Ul ul cept for a thickening to resist the high shear forces around today the top
ID: 1711941 • Letter: U
Question
Ul ul cept for a thickening to resist the high shear forces around today the top of each column. Traditional to reduce the formwork Iyx, this thickening was accomplished a drop panel to do the weavin Ciminated FIGURE 14.30 A two-way flat plate floor of a high-rise apartment building is poured with the aid of a concrete pump at the base of the building. The concrete is delivered up a telescoping tower to a nozzle at the end of an articulated boom. The column dowels in the center of the newly poured area demonstrate the ability of flat plate construction to adapt to irregular patterns and spacings of columns. (Courtesy of Schwing America, Inc.)Explanation / Answer
I found two problems with this picture.
1. as its casting of the slab, the slump of concrete is low and height of free fall of concrete is very fall. thence there is a chance of segregation. Generally, the free fall should not more than 3-5 feet.
2) The second one is concrete is freefalling on reinforcement. ACI's Guide for Measuring, Mixing, Transporting, and Placing Concrete (ACI 304R-89) in Section 5.4.1 gives some precautions for placing. The guide says equipment should be arranged so that the concrete has an unrestricted vertical drop to the point of the placement. The stream of the concrete shouldn't be separated by permitting it to fall freely over rods, spacers, reinforcement, or other embedded materials. If forms are sufficiently open and clear so that the concrete isn't disturbed in a vertical fall into place, direct discharge without the use of hoppers, trunks, or chutes is usually desirable.
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