Vertical City Series by George S. Mahaffey Jr.

In the midst of a global pandemic, a group of evacuees are marooned atop a skyscraper in a major city after a terrible helicopter crash. Abandoning the streets to millions of hungry infected, the survivors seal off the structure at the 10th floor and string wires between it and other buildings to avoid being eaten alive by the hordes rampaging below. But dwindling supplies force those still alive to take greater risks as they struggle to survive hundreds of feet off the ground.