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AE-390
CONCRETE FRAME
GROUP 9
Useful Numbers for Building
The figures given below and the illustration to accompany them are here to represent a typical office building and the loads that a concrete frame structure could be dependant on to support. These loads will vary with each building application and both live and dead loads will be greatly influenced by the machinery and typical day to day use of the building. The concrete can also change properties but the numbers given below are to reflect some typical values you are likely to experience. The end of this section will show you how to calculate the loads that you could expect on a column with your structure.
Concrete Floor Loads
A typical service live load for a building can be expected to be around 100 PSF, to find the total load you would add the dead load DL and the live load LL. The live load will sometimes use a scaling factor of 1.2 or 1.6 for a factor of safety in design.
Considering a 1 ft area and a concrete slab thickness of 6.5 inches, the concrete dead load that can be expected can be found using the weight of concrete which is typically 150 PSF multiplied by the nominal thickness divided by 12
Dead Load = 150 x 6.5/12 = 81 PSF
Live Load = 100 PSF
Factored DL + LL= 81 + 100*1.6 = 41 PSF
calculating column Reaction Loads
In the example to follow reactions are calculated for the columns in a three story building with typical concrete frame construction. Figure L1 shows the building rendition with the support members for each floor
Figure L1: Buidling Structure
Figure L2 is an intermediate calculation showing the intermediate calculation in finding sum of the PSF load experience for the portion under analysis which is a corner wing of the buildingd
Figure L2: PSF per floor calculation
The final figure used in calculating the reactions on the columns is to sum the weight of the consectutive floors to find the greates reaction in pounds experience by the column at the base.
Figure L3: Column reaction if lbs
Typical supporting live loads for concrete
Here a gantt chart is given to illustrate typical live load supporting weight that each different type of of slab construction can be expected to perform well under. A detailed description of these different methods can be seen in the "types" tab of this webpage for more clarification. The chart shows under what circumstances a construction type would be implemented. These can be seen in figure L4, below.
Figure L4: Live load supporting weights
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