillet weld = $0.707 \times a$ where $a$ = weld leg size (in)
$L_w$ = effective length of weld (in) — total for all weld lines
$\phi$ = 0.75 for weld metal strength limit state
For transverse welds ($\theta = 90°$): factor = $1.0 + 0.5(1.0)^{1.5} = 1.50$ (50% increase)
For longitudinal welds ($\theta = 0°$): factor = $1.0$ (no increase)
$A_w$ = effective throat area = $t_e \times L_w$ (in²)
$F_{BM}$ = controlling base metal stress: $F_u$ for tension, $0.6F_u$ for shear
$A_{BM}$ = base metal area at the weld throat (in²) = full column flange area for a flange CJP
6.5 Column Stability & Euler Buckling Check
$I$ = moment of inertia about the relevant axis (in⁴)
$K$ = effective length factor (1.0 for pinned-pinned, 0.7 for fixed-pinned, 0.5 for fixed-fixed)
$L$ = unbraced column length (in)
Used as reference to confirm the splice plate has adequate area relative to column capacity
6.6 AISC §J1.4 Minimum Splice Strength — The 50% Rule for LFRS Columns
This is the most commonly overlooked requirement in column splice design. Even when calculated loads at the splice are small, LFRS columns must develop a minimum strength to ensure robustness and structural integrity under extraordinary loading events.
$P_u$ = factored axial demand at splice from analysis (kip)
$0.50\,\phi P_n$ = 50% of the full factored compressive capacity of the column
If the 50% minimum exceeds $P_u$, the splice must be designed for the larger value regardless of analysis demand
6.7 Demand/Capacity Ratio — Interpreting Utilization
$\phi R_n$ = design strength for that limit state (kip)
DCR ≤ 1.0 = PASS; DCR > 1.0 = FAIL
DCR 0.90–1.00 = shown as WARNING (overstress risk with small error in load estimation)
Target range: 70–90% is considered efficient design. Below 60% may indicate over-design; above 90% provides minimal safety margin for load estimation uncertainty.
7 Reading the Results Tab — Limit States, D/C Ratios & Pass/Fail
After clicking "Run Design Check," the Results tab opens automatically. Here is what every element means and how to act on the information.
| Result Element | What It Shows | Action if FAIL |
|---|---|---|
| Overall Status Banner | PASS / WARNING / FAIL based on the highest D/C ratio across all active limit states | Review governing limit state; increase plate thickness or bolt count |
| Governing Limit State | Which check controls design — e.g., "Block Shear Rupture (D/C = 1.12)" | Target specifically: block shear → increase plate or edge distance; bolt shear → add bolts |
| Axial D/C Gauge | Demand/capacity for combined axial load across flange plates | Increase plate area (wider plate or more plates) or upgrade plate grade to A572 |
| Moment D/C Gauge | Flange force demand vs bolt/plate/weld capacity at compression flange | Add bolt rows, increase plate thickness, or switch to larger bolt diameter |
| Shear D/C Gauge | Shear demand vs web plate bolt group and plate shear capacity | Add web bolt rows, increase web plate thickness, or add a web plate |
| Limit State Table | Every check with demand, capacity, D/C ratio, and color-coded bar | Address highest D/C first; all rows must be green (≤ 1.0) for code compliance |
| AISC §J1.4 Check | 50% minimum strength compliance for LFRS columns | If 50% rule governs: increase bolt count or plate to meet higher demand level |
| Step-by-Step Report | Full calculation narrative with all formula references and intermediate values | Use for EOR review submission; copy with button or print |
8 Units & Input Validation — Imperial vs Metric
The calculator supports both Imperial (US Customary) and Metric (SI) unit systems. Toggle between them at the top of the calculator page. All unit labels update instantly, and all calculations recalibrate automatically.
| Parameter | Symbol | Imperial Unit | Metric Unit | Typical Range |
|---|---|---|---|---|
| Column Depth | d | in | mm | 8–36 in (200–900 mm) for W-shapes |
| Flange Width | bⁱ | in | mm | 6–17 in (150–430 mm) |
| Flange Thickness | tⁱ | in | mm | 0.25–2.5 in (6–64 mm) |
| Web Thickness | t˧ | in | mm | 0.2–1.5 in (5–38 mm) |
| Cross-Section Area | Aɡ | in² | mm² | 5–200 in² for W-shapes |
| Yield Strength | Fᵧ | ksi | MPa | 36–100 ksi (248–690 MPa) |
| Tensile Strength | Fᵦ | ksi | MPa | 58–125 ksi (400–860 MPa) |
| Elastic Modulus | E | ksi | MPa | 29,000 ksi (200,000 MPa) |
| Axial Load | P𝑢 | kip | kN | 0–5,000 kip (0–22,000 kN) |
| Bending Moment | M𝑢 | kip⋅ft | kN⋅m | 0–5,000 kip⋅ft (0–6,800 kN⋅m) |
| Shear Force | V𝑢 | kip | kN | 0–2,000 kip (0–8,900 kN) |
| Plate Thickness | t𝐍 | in | mm | 0.25–2 in (6–50 mm) |
| Bolt Diameter | d𝐋 | in | mm | 0.75–1.5 in (M20–M36) |
| Weld Leg Size | a | in | mm | 3/16–3/4 in (5–19 mm) |
Table 2 — Complete units reference. 1 kip = 1,000 lbf = 4.448 kN. 1 ksi = 6.895 MPa. 1 in = 25.4 mm. 1 kip⋅ft = 1.356 kN⋅m.
9 Common Column Splice Design Mistakes — Microcopy & How to Avoid Them
Engineers design for the dominant compression load but forget to check the load combination that produces maximum net tension. Under ASCE 7-22 seismic or wind combinations (e.g., 0.9D + 1.0W), uplift can reverse the axial force from +400 kip compression to −80 kip tension at the splice.
In a moment-resisting splice, both flanges AND the web must be spliced. The web plate carries shear and the residual bending moment not carried by the flanges (proportional to the web's share of total moment of inertia). Omitting the web splice plate leaves the shear path undefined.
A "3 rows × 2 columns" bolt pattern means 3 bolt lines running along the load direction and 2 bolt lines across the plate width (gage direction). This is frequently reversed, resulting in an overestimate of bolt group capacity when the fewer bolts in the critical direction are used.
The LRFD code method requires factored loads (D, L, W, E multiplied by their respective ASCE 7-22 load factors before input). Entering unfactored service loads with LRFD selected will produce D/C ratios that appear safe but are actually 25–60% non-conservative.
When the upper column (e.g., W14×53, tⁱ = 0.660 in) is shallower than the lower column (W14×99, tⁱ = 0.780 in), the 0.120-in flange thickness difference creates a gap that must be filled. Filler plates thicker than ¼ in must be developed per AISC §J5.
CJP groove welds are expensive: they require backing bars, pre-weld inspection, post-weld UT testing, and high skill level. They are only required for seismic special moment frames (SMF) per AISC 341. For most non-seismic and many IMF applications, properly sized fillet welds are sufficient and significantly more economical.
10 Worked Example — Bolted Flange Plate Splice on W14×82 Column
This example walks through a complete bolted column splice design calculation using the tool, matching AISC 360-22 LRFD method. All values match what you would see in the Step-by-Step Report output.
Column Section
- W14×82 (both upper and lower)
- d = 14.3 in, bⁱ = 10.1 in
- tⁱ = 0.855 in, t˧ = 0.510 in
- Aɡ = 24.1 in²
Material & Code
- A992 steel: Fᵧ = 50 ksi, Fᵦ = 65 ksi
- A36 splice plates: Fᵧ = 36 ksi, Fᵦ = 58 ksi
- A325-N bolts: Fᵏᵥ = 54 ksi
- LRFD (AISC 360-22)
Factored Loads at Splice
- P𝑢 = +200 kip (compression)
- M𝑢ₓ = 100 kip⋅ft = 1,200 kip⋅in
- V𝑢 = 30 kip
- Column classification: LFRS
Flange Plates
- 2 plates, A36, t𝐍 = ¾ in = 0.75 in
- b𝐍 = 7.0 in, L𝐍 = 12 in each side
- 3 rows × 2 cols of bolts
- Pitch s = 3.0 in, edge Lₑ = 1.5 in
Web Plates
- 2 plates, A36, t˧ = ½ in = 0.50 in
- h˧ = 8.0 in, L˧ = 10 in each side
- 3 rows × 1 col of bolts
Bolts
- 1-in diameter A325-N
- Standard holes, bearing type
- A𝐋 = π(0.5)² = 0.785 in²
- dₕ = 1 + 1/16 = 1.0625 in
Calculation Steps
Tension flange demand: $P_{f,tens} = 100 - 89.3 = \mathbf{+10.7 \text{ kip (still compression)}}$
11 Code Standards Reference — AISC, ASCE, Eurocode, IS 800
| Standard | Title | Scope | Key Sections for Splices |
|---|---|---|---|
| AISC 360-22 | Specification for Structural Steel Buildings (2022) | US standard for structural steel design | §J1.4, §J3, §J4, §J7, §E3 |
| AISC 341-22 | Seismic Provisions for Structural Steel Buildings | Seismic design of steel structures | §D2.5, §F2, §F3 (SMF/IMF splice requirements) |
| ASCE 7-22 | Minimum Design Loads and Associated Criteria | Load combinations and seismic hazard | §2.3 (LRFD combos), §12 (seismic loads) |
| Eurocode 3 | EN 1993-1-8: Design of Joints | EU standard for steel connections | §3 (bolts), §4 (welds), §6 (splice plates) |
| IS 800:2007 | General Construction in Steel — Code of Practice (India) | Indian standard for structural steel | §10 (connections), §11.5 (splices) |
| BS 5950-1 | Structural Use of Steelwork in Building | UK standard (superseded by EC3 in UK) | §6.2 (splices), §6.3 (bolted connections) |
| AWS D1.1 | Structural Welding Code — Steel | Weld quality, procedure, inspection | §3 (design), §4 (fabrication), §6 (UT inspection) |
Table 3 — Design standards referenced by this Column Splice Calculator. Primary compliance: AISC 360-22 LRFD.
12 Frequently Asked Questions — Column Splice Design
Column splices should be located approximately 2 to 4 feet above the finished floor level, within the lower quarter of the story height. At this location, the column bending moment is typically near its minimum value (since moment diagrams for laterally loaded frames often have an inflection point near mid-story), which minimizes the moment demand on the splice and reduces the required plate/bolt capacity.
For seismic moment frames (SMF/IMF): AISC 341-22 §D2.5 requires that splices in special moment frames be located at least $h/4$ from beam-to-column connections (where $h$ is the story height), away from the expected plastic hinge zones. The splice must also not fall within a "protected zone" as defined by the EOR. The typical practice of locating splices "4 ft above floor" generally satisfies this requirement in standard story heights.
A bearing splice relies on direct end-to-end contact between the milled or saw-cut column ends to transfer compressive axial loads. Bolts are provided only to maintain alignment and handle any nominal forces — they are not required to transfer significant loads. Bearing splices are economical and suitable for gravity-only columns where no net tension occurs under any load combination.
A bolted flange plate splice transfers all forces (axial, moment, shear) through bolted steel plates welded or bolted to each column flange face and the web. This type handles both compression and tension, making it suitable for LFRS columns, columns with significant moment demand, or any situation where uplift might develop. The bolted flange plate splice is the most common type in multi-story buildings and is what the calculator defaults to.
The minimum splice plate thickness is determined by ensuring the plate satisfies all applicable limit states — gross yielding, net rupture, and block shear — under the governing flange force. As a starting estimate:
- Calculate the required plate area: $A_{g,req} = P_{f,comp} / (0.90 F_{y,plate})$
- Choose a plate width $b_p$ equal to or slightly less than the column flange width
- Solve for minimum thickness: $t_p = A_{g,req} / b_p$
- Round up to the nearest standard plate thickness (¼, 5/16, ⅜, 7/16, ½, ╰, ¾ in)
- Verify rupture and block shear with this thickness — these may require additional thickness
For the W14×82 example above: $A_{g,req} = 542.3 / (0.90 \times 36) = 16.7$ in² for both plates → $A_{g,plate} = 8.35$ in² each → $t_p = 8.35 / 7.0 = 1.19$ in → round to 1.25 in or use wider plates.
Yes, for buildings assigned to Seismic Design Categories (SDC) C through F per ASCE 7-22, column splices must be designed for seismic demands per AISC 341-22. Key requirements include:
- SMF columns: Splices must develop the lesser of: (a) the expected strength of the smaller connected member using $R_y F_y A_g$, or (b) the maximum force that can be transferred to the splice by the structural system
- CJP weld requirement: Flange splices in SMF must generally use CJP groove welds, not fillet or bolted plates, to ensure ductility
- Net tension: Even in gravity-only columns, seismic overturning can induce significant tension at upper-story splices — always check 0.9D + 1.0Eᵎ load combination
- Protected zone: Splice must not fall within the protected zone (typically within $d$ of the beam-column joint)
Select "Seismic Frame Column (AISC 341)" from the Column Classification dropdown to activate seismic checks in the calculator.
Per AISC 360-22 Table J3.4, minimum edge distances from center of bolt hole to nearest edge of connected material depend on bolt diameter and hole type:
- ¾ in bolt, standard hole: 1 in minimum (preferred: 1.25 in)
- ⅜ in bolt, standard hole: 1.125 in minimum
- 1 in bolt, standard hole: 1.25 in minimum (preferred: 1.5 in)
- 1⅛ in bolt, standard hole: 1.5 in minimum
Maximum edge distance per §J3.5: lesser of $12t$ (where $t$ = thickness of connected part) or 6 in for unpainted/non-weathering steel; lesser of $8t$ or 5 in for painted or weathering steel. These limits are checked automatically in the calculator's tearout calculation.
The calculator currently supports W-shape and H-shape columns fully. For HSS (Hollow Structural Section) columns, you can use the "Custom" section type and manually enter the equivalent cross-sectional properties (area, depth, width). However, HSS splices have unique design considerations not yet fully integrated into the current tool version, including:
- External side plate splices on all four faces (rectangular HSS)
- Bearing area using projected area $A_{pb}$ per AISC §J7-1
- Blind fasteners (Hollo-Bolt, Lindapter) when access to inside of HSS is not possible
- End plate splice per AISC Design Guide 24 (round HSS)
For HSS column splices, cross-reference your results with AISC Design Guide 24 "Hollow Structural Section Connections" and AISC Steel Construction Manual Table 1-11 through 1-13 for section properties.
The calculator uses the exact formulas from AISC 360-22 for all limit states it checks. Results have been verified against standard AISC Manual examples. However, several important caveats apply:
- Simplified assumptions: The flange force method ($P_f = M_u/(d-t_f)$) is an industry-standard simplification — FEA or more rigorous bolt group analysis may give different results for eccentrically loaded connections
- Bolt group eccentricity: The calculator uses simplified direct bolt shear without accounting for in-plane eccentricity of the bolt group — for offset bolt patterns, use the Instantaneous Center Method per AISC Part 7
- Second-order effects: P-Delta amplification at the splice is not computed — the user must include these effects in the input loads from their analysis model
- Material variability: Standard nominal yield and tensile strengths are used — actual mill test properties vary by heat
For critical LFRS or seismic columns, always have results reviewed by a licensed structural engineer. This tool is intended to augment, not replace, engineering judgment.
Instant AISC 360-22 checks for bolted, welded, and bearing column splices — no login, no paywall.
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