پديد آورندگان :
جمع دار، مهشاد دانشگاه خوارزمي - دانشكده فني و مهندسي، تهران، ايران , القاصي، عرفان دانشگاه خوارزمي - دانشكده فني و مهندسي، تهران، ايران , مشكوه الديني، افشين دانشگاه خوارزمي - دانشكده فني و مهندسي، تهران، ايران , همامي، پيمان دانشگاه خوارزمي - دانشكده فني و مهندسي، تهران، ايران
كليدواژه :
سازه شبكه قطري , زلزله حوزه نزديك , زاويه تابش , دريفت طبقه , دوران المان
چكيده فارسي :
امروزه طراحي و ساخت سازههاي بلند مرتبه با پيكربندي شبكه قطري با توجه به كارايي مقاومتي بالا و نيز قابليت زيباشناسي معماري، مورد توجه است. در اين پژوهش، به بررسي پارامترهاي عملكرد لرزهاي سازههاي شبكه قطري با استفاده از تحليل تاريخچه زماني غيرخطي تحت ركوردهاي نيرومند حوزه نزديك زلزله پرداخته شده است. هدف اصلي اين پژوهش، بررسي تاثير زاويه تابش امواج زلزله در رفتار لرزهاي سازه شبكه قطري است. بدين منظور، رفتار سه سازه مطالعاتي20 طبقه شبكه قطري با زاويه پيكربندي 56 ، 64 ، 76 درجه و با چيدمان هندسي يكسان، تحت زاويههاي تابش صفر، 15، 30 و 45 درجه نسبت به دستگاه محورهاي اصلي مورد بررسي قرار گرفته است. چگونگي و روند تاثيرات زاويه تابش در دامنه تغييرات پارامترهاي لرزهاي شامل دريفت بيشينه طبقات، تاريخچه زماني تغييرمكان جانبي، بيشينه دوران اتصالات اسكلت مقاوم و ارزيابي ساختار شكلگيري مفاصل غيرخطي در سازه، مطالعه شده است. نتايج اين پژوهش نشان ميدهد كه تاثير زاويه تابش در پارامترهاي مختلف پاسخ لرزهاي، متفاوت بوده و نمود قابل توجهي در تغييرات دوران اتصالات ندارد. بررسي تاثير زاويه پيكربندي المانهاي تير-ستون مورب (اعضاي قطري) در رفتار لرزهاي سازه، نشان ميدهد كه ساختار شبكه قطري با زاويه 56 درجه، داراي كمترين ميزان تقاضاي لرزهاي تحت بارگذاريهاي زلزله است
چكيده لاتين :
In recent years, structural systems with diagrid skeletons comprising modular configurations have attracted lots
of attention due to having structurally efficient system and architecturally aesthetic advantages. In this study, the
seismic performance parameters of steel diagrid systems have been evaluated through conducting nonlinear time
history analyses subjected to near-field earthquakes. The main subject of this study is to assess the effect of
incidence angle of near-fault records containing forward directivity on the seismic behavior of steel diagrid systems.
Following this purpose, three 20-story diagrid studied structures with different diagonal angles of 56°, 64° and 76°,
having the same sizes and skeletal configurations were designed. Furthermore, a set of notified incidence angles
with respect to the main axis including 0, 15, 30 and 45 degrees have also been applied to all the studied structures.
It should be noted that the significant characteristics of strong ground motions are the frequency content,
effective duration of strong motions and peak ground motion parameters, i.e. PGV, PGA and PGD as well as
corresponding response spectra. According to the aforementioned characteristics, an ensemble of strong earthquake
records was selected. The selected ground motions include the main shock of the 1978 Tabas earthquake (Iran,
Mw=7.3), the Bam record due to the 2003 Bam earthquake (Iran, Mw = 6.6) as well as two other powerful records
entitled Rinaldi Receiving Station (RRS), and Sylmar Olive View (SYL) accelerograms related to the 1994
Northridge earthquake (Mw = 6.7) in California. It is worth mentioning that all the selected ground motions are
categorized as strong near-fault records containing forward directivity effects. The specific characteristics of
near-fault records containing forward directivity effects are the existence of long-period pulses.
These pulses are the evident result of the effects that manifest due to the occurrence of forward directivity
process. The forward directivity process causes the induced fault rupture propagation to move toward the site. It
usually happens when a velocity of rupture propagation is appropriately close to the earthquake shear wave velocity.
In this research, a number of engineering demand parameters (EDP) i.e. drift ratio, rotation of joints and plastic
hinges nonlinear domain have been computed and assessed through conducting nonlinear time history analyses
(NTHA). It is demonstrated that maximum seismic response parameters for all the studied structures do not occur
necessarily along the main skeletal axes. Furthermore, it is extremely difficult to define the specific structural
behavior trends subjected to a nominated critical incidence angle which can be imposed to earthquake records. It is
noticeable that the numerical trends in the structural response parameters would change remarkably under the
influence of the different frequency content of earthquake records, as well as the probable non-uniform variation for
the EDPs and the diagrid skeletal patterns.
The results of this research indicate that the influences of incidence angle of ground motions on the structural
seismic performance have different trends which evidently include mingle effects on the nonlinear rotation of joints
as well as a complicated distribution for the lateral drift parameter. Moreover, it was obtained that the embossed
structural skin containing the triangular modules with the diagonal angle of 56 degrees has relatively the lowest
seismic demands subjected to strong near-field earthquake records.
