تاثیر مؤلفه قائم زلزله بر تلاطم و لنگر پایه مخازن هوایی مخروطی به کمک روش های عددی و آزمایشگاهی

نوع مقاله : علمی - پژوهشی

نویسندگان

1 گروه مهندسی آب و سازه های هیدرولیکی، دانشکده مهندسی عمران، دانشگاه سمنان

2 دانشیار، پژوهشگاه بین المللی زلزله شناسی و مهندسی زلزله، تهران، ایران

چکیده

در تحلیل لرزه‌ای مخازن هوایی حاوی سیال، مؤلفه قائم زلزله به علت تأثیر در سطح متلاطم سیال درون مخزن و همچنین تشدید اثر "P-delta" از اهمیت ویژه‌ای برخوردار می‌باشد. به منظور بررسی عملکرد نوسانی مخزن و تاثیر تلاطم سطح سیال بر آن، به یک مخزن استونه ای به قطر 60 سانتیمتر که در آن آب با عمق های مختلف قرار گرفته، فرکانسهای هارمونیک توسط ابزاری ابداعی به نمونه های آزمایشگاهی اعمال گردید. به منظور تعیین تاثیر نوسانات بر سازه، از نرم افزار آباکوس برای مدلسازی بهره گرفته شده است. صحت سنجی و کالیبراسیون مدل عددی با مقایسه نتایج مدل آزمایشگاهی و مدل عدی از نوسانات سطح آب با ایجاد مدل متناظر در نرم‌افزار آباکوس و با ایجاد تعداد قابل ملاحظه‌ای از ترکیبات گوناگون از متغیرهای مدل‌سازی از قبیل روش شبکه‌بندی و اندازه مناسب سلولها به‌گونه‌ای انتخاب شدند تا نتایج حاصل از تحلیل عددی با نتایج آزمایشگاهی با دقت مناسبی منطبق گردد. نتایج مدلسازی عددی همبستگی 98% با نتایج آزمایشگاهی داشت. سپس مدل عددی مخازن با ابعاد بزرگ در نرم‌افزار آباکوس ایجاد و با متغیرهای مدلسازی که در مرحله صحت سنجی نهایی گردیده بود، تحلیل گردید. مدل عددی از مخازن هوایی با سه نسبت مختلف از ارتفاع سیال درون مخزن و شعاع به مقدار ارتفاع کل مخزن در نرم افزار ایجاد گردیدند. همچنین زاویه کف با افق در کلیه مخازن 45 درجه در نظر گرفته شده و مورد ارزیابی قرار گرفت. هرکدام از این حالت ها با 7 شتاب‌نگاشت مختلف از زلزله‌های متفاوت بارگذاری گردیدند. در کلیه این مخازن، اثر مؤلفه قائم زلزله بر مقادیر ارتفاع موج و ممان ایجاد شده در پایه با حالت بدون احتساب اثر مولفه قائم زلزله مقایسه گردید. نتایج نشان داد که احتساب مولفه قائم زلزله منجر به افزایش ارتفاع موج به میزان 38% و افزایش گشتاور در پایه به میزان 9% میگردد.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Effects of Earthquake Vertical Excitations on Sloshing Height in Conic Elevated Water Tanks and the Created Moment at Their Base: Experimental Validation and Numerical Simulation

نویسندگان [English]

  • Khosrow Hosseini 1
  • Soroush Heidari 1
  • Mahmood Hosseini 2
1 Hydraulic Structures Department, Civil Engineering Faculty - Semnan University
2 Associate professor, Structural Engineering Research Centre, International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran
چکیده [English]

In seismic analysis, vertical component of the earthquake due to the impact on fluid sloshing in a tank and intensifying of "P-delta" effects is of particular importance. In order to investigate the performance of the tank and the impact of the fluid surface sloshing, harmonic frequencies were applied to a tank of of water with 60 cm in diameter and different depths of water. Different frequencies were applied to the tank by an innovative tool. Abacous is a structural soft-ware which is capable to model numerically the interaction of structure and fluid. Verification and calibration of numerical model was performed by comparing water level fluctuations in experimental and numerical models. Different combinations of parameters such as hourglass coefficient, methods of grid generations and the cell sizes in numerical model were performed to obtain the consistent results with experiments. The results of numerical modeling had a correlation factor of 98% with laboratory results. Then, the numerical model of elevated tanks with large scales were created in software The numerical model of elevated tanks with three different ratios of fluid depth and tank radiuses to the tank height were created and modeled by software. The angle of the floor in all tanks was 45 degrees. Each case was evaluated by7 different mapping acceleration from different earthquakes. In all cases the effect of vertical component of earthquake, the wave height and moment in foundation were investigated. The results showed that the vertical component of the earthquake resulted in an increase of 38% in the height of water and 9% increase in the moment of foundation.

کلیدواژه‌ها [English]

  • elevated water tank
  • Dynamic analysis
  • Finite element method
  • earthquake vertical excitation
  • Sloshing height
  • base moment
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