Quote:
Originally Posted by amor de cosmos
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Ahhh. Now this is practical.
So many of the pedestrian bridges shown here seem to be both too expensive, and, show too much of the politician's inclination to "make a monument to me."
In my opinion, the best bridge design was largely worked out by US railroads by the 20s. Those bridges built by the railroads were built to support huge loads, whereas pedestrian bridges would not require such a huge amount of support weight due to the square/cube law. If classic truss systems which can be seen in almost any pre-sixties engineering handbook had a load limit 1/10 of a rail span, the mass needed for the trusses and truss support would require about 1/100th (the square root) the building mass per linear meter.
Keep pedestrian bridges light, under tension, and, free of oscillation harmonics. The simplest way to reduce oscillation is not to suspend the bridge- just mount it on support abutments.
Don't play with curves too much unless they are in the X,Y plane. Curves in the horizontal plane can have pretty complicated downward thrust problems... Build them with cheap materials- some old wooden rail trussels have lasted many decades (creosote replacement needed, of course). Steel tubing, IMO, is pretty cool, too, but, welding is more difficult. If concrete is used, make it pre-streesed, precast and truckable to the site. Stay away from too long spans, because pricing for increasing the spanlength is not linear, but exponential.