(Solved): a) A old bridge was going to be widened, but before the widening occurred, inspection of the cable ...

a) A old bridge was going to be widened, but before the widening occurred, inspection of the cable ties supporting the bridge showed that several of the ties had failed. The bridge and tie arrangement can be seen below: AA BB The cable ties are loaded in tension and free to sway in the breeze. They are also directly exposed to the weather and the environment. The failed ties are seen below: An engineer examines the fracture surface and she says, "Oh it's obvious what happened. The parallel lines on the fracture surface give it away and the changed failure mode at the top of the fracture surface makes it clear what happened." a) What causes the parallel lines the engineer is talking about? (1 mark) b) What caused the failure of the hook? (1 mark) c) What caused the change in the fracture surface at the bottom of the section? (2 marks) d) Which mechanical property needs to be considered when choosing the hook's replacement? Explain your answer. (2 marks)