Seismic Response of Steel SMFs Subjected to Vertical Components of Far- and Near-Field Earthquakes with Forward Directivity Effects

Jong Wan Hu,Iman Mansouri,Shahrokh Shahbazi,Noura Sam Daliri,Armin Karami

doi:10.1155/2019/2647387

Abstract

In the near-field earthquake, forward directivity effects cause long-period pulse with a short effective time and a large domain in the velocity time history. This issue increases the ductility needs of structures, and in recent decades, the destructive effects of these kinds of records have been evaluated in comparison with far-field earthquakes. This brings about the necessity to compare a structure’s behavior subjected to vertical components of near-field (NF) earthquakes, including forward directivity effects vs. the effects of vertical components of far-field (FF) earthquakes. The present study investigated 3-, 5-, 8-, and 20-story steel moment frames with special ductility (SMF) through which modeling effects of panel zone have been applied, subjected to vertical component of near-field (NF) earthquakes with forward directivity and the vertical component of far-field earthquakes. By investigating the results, it can be clearly seen that the average values of the maximum displacement, shear force of the stories, and the velocity of each story under the impact of the near-field earthquake are greater than the amount of that under the effect of a far-field earthquake. However, this comparison is not valid for the amount of acceleration, axial force, and moments in the columns of the structures accurately.

Highlights

Near-fault (NF) ground motions are specified by longperiod velocity and displacement pulses [1] and high values of the ratio between the peak of vertical and horizontal ground accelerations [2]
In comparison with other studies, these researches have determined that vertical response spectra are most susceptible to spectral period and source-to-site distance
The vertical-to-horizontal (V/H) response spectral ratios are higher on soil than on rock, and at shorter periods than at longer periods, in general [10]

Summary

Introduction

Near-fault (NF) ground motions are specified by longperiod velocity and displacement pulses [1] and high values of the ratio between the peak of vertical and horizontal ground accelerations [2]. E amplitude of this pulse depends on the directivity of rupture distribution to the site. Since the rupture diffusion velocity is almost the same as the velocity of shear wave diffusion, if the fault rupture propagates to the considered place, the waves in a short-term period will reach to the place resulted in a pulse with high amplitude and short period that is called forward-effect directivity [3, 4]. The vertical-to-horizontal (V/H) response spectral ratios are higher on soil than on rock, and at shorter periods than at longer periods, in general [10]

Objectives

Methods

Results