بررسي رفتار ديوارهاي برشي فولادي با ورق نازك تحت اثر مولفه‌هاي قايم و افقي زلزله

Study of Behavior of Thin Steel Plate Shear Walls under Vertical and Horizontal Components of Earthquake

فلسفه‌ي طراحي لرزه‌يي موجود در آيين‌نامه‌ها، تعيين تنش‌هاي حاصل در اعضا ناشي از اعمال شتاب افقي حركت زمين بدون درنظرگرفتن اثرات مولفه‌ي قايم را توصيه مي‌كند. در عين حال، شكل آسيب‌هاي سازه‌يي گزارش‌شده‌ي ناشي از زمين‌‌لرزه در محدوده‌ي نزديك گسل به گونه‌يي است كه متخصصان، مولفه‌ي قايم زلزله را در ايجاد چنين خرابي‌هايي دخيل مي‌دانند. از طرفي تاكنون رفتار ديوار برشي فولادي با ورق نازك تحت مولفه‌ي قايم زلزله بررسي نشده است. بر اين اساس در اين نوشتار رفتار غيرخطي مدل‌هاي ديوارهاي برشي 3، 10 و 20 طبقه، تحت چندين نگاشت مولفه‌ي افقي و قايم مختلف مورد مطالعه و روند تشكيل مفاصل خميري و همچنين مودهاي مختلف شكست مورد تجزيه و تحليل قرار گرفته‌اند. نتايج حاكي از رفتار مناسب اين سيستم تحت مولفه‌ي قايم و حتي هم‌زمان با حضور مولفه‌ي افقي زلزله است.

The current philosophy of seismic design in codes advises that member stresses, due to the impact of horizontal ground motion acceleration, be determined without consideration of vertical component effects. Nevertheless, the reported forms of structural damage due to near fault earthquakes are in the way that specialists allocate a role for vertical components of earthquakes in the formation of such damage. Thin steel plate shear walls are one of the newest resistant systems, whose behavior until now has not been investigated under vertical components of an earthquake Therefore, in this article, the nonlinear behavior of 3, 10 and 20 story shear wall models is studied under several ground motions of vertical and horizontal components of earthquakes, as well as the formation process of plastic hinges, and different modes of failure are also analyzed. Results show the suitable behavior of this system under vertical components of the earthquake, and even, simultaneously, with a horizontal one. First, damage occurs in the plate of the wall, then beams, and, finally, columns are damaged. In addition, results show that vertical components of earthquakes have a considerable effect on the axial force of columns (1000-1500%). The effect of this component on the axial force of columns in mid-storey and high-storey buildings is much more than in short-storey buildings. In short-storey buildings, the effect of the vertical component of the earthquake is more in the higher stories, but, the effect of this component in mid and high-storey buildings is more in lower stories. The vertical component of an earthquake has a considerable effect on the bending moment of columns (100-600%), and increasing the height of the building does not influence the effect of this component. In short-storey buildings, the effect of the vertical component of an earthquake on the bending moment of columns is more in the higher stories, but, the effect of this component in mid and high-storey buildings is more in mid-stories.