MODIFICATION OF STRUCTURAL INFLUENCE FACTORS FOR THE COUPLING EFFECT OF PULSE-LIKE GROUND MOTION AND STRUCTURAL ECCENTRICITY

The modification of the structural influence factors considering the adverse effects from both structural eccentricity and pulse-like earthquake effect was investigated for reinforced concrete frame systems. The modification method was established theoretically and the calculating process was described. Ten pulse-like and ten non-pulse-like ground motions were employed in the nonlinear dynamic time history analysis on frames with the most unfavorable strength eccentricity. The relationships between the modification factor and the pulse-like effect, eccentricity, ductility and story number were studied quantitatively. Based on the numerical results, a fitting formula was established to estimate the modification factor. It showed that the modification factors for pulse-like cases were clearly greater than those for non-pulse-like cases. In addition, the modification factor increased linearly first and subsequently nonlinearly with an increasing eccentricity. The ductility had a small effect on systems with lower eccentricities, while for systems with higher eccentricities the modification factor decreased as the ductility increased. The influence of story number was not significant. Furthermore, the fitted formula can be applied as a reference in seismic design to comprehensively consider the disadvantages of the pulse-like earthquakes and structural eccentricity.