While it is believed to be aic, this information should not be used or relied upon for any specific application without competent professional examination and verification of its accuracy, suitability and applicability by a licensed professional engineer, designer or architect. Therefore, the prequalification extends to both plate types. The pinching is caused by a combination of bolt slip and the sequence of yielding and strain hardening encountered in the connection. Compute the plastic section modulus at the center of the reduced beam section: the minimum column flange width to prevent flange tensile rupture: Tack welds for beam flange-to-column connections are preferably made in the weld groove. When the boxed wide-flange column participates in orthogonal moment frames, then neither the depth nor the width of the ais is allowed to exceed 24 in. Example calculation of shear at center of RBS cuts.
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These studies indicated that for bare steel specimens no composite slabinterstory drift angles of 0. The stiffener shall be clipped where it meets the beam flange and end-plate to provide clearance between the stiffener and the beam flange weld. Publications Tests conducted at the University of Minnesota Lee et al. N-mmgiven by Equation 2. It is believed that these resistance factors, when used in combination with the design, fabrication, erection and quality-assurance requirements contained in the Standard, will provide reliable service in the prequalified connections.
The collar bolts transfer these forces in tension through the orthogonal collar flanges, which then transfer the forces through the rear collar bolts attached to the collar flange on the opposite face of the column.
When placed within the joint, the HAZ of a tack weld is tempered by the subsequent passes for the final weld. This specimen performed acceptably and resulted in provisions for using concrete structural slabs when such flexible material is placed between the slab and the plate.
The shear force at the hinge location, Vh, shall be determined from a free-body diagram of the portion of the beam between the hinge locations. The beam web is connected to the column flange using a bolted shear tab with bolts in short-slotted holes. If the maximum moment occurs within the span and exceeds Mpe of the beam see Equation 5.
In the case of the WUF-W moment connection, the plastic hinge is not moved away from the face of the column. Some concerns were raised in the past that the presence of the RBS flange cuts might make the beam more prone to lateral-torsional buckling and that supplemental lateral bracing should be provided at the RBS. For column sections deeper than W14, continuity plates shall be provided.
The demands may be smaller because of the somewhat smaller strain-hardening moment increase achieved with the BFP moment connection as compared to the welded webwelded flange and other FR connections. These beam aisv flange weld requirements reflect the practices used in the test specimens that form the basis for prequalification of the WUF-W moment connection and reflect what are believed to be best practices for beam flange groove welds for SMF and IMF applications.
Two specimens were tested using a loading protocol intended to represent near-source ground motions that contain a large pulse. Confirm that the number of bolts in Step 4 is adequate.
Column with attached collar corner assemblies. In the aidc of a concrete structural slab, the rolled shape column depth is limited to W14 W maximum.
Aiac the base metal and weld root are ground smooth after removal of the backing, the reinforcing fillet adjacent to the beam flange need not extend to base metal. Column Limitations 1 Columns shall be any of the rolled shapes or welded built-up sections permitted in Section 2. Steel Backing at Continuity Plates. Tests on RBS specimens with composite slabs indicated that the presence of the slab provided a sufficient stabilizing effect that a supplemental brace at the RBS is not likely to provide significantly improved performance FEMA, f; Engelhardt, ; Tremblay et al.
Select a trial bolt diameter, db, not less than that required in Section 6. This test program was also supported by extensive finite element studies. Bracket Horizontal Radius, rh in. The maximum expected force in the flange plate, Fpr, is determined from Mf in Step 8. The use of box columns participating in orthogonal moment frames, that is, with RBS connections provided on iasc beams, is also prequalified. Punched holes are not permitted. Two means of demonstration are acceptable. Further, the majority of tests reported in the literature used radius-cut RBS sections.
Use of compressible material to isolate structural slab from connection. A special welding procedure specification WPS is required for this repair. This calculation shall assume the moment at the center of each reduced beam section is Mpr and shall include gravity loads acting on the beam based on the load combination 1.
If a beam at the node does not require a moment connection, the size of the CWX remains unchanged and a shear plate connection is shop-welded to the CWX to accommodate a nonmoment beam that does not need to match the nominal depth of the momentconnected beam s.
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Because weld access holes are not permitted, the beam-flange-to-end plate weld at the beam web is necessarily a partial-joint-penetration PJP groove weld. For these reasons, it was judged reasonable to permit the calculation of the width-to-thickness ratio a reasonable distance into the RBS cut. In the Northridge earthquake, a number of steel moment frame buildings were found to have experienced brittle fractures that initiated at the welded beam flange-to-column flange joints of moment connections. Two means of demonstration are acceptable. Tests conducted at the University of Minnesota Lee et al. The load combination of 1. Symbols without text definitions, used in only one location and defined at that location, are omitted in some cases.
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