research centers


Search results: Found 5

Listing 1 - 5 of 5
Sort by

Article
STRENGTHENING OF CONCRETE BEAMS WITH PRESTRESSED FRP REINFORCEMENTS

Author: Suhaib Sabah Abdulhameed
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 1 Pages: 13-25
Publisher: Al-Mustansyriah University الجامعة المستنصرية

Loading...
Loading...
Abstract

Strengthening of reinforced concrete beams with prestressed Fiber Reinforced Polymer (FRP) sheets showed to be efficient in enhancing the serviceability of the strengthened concrete beams. Yu et al.'s develop a mechanical prestressing device to prestress FRP sheets to strengthen reinforced concrete members. Yu et al. s experimental results showed that this device overcome the shortcomings associated by using the previously developed prestressing devices. In this research program Yu et al.'s mechanical device was modified to increase the efficiency of it by using light weight material to reduce the additional weight on the strengthened beams caused by the prestressing device in addition, the end anchorage plates were installed vertically rather than horizontally to extend the prestressed FRP sheets to the end regions of the member where high shear stress occurred. This modification in the end anchorage regions is efficient to reduce the possibility of the premature debonding failure. A numerical analysis by using ANSYS (R14.5) computer program was used to simulate the prestressing device. Numerical results showed that using aluminum material is efficient to produce a prestressing mechanical device. The maximum stresses and deflection that generated in the pretressing device upon prestressing Carbon Fiber Reinforced Polymer (CFRP) sheet (51% of the ultimate tensile stress in the CFRP) to strengthen 22.5m concrete beam are 46MPa and 83mm respectively. A theoretical formula was derived based on geometric relations of the prestressing system and the deformed CFRP sheet. It was used to predict the prestressing level in the CFRP sheet. Theoretical results showed that the percentage difference between Yu et al.'s formula and the derived formula is about 1%. This value changes based on the prestressing level in CFRP sheet and the length of the strengthened beam. The theoretical prediction of prestressing level in the CFRP sheet agreed well with the experimental results.


Article
PERFORMANCE OF DRIVEN REINFORCED CONCRETE PILES UNDER THE EFFECT OF DYNAMIC LOADING

Authors: Sura Amoori Abbas --- Zainab Hassan Shakir --- Mohammed Yousif Fattah
Journal: Journal of Engineering and Sustainable Development مجلة الهندسة والتنمية المستدامة ISSN: 25200917 Year: 2019 Volume: 23 Issue: 1 Pages: 117-134
Publisher: Al-Mustansyriah University الجامعة المستنصرية

Loading...
Loading...
Abstract

Dynamic analysis for reinforced concrete precast piles with (300x300 mm) in dimension and length (12 m) with different types of loading was carried out. The common precast pile in Iraq was adopted in this study. Finite element analysis by ANSYS software was adopted and dynamic loading was applied to check out the strength and performance of pile. The frequency range adopted is based on the low, medium and high frequency. The analysis consisted of single pile (without surrounding soil) and pile embedded in soil as nonlinear material (soil) analysis to evaluate the vertical and horizontal displacements at the location of applied load. According to the analysis of single pile without soil and when the model of pile embedded in the soil indicated that the soil – structure interaction represented the worst case that is mean the simulation of the pile must take into account the effects of soil on the behavior and performance of the precast pile. The applied static loading on the pile model and checking the results of pile strength capacity showed that the applied load equal to the value calculated as per ACI 543R-2000 suggested equation. Based on the finite elements analysis results in case of friction between the contact surface of soil and pile increased the strength capacity of the pile due to the forces developed along the pile so that these forces add to the bearing resistance of the pile. The displacements in case of low and medium frequency are tenth time more in case of soil-structure interaction as compared with the analysis results of single pile alone. It was concluded that the presence of friction between the contact surface of soil and pile increased the strength capacity of the pile due to the forces developed along the pile so that these forces add to the bearing resistance of the pile.


Article
NONLINEAR ANALYSIS OF REINFORCED CONCRETE CORBELS STRENGTHENED WITH CARBON FIBRE REINFORCED POLYMER STRIPS BY ANSYS

Authors: Muhammad Abed Attiya --- Anis A. Mohamad-Ali
Journal: KUFA JOURNAL OF ENGINEERING مجلة الكوفة الهندسية ISSN: 25230018 Year: 2019 Volume: 10 Issue: 2 Pages: 60-75
Publisher: University of Kufa جامعة الكوفة

Loading...
Loading...
Abstract

This research is devoted to investigate the effect of Carbon Fibre Reinforced Polymer (CFRP) strips on the behaviour and load carrying capacity of the strengthened concrete corbels. Numerical investigation was carried out. The experimental program variables include location, direction, amount of CFRP strips, effect of shear span to effective depth (a/d) ratio on the behaviour of strengthened corbels. All corbels had the same dimensions and flexural reinforcement and they were without horizontal shear steel reinforcement. ANSYS V.11.0 software was utilized in this work. Solid65, Solid45, Link8 and shell41 elements were used to model concrete, steel bearing plates, steel flexural reinforcing bars, and CFRP strips respectively. Full bond was assumed between CFRP sheets and concrete interface. The full Newton-Raphson method is used as a nonlinear solution algorithm. The displacement criteria are used for convergence. The adopted finite element analysis showed good agreement with experimental results throughout the load-deflection history, the maximum difference in the ultimate load was less by10%. However, the finite element models show a slightly stiffer response.


Article
Finite Element Analysis of the Geogrid-Pile Foundation System under Earthquake Loading

Authors: Qassun S. Mohammed Shafiqu --- Athraa A. Al-Ghanim --- Asma Thamir Ibraheem
Journal: AL-NAHRAIN JOURNAL FOR ENGINEERING SCIENCES مجلة النهرين للعلوم الهندسية ISSN: 25219154 / eISSN 25219162 Year: 2019 Volume: 22 Issue: 3 Pages: 202-207
Publisher: Al-Nahrain University جامعة النهرين

Loading...
Loading...
Abstract

The finite element method is one of the important methods in analyzing geotechnical engineering problems; its main advantage is the ability to apply for the materials exhibiting non-linear stress-strain behavior. In this study the finite element program PLAXIS 3D 2013 is used to study the behavior of the piles under the influence of seismic waves in saturated sandy soil and the effect of adding geogrid with the pile foundation. The program has been used to facilitate the representation of the real model, input the required soil parameters and implementation of seismic data. Seismic wave, the soil geometry and the pile dimensions were fixed in all models, while dimension and depth of the geogrid used were varied to study the influence of different depth and dimension in reducing the pile displacements and the pore water pressure of soil. The results show that The reduction in settlement ratio (the difference between settlement of pile without and with using geogrid to the settlement without using geogrid) for (L/2 ×L/2), (L×L) and (2L×2L) are 10.6%, 17% and 21.3% respectively. And the settlement ratio for geogrid at depths 8.33% and 12.5% of pile length are 9.6% and 17% respectively.


Article
Finite Element Analysis of Well Pads in Basra Province
التحليل بالعناصر المحددة لقواعد الآبار في مقاطعة البصرة

Authors: Haider Saad Al-Jubair حيدر سعد الجبير --- Hiba Abdul Hussein Saheb هبة عبد الحسين صاحب
Journal: Wasit Journal of Engineering Sciences مجلة واسط للعلوم الهندسية ISSN: 23056932 Year: 2019 Volume: 7 Issue: 1 Pages: 73-86
Publisher: Wassit University جامعة واسط

Loading...
Loading...
Abstract

After the year 2003, the oil / gas sector evolved and gained investment. International companies of different origins utilized heavy drilling rigs (to achieve high drilling depths) and entered our region. Meanwhile, some drilling problems were recorded, accompanied by well-pad failure cases. This research aims to study the behavior of well-pads with different geometric configurations, under the effects of drilling rigs with various characteristics, within the Basra province. Four case studies have been selected to represent four fields, namely: Siba, Zubair, West Qurna-2, and Zubair-Mishrif fields. The finite element method is utilized to conduct a stress analysis process, adopting an elastic–plastic constitutive relation for soil, based on Drucker-Prager's yield criterion. The maximum contact pressure applied on soil (under the working loads) is compared to its bearing capacity. When a rigid method is used to calculate the contact pressure, it is compared with the ultimate soil-bearing capacity, as calculated by Reddy and Srinivasan's method for cohesive soils, with allowable bearing capacity taken from the Peck, Hanson, and Thornburn's method for cohesionless soils. The contact pressure calculated via the finite element method is compared with the ultimate soil-bearing capacity calculated using the same method, based on a settlement of 50 mm. The extreme values of the bending moments and shear forces developed in the well-pad sections (under the factored loads), are compared with the section capacities calculated by using the ultimate strength design method. Regarding the geotechnical side, the results indicate insufficient safety factors against soil shear failure for some cases, especially for cohesive soil profiles. For cohesionless soil profiles, the provided safety factors are sufficient. The finite element method reveals higher contact pressures compared to the conventional rigid method. For cohesionless soil profiles, the Peck, Hanson, and Thornburn's method, gives a bigger safety margin than the finite element method. The immediate settlement values are almost tolerable. Regarding the structural side, it has been identified that a uniform section is adopted for all locations of each pad, for individual wells. In most cases, the provided reinforcing steel is less than the minimum code requirement. This leads to a violation of the section capacity of bending, at least near the cellar. The beam shear capacity is rarely violated. Using strip footings beneath the rig skids, permits utilizing a heavy section that satisfies the requirements of structural safety, without violating the economic considerations.

بعد عام (2003 م) ، شهد قطاع النفط / الغاز إستثمارا ً متناميا ً ، حيث دخلت إلى منطقتنا شركات عالمية ذات أصول مختلفة ، سخرت أبراج حفر ثقيلة (لتحقيق أعماق حفر كبيرة). في تلك الأثناء سجلت بعض مشاكل حفر ، ترافقت معها حالات فشل لقواعد الآبار.يهدف البحث إلى دراسة تصرف قواعد آبار ذات معالم هندسية مختلفة ، تحت تأثيرات أبراج حفر ذات خصائص متنوعة ، ضمن مقاطعة البصرة. تم إختيار أربع حالات للدراسة لتمثل أربعة حقول ، بالذات : حقول السيبة ، الزبير ، غرب القرنة-2 و الزبير- مشرف.سخرت طريقة العناصر المحددة لتنفيذ عملية تحليل الإجهادات،بتبني علاقة تكوينية مرنة - لدنة للتربة تستند إلى قاعدة إذعان دروكر – بريغر (Drucker-Prager) قورن ضغط التماس الأقصى المسلط على التربة (تحت الأحمال العاملة) مع قابلية تحملها. عند إستخدام الطريقة الجاسئة لحساب ضغط التماس ، فقد قورن مع قابلية التحمل القصوى المحسوبة من طريقة ريدي و سرينيفاسان(Reddy and Srinivasan) للترب المتماسكة و قابلية التحمل المسموحة المحسوبة من طريقة بيك وهانسون وثورنبيرن (Peck, Hanson, and Thornburn) للترب غير المتماسكة. ضغط التماس المحسوب بواسطة طريقة العناصر المحددة ، قورن مع قابلية التحمل القصوى من ذات الطريقة ، إستنادا ً لهبوط قدره (50 ملم). القيم المتطرفة لعزوم الإنحناء وقوى القص المتولدة في مقاطع قواعد الآبار (تحت الأحمال المكبرة) ، قورنت مع سعات المقاطع ، وكما حسبت من طريقة الجهد الأقصى.بالنسبة للجانب الجيوتقني ، أشرت النتائج معاملات أمان غير كافية ضد الفشل القصي للتربة لبعض الحالات ، وعلى وجه الخصوص لقطاعات تربة متماسكة. لقطاعات تربة غير متماسكة ، فإن معاملات الأمان الموفرة كانت كافية. عكست طريقة العناصر المحددة ضغوط تماس أعلى مقارنة بالطريقة الجاسئة الشائعة. لقطاعات التربة غير المتماسكة أعطت طريقة بيك وهانسون و ثورنبيرن هوامش أمان أكبر من طريقة العناصر المحددة. قيم الهبوط الآني كانت على الأغلب مقبولة. بالنسبة للجانب الإنشائي ، لوحظ تبني مقطع منتظم لجميع مواقع كل قاعدة ، للآبار المنفردة. في أغلب الحالات كان حديد التسليح الموفر أقل من متطلبات الحد الأدنى للمدونة. لقد أدى ذلك إلى خرق سعة المقطع للإنثناء ، على الأقل قرب القبو (Cellar) . سعة قص العتبة نادرا ً ما تم خرقها. إستخدام أسس شريطية تحت مزلقات البرج ، يسمح بتسخير مقطع كبير يستوفي متطلبات الأمان الإنشائي ، دون خرق الإعتبارات الإقتصادية.

Listing 1 - 5 of 5
Sort by
Narrow your search

Resource type

article (5)


Language

English (5)


Year
From To Submit

2019 (5)