CONTINUITY PLATES BASIC STANDARDS AND TUTORIALS

Continuity Plate Thickness

Where continuity plates are required, the thickness of the plates shall be determined as follows:

(a) For one-sided (exterior) connections, continuity plate thickness shall be at least one-half of the thickness of the beam flange.

(b) For two-sided (interior) connections, the continuity plate thickness shall be at least equal to the thicker of the two beam flanges on either side of the column. Continuity plates shall also conform to the requirements of Section J10 of the AISC Specification.

Continuity Plate to Column Attachment

Continuity plates, if provided, shall be welded to column flanges using CJP groove welds. Continuity plates shall be welded to column webs using groove welds or fillet welds.

The required strength of the sum of the welded joints of the continuity plates to the column web shall be the smallest of the following:

(a) The sum of the design strengths in tension of the contact areas of the continuity plates to the column flanges that have attached beam flanges.

(b) The design strength in shear of the contact area of the plate with the column web.

(c) The design strength in shear of the column panel zone.

(d) The sum of the expected yield strengths of the beam flanges transmitting force to the continuity plates.

Continuity Plates Welding

Along the web, the corner clip shall be detailed so that the clip extends a distance of at least 11/2 in. (38 mm) beyond the published “k” detail dimension for the rolled shape. Along the flange, the plate shall be clipped to avoid interference with the radius of the rolled shape and shall be detailed so that the clip does not exceed a distance of 1/2 in. (12 mm) beyond the published “k1” detail dimension.

The clip shall be detailed to facilitate suitable weld terminations for both the flange weld and the web weld. When a curved clip is used, it shall have a minimum radius of 1/2 in. (12 mm).

At the end of the weld adjacent to the column web/flange juncture, weld tabs for continuity plates shall not be used, except when permitted by the engineer of record. Unless specified to be removed by the engineer of record, weld tabs shall not be removed when used in this location.

Where continuity plate welds are made without weld tabs near the column fillet radius, weld layers shall be permitted to be transitioned at an angle of 0° to 45° measured from the vertical plane. The effective length of the weld shall be defined as that portion of the weld having full size. Non destructive testing (NDT) shall not be required on the tapered or transition portion of the weld not having full size.

COLUMN AISC STANDARDS IN STRUCTURES BASIC INFORMATION

Built-up columns shall satisfy the requirements of AISC Specification Section E6 except as modified in this Section. Transfer of all internal forces and stresses between elements of the built-up column shall be through welds.

1. I-Shaped Welded Columns

The elements of built-up I-shaped columns shall conform to the requirements of the AISC Seismic Provisions. Within a zone extending from 12 in. (300 mm) above the upper beam flange to 12 in. (300 mm) below the lower beam flange, unless specifically indicated in this Standard, the column webs and flanges shall be connected using CJP groove welds with a pair of reinforcing fillet welds. The minimum size of fillet welds shall be the lesser of 5/16 in. (8 mm) or the thickness of the column web.

2. Boxed Wide-Flange Columns

The wide-flange shape of a boxed wide-flange column shall conform to the requirements of the AISC Seismic Provisions. The width-to-thickness ratio (b/t) of plates used as flanges shall not exceed 0.6 SQRT(Es /Fy), where b shall be taken as not less than the clear distance between plates.

The width-to-thickness ratio (h/tw) of plates used only as webs shall conform to the provisions of Table I–8–1 of the AISC Seismic Provisions. Within a zone extending from 12 in. (300 mm) above the upper beam flange to 12 in. (300 mm) below the lower beam flange, flange and web plates of boxed wide-flange columns shall be joined by CJP groove welds. Outside this zone, plate elements shall be continuously connected by fillet or groove welds.

3. Built-up Box Columns

The width-to-thickness ratio (b/t) of plates used as flanges shall not exceed 0.6#Es /Fy #, where b shall be taken as not less than the clear distance between web plates.

The width-to-thickness ratio (h/tw) of plates used only as webs shall conform to the requirements of the AISC Seismic Provisions. Within a zone extending from 12 in. (300 mm) above the upper beam flange to 12 in. (300 mm) below the lower beam flange, flange and web plates of box columns shall be joined by CJP groove welds. Outside this zone, box column web and flange plates shall be continuously connected by fillet welds or groove welds.

4. Flanged Cruciform Columns

The elements of flanged cruciform columns, whether fabricated from rolled shapes or built up from plates, shall meet the requirements of the AISC Seismic Provisions.

User Note: For flanged cruciform columns, the provisions of AISC Specification Section E6 must be considered. Within a zone extending from 12 in. (300 mm) above the upper beam flange to 12 in. (300 mm) below the lower beam flange, the web of the tee-shaped sections shall be welded to the web of the continuous I-shaped section with CJP groove welds with a pair of reinforcing fillet welds.

The minimum size of fillet welds shall be the lesser of 5/16 in. (300 mm) or the thickness of the column web. Continuity plates shall conform to the requirements for wide-flange columns.