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INTRODUCTION OF AIR CUSHION TO REDUCE SEISMIC DEMAND IN CYLINDRICAL WATER STORAGE TANKS F. Ashrafzadeh, S. Tariverdilo and M. R. Sheidaii Abstract Water storage tanks not designed explicitly for seismic loading could require retrofit. One of the common ways of retrofit include some structural change in the lateral load resisting system that could be expensive and requires the tank to be out of service for relatively long time. This paper introduces a novel method to reduce seismic demand on tank’s wall without structural intervention. This is done by employing air cushions adjacent to the wall. The paper investigates the effect of air cushion system on the seismic response of the cylindrical water storage tanks. While in tank without air cushion, the boundary condition adjacent to tank wall is kinematic with no control on the wall pressure, in the proposed method this boundary condition becomes kinetic, enabling control of dynamic fluid pressure on the tank walls. The response parameters of the tank is developed in terms of wall pressure, wave height, base shear, and overturning moment in cylindrical tanks of different sizes with and without air cushions under the far field and near source ground motions. The results demonstrate that the proposed method is an effective way to reduce sloshing force demand. Keywords : Cylindrical water storage tanks, Air cushion, Seismic response, boundary condition, Wall pressure. چکیده مخازن ذخیره آب که برای بارهای لرزه ای طراحی نشده اند، اغلب نیازمند بهسازی هستند. روش‌ معمول بهسازی لرزه‌ای در برگیرنده تغییراتی در سیستم سازه‌ای مخازن می‌باشد که هزینه­بر بوده و توام با خروج از سرویس مخزن برای زمان طولانی است. مقاله حاضر روشی جدید مبتنی بر کاهش نیاز در دیواره‌های مخازن تحت بارگذاری لرزه‌ای معرفی مي­نمايد که نيازمند تغییر در سازه مخزن نیست. اين امر با تعبیه بالشتک هوا در حد فاصل ديوار مخزن و سيال انجام مي­شود. در مخازن عادی (بدون بالشتک) شرایط مرزی دیواره مخزن سینماتیکی است و هیچ‌گونه کنترلی روی فشار سیال وارد بر دیواره مخزن وجود ندارد. با تعبیه بالشتک، شرایط مرزی در دیواره سینتیکی شده، امکان کنترل فشار سیال بر روی دیواره مخزن ایجاد مي­گردد. در اين مقاله، پاسخ مخزن شامل فشار سیال بر دیواره، ارتفاع موج، برش و لنگر خمشی در مخازن استوانه‌ای به ابعاد مختلف با و بدون بالشتک هوا برای زلزله‌های حوزه دور و نزدیک ارائه شده و کارایی سيستم پيشنهادی بررسی شده است. نتایج نشانگر آن است که روش ارائه‌شده یک روش مؤثر برای کنترل نیروی ناشی از مواج شدگی است. 29-4-4.pdf

The Effect of soil-flexibility on seismic response of a typical Steel Plate Shear Wall subjected to Duzce Earthquake J. MIRLOHI*, P. MEMARZADEH*, F. BEHNAMFAR† Department of Civil Engineering, Najafabad Branch, Islamic Azad University, Najafabad Department of Civil Engineering, Isfahan University of Technology, Isfahan IRAN p-memar@iaun.ac.ir Abstract: - Steel Plate Shear Wall is commonly employed as a principal system to resist lateral loads due to wind or earthquake forces. An accurate model for SPSW needs to consider the effect of all components for analysis such as foundation and subsoil. One of most important aspects of structural analysis is soil-structure interaction (SSI). Such interaction may alter the dynamic characteristics of structures and consequently may be beneficial or detrimental to the performance of structures. This investigation is aimed to evaluate the effect of soil-structure interaction on seismic response of a typical multi-story SPSW designed according to AISC requirements. In this procedure, a time-direct method is used in which the unbounded soil is modeled by couple finite-infinite elements. To investigate the effects of SSI the following types of analysis are performed: in the first type, the structure is analyzed without subsoil (fixed base) and in the second type, analysis is carried out for the same structure with consideration of soil-structure interaction (flexible-base). Finally, the results of analysis with and without SSI effects are compared. Key-Words: - Steel Plate Shear Wall, Soil Structure Interaction, seismic response, dynamic analysis [Hidden Content] GEMESED-72.pdf

Seismic response of steel plate shear walls considering soil-structure interaction P. Memarzadeh, J. Mirlohi and F. Behnamfar Abstract—Due to structural efficiency, Steel Plate Shear Wall (SPSW) is widely employed in buildings as a principal system for resisting lateral loads due to wind and earthquakes. An accurate model of seismic demand for SPSW requires consideration the effect of all components for analysis such as structural, foundation, subsoil elements and the interaction between them. Such interaction may alter the dynamic characteristics of structures and consequently may be beneficial or detrimental to the performance of structures. This investigation considers two typical SPSW designed according to AISC requirements. The effects of soil-flexibility on seismic demands of such frames resting on two soil types subjected to two different earthquake ground motion is investigated using the time direct method and a comparison is presented with the results obtained from fixed-base. It is observed that soil–structure interaction affect the seismic performance of SPSW and the effect of soil-flexibility must be taken into account in dynamic analyses of SPSW. Keywords—Steel Plate Shear Wall, Soil Structure Interaction, seismic response, dynamic analysis [Hidden Content] ENGCO-18.pdf