EQUIVALENT BEAM MODEL FOR FLAT-SLAB BUILDINGS .1. INTERIOR CONNECTIONS

Flat-slab buildings are commonly modeled as two-dimensional frames to calculate lateral drift, unbalanced moments, and shear at slab-column connections. For gravity loads, the slab-column frames are analyzed us ing equivalent-column approach, while equivalent beam approach is typi cal for lateral loads. The equivalent beam approach is convenient for computer analysis, but no rational procedure exists for determining th e effective width of floor slabs. At present, the determination of the equivalent slab width and its stiffness is a matter of engineering ju dgment. To account for cracking, overly conservative assumptions are m ade regarding the stiffness of the slab. A rational approach is theref ore needed to realistically estimate the equivalent slab width and its stiffness for unbalanced moment and lateral drift calculations. Based on the test results of 40 interior connections, an equivalent beam mo del is proposed in which columns are modeled conventionally, and the e ffective slab width is determined as a function of column and slab asp ect ratios and the magnitude of the gravity load. The proposed approac h is verified with selected experimental results and is found to be pr actical and convenient for analyzing flat-slab buildings subjected to gravity and lateral loading.