I had no idea what 'Sprengwerk' means, so I googled it. The German page is pretty thorough, but the most interesting thing is that the English page linked on the page for 'Sprengwerk' is 'rigid-frame bridge'.

And yes, it is based on a meaning of 'sprengen' which I hadn't known, and it's more interesting than that: 'sprengen' mostly means to destroy with force, but also to use a sprinkler (not what came to mind, but fair do), and to drive animals out of their burrows with dogs, and to move lively and with force (this is archaic, sometimes said of horses. 'Springbrunnen', and indead the english 'spring' [water] are related. 'Absprengen', on the other hand means to separate with force, and here we come to the etymology of 'Sprengwerk': the force is pushed onto the angled supports (trusses?).

Learnt something today!