Signatures upon petitions, and sections thereof, shall be secured, and the petition, together with all sections thereof, shall be filed, within 30 days from the date of the adoption of the ordinance to which it relates. Petitions and sections thereof shall be filed with the elections official of the legislative body of the city in his or her office during normal office hours as posted. Petitions which are not filed within the time permitted by this section shall be void for all purposes.