Investigation of the effect of cold joints on the strength and ductility of the joints in reinforced concrete buildings

There are certain time differences during the concrete casting processes in today's manufacturing methods of reinforced concrete structures. It is unlikely to be possible to pour all the concrete of a building at once in the current manufacturing techniques. Concrete pouring at different times causes cold joint formation especially between column-beam joints. As it is known, the most stressed and damaged areas of a building during an earthquake are the column-beam junction areas. Sections that are most exposed to moment in structural analysis are those with these joint areas. Therefore, it is important to investigate the effect of cold joints formed in these joint regions on the strength and ductility of the structure during an earthquake. In the scope of this study, the effect of the cold joint formed in the column-beam joints of the structures on the strength and ductility of the structure was examined. At the same time, the effect of axial force on columns on the behavior of these joint regions was investigated. In this study, four samples containing column-beam joints was built. Two of the samples were cast at once. The first of these monolithic samples was subjected to cyclic loading by exposing axial load to their columns. The other sample was subjected to cyclic loading without axial force in the column. In the other two samples, two cold joints were left on the upper and lower ends of the beam. The first of these samples was tested by applying an axial load to the column, and the other was tested without applying an axial load to the column, as in the monolithic samples. As a result of these experiments, both the effect of the axial force on the cold joints and the effects of the cold joints on the column beam joint are investigated experimentally.