Why a Beam’s Span Is Only the Start of the Sizing Decision

What steel beam span tables can—and cannot—tell you

No steel beam can be selected safely from span alone. Span matters, but so do loads, tributary width or beam spacing, support arrangement, continuity, steel grade, compression-flange restraint, composite action, and serviceability limits. Change any one of those inputs and the appropriate section may change—even when the opening remains exactly the same.

1. Preliminary depth tables estimate likely framing depth during early planning.
2. Narrowly scoped span or load tables list sections for fixed combinations of loading, spacing, supports, material, restraint, construction type, and deflection.
3. Interactive member-design calculators analyze trial sections using project-specific inputs.

Confusing those resources is risky. A preliminary depth range is not an allowable span, and a section shown in a specialized table is not automatically suitable outside that table’s defined conditions.

Their purpose is coordination, not final selection.

A narrowly scoped table may appear more definitive because it lists particular sections. It can do so only because its author has fixed many variables. Those may include a full-length uniform load, simple supports, a particular steel grade, continuous lateral restraint, fixed beam spacing, and stated deflection criteria. The listed section loses its meaning when separated from those assumptions.

A calculator permits more detailed inputs and iterative trial sections. That flexibility does not guarantee correctness. Its output is only as reliable as the geometry, loads, load combinations, support model, bracing assumptions, material properties, design standard, software implementation, and the user’s interpretation.

Resource type	Typical output	Appropriate use	Required inputs or fixed assumptions	Commonly omitted checks	Final design?
Preliminary depth table	Nominal depth or depth range	Reserving structural depth; comparing framing schemes	Span, bay geometry, loading category, spacing, and the table’s fixed material and system assumptions	Connections, detailed vibration, unusual loads, local effects, complete stability, and load path	No
Narrowly scoped span/load table	Listed section, load capacity, or bounded span	Screening candidates when the project closely matches the stated scope	Loading, spacing or tributary width, support condition, grade, restraint, deflection criteria, and construction type	Conditions outside the table; connections; framing around openings; posts, foundations, and lateral-system effects	No
Interactive calculator	Demands, capacities, deflections, utilization, or suitable-section list	Testing project-specific inputs and trial members	Geometry, supports, loads, combinations, grade, bracing, design method, serviceability limits, and sometimes composite properties	Checks not implemented or modeled, potentially including vibration, bearing, connections, stability, and construction-stage conditions	No—not without complete design and qualified review

Warning: Never copy a familiar span and beam designation into another project unless every governing assumption has been verified. The same span does not mean the same load, restraint, support behavior, serviceability requirement, or capacity.

A useful table answers a limited question: Under these stated assumptions, what depth range or candidate section deserves further investigation? It does not answer the broader question: What beam should be ordered and built?

The input worksheet to complete before opening a table

A table search should begin with a framing worksheet, not a span. If an item is unknown, mark it as unresolved rather than silently substituting a convenient assumption.

Input category	Information to record
Application and jurisdiction	Floor, roof, lintel, ridge, wall removal, equipment support, platform, or other use; project location and authority having jurisdiction
Governing requirements	Current building code, structural standard, local amendments, and project-specific criteria
Geometry	Effective span; clear opening; bearing dimensions; beam spacing; framing-depth constraints
Gravity and environmental loads	Dead, live, snow, rain, partition, equipment, storage, and construction loads as applicable
Other applicable actions	Wind or seismic demands where relevant to the member, frame, supports, or load path
Load distribution	Full uniform loads, partial uniform loads, point loads, wall loads, reactions from other members, and exact load locations
Tributary area	Tributary width or beam spacing and the floor or roof area delivering load to the beam
Structural arrangement	Support types, releases, number of spans, continuity, cantilevers, framing orientation, and edge-beam conditions
Material	Known steel specification and grade; verified section properties for existing work
Composite behavior	Composite or non-composite design; deck orientation; slab and connector concept; propped or unpropped construction
Restraint and stability	Compression-flange bracing, bracing spacing, unbraced length, temporary restraint, and destabilizing loads
Supports and bearings	Available bearing length, support material, connection concept, posts or columns, walls, and foundations
Serviceability	Applicable deflection limits by load case; vibration criteria; requirements arising from finishes, glazing, doors, partitions, drainage, or equipment
Coordination	Openings, penetrations, fire protection, camber, ceiling zones, erection access, and construction sequence

Effective span is not necessarily the clear opening

A commercial Eurocode calculator guide defines effective span as the distance between the centers of the two end bearings. Its example starts with a 3.0 m clear opening and 0.1 m bearing at each end:

3.0 m + 0.1 m ÷ 2 + 0.1 m ÷ 2 = 3.1 m

Under that method, the effective span is therefore 3.1 m, not 3.0 m. The guide also distinguishes full uniform, partial uniform, and point loads and asks users to enter section, grade, restraint, and deflection information (Eurocode steel beam calculator guide).

Do not assume every code, table, or analysis program defines span identically. Use the definition required by the governing standard and the selected resource. Record both the clear opening and bearing geometry so the effective span can be reconstructed and checked.

Convert area loads into beam loads

Floor and roof loads are often expressed as force per unit area, such as pounds per square foot. A beam is generally analyzed using load along its length, such as pounds per linear foot. Tributary width connects the two.

Edge beams and irregular framing require closer attention because load may reach them asymmetrically.

The basic conversion is:

Area load × Tributary width = Beam line load

For example:

50 psf × 10 ft = 500 plf

That 500 plf is only the converted area load. Add applicable beam self-weight, partitions, walls, cladding, equipment, reactions from secondary members, point loads, and other demands. Keep dead, live, snow, and other load categories separate so the appropriate combinations and serviceability cases can be evaluated.

Distinguish the load patterns

A full uniformly distributed load acts evenly over the beam’s full length. A partial uniformly distributed load acts over only part of the span. A point load acts at a defined location and may represent a column reaction, supported beam, or concentrated equipment load.

A uniform-load table cannot automatically be applied to a partial load or point load simply because the total force is the same. Load location matters.

For an existing beam, do not guess the steel grade, deterioration, modifications, holes, welds, fire exposure, bearing condition, or lateral restraint. The Eurocode-oriented commercial guide says newer UK steel is commonly S355 and older steel may be S275, but that general guidance does not verify any particular member’s grade.

How to read the AISC preliminary beam and girder tables

The American Institute of Steel Construction resource is a preliminary depth-planning tool, not a collection of universal allowable spans. It estimates nominal depth ranges for beams and girders so designers can establish early floor and roof framing zones. It does not provide final member sizes.

The published tables cover beam and girder spans from 15 to 45 feet in 5-foot increments, square and rectangular bays from 15 by 15 feet through 45 by 45 feet, and three live-load conditions for each span range (AISC preliminary beam, girder, and column size tables).

AISC table assumptions

• 50 ksi steel
• 3,000 psi concrete
• Composite beams and girders
• Uniformly distributed live and dead loads over the entire bay
• Full live load without reduction
• Live-load deflection limited to L/360

These are the published assumptions of the cited AISC preliminary tables, not universal design criteria.

Those assumptions explain why the result is a planning range rather than a broadly applicable beam choice. Composite framing uses the slab and steel beam together in the intended structural model. AISC says comparable non-composite members would likely be somewhat deeper. A composite depth range should not be transferred directly to an ordinary non-composite beam.

A result such as W16-W18 identifies nominal-depth families. It does not identify flange width, web and flange thicknesses, weight per foot, strength, stiffness, or exact dimensions. Actual W-shape depths can differ from the nominal numbers in their labels, so detailed coordination must use verified section data once a complete section is selected.

Depth also involves a weight tradeoff. AISC gives a planning rule of thumb that reducing a member by one nominal depth size may increase its weight by about 25%. That is not a project-specific weight or cost forecast; it warns that forcing a shallower structure may require a heavier section within the shallower family.

Conditions that can invalidate or materially change a preliminary result include:

• Different dead loads or live loads
• Concentrated or partial-span loads
• Snow, rain, wind, or seismic effects
• Construction loads and erection methods
• Fire-rating requirements
• Different material properties
• Unusual supports or continuity
• Inadequate compression-flange restraint
• Local site or jurisdictional requirements
• Participation in the lateral-force-resisting system

AISC specifically identifies project variables including environmental loads, construction methods, dead loads, fire requirements, local conditions, vibration, connections, seismic effects, and lateral-system participation as matters outside or capable of changing the preliminary table result.

The correct reading is not “this span permits this beam.” It is: “This framing system, under these assumptions, suggests this nominal depth range for early coordination.”

Worked example: what W16-W18 means for a 35-foot beam

AISC provides a tightly bounded planning example: a 35-foot composite beam, at no more than 10-foot spacing, carrying a 100 psf live load, produces a preliminary nominal-depth range of W16-W18 under the published table assumptions. In the same example, a 30-foot girder supporting those beams at no more than 10-foot spacing produces a preliminary range of W21-W24 (AISC preliminary tables).

Those results belong to the stated composite floor model: 50 ksi steel, 3,000 psi concrete, full-bay uniform loading, unreduced live load, and the stated serviceability basis. They do not establish that every 35-foot beam should be 16 to 18 inches deep or that every related 30-foot girder should be 21 to 24 inches deep.

W16-W18 is not a complete orderable section. It refers to nominal-depth families. A complete W-shape designation also includes nominal weight per foot after the multiplication sign. For example, a commercial calculator display uses W8×15, meaning a W-shape in the nominal 8-inch-depth family with a nominal weight of 15 pounds per foot (WebStructural beam designer). Even then, the label is not a substitute for verified geometric and section properties.

Nominal labels are convenient identifiers, not guaranteed exact dimensions. Flange width, actual depth, web thickness, flange thickness, fillet geometry, section modulus, moment of inertia, and other properties must come from current section data for the exact selected shape.

The functional distinction between the two members is important:

• The beam receives floor load over its tributary area.
• The girder receives concentrated reactions from the beams it supports.

Do not copy this result.

A new evaluation is required for wider spacing, higher loading, concentrated loads, non-composite construction, different supports, inadequate bracing, tighter deflection criteria, or a different governing jurisdiction. The W16-W18 and W21-W24 ranges end the preliminary depth-coordination exercise; neither is ready for procurement, shop drawings, alteration, or construction.

The checks a span table does not finish

A plausible beam depth is only the beginning of member design. A complete evaluation separates failure modes and service criteria rather than treating “capacity” as one number.

Bending strength

The design must compare required flexural strength with available strength under the governing load combinations while accounting for section classification, material properties, restraint, and applicable limit states.

A depth table does not necessarily identify the exact section modulus or strength. Two W-shapes in the same nominal-depth family can have substantially different weights and properties.

Shear strength

Openings, copes, connection geometry, and local load introduction may require checks beyond a basic member-wide shear calculation.

Passing bending does not prove that shear is adequate, and passing shear does not prove that bending is adequate.

Deflection

Strength asks whether the beam has adequate resistance. Serviceability asks whether it performs acceptably in ordinary use.

Deflection ratios are tied to a span and specified load case; they are not universal beam-sizing rules. The cited resources illustrate that variation:

• AISC’s preliminary tables use L/360 for live-load deflection.
• The commercial Eurocode guide describes L/360 for variable load and recommends L/200 for total permanent-plus-variable load, while noting that some engineers use L/250.
• The expired Canadian technical note states L/360 for live load and L/240 for total load.

The AISC and Eurocode figures are documented in the sources cited above. The Canadian values come from an expired technical note whose supplied title and URL metadata do not align reliably with its extracted conversion-table content. They should therefore be treated only as an illustration of why source identity, currency, and governing context must be verified—not as usable design criteria.

Lateral-torsional buckling

A beam’s compression flange can move laterally while the member twists. This lateral-torsional buckling behavior can reduce flexural strength when restraint is inadequate. The unbraced length and restraint details therefore matter directly to capacity; the cited commercial beam calculator likewise states that inadequate compression-flange bracing reduces flexural strength through lateral-torsional buckling.

Do not assume that a floor deck or framing member provides adequate bracing merely because it touches the beam. The force path, attachment, spacing, stiffness, and construction stage all matter. The completed structure and the partially erected structure may have different restraint conditions.

Vibration

Floor vibration is not resolved merely by passing a static deflection check. Occupancy, framing frequency, mass, damping, bay geometry, walking excitation, equipment, and sensitive uses can affect acceptability.

A table may report natural frequency without establishing satisfactory performance. The historical Australian handbook explicitly says its tabulated frequencies still require a separate vibration-acceptability assessment (Australian Structural Steel Handbook office-floor tables).

Bearing and local web effects

A beam that works globally can still be unsuitable at a bearing or load-introduction point.

Member and frame stability

The analysis must represent whether supports are pinned, fixed, partially restrained, continuous, or prone to movement. Stability bracing needs a viable load path. Members contributing to a frame or lateral system require analysis beyond a gravity-beam table.

It should not be claimed unless the connections and supporting members can develop the assumed behavior.

Connections

Beam end connections, splices, shear connections, moment connections, bracing attachments, and shear connectors require separate evaluation.

A member check alone does not establish that forces can pass safely through its connections.

Load transfer beyond the beam

The complete load path must be checked.

The slab, deck, effective slab width, shear connectors, construction sequence, temporary restraint, and propped or unpropped condition must be deliberately modeled and detailed. Composite behavior cannot simply be assumed to obtain a shallower result.

Common elements omitted from preliminary tables include connections, camber, bearings, columns or posts, foundations, fire protection, erection stages, construction loading, seismic effects, and responsibility for the lateral system. AISC’s preliminary resource expressly excludes final connection and vibration design and does not address earthquake loading or members participating in lateral resistance.

Move directly to project-specific analysis when the framing includes:

• Point or partial-span loads
• Cantilevers or overhangs
• Multiple spans or continuity
• Unrestrained compression flanges
• Edge beams or destabilizing loads
• Web or slab openings
• Sensitive finishes, partitions, doors, or glazing
• Vibration-sensitive occupancies or equipment
• Members participating in lateral resistance
• Unusual support movement or connection stiffness

When to move from a static table to a beam calculator

A calculator becomes useful when the real problem no longer fits a table’s fixed assumptions. It can model the actual span arrangement, supports, load locations, material, bracing, and design criteria—but it should be used as an iterative analysis tool, not a beam vending machine.

A sound workflow is:

1. Enter geometry and effective spans.
2. Define supports, releases, continuity, and cantilevers.
3. Enter separate load cases and precise load locations.
4. Select the material grade and governing design method.
5. Define compression-flange restraint and unbraced lengths.
6. Enter serviceability limits for the relevant load cases.
7. Choose or generate a trial section.
8. Review every reported strength, stability, and deflection result.
9. Revise the member or framing assumptions and rerun the model.
10. Identify and check what the software did not evaluate.

The cited commercial WebStructural tool accepts uniform and point loads, permits support adjustments, offers AISC 360 LRFD or ASD methods, and reports bending, shear, deflection, and lateral-torsional-buckling checks. These are tool capabilities, not proof that every project condition or governing check has been modeled.

Its displayed W8×15 example is useful for understanding output categories, not for selecting a beam. The interface shows section weight, whether self-weight is included, moment demand and capacity, shear demand and capacity, service-case deflection, and utilization values. Those are the categories a user should inspect rather than relying on a single status indicator.

The extracted interface displays both “Design Passed” and “Beam Design Failed.” That contradiction means the displayed model should not be declared either passing or failing from the page alone. Contradictory status messages are themselves a reason to stop and investigate.

Use this validation checklist before trusting a calculator result:

• [ ] Units are consistent for length, force, area load, line load, stress, and deflection.
• [ ] The governing code, standard, and edition are correct.
• [ ] Steel grade and section database are correct and current.
• [ ] Effective span matches the governing definition.
• [ ] Supports, releases, continuity, and fixity match the intended details.
• [ ] All applicable load cases and combinations are included.
• [ ] Beam self-weight is included exactly once.
• [ ] Area loads have been converted using the correct tributary width.
• [ ] Point loads have correct magnitudes and locations.
• [ ] Partial loads cover the correct portion of the beam.
• [ ] Compression-flange restraint and unbraced lengths are realistic in service and during construction.
• [ ] Composite action is either correctly modeled and detailed or excluded.
• [ ] Strength utilization is reviewed for bending, shear, and applicable interaction.
• [ ] Service-load deflection is checked under the correct load cases and limits.
• [ ] Reactions are plausible and carried through the supporting structure.
• [ ] Omitted vibration, bearing, local web, stability, and connection checks are identified.

Investigate contradictory messages, implausible reactions, absent load combinations, unexpected uplift or negative reactions, and large changes after small input revisions. Sometimes those results reflect real structural behavior; sometimes they reveal a modeling mistake. Either way, they require explanation.

Perform an independent reasonableness check. That might include hand-calculating tributary load and reactions, comparing the result with a properly matched preliminary table, or running a second validated model. As conservative safety guidance, a result should receive project-specific review by a qualified structural engineer familiar with the governing local requirements before it is used for drawings, procurement, alteration, or construction.

Why tables from different countries are not interchangeable

Steel tables carry the assumptions of their standards, markets, section series, material grades, and units. Translating feet to metres does not translate the design basis.

Resource	Units and sections	Material assumptions	Design basis and intended use	Major limitations
US—AISC preliminary tables	US customary units; W-shape nominal-depth families	50 ksi steel; 3,000 psi concrete	Preliminary depth planning for composite beams and girders under fixed bay-loading assumptions	Not final sizes or allowable spans; omits many project-specific strength, vibration, connection, seismic, and lateral-system issues
UK/European commercial calculator guide	Metric units; Universal Beams, Universal Columns, channels, hollow sections, and European categories	Discusses S355 and S275	Eurocode-oriented workflow using entered span, loads, restraint, safety factors, and deflection limits	Not a general span table; vendor defaults and recommendations are jurisdiction-specific
Canadian technical note	US customary and metric references; W-shapes converted to glulam or LVL alternatives	Extracted content specifies Grade 350W/50W steel	Fixed simple-span, uniform-load conversion cases with continuous lateral support and stated deflection limits	Expired; not a general steel span table; supplied title and URL metadata conflict with the extracted document content, so the source should be independently verified before use
Australian office-floor tables	Metric units; UB and WB sections	300PLUS-grade beams	Historical preliminary design and costing for simply supported composite office-floor systems under AS 2327.1-2003	Based on 2005–2008 material and older software; fixed deck, spacing, camber, construction, slab, load, and serviceability assumptions; not evidence of current compliance

The AISC material is a composite-framing depth resource. It should remain within its stated US planning context rather than being treated as a global span chart.

The UK/European source is a commercial calculator guide, not a list of maximum spans. It discusses Universal Beams and other European section categories, as well as S355 and S275 steel. Its safety-factor and deflection guidance belongs to its Eurocode-oriented context and does not verify the grade of an existing member.

The Australian tables demonstrate how narrow a true section table can be. They came from a November 2005 design note reproduced in a 2008 handbook and were generated for simply supported composite systems under AS 2327.1-2003 using COMPBEAM version 2.0. Fixed assumptions include 2.8 m secondary-beam spacing, 1.0 mm re-entrant deck, unpropped construction, and a maximum 50 mm camber. For one defined office-floor case, the secondary-beam listings range from 310UB40.4 at 8 m to 700WB115 at 17 m. These are historical, tightly constrained examples—not current or transferable sizing advice (Australian office-floor span tables).

The supplied Canadian material appears to be an expired steel-to-engineered-wood conversion note rather than a general steel capacity table. Its extracted content describes simple spans, uniform loading, specified tributary widths, Grade 350W/50W steel, continuous lateral support, and stated deflection limits, with an displayed expiry date of December 31, 2022. However, the supplied registry title and destination URL do not match that extracted subject matter. Because the document identity cannot be established reliably from the supplied materials, its figures should not be used as design guidance or treated as a verified current reference.

AISC, Eurocode, Australian, and Canadian grades are not interchangeable labels. Neither are their section series, load factors, resistance formats, serviceability conventions, or referenced standards. Using a foreign table requires a new design under the project’s governing requirements, not merely a unit conversion.

Before relying on any table, verify:

• Publication and revision date
• Governing standard and edition
• Applicable local amendments
• Intended building type and framing system
• Material grade and section series
• Current local section availability
• Load definitions and combinations
• Supports, continuity, and restraint assumptions
• Composite or non-composite construction
• Deflection and vibration criteria
• Whether the resource is still current
• Whether it actually addresses the proposed application

If a resource is undated, verify its current status and referenced design basis before relying on it.

A safe decision path from early planning to final design

A disciplined process preserves the value of steel beam span tables without asking them to answer questions they were not built to answer.

1. Define the framing problem and jurisdiction. Identify the beam’s function, project location, governing requirements, framing arrangement, load path, support concept, and constraints. Decide whether the member is a simple gravity beam or part of a more complex frame.

2. Complete the input worksheet. Establish effective span, clear opening, bearings, loads, tributary width, load locations, supports, continuity, steel grade, composite status, bracing, unbraced length, and serviceability requirements. Keep unresolved inputs visible.

3. Use an applicable table for preliminary depth or candidate screening only. Choose a resource whose framing system and assumptions match the project as closely as possible. Use the output to reserve depth, compare layouts, identify likely conflicts, or form a trial-section list. Do not represent it as a final selection.

4. Model and check project-specific behavior. Switch to project-specific analysis whenever loading, supports, grade, restraint, composite action, code basis, or serviceability criteria differ from the table. Evaluate bending, shear, deflection, lateral-torsional buckling, vibration, bearing, local effects, stability, reactions, and load transfer.

5. Obtain qualified structural review and coordinated final design. Final design should integrate the member with connections, bearings, columns or posts, foundations, penetrations, fire protection, erection sequence, temporary stability, and surrounding construction. The appropriate responsibilities and required approvals depend on the project and jurisdiction, but high-stakes structural decisions should be made by a qualified structural engineer who can evaluate the complete load path and applicable requirements.

Early architectural documentation can responsibly say that a depth has been reserved or that a framing range is preliminary. It should not imply that a section has been approved. Any preliminary selection placed in meeting notes or drawings should record:

• Resource title, publication date, and version
• Governing code or design basis
• Span definition and bearing assumptions
• Dead, live, environmental, and concentrated loads
• Beam spacing or tributary width
• Support and continuity assumptions
• Bracing and unbraced length
• Composite or non-composite status
• Preliminary depth range or screened candidates
• Excluded checks and unresolved inputs
• Required structural verification

Steel beam span tables are most valuable as disciplined planning tools, not shortcuts to a final section. Define the effective span and load path, convert area loads using tributary width, document supports and restraint, confirm the table’s code and assumptions, and interpret depth ranges as preliminary. Then evaluate strength, deflection, buckling, vibration, bearings, connections, and the surrounding structure.

If an assumption differs—or the member will be drawn, ordered, altered, or built—the work should advance to project-specific analysis under the current applicable requirements and review by a qualified structural engineer responsible for the project conditions and complete load path.

What size steel beam do I need for a 20-, 25-, 30-, or 35-foot span?

Span alone cannot determine the beam. For any of those lengths, the answer depends on effective span, loads, tributary width, point loads, supports, continuity, grade, bracing, composite action, and deflection or vibration criteria.

A preliminary table may suggest a depth range when the project matches its assumptions. For example, AISC’s 35-foot composite-floor example produces a preliminary W16-W18 range only under its defined loading, spacing, material, composite, and serviceability assumptions. It is not a general answer for all 35-foot beams. Project-specific analysis is required before choosing a complete section.

Is steel beam span measured across the clear opening or between the bearing centers?

It depends on the governing standard and the definition used by the table or calculation method. The cited commercial Eurocode guide uses the distance between bearing centers. Under its example, a 3.0 m clear opening with 0.1 m bearing at each end becomes a 3.1 m effective span.

Record the clear opening and both bearing dimensions, then apply the definition required by the governing standard. Do not assume every resource uses the same convention.

What is the difference between W16-W18 and W8×15?

W16-W18 describes a range of nominal-depth families. It says that preliminary planning points toward W-shapes nominally in the 16- to 18-inch-depth families, but it does not identify a complete section.

W8×15 is a complete W-shape designation format: nominally an 8-inch-depth family and 15 pounds per foot. Even so, actual dimensions and properties must be taken from verified current section data rather than inferred from the label.

Can a steel beam calculator replace a structural engineer?

No. A calculator can organize inputs, analyze trial members, apply selected combinations, and report checks implemented by the software. It cannot determine by itself whether the model accurately represents the building, resolve missing field information, coordinate the complete load path, or address every behavior and detail outside its scope.

For construction decisions, a qualified structural engineer should establish the applicable requirements, validate assumptions, address omitted behavior, and coordinate the beam with connections, supports, foundations, construction stages, and the rest of the structure.

Why might deflection or bracing require a larger beam even when strength is adequate?

A beam can resist the calculated bending and shear forces yet be too flexible for the supported finishes, occupancy, glazing, doors, equipment, or vibration criteria. A larger or stiffer section may be needed to control movement even though strength utilization is acceptable.

Insufficient compression-flange bracing can also reduce flexural strength through lateral-torsional buckling. A section that appears adequate when continuously restrained may not be adequate with a longer unbraced length—especially during construction, when the final deck, slab, or bracing system may not yet be effective.