N.Y.C. Admin. Code § BC 2206: Section BC 2206: Composite Structural Steel and Concrete Structures

2206.1 General.

Systems of structural steel elements acting compositely with reinforced concrete shall be designed in accordance with AISC 360 and ACI 318, excluding ACI 318 Chapter 14.

2206.2 Seismic design.

Where required, the seismic design, materials, fabrication and erection of composite steel and concrete systems shall be in accordance with Section 2206.2.1.

2206.2.1 Seismic requirements for composite structural steel and concrete construction.

Where a response modification coefficient, R, in accordance with Table 1613.5, is used for the design of systems of structural steel acting compositely with reinforced concrete, the structures shall be designed and detailed in accordance with the requirements of AISC 341.

2206.3 Fabrication, erection and quality control.

The fabrication, erection and quality control of composite structural steel and concrete construction shall comply with the applicable requirements of Sections 2205 and 3305, and Chapter 19 of this code, AISC 360, AISC 341 and ACI 318.

2206.4 Concrete-filled steel columns.

Concrete-filled steel columns shall comply with Section 2206.4.1 through 2206.4.5 and shall be filled with concrete so placed and manipulated as to secure maximum density and to ensure complete filling of the steel without voids.

2206.4.1 Design.

The safe supporting capacity of concrete-filled steel columns shall be computed in accordance with AISC 360 or as determined by a test approved by the commissioner.

2206.4.2 Connections.

Caps, base plates and connections shall be in accordance with AISC 360 and shall be positively attached to the shell and anchored to the concrete core. Welding of brackets without mechanical anchorage is prohibited. Where the pipe is slotted to accommodate webs of brackets or other connections, the integrity of the shell shall be restored by welding to ensure hooping action of the composite section.

2206.4.3 Reinforcement.

Steel reinforcement shall be in the form of rods, structural shapes or pipe embedded in the concrete core in accordance with AISC 360 with sufficient clearance to ensure the composite action of the section, but not nearer than 1 inch (25 mm) to the exterior steel shell. Structural shapes used as reinforcement shall be milled to ensure bearing on cap and base plates.

2206.4.4 Fire-resistance-rating protection of concrete filled columns.

Concrete-filled steel columns shall comply with the required fire-resistance ratings specified in Table 601. Where an outer steel shell is used to enclose the fire protective covering, the shell shall not be included in the calculations for strength of the column section. The minimum diameter of steel columns shall be 4 inches (102 mm) except that in structures of Type V construction not exceeding three stories or 40 feet (12 192 mm) above grade plane, steel columns used in basements and as secondary steel members shall have a minimum diameter of 3 inches (76 mm).

2206.4.4.1 Vent holes.

Concrete-filled steel columns shall have a minimum of four 1/2 in. (12.7 mm) diameter holes that shall be placed opposite each other with two at the top and two at the bottom of the column. The two bottom holes shall be rotated 90° relative to the two top holes.

2206.4.5 Approvals.

Details of column connections and splices shall be shop-fabricated in accordance with AISC 360. Concrete-filled steel columns shall be inspected by an approved agency pursuant to Chapter 17 of this code.