Influence of External Steel Plates on the Characteristics of Existing RC Columns under Near Field Ground Motion

Abstract eng:
Near field ground motions are different from ordinary ground motions in that they often contain strong coherent dynamic long period pulses and permanent ground displacements. The dynamic motions are dominated by a large long period pulse of motion that occurs on the horizontal component perpendicular to the strike of the fault, caused by rupture directivity effects. Near fault recordings from recent earthquakes indicate that this pulse is a narrow band pulse. These characteristics make near field earthquakes unique compared to far field ground motions, which nearly all seismic design criteria are based on. Older buildings built before 1987 in Iran are known to demonstrate poor seismic performance in terms of ductility and energy dissipation capacity during severe seismic events. Various methods are developed for strengthening of reinforced concrete columns against shear. Strengthening of reinforced concrete columns using external bounding of steel plates was one of the popular research areas of recent years. This paper presents the effect of near field motions on reinforced concrete columns strengthen by external bonding of steel plates. Five reinforced concrete columns were analyzed under seismic loading. Three main types of steel members with different arrangements were bonded to the column. The purpose was to obtain ductile behavior for shear deficient reinforced concrete columns. The analysis result confirmed that all steel plate arrangements improved the strength and stiffness of the specimens significantly. The tension reinforcement of all strengthened reinforced concrete specimens was yielded. The failure modes and ductility of specimens were proved to differ according to the type of the steel member and arrangement along the column.

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