What is the standard sequence for erecting a multi-story steel building?

The standard erection sequence follows a tiered approach per AISC 303-22 Code of Standard Practice: (1) Foundations and anchor bolts — survey bolt locations, verify embedment depth and projection, check template dimensions, confirm concrete strength ≥ 3,000 psi. (2) First-tier columns — erect corner columns first (establishes the grid), install temporary guy wires, connect base plates to anchor bolts snug-tight, plumb with theodolite or laser, final-tighten anchor bolts. (3) First-tier beams and girders — install main girders between columns, then filler beams, with minimum 2 temporary erection bolts per connection. Do NOT final-tighten until the entire tier is plumbed. (4) Bracing and stability — install permanent lateral bracing (X-braces, chevron braces) and temporary bracing where needed. Never leave unbraced framing overnight. (5) Repeat for subsequent tiers — second tier columns splice onto first tier, beams follow, bracing follows, and continue upward. (6) Final plumb and bolt-up — after all steel is erected and plumbed, final-tighten ALL connections. (7) Decking and studs — install steel deck, weld shear studs. (8) Final — touch-up paint, cleanup. A typical 5-story steel frame erection takes 4-8 weeks depending on crane capacity, crew size, and piece count. The critical path is crane time — each pick should install multiple members when possible.

What temporary bracing is required during steel erection?

Per OSHA 1926.754(b) and AISC 303 requirements, temporary bracing is required at all times during erection. The key requirements: (1) Columns — each column must have a minimum of 2 temporary guy cables (or equivalent braces) at 90° to each other until permanent bracing is connected. Cables must have a minimum breaking strength of 4,500 lb for typical columns. (2) Beams and girders — each beam must have a minimum of 2 bolts per end in standard holes before the lifting connection is released (OSHA 1926.756). For beams over 25 ft long and 30 in deep, additional mid-span lateral support may be needed during erection to prevent lateral-torsional buckling under self-weight. (3) Bay completion — at minimum, complete one full bay (two columns with girders spanning between them, fully braced and plumbed) before proceeding outward. This 'stabilizing bay' provides a rigid reference for the rest of the frame. (4) Overnight bracing — a partially erected structure must be left in a stable condition: all connections minimum 2 bolts, all columns guyed, permanent bracing installed where available. (5) Removal — temporary bracing shall remain in place until permanent bracing is installed and connections are fully tightened. The erector is responsible for designing and providing temporary bracing per AISC 303 Section 7.4, though the structural engineer of record should be consulted for unusual framing configurations.

How many erection bolts are required per connection?

Per OSHA 1926.756(a)(1): during the initial erection, a minimum of 2 bolts of the same diameter as the final bolts must be installed in each connection before the lifting connection (crane or hoist) is released. These temporary erection bolts must be installed in standard holes only — not oversized or slotted. For connections with 4 or fewer total bolts, one additional bolt beyond 50% may be required by the erector's safety protocol. The erection bolts are typically snug-tight only. Full pretensioning and final bolt installation occurs during the 'bolt-up' phase after the entire tier or structure is plumbed. Exception: for connections critical to stability during erection (e.g., beam splices in long-span members, column splices before permanent bracing is active), the erection drawing or engineer may require all bolts installed and snug-tightened before release. Per AISC 303 Section 7.4, the erector is responsible for determining the minimum bolting condition at each erection stage to maintain stability. The structural engineer of record specifies the final condition; the erector's qualified person specifies the erection condition.

How is a steel structure plumbed during erection?

Plumbing a steel structure during erection involves aligning columns to within specified tolerances. Per AISC 303-22 Section 7.13, columns must be plumb within 1:500 for individual columns adjacent to elevator shafts and within the specified envelope for others. The process: (1) Set reference columns (corner columns) using a theodolite, total station, or laser plumb device. Measure at two orthogonal faces simultaneously. (2) Shim at base plates to correct any out-of-plumb condition — the gap between base plate and foundation ≤ 1" typically filled with steel shims or leveling nuts. (3) After reference columns are within tolerance, install connecting beams and plumb intermediate columns by adjusting beam end connections. (4) Check diagonals for squareness — bay diagonals should match within ±1/8" for 30 ft bays (AISC 303 tolerance). (5) Tier-by-tier: after each tier is plumbed and bolted up, verify the tier below hasn't shifted before proceeding. (6) For high-rise construction, GPS/GNSS survey methods supplement traditional optical instruments, especially above 30 stories where building movement from wind and thermal expansion complicates plumbing. Temperature differentials can cause 1-2" of movement at the top of a 40-story building between the sunny and shaded faces — plumbing should be done during overcast conditions or early morning.

What are the OSHA 1926 Subpart R safety requirements for steel erection?

OSHA 1926 Subpart R (Steel Erection) establishes comprehensive safety requirements: Fall protection (1926.760) — at 15 ft for connectors and 30 ft for deckers using controlled decking zones; conventional fall protection (guardrails, safety nets, personal fall arrest) required for all others above 15 ft; connectors working at heights up to 30 ft may use the fall protection plan exception. Training (1926.761) — all workers must be trained in hazard recognition, and a qualified person must train connectors and riggers. Column anchorage (1926.755) — base plates with 4 anchor bolts require no temporary bracing during the initial guying; base plates with fewer than 4 anchor bolts always require temporary guying. Beams and columns (1926.756) — solid web structural steel shall be secured with minimum 2 bolts; at no time shall there be more than 8 floors or 100 ft of unsecured steel above a secured floor under construction. Multiple lift rigging (1926.753) — permitted for up to 5 members of the same type in a single lift with engineered rigging. The erector must have a written erection plan (1926.752) addressing pre-planning, site-specific erection sequence, and crane/hoisting requirements.

Steel Erection Sequence — Planning & Safety

Steel erection is the process of assembling and connecting fabricated steel members into the final structure. The erection sequence affects safety, quality, schedule, and cost. This page covers the planning process, typical sequences, and regulatory requirements per AISC and OSHA.

Erection Planning Overview

Phase	Activities	Duration
Pre-erection	Shop drawing review, sequencing, logistics	2-8 weeks
Foundation prep	Anchor bolt placement, grout preparation	1-2 weeks
Erection	Lifting, connecting, plumbing, bracing	Project-dependent
Bolting	Installing, tightening, inspecting bolts	Concurrent
Welding	Field welding, inspection	Concurrent
Decking	Installing steel deck, welding studs	After framing
Final	Final plumbing, touch-up paint, cleanup	1-2 weeks

Typical Erection Sequence for a Steel Building

Step 1: Foundations and Anchor Bolts

Survey anchor bolt locations per the structural drawings
Verify anchor bolt diameter, projection, and embedment
Check template dimensions against column base plate holes
Verify foundation concrete strength (typically 3,000+ psi)
Grout base plates after columns are set and plumbed

Step 2: Columns — First Tier

Erect columns in planned sequence (typically corner columns first)
Install temporary guy wires or bracing for stability
Connect base plates to anchor bolts (snug-tight initially)
Plumb columns using theodolite or laser
Final-tighten anchor bolts after plumbing

Step 3: Beams and Girders — First Tier

Install main girders between columns
Install secondary beams (filler beams) between girders
Install temporary erection bolts (minimum 2 per connection)
Do NOT fully tighten bolts until the tier is plumbed
Check bay diagonals for squareness

Step 4: Bracing and Stability

Install permanent lateral bracing (X-braces, chevron braces)
Install temporary bracing where permanent bracing is not yet in place
Verify the erected portion is self-supporting and plumb
Never leave a partially erected structure unbraced overnight

Step 5: Repeat for Subsequent Tiers

Repeat the column-beam-brace sequence for each floor level
Each tier must be plumb and stable before erecting the next tier
Connections are progressively tightened as each tier is completed

Step 6: Steel Deck and Studs

Install steel floor deck after framing is complete on each tier
Attach deck to beams with puddle welds or screws
Weld shear studs through the deck
Install side lap fasteners between deck sheets

Erection Engineering

Erection engineering ensures the structure is stable during the construction phase, when it is most vulnerable.

Temporary Stability Analysis

Check	Requirement
Column stability	Cantilever column check during erection
Bracing adequacy	Temporary bracing resists wind on partial frame
Connection capacity	Erection bolts carry temporary loads
Crane capacity	Lift analysis for each member weight and radius
Wind restrictions	Stop erection above specified wind speed
Sequencing	Each stage must be self-stable

Critical Lifts

Lifts that require special planning:

Lift Type	Criteria	Required Plan
Standard lift	Below crane capacity at radius	Lift plan optional
Critical lift	> 75% of crane capacity	Written lift plan
Super lift	> 90% of crane capacity or unusual geometry	Engineered lift plan
Tandem lift	Two cranes on one piece	Engineered lift plan
Night lift	Reduced visibility	Additional lighting plan

OSHA Requirements for Steel Erection

OSHA 29 CFR 1926 Subpart R governs steel erection safety.

Key OSHA Provisions

Requirement	OSHA Standard	Details
Training	1926.761	All ironworkers must be trained
Fall protection	1926.760	Required above 15 ft (connectors) or 6 ft (all others)
Multiple lift rigging	1926.753(c)(2)	Up to 4 members in single lift (conditions apply)
Hoisting	1926.753	Crane inspections, operator qualifications
Structural integrity	1926.754	Walking/working surfaces must be secured
Bolting	1926.755	Two bolts per connection minimum
Column anchorage	1926.755(b)	Columns must be anchored on 4 anchor bolts
Beams and columns	1926.756	Cannot be released until bolted/welded
Flooring	1926.757	Metal decking requirements

Two-Bolt Rule

Every connection must have a minimum of two erection bolts installed before the crane releases the member. This applies to all beam-to-column and beam-to-beam connections. Snug-tight condition is sufficient during erection; final tightening occurs after plumbing.

Column Safety

Columns must have a minimum of 4 anchor bolts
The column base must be secured before the crane releases
Double columns (splice above floor level) must be stabilized before the upper column is erected

AISC Code of Standard Practice

The AISC Code of Standard Practice (COSP) defines the responsibilities of the structural engineer, fabricator, and erector.

Key COSP Provisions

Topic	Responsibility	Standard
Erection drawings	Fabricator provides	COSP Section 4
Erection sequence	Erector proposes, EOR approves	COSP Section 7
Temporary bracing	Erector designs	COSP Section 7.10
Tolerances	Per COSP tables	COSP Section 7.13
Field connections	Erector executes	COSP Section 7
Corrections	Fabricator/erector per agreement	COSP Section 7

Erection Tolerances

Element	Tolerance
Column plumb	1/500 × height (approx L/500)
Column offset	±1/8 in per floor, ±1/4 in total
Beam level	±1/8 in from theoretical
Beam alignment	±1/4 in from theoretical
Splice alignment	Per AISC COSP Section 7.13

Equipment and Methods

Equipment	Capacity	Use
Mobile crane	20-300 ton	Most building erection
Tower crane	5-20 ton	Tall buildings, urban sites
Crawler crane	50-1000 ton	Heavy industrial
Cherry picker	1-5 ton	Light steel, decking
All-terrain crane	30-200 ton	Versatile, rough terrain

Common Rigging Methods

Method	Application	Notes
Choker hitch	Columns, beams	Most common
Basket hitch	Wide members	Two-point pick
Beam clamp	Beams with flanges	Quick attach/detach
Spreaders	Long members	Prevents damage to flanges
Lifting lugs	Heavy members	Shop-welded, engineered

Frequently Asked Questions

What is the sequence of steel erection? The standard sequence is: (1) foundations and anchor bolts, (2) first-tier columns, (3) first-tier beams and girders, (4) permanent bracing, (5) plumb and bolt, (6) repeat for next tier, (7) steel deck and studs. Each tier must be stable before the next begins.

How many bolts are required during erection? A minimum of two bolts per connection must be installed before the crane releases the member. This is an OSHA requirement. For moment connections and heavy members, more bolts may be required by the erection plan.

Who designs the temporary bracing? The erector is responsible for designing and installing temporary bracing. The AISC Code of Standard Practice places this responsibility on the erector. The structural engineer of record (EOR) may provide bracing guidelines but does not design temporary bracing.

How fast is steel erected? A typical steel building erection rate is 10-20 tons per day for a medium-sized crew (8-12 ironworkers) with one crane. Simple structures may achieve 20-30 tons/day. Complex structures with heavy members may be 5-10 tons/day.

Connection Types Explained — All connection types
Weld Inspection Methods — VT, MT, UT, RT
Bolted Connections — Bolt capacity calculator
Steel Weight Calculator — Weight by dimensions
Base Plate Design — Base plate calculator

Disclaimer

This is a calculation tool, not a substitute for professional engineering certification. All results must be independently verified by a licensed Professional Engineer (PE) or Structural Engineer (SE) before use in construction, fabrication, or permit documents. The user is responsible for the accuracy of all inputs and the verification of all outputs.