between the top and bottom edges of the web doubler plate and the column web. This is also the case when transverse stiffeners are used and the web doubler plate is extended past the transverse stiffeners as illustrated in Figures 4-4 and 4-5. In these cases, a minimum-size fillet weld per LRFD Specification Table J2.4 is used, except that the minimum size need not exceed the web doubler plate thickness minus When transverse stiffeners are used and the web doubler plate extends to (but not past) the transverse stiffener, the joint between the transverse stiffener, column web and web doubler plate must be detailed consistently with the load path for the unbalanced force in the transverse stiffeners. Several common details are illustrated in Figures 4-11 and 4-12. The strength checks required for each of these details are illustrated in Examples 6-13 and 6-14. In Figures 4-11a and 4-12a, a CJP groove welded joint detail is used at the top and bottom edges of the web doubler plate(s). In Figures 4-11b and 4-12b, the joint details are essentially the same, except a fillet weld is first made connecting the transverse stiffener to the column web and the remaining gap to the web doubler plate is subsequently filled with weld metal. In each of these cases, the resulting joint can be used successfully on the thinner range of web doubler plates, say up to thick. Beyond this thickness it is advisable to bevel the edge of the plate. Although this adds to the fabrication costs, it will benefit the welder and increase the probability of making a sound weld. In each of the details illustrated in Figures 4-11a, 4-11b, 4-12a, and 4-12b, one-quarter of the unbalanced force in the transverse stiffeners is transferred at each weld. In Figure 4-11c, a CJP groove weld is used to connect one transverse stiffener to the column web. The web doubler plate extends to contact the transverse stiffener and is fillet welded to it. In Figure 4-12c, a similar detail is used with web doubler plates on both sides of the column web. If the column web thickness is sufficient to transmit the full unbalanced force from the transverse stiffeners (Equations 4.4-2 and 4.4-3 can be used for this check), the fillet weld between the transverse stiffener and the web doubler plate is selected as a minimum-size fillet weld per LRFD Specification Table J2.4. Otherwise, the joint detail must be configured to transmit the portion of the unbalanced force in excess of the column web strength to the web doubler plate. In Figure 4-11d, the fillet welds on the right side connect one side of the transverse stiffener to the column web and the other side to the web doubler plate. In Figure 4-12d, a similar detail is used with web doubler plates on both sides of the column web. In each of these details, one-quarter of the unbalanced force in the transverse stiffeners is transferred at each weld.
4.4.2) and fillet-weld size. There is both a strength and geometric relationship that must be satisfied. When the bevel dimension and plate thickness are equal, as illustrated in Figure 4-13b, the minimum fillet-weld size to develop the required effective throat in the web doubler plate
is: Rev. 3/1/03
( 2) (4.4-7)
When the bevel dimension is less than the plate thickness, as illustrated in Figure 4-13c, the minimum filletweld size to develop the required effective throat in the web doubler plate is: (4.4-8)
where web doubler plate specified minimum yield strength, ksi minimum web doubler plate thickness required for strength per Equation 4.4-1, in. welding electrode specified minimum strength, ksi If a complete-joint-penetration groove weld is used, this joint is generally not an AWS prequalified weld joint, but can be successfully made with slight modification to the following AWS prequalified weld joint designations: (a) C-L1a or C-L1a-GF for web doubler plates that meet the thickness limitation ( ) and plate edges cut square (b) TC-U4a (series) for plate thicknesses exceeding the qualifications of (a) with beveled plate edges The two primary deviations from the prequalified joints are: (1) the root opening will exceed the maximum tolerance, assuming the plate width is selected to match the T-dimension of the column; and, (2) the weld throat will be slightly reduced, due to the flange-to-web fillet radius. As with a fillet weld, however, allowing a slight encroachment into the flange-to-web fillet radius reduces the shop labor required to make the weld by reducing the volume to be filled. The above practices are therefore recommended. 4.4.4 Connecting Web Doubler Plates Along the Top and Bottom Edges When transverse stiffeners are not used and the web doubler plate is extended past the beam flange or flange plate as recommended in Section 4.4.1, there is no force to transfer
32
Š 2003 by American Institute of Steel Construction, Inc. All rights reserved. This publication or any part thereof must not be reproduced in any form without permission of the publisher.