ACI 352.1R-11 Guide for Design of Slab-Column Connections in Monolithic Concrete Structures

ACI 352.1R-11 Guide for Design of Slab-Column Connections in Monolithic Concrete Structures. 4.3—Determination of connection forces 4.3.1 Forces on the connection may be determined by any method satisfying requirements of equilibrium and geometric compatibility for the structure. Time-dependent effects should be evaluated. 4.3.2 For normal gravity loads, Section 4.3.1 may be satis- fed using the Direct Design Method, the Equivalent Frame Method of ACI 318-08, the Effective Slab Width Method, or the Finite Element Method of ASCE/SEI 41-06. For uniformly loaded slabs with nearly equal spans, with no more than 20 percent difference, slab shears at the connec- tion may be determined for loads within a tributary area bounded by panel centerlines; slab shears at frst interior supports should not be taken less than 1.2 times the tribu- tary area values unless a compatibility analysis shows lower values are appropriate. The design should account for the worst combinations of actions at the connection. Analysis for connection forces should consider at least (a) loads producing the maximum slab shear on the shear-critical section; and (b) loads producing the maximum transfer moment at the shear-crit- ical section. Factored slab shear at the connection can be determined by procedures such as yield line and strip design methods (Johansen 1962; Park and Gamble 1980) and the equivalent frame method. However, in typical designs, simpler proce- dures such as the use of tributary areas are acceptable. The designer is cautioned, when using simplifed procedures, that the actual shear at frst interior supports is likely to be as much as 20 percent higher than the shears calculated using the tributary area (Hatcher et al. 1965; Criswell 1972) because of continuity effects. For cases with unequal spans, this increase may exceed 20 percent. 5.1—General principles and recommendations Connection strength may be determined by any method that satisfes the requirements of equilibrium and geometric compatibility and that considers the strength of the adjoining members. Instead of a general analysis, the strength of the slab included at the connection may be determined according to Sections 5.2, 5.3, and 5.4. The joint strength may be deter- mined according to Section 5.5. Methods of calculating strength of the slab at the connec- tion in shear and moment transfer have received consider- able attention in the literature. Available methods include applications of yield line theory, elastic plate theory, beam analogies, truss models, and others (Joint ACI-ASCE Committee 426 1974; Park and Islam...