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آزمایش شکافت استوانه بنایی و مدل‌سازی رفتار محصور شده ملات بر مبنای انرژی شکست | ||
| نشریه مهندسی عمران امیرکبیر | ||
| مقاله 4، دوره 55، شماره 3، خرداد 1402، صفحه 555-582 اصل مقاله (2.27 M) | ||
| نوع مقاله: مقاله پژوهشی | ||
| شناسه دیجیتال (DOI): 10.22060/ceej.2023.21192.7647 | ||
| نویسندگان | ||
| حمید توانایی فر؛ امیرهوشنگ اخویسی* | ||
| دانشکده فنی، دانشگاه رازی، کرمانشاه، ایران | ||
| چکیده | ||
| در این مقاله از تست برزیلی (شکافت) که یک آزمایش نیمه مخرب بوده و حداقل دست خوردگی را در سازه ایجاد می کند، جهت تخمین پارامترهای مقاومتی بنایی های با ملات ماسه و سیمان استفاده می گردد. در این شیوه، به وسیله استخراج مغزه های دارای یک بندِ ملات، و اجرای تست برزیلی تحت زوایای مختلف ملات نسبت به راستای اصلی، می توان پارامترهای مقاومتی بنایی را (c و ) استخراج کرد. این تست را می توان جایگزین مناسبی برای سایر تست های نیمه مخرب خصوصاً تست برش ملات به شمار آورد. تست اخیر نواقصی دارد که عمده آن وجود عدم لحاظ اثر اتساع در ملات است. نقص مذکور، موجب تشدید تنش عمودی موجود بر روی آجر مورد آزمایش شده و در نتیجه مقادیر پارامترهای مقاومتی را بیشتر از مقدار واقعی، برآورد می کند. در ادامه یک ریزمدل پیوسته سه بعدی جهت پیش بینی رفتار بنایی غیرمسلح در فشار، ارائه می گردد. با توجه به تفاوت در مدول الاستیسیته، ضریب پواسون و ضخامت دو مصالح آجر و ملات در بنایی، تلاش های متعددی برای شبیه‌سازی رفتار فشاری بنایی انجام شده است. برای بررسی این رفتار که تحت تأثیر اندرکنش واحدها و ملات است، مدل های دو بعدی قادر به لحاظ محصورشدگی سه محوره ملات نیستند. از طرفی مدل های سه بعدی موجود به سادگی قادر به کنترل اثر اتساع به صورت صریح و لحاظ محصورشدگی سه محوره نمی باشند. مدل ارائه شده بر مبنای مفهوم ریز صفحه (چند صفحه) است و برای مدل‌سازی شکست در سازه بنایی در اثر فشار توسعه می یابد. در ادامه توانایی مدل ارائه شده در مقابل نتایج آزمایشگاهی و سایر مدل های عددی، بررسی شده و جهت مدل‌سازی کار آزمایشگاهی حاضر استفاده می‌گردد. مقایسه نتایج، دقت مناسب نتایج حاصل از مدل عددی پیشنهادی و قابلیت اجرای تست مغزه در بناییهای آجری با ملات ماسه-سیمان را نشان می‌دهد. | ||
| کلیدواژه‌ها | ||
| آزمایش مغزه؛ ریز مدل‌سازی؛ مدل چند صفحه‌ای؛ ملات محصور شده؛ اثر اتساع | ||
| موضوعات | ||
| تحلیل خطی و غیر خطی؛ مکانیک خرابی و پلاستیسیته؛ مکانیک شکست | ||
| عنوان مقاله [English] | ||
| Splitting Test on Masonry Cores and modeling of the Confined mortar behavior based on fracture energy | ||
| نویسندگان [English] | ||
| hamid tavanaeifar؛ Amir Hoshang Akhaveissy | ||
| Department of Civil Engineering, Engineering Faculty, Razi University, Kermanshah, Iran. | ||
| چکیده [English] | ||
| The in situ evaluation of the masonry's mechanical properties is a very complicated task. A viable alternative is based on the use of brick cores including a central mortar layer lying on a symmetry plane. In fact, these specimens can be extracted very easily by cutting cores spanning two bricks at least. The obtained core is then subjected to a splitting test with a setup providing a different inclination of the mortar layer with respect to the loading plane. This type of test is similar to a diagonal wallet test and induces a mixed compression–shear stress state in the central mortar layer. Here, This test is used for masonry with sand and cement mortar. By using a Mohr-Coulomb failure criterion the test result can be interpreted in order to obtain all the mechanical properties of the masonry. This test can be a good alternative to other semi-destructive tests, especially the shove test. The latter test has a defect, that’s due to the lack of effect of dilatancy in the shear behavior of mortar in the shove test, the values obtained in terms of cohesion and friction angle will be greater than the actual value. In the following, a 3D continuous micromodel is presented in order to predict unreinforced masonry behavior. Due to the difference in the modulus of elasticity, the Poisson ratio and the thickness of the brick and mortar, several efforts have been made to simulate the compressive behavior of the masonry using different models with different goals and results. To examine this behavior, which is influenced by the interaction of units and mortar, in one hand, two-dimensional models are not able to consider the 3D confined effect. On the other hand, the three-dimensional models are not able easily to control the effect of 3D confined and dilatation explicitly. The proposed model is based on the concept of micro-plane and is developed to model failure in masonry structures. | ||
| کلیدواژه‌ها [English] | ||
| Core test, Micro modeling, Multi-laminate model, Confined effect, Dilatancy effect | ||
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| مراجع | ||
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