(A) It is the intent of this section to recognize that the eventual elimination, as expeditiously as it is reasonable, of existing signs that are not in conformity with the provisions of this ordinance, is as much a subject of health, safety, and welfare as is the prohibition of new signs that would violate the provisions of this ordinance. It is also the intent of this section that any elimination of nonconforming signs shall be effected so as to avoid any unreasonable invasion of established private property rights.
(B) Any sign, billboard, commercial advertising structure, or similar object which lawfully existed and was maintained at the time this ordinance became effective may be continued although the use does not conform with the provisions of this ordinance, provided that it shall not be:
(1) Changed to another nonconforming sign;
(2) Structurally altered as to prolong the life of the sign;
(3) Expanded;
(4) Reestablished after its discontinuance for 90 days; or
(5) Reestablished after damage or destruction if the estimated expanse of reconstruction exceeds 50% of the appraised replacement cost.