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CONCLUSIONS The behavior of the structure was i n general accord with e x i s t i n g design theories, though a shear weakness was observed at edge columns. However, damage t o the structure before t e s t i n g began may have i n - fluenced both performance and strength. Performance of the t e s t structure was satisfactory \ander 350 psf applied load (added dead plus about 1.0 l i v e load). Steel stresses were low and deflections were w i t h i n acceptable l i m i t s . No ab- normal increases i n crack width were observed at service load. Deflections computed using an equivalent frame analysis were i n good agreement with measured values. Although the frame analysis i s cvmibersome, i t appears t o be a r e l i a b l e method f o r p r e d i c t i n g deflections at the center of panels. For a l l t e s t s the structure s a t i s f i e d c r i t e r i a f o r eval\xation of load tests stipulated i n the 1963 ACI Code. Flexural capacity was not reached i n any of the three t e s t s . Ul- timate strength was governed by shear at i n t e r i o r and edge columns before a y i e l d mechanism coTild be developed. Shear strength of the slab at the i n t e r i o r column loaded from a l l four sides was about 20 percent greater than that implied by ultimate strength design methods of the I963 ACI Code. Shear strength of the slab at edge coltmins was less than t h a t implied by slab design procedures of the Commentary on the 1963 ACI Code. However, measured and computed strengths were i n good agreement when the shear was considered carried by the edge beams. Shear strength of the slab at an i n t e r i o r column supporting a single loaded panel was about 60 percent of t h a t implied by design methods of 1- 55
the Commentary on the 1963 ACI Code. Measured and computed strengths were i n good agreement when applied load was assumed to enter the column through the two faces Joining the loaded area. The structure possessed some strength under t e s t load conditions a f t e r each shear f a i l u r e . This capacity could be accounted f o r almost en- t i r e l y by y i e l d l i n e a n a l y s i s . L i t t l e strength was available at the columns a f t e r the i n i t i a l punching f a i l u r e had occurred. The t e s t s involved successful application of many laboratory proce- dures i n the f i e l d . Control of the t e s t and data c o l l e c t i o n were within tolerances somewhat better than those customarily obtained i n the f i e l d . P r i o r to application of t e s t loads, d i f f e r e n t i a l settlement of the structure probably took place; diagonal cracks were v i s i b l e i n a wall and i n edge beams. Analysis indicated that t h i s settlement could have caused added loads on columns. Settlement combined with shrink- age may also have produced t e n s i l e in-plane forces in the slab. These i n t e r n a l forces probably reduced shear capacity, p a r t i c u l a r l y at edge columns. 1-56
