Diseño De Conexiones Con Platina Sencilla

Designing with Single Plate Connections
M. Thomas Ferrell

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M. Thomas Ferrell is president of Ferrell Engineering, Inc., of Birmingham, AL. He is a member of the AISC Committee on Manuals and Textbooks, the AISC TC6 Connections Committee, the ASCE Committee on Design of Steel Buildings, and the ASCE Connections Committee.

wo basic types of single plate connections are used for “simpleframing” (where connection end restraint is ignored for member design): single plate shear connections and extended single plate shear connections. The first type is used for beam-to-beam and beam-to-column-flange connections, where the end of the supported beam frames close to the face of the supporting member. The second type is used for beam-to-beam and beam-tocolumn-web connections, where the endof the supported beam stops short of either the flanges of the supporting beam or the flanges of the column. SINGLE PLATE SHEAR CONNECTIONS Support Conditions The behavior of single plate shear connections is affected by the support conditions, which are idealized as being either flexible or rigid. If the beam is supported by an ideal flexible support such as a beam, which is torsionallyunrestrained, then the beam end rotation is entirely accommodated by rotation of the support. However if the beam is supported by a fully rigid support, such as the flange of a Wshape column, then the welded edge of the plate will remain vertical when loaded by a gravity shear force and rotation is accommodated by deformation within the connection. In the ideal flexible connection, the inflection point isat the face of the supporting member; but in the ideal rigid connection the inflection point moves away from the inflection point. Since “real” supports seldom behave exactly as flexible or rigid connections, redundant design procedures are necessary to provide a safe and efficient design. New Tables and Concepts New tables are provided to include X-bolt capacities for ASD design. The

new ASDtables will also expand to include 9 to 12 rows of bolts for the single vertical column. These concepts are already provided in the AISC LRFD 3rd Edition Manual. Tables are presented for both ASD and LRFD single plate connection capacities/strengths utilizing both ASTM A36 plate and A572 GR50 plate. Design procedures with example calculations are presented for extended single plate shearconnections to girders and column webs. General Requirements for Connecting Plates, Bolts, and Welds The connection can have one or two vertical columns of bolts, with two to 12 horizontal bolt rows spaced at 3”vertical pitch spacing. The horizontal bolt gage for the double-vertical columns of bolts may be 3” or 3 ½ ” as required to satisfy AISC minimum bolt-spacing requirements for standard holes orhorizontal short slotted holes. The horizontal and vertical boltedge distances for the beam web (Lh & Lv) and the shear plate (Edh & Edv) shall be the greater of 1.5 times the bolt diameter or 1-½” in the as-built condition. The horizontal beam-web endedge distance (Lh) shall exceed this dimension by ¼” as detailed on shop fabrication drawings. The horizontal distance from the face of the support tothe first line of bolts shall be a minimum of 2½” to a maximum of 5¼”. Bolts can have standard holes or short slots, and can be snug-tight or pretensioned. Material for the shear plate can be either A36 or A572 GR50. Welds for the shear plate to the supporting member must be double-fillet welds, equivalent-strength partial-penetration welds, or full-penetration welds using E70XX electrodes.

April2003 • Modern Steel Construction

To provide for stability during erection, it is recommended that the minimum plate length be at least one half of the T-dimension of the beam being supported. If the beam has no intermediate lateral support such that it is unsupported laterally between the connections at its ends, then the plate length shall be increased to at least accommodate one extra row...