The provisions of this chapter shall not be construed as relieving or limiting in any way the responsibility or liability of any person, firm or corporation erecting or owning any sign from personal injury or property damage resulting from the placing of the sign, or resulting from the negligence or willful acts of such person, firm or corporation, its agents, employees or workmen, in the design, construction, maintenance, repair or removal of any sign erected in accordance with a permit issued under the provisions of this chapter. Nor shall it be construed as imposing upon the city or its officers or employees, any responsibility or liability by reason of the approval of any signs, materials, or devices under the provisions hereof.