Composite columns in Dubai: concrete-encased and concrete-filled steel members

The question

How is a concrete-encased or concrete-filled steel column designed on a Dubai project, and what makes it work as one member?

Short answer

A composite column is a steel section that works with concrete: a steel shape encased in reinforced concrete, or a steel tube or box filled with concrete. AISC 360 Chapter I covers both, and in Dubai the steel is designed to AISC 360 and the concrete to ACI 318-19, with seismic design following AISC 341.¹²³⁴ The concrete adds squash strength and stiffness, and in a filled member the steel confines the concrete and serves as its formwork. The strength counts only if the floor load reaches the concrete: AISC 360 requires the force applied at each floor to be passed between steel and concrete by bearing, by steel anchors or, in filled members only, by bond, within a limited length above and below the connection.⁵⁶⁷ Load effects are found for the sections that exist when each increment of load is applied, so, in our reading, until the concrete hardens the steel carries the load alone.⁸ Filled members also need a local buckling check of the steel wall, which encased members do not.⁹

Source and applicability: ANSI/AISC 360-16, the edition held. The Dubai Building Code references AISC 360 for steel design (F.6.5.1) without stating an edition, so confirm the edition adopted for the project.

A thin steel wall buckles locally, before filling or because the section is slender
The floor load never reaches the concrete: no bearing, too few anchors or too little bond
Voids or poorly compacted concrete inside the tube
Encased section: ties too far apart, too little reinforcement or too little clear space
The whole column buckles sideways (flexural buckling)

Reference drawing: the three common forms of composite column in cross-section, and an elevation of a filled column at a floor showing where the beam reaction enters the steel and the length within which it must be passed into the concrete. Until the concrete hardens the steel carries the load alone; after that, both share it only where the load reaches the concrete. Illustrative only; not to scale and not a construction detail.

What a composite column is, and why it is chosen

AISC 360 Chapter I covers members made of rolled or built-up structural steel, or steel tubes, acting together with structural concrete, and the axial-force rules of Section I2 apply to two kinds of column: encased composite members and filled composite members.⁸¹⁰

Engineering explanation

An encased column is a steel shape, usually an H-section, surrounded by reinforced concrete with longitudinal bars and ties. A filled column is a steel tube or welded box with concrete poured inside. In both, the steel and the concrete shorten together under load, so each carries a share in proportion to its stiffness and strength. The concrete is cheap strength in compression; the steel gives strength in tension and bending, ductility and, in a filled member, a permanent mould and confinement for the concrete.

Engineering explanation

Composite columns are chosen where a steel column alone would be very heavy, or a concrete column very large: lower storeys of tall buildings, heavily loaded transfer levels, and long columns where stiffness governs. Against a steel column they add stiffness and squash strength for less steel, and the concrete helps in fire; against a reinforced concrete column they are smaller and, in the filled form, need no formwork. The price is a more complex design: two materials, two codes, a construction stage in which the steel stands alone, and connections that must pass load into the concrete.

Item	Encased steel shape	Filled tube or box
Formwork	Needs formwork and cover around the steel	The steel is the formwork
Reinforcement	Longitudinal bars and ties required	Not required for strength; bars optional
Local buckling of the steel	Need not be evaluated	Evaluated: the wall is classified compact, noncompact or slender
Concrete strength credit (plastic stress method)	0.85f'c	0.85f'c, or 0.95f'c for round tubes, for confinement
Bond as a way to pass load into the concrete	Not permitted	Permitted, with a small nominal bond stress
Beam connections	To the steel shape through the concrete, or to cast-in parts	Directly to the steel face; inside the tube needs planning

Encased or filled: the main differences (our comparison)

Sources for each row: AISC 360 I1.2, I2.1a, I2.2a and I6.3.⁹³⁴⁶ The formwork and connection rows are our description of practice, not requirements.

Which rules apply in Dubai

The Dubai Building Code requires structural steel to be designed to AISC 360 and the standards it references, with seismic design following AISC 341, and concrete for structural purposes to conform to ACI 318-19. Structural concrete must have a compressive strength of at least f'c = 28 N/mm² (fcu = 35 N/mm²).¹² The Code lists AISC 360 among its steel references without an edition year, so this guide uses ANSI/AISC 360-16, the edition held; confirm the edition adopted for the project.¹¹

AISC 360 applies ACI 318 to the concrete and reinforcement of composite construction, with exceptions: ACI 318's own provisions for composite columns are excluded entirely, the material limits are those of AISC 360 Section I1.3, and the transverse reinforcement limits of AISC 360 apply in addition to ACI 318's; the concrete and reinforcement are designed at the level of LRFD load combinations.⁸

AISC 360 intends the concrete and reinforcing steel of a composite member to be detailed with the non-composite provisions of ACI 318, as modified by AISC 360, and notes that ACI 318 uses strength design, so designers using allowable strength design for the steel must watch the different load factors.⁹

Practical consideration

This library does not hold ACI 318-19 or AISC 341. Tie and spiral details beyond the AISC minimums, concrete cover and concrete shear strength come from ACI 318-19. A composite column in a seismic force-resisting system needs the composite provisions of AISC 341. Neither is stated here. For the other emirates, no building code is held by this library, so no requirement outside Dubai is given.

Material limits

For calculating available strength, AISC 360 limits concrete to a specified compressive strength of 21 to 69 MPa for normal-weight concrete and 21 to 41 MPa for lightweight concrete; a user note adds that higher-strength concrete may be used for stiffness but not relied on for strength unless testing or analysis justifies it. The specified minimum yield stress used in calculation may not exceed 525 MPa for structural steel or 550 MPa for reinforcing bars.¹²

Practical consideration

In Dubai the Code's own minimum of f'c = 28 N/mm² also applies, so the usable band for a composite column's strength is 28 to 69 MPa for normal-weight concrete. A concrete grade above 69 MPa can still be specified for durability or stiffness, but the strength calculation stops at 69 MPa unless justified.

Concrete-encased columns

Minimum steel and reinforcement: an encased column's steel core must be at least 1% of the total cross-section. The encasement is reinforced with continuous longitudinal bars and with ties or spirals: ties of at least 10 mm bars at no more than 300 mm centres, or 13 mm or larger bars at no more than 400 mm, and never more than half the least column dimension apart; the longitudinal reinforcement ratio, the bar area divided by the gross area, must be at least 0.004.¹⁰³

The clear space between the steel core and the longitudinal bars must be at least 1.5 bar diameters and at least 38 mm. Where the column is built from two or more encased shapes, the shapes are tied together with lacing, tie plates or similar parts, so that each cannot buckle on its own under loads applied before the concrete hardens.¹³

The axial strength of a doubly symmetric encased member is found for flexural buckling. The squash load is Pno = FyAs + FysrAsr + 0.85f'cAc, the sum of the steel section at yield, the bars at yield and the concrete at 0.85f'c. The elastic buckling load is Pe = π²EIeff/Lc², with EIeff = EsIs + EsIsr + C1EcIc and C1 = 0.25 + 3(As + Asr)/Ag, not more than 0.7. When Pno/Pe is at most 2.25, Pn = Pno·0.658^(Pno/Pe); otherwise Pn = 0.877Pe. The resistance factor is 0.75 (LRFD; Ω = 2.00 for ASD), and Ec = 0.043wc^1.5√f'c in MPa for concrete densities of 1,500 to 2,500 kg/m³.³¹³

The available compressive strength need not be taken as less than that of the bare steel member under Chapter E. In tension, only the steel and the bars count: Pn = FyAs + FysrAsr, with a resistance factor of 0.90.¹³

Engineering explanation

Why the stiffness term matters: C1 is the share of the concrete's gross stiffness that is counted against buckling. Cracking, creep and the loss of bond near failure all reduce the concrete's effective stiffness, so the concrete is credited with between a quarter and seven-tenths of it, rising with the amount of steel. A slender encased column therefore gains less from its concrete than a squat one.

Concrete-filled tubes and boxes

In a filled member the steel section must again be at least 1% of the cross-section, no minimum longitudinal reinforcement is required, and if bars are provided, internal ties are not required for strength. The steel wall is classified for local buckling in compression as compact, noncompact or slender.⁴¹²

For axial compression, the walls of rectangular tubes and boxes are compact up to b/t = 2.26√(E/Fy), noncompact up to 3.00√(E/Fy), and may not exceed 5.00√(E/Fy); round tubes are compact up to D/t = 0.15E/Fy, noncompact up to 0.19E/Fy, with a maximum of 0.31E/Fy.¹⁴ For a welded box, b is the clear distance between the plates that stiffen the wall; for a hollow section the thickness used is the design wall thickness, which is the nominal thickness for box sections and for tubes to ASTM A1065 or A1085, and 0.93 times the nominal thickness for tubes to other standards.¹⁵¹⁶

A compact filled member's squash load is Pp = FyAs + C2f'c(Ac + AsrEs/Ec), with C2 = 0.85 for rectangular sections and 0.95 for round ones. A noncompact member's value falls from Pp towards Py = FyAs + 0.7f'c(Ac + AsrEs/Ec) as the wall slenderness rises from the compact to the noncompact limit, and a slender member uses the wall's local buckling stress, Fcr = 9Es/(b/t)² for rectangular walls, with 0.7f'c for the concrete.⁴

For round slender tubes, Fcr = 0.72Fy/[(D/t)(Fy/Es)]^0.2. The effective stiffness of every filled section is EIeff = EsIs + EsIsr + C3EcIc, with C3 = 0.45 + 3(As + Asr)/Ag, not more than 0.9; the flexural buckling rule of the encased section then applies. The strength need not be less than the bare steel member's, and in tension only the steel and any bars count.¹⁷

Engineering explanation

Why a filled tube is stronger than its parts: the tube stops the concrete from spreading sideways as it crushes, which raises the concrete's strength, most of all in a round tube, hence the higher 0.95 factor; and the concrete stops the wall from buckling inwards, so the wall can reach yield at a larger width-to-thickness ratio than a hollow tube could. The two effects need the concrete to be in full contact with the wall, which is why compaction and filling matter.

Stiffness to use in the frame analysis

In the direct analysis method, the flexural stiffness of composite columns in net compression is taken as EIeff and the axial stiffness as the sum of the components' elastic axial stiffnesses, with the Section C2 stiffness reductions and τb taken as 0.8; the user note explains that this amounts to 0.64EIeff for bending and 0.8 times the nominal axial stiffness. Members in net tension use the bare steel stiffness.¹⁰

Practical consideration

Stiffness for deflections and drift, and for the effective length method, is discussed in the AISC Commentary, which this library does not hold. State in the design basis which stiffness is used for which check, because a composite frame modelled with the full uncracked concrete stiffness will predict less drift than it will show.

Getting the floor load into the concrete

Where an external force is applied to an axially loaded encased or filled column, AISC 360 requires the introduction of that force and the transfer of longitudinal shear within the member to be designed, with the chosen transfer mechanism at least as strong as the longitudinal shear to be transferred and located within the load introduction length.⁵

If the whole force is applied to the steel section, as through a shear tab on the tube face, the part that must pass to the concrete is V'r = Pr(1 − FyAs/Pno). If it is applied to the concrete, the part that must pass to the steel is V'r = Pr(FyAs/Pno) for compact and noncompact members; for force applied to both at once, V'r follows from equilibrium of the cross-section.⁵⁶

Three mechanisms are recognised: direct bearing, shear connection by steel anchors, and direct bond. The strongest single mechanism may be used, but mechanisms may not be added together, and bond may not be used in encased members. Direct bearing of the concrete has a nominal strength of 1.7f'cA1 with a resistance factor of 0.65, where A1 is the loaded area of concrete; an internal steel plate inside a filled member is an example.⁶¹⁸

Direct bond in a filled member has a nominal strength of pbLinFin with a resistance factor of 0.50, where pb is the perimeter of the steel-concrete interface, Lin the load introduction length and Fin the nominal bond stress: 2,100t/H² for rectangular sections, not more than 0.7 MPa, and 5,300t/D² for circular sections, not more than 1.4 MPa, with t, H and D in mm. Anchors used for shear connection are designed to Section I8.3.¹⁸

The load introduction length may not exceed two times the minimum transverse dimension of the column, or two diameters for a round tube, above and below the load transfer region; for load applied to the concrete of an unreinforced filled member it extends only in the direction of the force. In encased members, anchors transferring the force are placed on at least two faces of the steel shape, generally symmetrically.⁷

Engineering explanation

Why this is where composite columns most often go wrong: the formulas for squash load assume that steel and concrete share every floor's load, but a beam bolted to the outside of a tube delivers its reaction to the steel only. Unless bearing plates, studs or enough bond move part of that force into the concrete within a short distance, the concrete near the floor carries less than the design assumes and the steel carries more. The worked example below shows that bond alone can be far short of what a typical floor reaction needs.

Bending, shear and combined forces

Encased members in bending use a resistance factor of 0.90 and one of three methods: elastic stresses on the composite section considering the shoring, the plastic moment of the steel section alone, or the plastic moment of the composite section, which requires steel anchors. Filled members are classified for local buckling in bending; a compact section reaches the plastic moment of the composite section, a noncompact section falls linearly towards the first-yield moment, and a slender section is limited to first yield with the wall stress limited to its buckling stress.¹⁹²⁰¹⁴

Shear in encased and filled members may be taken as the steel section alone under Chapter G, the reinforced concrete alone under ACI 318 with a resistance factor of 0.75, or the steel section plus the reinforcing steel, also at 0.75. Combined axial force and bending must account for stability under Chapter C: encased members and compact filled members use the interaction equations of Section H1.1 or one of the methods of Section I1.2, and noncompact or slender filled members use the interaction equations of Section H1.1, the method of Section I1.2d, or Equations I5-1a and I5-1b with the coefficients of Table I5.1.²¹²²

Worked example: a concrete-filled welded box column

Step	Value	Basis
Section	Square box 400 × 400 mm of 12 mm plates; Fy = 345 MPa and f'c = 40 MPa normal-weight concrete of 2,400 kg/m³ assumed	Assumed for illustration; within the I1.3 limits and above the DBC minimum f'c
Wall width and slenderness	b = 400 − 2 × 12 = 376 mm; b/t = 31.3	B4.1b(e): clear distance between the stiffening plates
Classification	λp = 2.26√(200,000/345) = 54.4, so the wall is compact	Table I1.1a
Areas	As = 18,624 mm² (11.6% of Ag, above 1%); Ac = 141,376 mm²	I2.2a(a)
Squash load	Pp = 345 × 18,624 + 0.85 × 40 × 141,376 = 11,232 kN; the concrete gives 43% of it	Eq. I2-9b, C2 = 0.85
Concrete modulus	Ec = 0.043 × 2,400^1.5 × √40 = 31,975 MPa	I2.1b
Effective stiffness	C3 = 0.45 + 3 × 0.116 = 0.799; EIeff = 1.361 × 10¹⁴ N·mm²	Eq. I2-12, I2-13
Buckling load	Lc = 4.0 m assumed (K = 1, braced storey): Pe = 83,960 kN; Pno/Pe = 0.134	Eq. I2-5
Axial strength	Pn = 11,232 × 0.658^0.134 = 10,620 kN; φPn = 0.75 × 10,620 = 7,965 kN	Eq. I2-2, φc = 0.75
Bare steel box, for comparison	r = 158.5 mm, Lc/r = 25.2, Fcr = 329 MPa; φPn = 0.90 × 329.3 × 18,624 = 5,519 kN	E1, E3; nonslender, b/t below 1.49√(E/Fy)
Force to pass into the concrete at one floor	Illustrative factored beam reactions of 1,000 kN on the steel: V'r = 1,000 × (1 − 6,425/11,232) = 428 kN	Eq. I6-1
Direct bond available	Fin = 2,100 × 12/400² = 0.158 MPa; pb = 4 × 376 = 1,504 mm; Lin up to 800 mm above and 800 mm below: φRn = 0.50 × 1,504 × 1,600 × 0.158 = 190 kN	Eq. I6-5, I6.4b
Result	Bond (190 kN) is short of 428 kN, so this connection needs a bearing plate or steel anchors inside the box, designed to I6.3a or I6.3b and I8.3	I6.3: the strongest single mechanism, not the sum

Worked example: axial strength and load transfer of a filled box column (our calculation, illustrative only)

Our arithmetic, checked by an independent recalculation; the section, grades, length and load are assumptions for illustration, not a proposed design. Clauses: AISC 360 I1.3, Table I1.1a, B4.1b, I2.2, I2.1b, E1, E3, I6.2a, I6.3c and I6.4b.¹⁴¹⁵⁴¹⁷³²³²⁴²⁵⁵¹⁸⁷

Source and applicability: Illustrative calculation (ours) to AISC 360-16 with an assumed section, grades, effective length and load. It is not a design and proposes no member for any project.

Practical consideration

Read the example for its proportions, not its numbers: the concrete added about 44% to the bare box's design strength here, and one floor's reactions already needed more than bond can carry. The engineer of record chooses the section, the concrete, the effective length and the load transfer detail for the actual column.

Fire, seismic design and other checks

In Dubai, the construction type and fire resistance rating of structural elements come from the UAE Fire and Life Safety Code, fire protection products and systems must be tested and certified by accredited laboratories and approved by Dubai Civil Defence, the ratings must be taken into account in the structural design and stated on the drawings, and fire resistance of steel structures is to conform to AISC Design Guide 19.²⁶

AISC 360 provides two methods of design for fire conditions in its Appendix 4, by analysis and by qualification testing, and deems compliance with the fire-protection requirements of the applicable building code to satisfy that appendix.²⁷

Practical consideration

AISC Design Guide 19 is not held, and Appendix 4's provisions for composite columns were not read for this guide, so no fire resistance rating in hours, concrete cover thickness or unprotected-tube rule is stated for encased or concrete-filled columns. Filled tubes in particular need the fire engineer's agreement on the fire design method and on how the tube is detailed for fire. Seismic composite systems need AISC 341 (not held).

Where composite columns go wrong

Engineering explanation

1. Local buckling of a thin wall. A tube or box with a high width-to-thickness ratio can buckle outwards between its corners, most of all before it is filled, when the steel carries the construction loads alone. The classification limits above apply to the filled condition; the empty tube during construction is a bare steel member.

Engineering explanation

2. Load that never reaches the concrete. As the worked example shows, a floor reaction delivered to the tube face must be passed into the concrete within the load introduction length. Leaving out bearing plates or anchors, or relying on bond beyond its small allowance, leaves the steel overloaded near the connection.

Engineering explanation

3. Voids and poor compaction. The confinement and wall restraint that make a filled tube strong assume the concrete fills it completely. Concrete that segregates, is poorly compacted or shrinks away from the wall loses both, so the method of filling, venting and checking belongs in the specification and the inspection plan.

Engineering explanation

4. Encased columns without enough reinforcement or space. Ties further apart than the limits, bars below the minimum ratio, or too little clear space between bars and the steel shape let the concrete spall and the bars buckle, and make the concrete hard to place around the steel.

Engineering explanation

5. Overall buckling. A long composite column can still buckle sideways as a whole. The effective stiffness credits only part of the concrete, so slender columns gain less from their concrete than stocky ones, and the frame's stability analysis must use the reduced stiffness.

What to settle before a composite column is designed

Encased or filled, and why; steel section and concrete grade, with the strength used within the AISC limits and the DBC minimum
Whether the column belongs to the seismic force-resisting system (AISC 341, not held here)
Construction stage: the loads the bare steel carries before the concrete hardens, and the filling sequence
Load transfer at every floor: where each beam reaction enters, the force to pass between steel and concrete, and the mechanism chosen
Stiffness assumptions for the frame analysis and for drift
Fire resistance rating from the UAE FLSC and the fire design method for the column
Concrete placement, compaction and inspection inside tubes, and tie and cover details to ACI 318-19 for encased columns

A working list for a junior engineer. It is not an approval checklist.

Scope and limits

Practical consideration

Written from the 2021 Dubai Building Code, ANSI/AISC 360-16 and the library's own calculation as checked on 26 September 2026; later amendments were not audited. ACI 318-19, AISC 341, AISC Design Guides 6 and 19 and the AISC Commentary are named but not held, so their rules are not stated. No other emirate's code is held. This guide explains the method; it is not a design, and it proposes no section, grade, anchor layout or fire protection for any project.

Questions this guide answers

What is a composite column, and when is an encased or a concrete-filled steel column chosen?
How is the axial strength of a concrete-filled steel tube or box calculated to AISC 360?
What steel ratio, bars and ties does a concrete-encased steel column need?
How does a beam's load get into the concrete of a filled composite column?
Which concrete strengths and steel yield stresses may be used for a composite column's strength in Dubai?
What stiffness should a composite column have in the frame analysis?

Source notes

Numbered notes point to the exact section and physical PDF page. Page numbers are the PDF viewer’s page, which can differ from the number printed on the page. Sources checked 26 September 2026. These notes support the statements; they are not a substitute for reading the current document for a project.

Dubai Building Code, 2021 Edition. Government of Dubai; official copy hosted by Dubai Development Authority. Part F, F.6.5.1 Design basis and F.6.5.2 Steel grades (printed page F29), PDF page 355. Open the publisher PDF at page 355 (opens in a new tab) ↩ ↩
Dubai Building Code, 2021 Edition. Government of Dubai; official copy hosted by Dubai Development Authority. Part F, F.6.2.1 Structural concrete, design basis and F.6.2.2 Concrete strength (printed page F17), PDF page 343. Open the publisher PDF at page 343 (opens in a new tab) ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I2.1a(b) and (c) Limitations and I2.1b Compressive strength of encased composite members, Eq. I2-1 to I2-5, printed page 16.1-91. Publisher page (opens in a new tab) ↩ ↩ ↩ ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I2.2 Filled composite members, I2.2a Limitations and I2.2b Compressive strength, Eq. I2-9a to I2-10, printed page 16.1-93. Publisher page (opens in a new tab) ↩ ↩ ↩ ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I5 continued (Eq. I5-2), I6 Load transfer, I6.1 General requirements, I6.2 Force allocation and I6.2a, printed page 16.1-101. Publisher page (opens in a new tab) ↩ ↩ ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I6.2b, I6.2c and I6.3 Force transfer mechanisms, printed page 16.1-102. Publisher page (opens in a new tab) ↩ ↩ ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I6.4 Detailing requirements, I7 Composite diaphragms and collector beams and I8.1 Steel anchors, general, printed page 16.1-104. Publisher page (opens in a new tab) ↩ ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). Chapter I introduction, I1 General provisions and I1.1 Concrete and steel reinforcement, printed page 16.1-86. Publisher page (opens in a new tab) ↩ ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I1.1 User Note and I1.2 Nominal strength of composite sections, I1.2a to I1.2c, printed page 16.1-87. Publisher page (opens in a new tab) ↩ ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I1.4 User Note, I1.5 Stiffness for calculation of required strengths, I2 Axial force and I2.1a(a), printed page 16.1-90. Publisher page (opens in a new tab) ↩ ↩ ↩
Dubai Building Code, 2021 Edition. Government of Dubai; official copy hosted by Dubai Development Authority. Part F, F.3.1.3 Steel references (printed page F7), PDF page 333. Open the publisher PDF at page 333 (opens in a new tab) ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I1.2d, I1.3 Material limitations and I1.4 Classification of filled composite sections for local buckling, printed page 16.1-88. Publisher page (opens in a new tab) ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I2.1b continued, Eq. I2-6 and I2-7, I2.1c Tensile strength, I2.1d Load transfer and I2.1e Detailing requirements, printed page 16.1-92. Publisher page (opens in a new tab) ↩ ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). Tables I1.1a and I1.1b Limiting width-to-thickness ratios for compression steel elements in composite members, printed page 16.1-89. Publisher page (opens in a new tab) ↩ ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). Section B4.1b(c) to (f), widths of stiffened elements including box sections, and the design wall thickness, printed page 16.1-18. Publisher page (opens in a new tab) ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). Section B4.2 Design wall thickness for HSS, printed page 16.1-20. Publisher page (opens in a new tab) ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I2.2b continued, Eq. I2-11 to I2-13, I2.2c Tensile strength, I2.2d Load transfer and I3 Flexure, printed page 16.1-94. Publisher page (opens in a new tab) ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I6.3a Direct bearing, I6.3b Shear connection and I6.3c Direct bond interaction, printed page 16.1-103. Publisher page (opens in a new tab) ↩ ↩ ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I3.2 Load transfer for negative flexural strength and I3.3 Encased composite members, resistance factor, printed page 16.1-97. Publisher page (opens in a new tab) ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I3.3 continued and I3.4 Filled composite members, Eq. I3-3a and I3-3b, printed page 16.1-98. Publisher page (opens in a new tab) ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). I4 Shear, I4.1 Filled and encased composite members, and I5 Combined flexure and axial force, printed page 16.1-99. Publisher page (opens in a new tab) ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). Table I5.1 Coefficients cp and cm for Equations I5-1a and I5-1b, printed page 16.1-100. Publisher page (opens in a new tab) ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). Chapter E, E1 General provisions, printed page 16.1-33. Publisher page (opens in a new tab) ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). Sections E2 Effective length and E3 Flexural buckling, Eq. E3-1 to E3-3, printed page 16.1-35. Publisher page (opens in a new tab) ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). Section E3 continued, Eq. E3-4, printed page 16.1-36. Publisher page (opens in a new tab) ↩
Dubai Building Code, 2021 Edition. Government of Dubai; official copy hosted by Dubai Development Authority. Part F, F.5.7 Fire resistance (printed page F17), PDF page 343. Open the publisher PDF at page 343 (opens in a new tab) ↩
Specification for Structural Steel Buildings (ANSI/AISC 360-16), ANSI/AISC 360-16, July 7, 2016. American Institute of Steel Construction (AISC). Sections B3.10 to B3.13, including B3.12 Design for fire conditions, printed page 16.1-15. Publisher page (opens in a new tab) ↩

What a composite column is, and why it is chosen

Which rules apply in Dubai

Material limits

Concrete-encased columns

Concrete-filled tubes and boxes

Stiffness to use in the frame analysis

Getting the floor load into the concrete

Bending, shear and combined forces

Worked example: a concrete-filled welded box column

Fire, seismic design and other checks

Where composite columns go wrong

What to settle before a composite column is designed

Scope and limits

Questions this guide answers

Source notes

Related

Other guides

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