I am currently going through the Six minute solutions for the PE construction exam and problem 45 in the depth section is a tower crane lifting radius question. The problem gives you the boom length, the weight of the boom and its rigging accesories, and a load weight. They also give you a chart that lists lifting capacities for different radii. The question is asking for the maximum safe lifting radius to lift a 15,000 lb. load. The solution states to add the weight of the boom to the load weight (in this case 2,000 lbs. + 15,000 lbs.) which gives you 17,000 lbs. and iterpolate between the values in the chart to give an exact lifting radius. (The chart lists a lifting capacity of 18,440 lbs. for a 150' radius and 15,940 lbs. for a 170' radius). The answer choices are 150, 160, 170, and 230. From interpolation it comes out to be 161' so they claim the correct answer is 160'. However, in my "Guide to Passing the Construction PE Exam" that I purchased from a user on this site, it specifically says to not interpolate between values in these charts given for crane lifting capacities and to use the nearest radius to your lifting weight that is more conservative. In that case the answer would be 150' because thats the next radius listed in the chart. Can anyone clarify which way is correct for the test? Thanks in advance for your help.
Interpolate tower crane lift radius charts or not?
- Thread starter wtindal
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If i remember correctly, in my prep course, we always chose the conservative value as listed in the load chart. I know in the "real world", when planning a crane pick, you never interpolate the load chart.
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