scholarly journals Recent advances in engineering characteristics of near-fault ground motions and seismic effects of building structures

2015 ◽  
Author(s):  
Dixiong Yang ◽  
Kaisheng Yang ◽  
Guohai Chen
Keyword(s):  
Ground Motions ◽  
Building Structures ◽  
Seismic Effects ◽  
Near Fault ◽  
Engineering Characteristics ◽  
Recent Advances

Seismic Responses of Isolated Buildings With Supplemental Devices Subjected to Near-Fault Earthquake

2016 ◽  
Author(s):  
Wen-I Liao ◽  
Sheng-Qing Wang
Keyword(s):  
Dynamic Response ◽  
Ground Motions ◽  
Response Characteristic ◽  
Building Structures ◽  
Velocity Pulse ◽  
Near Fault ◽  
Large Velocity ◽  
Parametric Studies ◽  
Spectral Velocity ◽  
Better Than

Near-fault ground motions, which caused much of the damage in recent major earthquakes (Kobe 1995, Chi-Chi 1999), are characterized by a pulse-like motion that exposes the structure to high input energy at the beginning of the record. The first objective of this research is to compare the dynamic response of seismic isolated and non-isolated building structures subjected to near-fault ground motions with large velocity pulse. Two typical building structures with three stories and eight stories designed by Taiwan seismic design specifications of buildings are adopted for this study. Numerical results show that the seismic performance of isolated buildings is not definitely better than the no-isolated one under some near-fault ground motions with large velocity pulse. Secondly, the isolated building structures retrofitted with supplemental elastic device (SED) or supplemental viscous damper device are analyzed. Parametric studies for the dynamic response of seismic isolated buildings with and without supplemental devices are developed. Analyzed results show that the parameters PGV/PGA ratio and spectral velocity may govern the isolated building response characteristic for input near-fault pulse-like ground motions.

scholarly journals Effectiveness of modified pushover analysis procedure for the estimation of seismic demands of buildings subjected to near-fault ground motions having fling step

2013 ◽  
Vol 13 (6) ◽  
pp. 1579-1593 ◽  
Author(s):  
A. Mortezaei ◽  
H. R. Ronagh
Keyword(s):  
Ground Motions ◽  
Pushover Analysis ◽  
Time History ◽  
Building Structures ◽  
Seismic Demands ◽  
Near Fault ◽  
Load Pattern ◽  
Dynamic Time ◽  
Near Fault Earthquakes ◽  
Nonlinear Time History

Abstract. Near-fault ground motions with long-period pulses have been identified as being critical in the design of structures. These motions, which have caused severe damage in recent disastrous earthquakes, are characterized by a short-duration impulsive motion that transmits large amounts of energy into the structures at the beginning of the earthquake. In nearly all of the past near-fault earthquakes, significant higher mode contributions have been evident in building structures near the fault rupture, resulting in the migration of dynamic demands (i.e. drifts) from the lower to the upper stories. Due to this, the static nonlinear pushover analysis (which utilizes a load pattern proportional to the shape of the fundamental mode of vibration) may not produce accurate results when used in the analysis of structures subjected to near-fault ground motions. The objective of this paper is to improve the accuracy of the pushover method in these situations by introducing a new load pattern into the common pushover procedure. Several pushover analyses are performed for six existing reinforced concrete buildings that possess a variety of natural periods. Then, a comparison is made between the pushover analyses' results (with four new load patterns) and those of FEMA (Federal Emergency Management Agency)-356 with reference to nonlinear dynamic time-history analyses. The comparison shows that, generally, the proposed pushover method yields better results than all FEMA-356 pushover analysis procedures for all investigated response quantities and is a closer match to the nonlinear time-history responses. In general, the method is able to reproduce the essential response features providing a reasonable measure of the likely contribution of higher modes in all phases of the response.

Effects of Fling Step and Forward Directivity on Seismic Response of Buildings

2006 ◽  
Vol 22 (2) ◽  
pp. 367-390 ◽  
Author(s):  
Erol Kalkan ◽  
Sashi K. Kunnath
Keyword(s):  
Seismic Response ◽  
Ground Motions ◽  
High Amplitude ◽  
Moment Frames ◽  
Steel Moment Frames ◽  
Damage Potential ◽  
Near Fault ◽  
Forward Directivity ◽  
Fling Step ◽  
Far Fault

This paper investigates the consequences of well-known characteristics of near-fault ground motions on the seismic response of steel moment frames. Additionally, idealized pulses are utilized in a separate study to gain further insight into the effects of high-amplitude pulses on structural demands. Simple input pulses were also synthesized to simulate artificial fling-step effects in ground motions originally having forward directivity. Findings from the study reveal that median maximum demands and the dispersion in the peak values were higher for near-fault records than far-fault motions. The arrival of the velocity pulse in a near-fault record causes the structure to dissipate considerable input energy in relatively few plastic cycles, whereas cumulative effects from increased cyclic demands are more pronounced in far-fault records. For pulse-type input, the maximum demand is a function of the ratio of the pulse period to the fundamental period of the structure. Records with fling effects were found to excite systems primarily in their fundamental mode while waveforms with forward directivity in the absence of fling caused higher modes to be activated. It is concluded that the acceleration and velocity spectra, when examined collectively, can be utilized to reasonably assess the damage potential of near-fault records.

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