This paper presents results of welding inspection and loading tests conducted to beam-to-column connections cut out from an existing steel building constructed in 1986. From the results of thorough welding inspections, inner defects are frequently detected at corner of square tube column, and differences among individuals of inspectors are examined. From the results of dynamic loading tests conducted on the beam-to-column connections, the influence of defects on the deformation capacity and the failure procedure are observed. Though deformation capacity of existing steel subassemblages meets minimum requirements of current seismic design, it is less than half that of new steel subassemblages fabricated according to current design practice.
