Part 1 — Geometry and Modeling (Checks 1-4)

Check 1: Verify grid, story heights, and member orientations

Confirm that the analysis model exactly matches the architectural and structural drawings:

• Grid lines: Check spacing in both directions. A 6-inch difference in grid spacing changes tributary areas by 1-2%.
• Story heights: Floor-to-floor, not floor-to-ceiling. Basement levels have taller story heights (10-14 ft) than typical floors (12-14 ft for office, 10-12 ft for residential).
• Beam orientations: Strong-axis (major) bending should be about the vertical axis for columns. Verify local axes — a 90-degree rotation error in a W24 beam makes it effectively a W9 section.
• Member connectivity: Every beam must connect to a column, girder, or wall. Floating nodes (unconnected members) produce zero-stiffness warnings.
• Diaphragms: Rigid diaphragm constraint at each floor level (or semi-rigid for long, narrow buildings). Verify that diaphragm shear is transferred to the lateral system elements.

Check 2: Confirm boundary conditions

Boundary conditions determine the global stiffness and force distribution:

Column bases:

• Pinned: Releases Mx and My. K = 1.0 in both directions. Used for gravity-only columns and braced frame columns on spread footings.
• Fixed: Restrains all 6 DOFs. Used for moment frame columns and columns on deep foundations. In reality, "fixed" bases have some rotational flexibility — consider partially restrained (PR) base plates with rotational springs for more accurate modeling.

Beam ends:

• Pinned: Releases M3 (major-axis moment) and typically M2 (minor-axis). Used for simple shear connections.
• Fixed: Restrains all moments. Used for moment frame beams.
• Partially restrained (PR): Use rotational springs per AISC commentary. PR connections reduce beam moments by 15-30% but increase column moments.

Diaphragm constraints: Rigid diaphragm (all nodes at a floor level have the same lateral displacement) is acceptable if the diaphragm aspect ratio < 3 and openings are < 50% of floor area.

Check 3: Verify material properties and member sizes

• Wide flange shapes: A992 (Fy = 50 ksi, Fu = 65 ksi)
• HSS shapes: A500 Gr. B (Fy = 46 ksi, Fu = 58 ksi) or Gr. C (Fy = 50 ksi, Fu = 62 ksi)
• Plates and angles: A36 (Fy = 36 ksi, Fu = 58 ksi) or A572 Gr. 50 (Fy = 50 ksi, Fu = 65 ksi)
• Bolts: A325 (Fub = 120 ksi) or A490 (Fub = 150 ksi)
• Welds: E70XX electrodes (FEXX = 70 ksi)

Member sizes should match the preliminary design from hand calculations. Check that every member in the model has an assigned section — a member with no section (default section) can produce wildly incorrect stiffness and force distribution results.

Check 4: Verify that the lateral system is complete

Walk through the lateral load path in both directions:

Roof: Wind/seismic force enters the roof diaphragm → diaphragm shear is collected by chords and drag struts → collectors transfer force to vertical LFRS elements (braces or moment frames).

Each floor: Forces accumulate floor by floor. The shear at level i includes forces from levels i through the roof. A brace at the 3rd floor carries the cumulative lateral load from floors 3, 4, 5, and the roof.

Foundation: The vertical LFRS elements transfer overturning forces to the foundation as axial load couples (compression on one column, tension/uplift on the other). The foundation must resist the overturning moment through bearing pressure, pile tension, or dead load weight.

Redundancy check: If one brace or moment frame bay fails, does the building have an alternative load path? For Seismic Design Category D and higher, ASCE 7 requires redundancy factor rho = 1.3 unless sufficient bays exist to provide redundancy.

Part 2 — Load Determination (Checks 5-8)

Check 5: Confirm dead and live loads

Tabulate all dead loads with sources:

• Floor dead load: Slab (150 pcf * thickness), deck (2-4 psf), finishes (5-15 psf), ceiling/MEP (5-10 psf), partitions (15-20 psf for office). Total typical office floor: 65-90 psf dead.
• Roof dead load: Roofing membrane (3-5 psf), insulation (2-5 psf), deck (2-4 psf), ceiling/MEP (5-10 psf), mechanical units (point loads, 2-20 kips each). Total typical roof: 15-30 psf dead.
• Cladding: Curtain wall (10-15 psf of wall area), precast panels (50-80 psf of wall area), brick veneer (40-50 psf of wall area). Cladding weight is applied as line loads on spandrel beams.

Live loads per ASCE 7 Table 4.3-1:

• Office: 50 psf + 15-20 psf partitions = 65-70 psf unreduced
• Lobbies: 100 psf
• Corridors: 100 psf (first floor), 80 psf (upper floors)
• Storage: 125 psf (light), 250 psf (heavy)
• Roof: 20 psf (ordinary flat roof)

Apply live load reduction (ASCE 7 4.7.2): Lo _ (0.25 + 15/sqrt(KLL _ AT)) >= 0.50 _ Lo for members supporting one floor; >= 0.40 _ Lo for columns supporting multiple floors.

Check 6: Determine wind loads

Per ASCE 7-22 Chapter 27 (directional procedure):

1. Basic wind speed V per ASCE 7 wind speed map (Risk Category II, 700-year or 1700-year MRI or 300/700/1700 for different risk categories per ASCE 7-22).
2. Exposure category (B, C, or D) based on terrain roughness.
3. Topographic factor Kzt (1.0 for flat terrain, > 1.0 for hills/escarpments).
4. Velocity pressure: qz = 0.00256 _ Kz _ Kzt _ Ke _ V^2 (psf).
5. External pressure coefficients (GCp) per Fig. 27.3-1 for MWFRS, Fig. 30.3-1 for C&C.
6. Wind load cases: Case 1 (full wind + torsion), Case 2 (partial wind + torsion), Case 3 (diagonal wind), Case 4 (torsion only).

For a typical office building in Exposure B with V = 115 mph: qh (roof height) ~ 22-28 psf. Total wind base shear ranges from 1-3% of building weight for low-rise buildings to 3-5% for mid-rise.

Check 7: Determine seismic loads

Per ASCE 7-22 Chapter 12 (equivalent lateral force procedure, ELF):

1. Obtain Ss and S1 from the USGS Seismic Design Maps web application.
2. Determine site class (A through F) from the geotechnical report.
3. Compute SMS = Fa _ Ss, SM1 = Fv _ S1; then SDS = 2/3 _ SMS, SD1 = 2/3 _ SM1.
4. Determine Risk Category (I-IV) and Seismic Design Category (A-F) from Tables 11.6-1 and 11.6-2.
5. Select lateral system (bearing wall, building frame, moment frame, dual system) and obtain R, Cd, omega_0 from Table 12.2-1.
6. Approximate period: Ta = Ct * hn^x (Ct = 0.028, x = 0.8 for steel moment frames; Ct = 0.020, x = 0.75 for all others).
7. Seismic response coefficient: Cs = SDS / (R/Ie), limited to SD1 / (T * R/Ie) for T <= TL.
8. Base shear: V = Cs _ W, distributed vertically per Fx = Cvx _ V.

For a typical office building in SDC D (SDS = 0.8g, R = 8 for steel SMF): Cs = 0.8 / (8/1.0) = 0.10W. Base shear = 10% of building weight, significantly higher than wind (1-3%). Seismic governs the lateral design in high-seismic regions.

Check 8: Verify load combinations

Ensure all governing combinations are included. The following combos are the most likely to govern:

Include orthogonal earthquake effects (100% Ex + 30% Ey, then 30% Ex + 100% Ey) per ASCE 7 12.5.3 for columns shared by both orthogonal frames.

Part 3 — Analysis (Checks 9-13)

Check 9: Verify analysis method is appropriate

The analysis method must match the structural configuration per ASCE 7 Table 12.6-1:

• Equivalent Lateral Force (ELF): Permitted for buildings <= 160 ft with no vertical or horizontal irregularities. The simplest method.
• Modal Response Spectrum Analysis (MRSA): Required for buildings with horizontal irregularity Type 1a, 1b; vertical irregularity Type 1a, 1b, 2, 3; or height > 160 ft. MRSA accounts for higher mode effects.
• Linear Response History: Same as MRSA but uses ground motion records.
• Nonlinear Response History: Required for buildings > 240 ft in SDC D and above, or with special seismic systems.

For most low-rise and mid-rise buildings: ELF is sufficient. For buildings over 160 ft or with irregular configurations: MRSA is required.

Check 10: Run second-order analysis (P-delta and P-Delta)

Per AISC 360 Ch. C and ASCE 7 12.8.7:

The direct analysis method (DAM) is the preferred approach:

1. Apply notional loads: Ni = 0.002 * Yi at each floor level in both directions (Yi = total gravity load at level i).
2. Reduce stiffness: EI* = 0.8 * taub * EI (taub = 1.0 for tau_b * alpha _ Pr/Py <= 0.5; otherwise tau_b = 4 _ (alpha*Pr/Py) * (1 - alpha*Pr/Py)).
3. Run a second-order (P-delta with large displacement) analysis. The software automatically includes both P-delta (member curvature) and P-Delta (global sidesway) effects.

Stability coefficient check:

theta = Px * delta * Ie / (Vx * hsx * Cd)

Where Px = total vertical load at level x, delta = first-order story drift, Vx = story shear, hsx = story height. If theta > 0.10: P-delta is significant. If theta > 0.25: structure is unstable — redesign required.

Check 11: Verify modal properties (if using MRSA)

Per ASCE 7 12.9.1:

• Number of modes: Capture at least 90% of the modal mass participation in each horizontal direction (ASCE 7 12.9.1.1).
• Base shear scaling: If the MRSA base shear Vt < 85% of the ELF base shear V, scale all forces by 0.85 * V / Vt (ASCE 7 12.9.1.4).
• Modal combination: Use CQC (Complete Quadratic Combination) for closely spaced modes, SRSS (Square Root of Sum of Squares) for well-separated modes.

For a 10-story steel moment frame: 15-25 modes are typically needed to capture 90% mass participation due to torsional modes and higher translational modes.

Check 12: Check story drift against code limits

Drift is often the governing design criterion for moment frames:

Wind drift (IBC):

• Typical limit: h/400 for buildings <= 10 stories
• For buildings with brittle finishes: h/500
• Interstory drift under 10-year MRI wind (serviceability): h/400 to h/500

Seismic drift (ASCE 7 12.12):

delta_x = Cd * delta_xe / Ie
delta_x <= allowable = 0.020 * hsx (RC I-II), 0.015 * hsx (RC III), 0.010 * hsx (RC IV)

Where delta_xe is the elastic deflection from the code-prescribed forces (amplified by Cd). For a typical 12 ft story height in SDC D (Cd = 5.5, RC II):

• Elastic drift: delta_xe ~ 0.4 in. (typical for stiff frame)
• Inelastic drift: delta = 5.5 * 0.4 / 1.0 = 2.2 in.
• Allowable: 0.020 * 144 = 2.88 in. → OK (77% utilization)

If drift exceeds limits: increase member sizes in the moment frame bay, add bays to the lateral system, or switch to a stiffer system (CBF instead of MRF).

Check 13: Verify torsion and accidental torsion

Per ASCE 7 12.8.4:

• Inherent torsion: From the offset between the center of mass (CM) and center of rigidity (CR). The analysis model automatically captures this if masses are correctly assigned and the model has 3D stiffness.
• Accidental torsion: 5% eccentricity applied to account for unforeseen mass or stiffness variations. This is ±5% of the building dimension perpendicular to the load direction.

For a 150 ft x 100 ft building: Accidental torsion moment Mta = V _ (0.05 _ 150) for load in the 100 ft direction. This adds axial forces to columns on the perimeter, which can be 15-30% of the direct lateral load.

If the inherent torsion is large (amplification factor Ax > 1.0 per ASCE 7 12.8.4.3), the accidental torsion moment must be amplified. Ax = (delta_max / (1.2 * delta_avg))^2 <= 3.0.

Part 4 — Member Design Verification (Checks 14-19)

Check 14: Verify all beams for flexure, shear, and deflection

For every unique beam size and span condition:

• Flexural strength (AISC Ch. F): Check compactness, LTB with correct Lb, and Cb.
• Shear strength (AISC Ch. G): Verify at supports and at concentrated loads.
• Deflection (service loads): Compare to IBC Table 1604.3 limits. Camber long-span beams if deflection > L/480.
• Web yielding and crippling (AISC J10): At column supports and point loads. If the web fails, add bearing stiffeners.

Hand-check at least one beam per size. A W21x44 at 28 ft span with composite action should have a D/C ratio of 0.6-0.8 for flexure and 0.4-0.7 for deflection. If your software output shows D/C = 0.95 or 0.15, investigate immediately.

Check 15: Verify all columns for axial + bending interaction

For each column:

• Axial capacity (AISC Ch. E): phi*Pn for the governing K factor.
• Interaction check (AISC H1.1): Pr/Pc + 8/9 * (Mrx/Mcx + Mry/Mcy) <= 1.0.
• Include both strong-axis and weak-axis bending. Weak-axis bending from beam reactions applied to the column web is frequently the governing condition for interior columns.
• Check the 0.9D + 1.0W/E combination for net tension in exterior and corner columns (uplift).

Column demand typically peaks at the lowest level (largest accumulated axial load). However, for moment frame columns in taller buildings, the mid-height columns may govern due to higher bending moments from frame action (column hinge formation).

Check 16: Verify all braces for tension and compression

For concentrically braced frames (CBF):

• Tension yielding: phi*Pn = 0.90 * Fy * Ag (AISC D2). Tension braces typically have D/C ratios of 0.3-0.5 — well under capacity because compression buckling governs.
• Compression buckling: phi*Pn = 0.90 * Fcr * Ag (AISC E3). The unbraced length is the full brace length (work point to work point) with K = 1.0 for single diagonal bracing.
• Slenderness: KL/r <= 200 for primary bracing.
• For seismic (AISC 341): Brace slenderness limits and width-to-thickness limits are more restrictive. Braces must meet highly ductile (HD) or moderately ductile (MD) section requirements per AISC 341 Table D1.1.

Check 17: Verify collectors, chords, and drag struts

These elements transfer diaphragm forces to the lateral system and are easily overlooked:

• Collectors (drag struts): Transfer accumulated diaphragm shear into the vertical LFRS element. The collector force at each floor = the diaphragm shear from the area tributary to that LFRS element.
• Chords: Resist the tension/compression couple from diaphragm bending. The chord force at the diaphragm edge = M_diaphragm / b (diaphragm width). For a 150 ft wide building with maximum chord force at mid-length: typically 20-40 kips, requiring W10-W12 sections or continuous angles.
• Overstrength factor (omega_0): Per ASCE 7 12.10.2.1, collectors and their connections in SDC C and above must be designed for the overstrength load: omega*0 * QE + 1.0 _ QG. This can double the collector design force compared to the basic seismic load.

Check 18: Verify diaphragm design

The floor/roof diaphragm must transfer lateral forces to the vertical LFRS elements:

• Flexible diaphragm (steel deck without concrete fill): Distribution of lateral forces is based on tributary area (not stiffness). For untreated metal deck: shear capacity typically 1-3 kips/ft.
• Rigid diaphragm (concrete slab on metal deck, >= 3 in. concrete): Distribution based on relative stiffness of LFRS elements. For 3-1/2 in. lightweight concrete on 1-1/2 in. deck: shear capacity 8-15 kips/ft.
• Semi-rigid diaphragm: Accounts for diaphragm flexibility. For long, narrow buildings (aspect ratio > 3), the diaphragm may not be truly rigid, and a semi-rigid analysis (shell elements modeling the slab) is recommended.

Check diaphragm shear: V_diaphragm / b <= V_allow per SDI or AISC Design Guide 16.

Check 19: Verify stability bracing requirements

Per AISC 360 App. 6:

• Nodal bracing of beams: At each lateral brace point, the brace must provide strength >= 0.01 _ Mr / ho and stiffness >= (1/phi) _ (4 _ Mr _ n) / (Lb * ho).
• Relative bracing of columns: Bracing stiffness >= (1/phi) _ (2 _ Pr) / Lb. A diagonal brace or shear wall must stiffen the column at the braced point.
• Lean-on bracing: In braced frames where only some columns are part of the lateral system, the gravity columns "lean" on the braced frame for stability. Their P-delta effect must be included in the analysis per AISC App. 7.

Part 5 — Connection and Foundation (Checks 20-22)

Check 20: Design all typical connections

Prepare connection schedules for:

• Beam-to-column shear connections (shear tab, double-angle, end plate)
• Beam-to-girder shear connections
• Column splices (typically every 2-3 stories, 4 ft above finished floor)
• Brace-to-beam/column connections (gusset plates)
• Moment connections (if moment frames are used)

Each connection schedule must specify: bolt diameter and grade, number of bolts, plate thickness and dimensions, weld size and length, and any special requirements (slip-critical, pretensioned, etc.).

For seismic connections (AISC 341): The connection must develop the expected member strength, not the analysis force. This requires a capacity-based design check where the connection capacity >= 1.1 _ Ry _ Mp (for moment connections) or Ry _ Fy _ Ag (for brace connections).

Check 21: Design column base plates and anchor rods

Base plates for every column on the schedule:

• Bearing area: A1*req = Pu / (0.65 * 0.85 _ f'c * sqrt(A2/A1), limited to 2.0)
• Plate thickness per AISC DG 1
• Anchor rod diameter, quantity, embedment, and hook/head type
• For moment-resisting bases: check the tension side anchor rods and the bearing stress block (AISC DG 1, large moment procedure)

Grout: Specify non-shrink grout under all base plates, minimum 1 in. thickness for leveling. Grout compressive strength >= concrete foundation strength.

Check 22: Coordinate foundation design loads

Extract foundation reactions at every column base:

• Maximum compression: Pu_max (governing combination)
• Maximum tension (uplift): Pu_min (0.9D + 1.0W/E)
• Maximum shear: Vu_max
• Maximum moment: Mu_max

Organize reactions by foundation type: spread footings, combined footings, pile caps, and mat foundations. The geotechnical engineer needs both the service (ASD) and strength (LRFD) reactions.

Part 6 — Documentation and Review (Checks 23-25)

Check 23: Prepare the structural calculation package

A complete calculation package must include:

1. Design criteria: Codes (IBC, ASCE 7, AISC 360, AISC 341 if seismic, ACI 318 for foundations), material grades, design assumptions.
2. Load calculations: Tabulated dead loads, live loads, wind parameters (V, exposure, Kzt, GCp), seismic parameters (Ss, S1, site class, R, Cd, omega_0, SDC).
3. Analysis model description: Software used, element types, boundary conditions, diaphragm modeling, P-delta settings.
4. Analysis results: Base shear (wind and seismic, both directions), story drift (all levels, both directions), modal properties (if MRSA), torsion amplification.
5. Member design: Beam schedule, column schedule, brace schedule — each with D/C ratios for all governing limit states.
6. Connection design: Connection schedule, standard detail references, special connection calculations.
7. Foundation reactions: Column base reactions table.
8. Signed and sealed cover sheet: PE/SE stamp, signature, date.

Check 24: Peer review / senior engineer review

Before submission, have a second engineer review:

• Global stability: Is the lateral system complete and continuous?
• Governing loading: Is seismic or wind controlling? Does this match expectations for the site?
• Drift: Are drift ratios reasonable for the building height and seismic risk?
• Key members: Hand-check the most heavily loaded beam, column, and brace.
• Connections: Review the typical connection details for constructability.
• Foundation: Review reactions for consistency (sum of vertical reactions = total weight).

Check 25: Final coordination check

Verify that the structural design is coordinated with:

• Architectural: Column locations don't obstruct doors/windows. Beam depths don't conflict with ceiling heights. Expansion joints align.
• Mechanical: Large ducts can pass through beam web openings (accounted for in design). Mechanical units have structural support.
• Electrical: Conduit sleeves through beams are coordinated. Equipment pads are shown.
• Plumbing: Floor penetrations don't conflict with beams. Roof drains are coordinated.
• Geotechnical: Foundation bearing pressures are within allowable limits. Pile capacities match the structural loads.
• Construction: Erection sequence and temporary bracing requirements are shown on the drawings or specified.

Frame Design Checklist — Quick Reference Card

Related References

• AISC 360 Design Examples
• Load Combinations Reference
• Seismic Design of Steel
• Bracing Design Guide
• Steel Connection Design Guide
• Base Plate Design Guide
• ASCE 7 Wind Load Guide
• Portal Frame Design Example
• Your First Steel Design Project

Disclaimer

This page is for educational and reference use only. It does not constitute professional engineering advice. All frame designs must be verified against the applicable standard and project specifications by a licensed Professional Engineer (PE) or Structural Engineer (SE). The checklist is a verification aid, not a substitute for engineering judgment.