بررسي برش و نسبت جابه جايي ديوارهاي برشي فولادي با ورق

Story Shear and Story Drift Determination of Thin Steel Plate

در سال هاي اخير با مطالعه انجام گرفته روي زلزل ههاي مخرب و زمين لرزه هاي متفاوت روي سيست م هاي سازه اي مختلف و ثبت نگاشت شتاب زلزل ههاي به وقوع پيوسته، تفاوت آثار خراب يهاي ايجاد شده در محدوده 15 تا 60 كيلومتري مركز وقوع زمين لرز هها (كه حوزه نزديك گسل ناميده مي شود) نسبت به خرابي هاي پيدا شده در خارج از اين حوزه مشخص شده است. با توجه به سختي مناسب سيستم ديوار برشي فولادي براي كنترل تغيير شكل سازه و مكانيزم شكست شكل پذير و اتلاف انرژي بالا، در اين مقاله به بررسي رفتار ديناميكي ديوار برشي فولادي داراي اتصال تير به ستون مفصلي تحت زلزله هاي نزديك و دور از گسل پرداخته شده است. 15 و 25 طبقه ديوار برشي فولادي به وسيله تحليل ديناميكي غيرخطي تحت چهار جفت ،7 ، چهار مدل اجزا محدود 3 تحليل شد. پاسخ سازه ها شامل برش و زاويه دريفت طبقات نشان ABAQUS نگاشت دور و نزديك گسل در نرم افزار اجزا محدود دهنده آثار بيشتر توزيع برش در حوزه دور از گسل بوده كه اين موضوع به دليل آثار بيشتر مودهاي بالاتر در حوزه دور از گسل 0 ثانيه) اثر حركات نزديك گسل بر پارامترهاي پاسخ / نسبت به حوزه نزديك گسل است. در قا بهاي بلن دمرتبه (بيش از پريود 7 سازه بيشتر از حركات حوزه دور از گسل بوده كه اين مساله به دليل بيشتر بودن محتواي فركانسي نگاشت هاي دور از گسل در محدوده پريود كوتاه و محتواي فركانسي بيشتر حوزه نزديك گسل در محدوده پريود بلند است.

Regard to investigations that are done about destructive earthquakes contemporarily and by contemplating on effects of different earthquakes on various types of structural systems and by recording acceleration of ground motions , researchers detected different effects of destruction in range about 15 to 60 kilometers far from epicenter of earthquake that is nominated as near fault earthquakes. the subsequences of researches which have been done in this field shows that mapping near to the fault have less effective time than mapping which are far from the fault and have one or more special pulse with a large domain and with medium to large frequency which causes to increase the domain of response spectrum in the zone of large period. and applying huge energy in short time and Sudden intense pulse in the beginning of near fault timehistories causes increasing the demand of rotational ductility in some stories and joints. In this article Regard to reliability of steel plate shear walls in recent four decades and also the fact that these structural systems have appropriate ductility to control displacements, height energy dissipation and ductile failure mechanism, the dynamic behavior of these systems is investigated .Four finite element models of 3,7,15 and 25 story buildings that used steel thin plate shear wall with hinge beam to column connections as resistant systems has created and analyzed through nonlinear dynamic analysis in ABAQUS finite element software and then response of structures such as story shear and drift angles of stories were detected. Results postulate the effects of shear distribution in near fault and regard to these purposes it seems that this fact is caused of effects of higher modes in far fault earthquakes. This situation cause of the fact that the frequency containers of near fault earthquakes are higher in range of height periods .besides Response of structures such as damage index and base shear, show that in tall steel plate shear walls (T > 0.7s) effect of near fault movements on response parameters are more than those in the far fault zone. It also can be seen that base shear of the structures in far fault earthquakes fluctuates in more extended range compared to which happens in near fault structures and in near fault earthquakes base shear of most time histories don’t have much differences but in far fault earthquakes differences are relatively much.By increasing the height of SPSW’s differences between displacements in near fault and far fault earthquakes ascends. Maximum of differences between near fault and far fault responses appear in boundary of 40% to 60% of height of walls. Eventually can be said that not only higher PGA of most near fault earthquakes is a distinctive attribute in accordance with far fault earthquakes, but also higher frequency container in long period range would be devastating, regardless to higher PGA of these earthquakes.