SURFSIDE, Fla.—Rescue efforts at the site of a partially collapsed Florida condominium building resumed Thursday evening after a 15-hour pause for safety concerns, and officials said they had started planning for the likely demolition of the remaining structure. Miami-Dade County Mayor Daniella Levine Cava said the decision about the demolition needs to be made “extremely carefully and methodically,” considering the potential impact on the pile of debris and the effect on the search-and-rescue operations. An engineer from the Federal Emergency Management Agency said it would likely be weeks before officials schedule the demolition. The rescue work was halted shortly after 2 a.m. amid concerns about the stability of the part of the tower that still stands. Crews noticed widening cracks and up to a foot of movement in a large column. Work resumed shortly before 5 p.m. after the site was evaluated by structural engineers, Cava said, describing firefighters as …