4" Hollowcore plank load table
4" Hollowcore plank load table
(OP)
I am checking an existing building that was built in 1970 and it appers that at the roof level over the main corridor they used 4" precast hollowcore plank with a light weight topping that slopes from 1 1/2" to 6 3/8". The PCI load tables only go down to 6", so I was curious to see if anyone knew of any literature that would have the information I am looking for.
Thank you for you help.
Thank you for you help.






RE: 4" Hollowcore plank load table
RE: 4" Hollowcore plank load table
RE: 4" Hollowcore plank load table
BA
RE: 4" Hollowcore plank load table
RE: 4" Hollowcore plank load table
BA
RE: 4" Hollowcore plank load table
RE: 4" Hollowcore plank load table
RE: 4" Hollowcore plank load table
RE: 4" Hollowcore plank load table
The earlier precasters usually had good load/capacity tables. Because the volume of 4" hollow was limited, there was little changing in the configuration and reinforcement through the years, so some current information may be referred to. The plants/equipment used in 1970 may have been acquired and operated under different producer names today.
The 4" would have been a common product (length can always be changed by cutting). Two possible products in the 1970's would have been one of the Flexicore licensed producers and some Spancrete. The older Flexicore would have been either 16" or 24" wide with true circular cores) and actually wet cast in heated forms is 60' lengths (commonly) before cutting. You can spot it by looking at the smooth (steel forms with corner radiuses) and it was commonly exposed because of the surface quality. The Spancrete would probably been wider (36" or more) and would have a coarser bottom texture since it is is an extruded product with low slump and core are "pyramid-shaped" and casting beds are many time longer.
There is some enjoyment in tracking down products since many of the old plants and processes have some continuity and the producers were manufacturers and kept records on both standard products and items for separate projects that has led to the popularity and reliability of the current PCI certification.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: 4" Hollowcore plank load table
Probably a minimum of 4000 psi. But it makes little difference to the issue at hand. You have the value of φ*Mn for each type of plank and also the allowable load for various spans.
Assuming the 36" wide planks were built similarly to the 48" planks, there would be no reason to reduce the values because the values are given per foot of width.
The topping should conservatively be considered unbonded. Assuming φ*Mn = 4.71'k/' as given for the least capacity, would that be enough for your case? If so, you may be okay if the original supplier used the same reinforcement.
BA
RE: 4" Hollowcore plank load table
RE: 4" Hollowcore plank load table
At a span of 8', the slab can carry an allowable load of 342 psf, so the total load is 376 psf and the moment is 3008. The average load factor is 4710/3008 = 1.56.
Let D and L be the dead and live load factors. Assume all spans are controlled by the moment capacity of the slab. Check at spans of 8' and 18', then confirm at 15'.
At 8' span, 34D + 342L = 4710/8 = 588.8
At 18' span, 34D + 47L = 4710/40.5 = 116.3
So L = 1.60 and D = 1.22
At 15', (34*1.22 + 79*1.6)152/8 = 4721 (close enough to 4710).
BA