Chapter 4, Problem 33QAP

A +7.5% grade meets a horizontal grade on a section of a rural mountainous highway. If the length of the crest vertical curve formed in that section is 300 ft long, determine the safe operating speed on the highway.

A sawn timber beam of dimensions 8"x14" has is required for a span of 16 ft. The uniformly distributed loads are Dead (D) = 350 lbs./ft and live (L) = 400 lbs./ft. The dead load includes the beam self-weight and lateral torsional buckling is prevented. The beam is to be used in an indoor environment (MC > 19º) in normal temperatures. Using Caribbean Pitch Pine (Select Structural), check that the section chosen is adequate.

1. Copper is known to be toxic to fish, and in particular, the free ion Cu²+ species typically shows greatest toxicity. a. Calculate the speciation of Cu(II) for freshwater at a pH value of 8.3 as the hardness increases from 20 (soft) to 100 (moderately hard) to 200 (very hard) mg/L as CaCO3. Assume that the total divalent Cu(II) concentration is 10 µg/L. b. Based on your findings in part (a), do you think it is appropriate to set a single regulatory limit or should it depend on variables such as pH and hardness? Explain your answer.