I l til ise were ued to 25 it what would be the horizontal

. I l til ise were ued to 25 it, what would be the horizontal component of the reaction? Discuss the advantages and disadvantage this change. 6. Craigellachie Bridge. The 1814 arch bridge over the Spey River at Craigel- 4 lachie, Scotland, designed by Thomas Telford, has a span L of 150 ft. and a rise d of 20 ft. Assuming that a uniformly distributed dead load q of 2 kips/ft. acts on the deck, compute the horizontal reaction force H at the base 8 of the arch. 7. A rch Form. The curvature of an arch is both an aesthetic and a scientific choice. Notice that visually, the arch of the Craigellachie Bridge appears flatter than the arch in the earlier Iron Bridge. Scientifically, this quality is described by a span-to-rise ratio (LId), which affects the horizontal thrust of the arch. a. Calculate the LId ratio for both bridges and compare the values. b. If Telford had chosen to increase the rise of the Craigellachie Bridge by two times, how would this have affected the LUd ratio and the horizontal thrust of the arch at its supports (assuming all other values remained th same )2

Solution

For a arch, the horizontal reaction at the base is given by wl²/8h where w is unifrom load, l is span and h is rise of arch

In the gioven problem,w=2 kip/ft/l=150 ft and h=20

Therefore, horizontal reaction = 2*150²/8*20=281.25 kips