# How Bridges Work 8, Exercise 3: how far ahead can one side get?
# During balanced cantilever construction each deck segment weighs 3000 kN
# (illustrative: 250 kN/m x 12 m). If one side gets k segments ahead, the extra
# weight at the tip of an arm of length L puts a moment k x 3000 x L on the
# tower. The tower can take an out-of-balance moment of 700,000 kN m
# (illustrative). For arm lengths of 96, 192, 288 and 324 m find the largest
# whole number of segments one side may be ahead, and the moment for that number.
seg_weight, allow = 3000, 700000

for arm in (96, 192, 288, 324):
    k = int(allow // (seg_weight * arm))
    print(arm, k, k * seg_weight * arm)

# Output when run:
# 96 2 576000
# 192 1 576000
# 288 0 0
# 324 0 0
#
# Columns: arm length (m), largest number of segments one side may be ahead,
# the out-of-balance moment for that number (kN m). With these illustrative
# numbers, a 96 m arm tolerates two segments of lead, a 192 m arm one, and arms
# of 288 m and 324 m none at all: one segment at that distance (864,000 kN m
# and 972,000 kN m) is already beyond the 700,000 kN m limit. This is why
# long balanced cantilevers are built by adding segments at alternate
# ends in step, and why wind (How Bridges Work 9) during erection is so
# serious.