AN EXPERIMENTAL-STUDY OF A MIDBROKEN 2-BAY, 6-STORY REINFORCED-CONCRETE FRAME SUBJECT TO EARTHQUAKES

A 2-bay, 6-storey model test reinforced concrete frame (scale 1:5) sub jected to sequential earthquakes of increasing magnitude is considered in this paper. The frame was designed with a weak storey, in which th e columns are weakened by using thinner and weaker reinforcement bars. The aim of the work is to study the global response to a damaging str ong motion earthquake event of such buildings. Special emphasis is put on examining to what extent damage in the weak storey can be identifi ed from global response measurements during an earthquake where the st ructure survives, and what level of excitation is necessary in order t o identify the weak storey. Furthermore, emphasis is put on examining how and where damage develops in the structure and especially how the weak storey accumulates damage. Besides the damage in each storey the structure is identified by a static load at the top storey while measu ring the horizontal displacement of the stories and also visual inspec tion is performed. From the investigations it is found that the reason for failure in the weak storey is that the absolute Value of the stif fness deteriorates to a critical Value where large plastic deformation s occur ard the storey is not capable of transferring the shear forces from the storeys above so failure is unavoidable. (C) 1997 Elsevier S cience Limited.