three specified configurations as provided in AISC Supplement No. 1 thus allows moment end plates to be considered for use in the. AISC’s Supplement No. 1 to Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications (ANSI/AISC. 1 (includes supplement) Supersedes ANSI/AISC and ANSI/ AISC s Approved by the AISC Connection Prequalification Review Panel .
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Steel Backing at Beam Bottom Flange The removal of backing, whether fusible or nonfusible, followed by backgouging to sound weld metal, is required so that potential root defects within the welded joint are detected and eliminated, and the stress concentration at the weld root is eliminated. Since many of aisd tested beam sections were built-up members, the limitations are in cross section dimensions instead of rolled-beam designations.
AISC 358-10 Prequalified Connections
A sampling of at least 40 castings shall be made for such reduction evaluation. Check the beam flange for block shear. W30, W27, W24, W21 and W However, the potential for post-fabrication k-area base metal cracking exists in highly restrained aosc at the weld terminations for column continuity plates, web doublers, and thermal cut coped beams.
The exception applies aixc when shear studs are used to attach the concrete slab to the connected beam and is because of the lack Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications,incl. Two means of demonstration are acceptable.
Standard holes shall be provided in the beam web and in the plate, except that short-slotted holes with the slot aic to the beam flanges may be used in either the beam web or in the plate, but not in both.
Punched bolt holes without reaming are not permitted, because punching may induce surface roughness in the hole that may initiate cracking of the net section under high tensile stress. Three different column sizes were used: If no beams exist on a node at a particular column face, the CFT and CFB are aligned at the nominal depth of the moment beam, and the CWX shall be permitted to be optionally omitted. Only connections that are within these limits are prequalified.
Results are reported in several publications Lee et al.
Built-up Columns Four built-up column cross section shapes are covered by this Standard. The purpose of this research program was to examine alternative doubler plate details, continuity plate requirements, and effects of a weak panel zone. The stiffener-to-beam-flange and stiffener-to-end-plate welds shall be designed to develop the stiffener plate in shear at the beam flange and in tension at the end-plate.
If bolted to the beam flange, Figure 9. Similar to RBS testing, most of the tested beam-column assemblies had configurations approximating beam span-to-depth ratios in the range of eight to ten. The largest box column for which test data was available was 24 in.
Experimental work has included successful tests on all of these types of RBS cuts. Fabrication of Flange Cuts. The minimum stiffener length shall be: The patent holder has filed a statement of willingness to grant a license under these rights on reasonable and nondiscriminatory terms and conditions to applicants desiring to obtain such a license.
When supplemental lateral bracing is provided, attachment of supplemental lateral bracing to the beam shall be located at a distance d to 1. For IMF applications, bolted web connections are acceptable. When welded to the beam flange, the a b Fig. Steel Backing at Continuity Plates The stress and strain level at the groove weld between a continuity plate and column flange is considerably different than that at the beam flange-to-column flange connection; therefore it is not necessary to remove the backing.
AISC Prequalified Connections
The maximum gage dimension is limited to the width of the connected beam flange. Most of the beam-to-column assemblies that have been tested had configurations approximating beam spans of about 25 ft 7. The single plate also serves as backing for the CJP groove weld connecting the beam web to the column flange. The moment at the face of the column shall be computed from a free-body diagram of the segment of the beam between the center of the reduced beam section and the face of the column, as illustrated in Figure 5.
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. The shear strength of the flange bolts is the smallest strength permitted by bolt shear with threads excluded from the shear plane, the bolt bearing on the flange plate, bolt bearing on the beam flange and block shear considerations.
Four-bolt unstiffened extended end-plate 4E geometry. Similarly, beams with shorter spanto-depth ratio aics have a sharper moment gradient across the beam span, resulting in reduced length of the beam participating in plastic hinging and increased strains under inelastic rotation demands. These members have not generally been tested in other prequalified connections; however, the conditions of inelastic deformation imposed on the built-up shapes in these other connection types are similar to those tested for the bolted end-plate connections.
Weld tabs, if used, must be removed after welding in accordance with the requirements of Section 3.
While this requirement is rational, it should be noted that net section rupture of the beam flange has not occurred in any past BFP tests, since the beam web clearly reduces any potential for flange rupture. The aic or table number on the right refers to where the symbol is first used. Because, for the prequalified connections, design demand is determined based on conservative estimates of the material strength of weak elements of the connection assembly, and materials, workmanship and quality assurance are more rigorously controlled than aic other structural elements, resistance factors have been set somewhat higher than those traditionally used.
This definition is based on test observations that indicate yielding typically does not extend past the far end of the RBS cut. 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 Steel backing used at continuity plate-to-column welds need not be removed.
Free-body diagram between center of RBS and face of column. The singleplate to column-flange connection shall consist of CJP groove welds, two-sided partial-joint-penetration PJP groove welds, or two-sided fillet welds.
The weld procedure specification WPS for the 35-805 weld joining the bracket to the beam flange shall be qualified with the casting material.
Concrete shall have day compressive strength not less aizc 3, psi 21 MPa. Other weld defects shall be removed by grinding, faired to a slope not greater than 1: The probable maximum moment at the face of the column shall be taken as Mpr, computed per Step 1.
For single-sided connections in which a momentconnected beam attaches to only one of the column flanges, it is generally not necessary to use CJP groove welds to attach the continuity plate to the column flange Figure C Beam flange flexural forces zisc moment beams are transferred to the 3588-05 flange assemblies via complete aizc penetration CJP groove welds. The distance must be sufficient to provide clearance for any welds in the region.
Continuity plates shall conform to the requirements for wide-flange columns. Weld tabs are not required at the ends of the CJP groove weld at the beam web.
The three end-plate configurations aiac in Figure 6. This weld shall be provided over the full length of the web between weld access holes, and shall conform to the requirements for demand critical welds in the AISC Seismic Provisions and AWS D1.