Cover Plated Beams Used in renovation or restoration projects or to meet difficult depth limitations

Possible cover plate configurations The additional steel adds to the plastic section modulus increasing the moment capacity Z x,add = 2Ay (for beams symmetric about PNA) A = cross sectional area of steel attached to one flange y = distance from PNA to centroid of added steel

Cover Plate Example p. 49 notes Design a cover plated alternative for the girder originally chosen for the office building design. A W24 x 117 was chosen to support the required load and meet the 24.5” depth limitation.

Biaxial Bending of Beams Load causes bending about both principal (x and y) axes.

Members Under Combined Forces p – 38 If P u = 0 (no axial load) Where, H1-1b If laterally supported From beam charts 5-71 – if not laterally supported

Biaxial Bending Example p. 46 notes Roof trusses for a pitched industrial building roof are spaced 14.8 ft c.c. along the length of the building. The A36 steel purlins which carry the actual roofing must therefore span 14.8 m. The roof deck will provide lateral support to the top flange of the purlins. In-plane bracing will be provided in the roof, so as to shorten the weak axis span of the purlins. See the partial plan view of the roof. The following loads must be considered: Snow & ice20 psf Roofing & sheathing25 psf Purlins & bracing 4 psf Wind load10 psf

4.4 ft