In this study the behavior of RC weak column-beam connections which have no joint stirrups and lack of column stirrups, are investigated experimentally under earthquake loads. Edge beam to column joints were tested under reversed cyclic loads. It is the prestudy of which has seven joint strengthening techniques. 1/2 scaled one reference and seven weak joint specimens with no stirrups were prepared and tested. The building defects in real structure exactly tried to create when producing the weak specimens. These building defects include lacking stirrups in joint region, low compressive strength of concrete and in progress of time pouring out of concrete cover. The weak specimens' behaviors compared with the reference specimen and load-deflection graphics taken. The main parameters are constant axial load and the distance of lacking stirrups at the joint region. As a result of the experimental study in reference specimen achieved to carrying capacity from the beam. Damages in joints are dangerous. In all weak specimens reached to carrying capacity from the joint before the beam. In some weak specimens columns' shear damages and joints' hard damages together determined the carrying capacity.