Abstract
Mechanical behavior of reinforced concrete noticeably changes because of creep, shrinkage, temperature, cracking and other similiar disturbances. Therefore, elastic analysis shows that there are slight significances in calculating stress and strain of reinforced structures. In addition, the ultimate load bearing capacity of the structures can not be determined by elastic theory. It is believed that the structural designed of shell roofs would be more satisfactory if the ultimate load theory was used. Therefore, in order to test the failure of the mechanism of the long shell roofs, the author conducted several tests on scale models of long shell roofs. Seventeen of these scale model cylindrical long shell roofs were tested. These tests showed the following results: There are crack patterns in all of these cylindrical long shell roof models at the time of their failure. Thus the mechanism of failure of the cylindrical long shell roofs has been proved as a result of these tests.
