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https://doi.org/10.26518/2071-7296-2022-19-2-300-306
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БЕТОН КАК ОДИН ИЗ ФАКТОРОВ ОБРУШЕНИЯ ЖЕЛЕЗОБЕТОННЫХ ЗДАНИЙ В БУРУНДИ
Э. Микерего* Ж. Ндикумана
Университет Бурунди, факультет инженерных наук;
департамент строительства г. Бужумбура, Бурунди
mikeregoemmanuel@hotmail.com, http://orcid.org/0000-0002-5743-6476, ndimanajustin@gmail.com, http://orcid.org/0000-0002-9875-4112
Ответственный автор
АННОТАЦИЯ
Введение. В данной статье представлены результаты натурной оценки участия бетона в обрушении железобетонных зданий в Бурунди.
Материалы и методы. Исследование проводилось определением прочности на сжатие бетонных конструктивных элементов исследуемых железобетонных зданий. Прочность на сжатие определялась на колоннах, балках и перекрытиях с помощью промышленного склерометра «SCHMIDT 2000» в соответствии с протоколом, описанным в «NFEN12504-2(2003)». Было изучено 17 (семнадцать) строящихся трехэтажных зданий. Для каждого здания, участвующего в исследовании, были исследованы железобетонные несущие элементы первого этажа. Полученные результаты были классифицированы в соответствии с марками цемента (32,5) и (42,5), которые использовались в бетонах исследованных зданий. Было проведено сравнение прочностей на сжатие, полученных в натурных условиях, с нормативными значениями. Достоверность полученных результатов была подтверждена корреляцией между результатами, полученными в натурных и лабораторных условиях.
Результаты. Данное исследование показало, что в Бурунди до 100% обрушений приходится на сооружения, построенные частными лицами. Было выявлено, что 100% колонн, 82% балок и 82% плит из бетона, изготовленного с использованием цемента марки (32,5), имели прочность на сжатие ниже нормативного значения (25 МПа). Также 50% колонн, 50% балок и 84% плит из бетона на основе цемента высокой марки (42,5) была ниже нормативного значения (35МПа).
Обсуждение и заключение. В данном исследовании была доказана достоверность результатов, полученных методом склерометрического испытания на железобетонных зданиях. Показано, что бетон является одним из факторов обрушения железобетонных зданий, построенных частными лицами в Бурунди. Отмечено, что низкосортный цемент оказывает большее влияние на разрушение желЗезобетонных конструкций, чем высокосортный. В качестве рекомендации: процесс строительства железобетонных зданий в Бурунди необходимо регулировать и контролировать.
КЛЮЧЕВЫЕ СЛОВА: бетон, железобетонные конструкции, факторы обрушения конструкций, обрушение зданий в Бурунди.
Статья поступила в редакцию 11.11.2021; одобрена после рецензирования 10.03.2022; принята к публикации 12.04.2022.
Авторы прочитали и одобрили окончательный вариант рукописи.
Прозрачность финансовой деятельности: авторы не имеют финансовой заинтересованности в представленных материалах и методах. Конфликт интересов отсутствует.
Для цитирования: Микерего Э., Ндикумана Ж. Бетон как один из факторов обрушения железобетонных зданий в Бурунди // Вестник СибАДИ. 2022. Т. 19, № 2(84). С. 300-306. https://doi.org/10.26518/2071-7296-2022-19-2-300-306
© Микерего Э., Ндикумана Ж., 2022
Контент доступен под лицензией Creative Commons Attribution 4.0 License.
https://doi.org/10.26518/2071-7296-2022-19-2-300-306
https://elibrary.ru/WMDFPG
Original article
CONCRETE AS A FACTOR IN REINFORCED CONCRETE BUILDINGS COLLAPSE IN BURUNDI
Emmanuel Mikerego * Justin Ndikumana
University of Burundi; Engineering Sciences Faculty;
Department of Civil Engineering Bujumbura - Burundi
mikeregoemmanuel@hotmail.com, http://orcid.org/0000-0002-5743-6476, ndimanajustin@gmail.com, http://orcid.org/0000-0002-9875-4112
Corresponding author
ABSTRACT
Introduction. This paper presents the results of the assessment in-situ of the involvement of the concrete in the collapse of reinforced concrete buildings in Burundi.
Materials and Methods. The study consisted in the identification of the compressive strengths of the concrete structural elements of the reinforced concrete buildings under study. The compressive strengths were identified on the columns, beams and slabs using an industrial SCHMIDT 2000 sclerometer according to the protocol described in NF EN 12504-2(2003). Seventeen (17) three-storey buildings under construction were studied. For each building involved in the study, the reinforced concrete bearing elements of the first floor were studied. The results obtained were classified according to the cement grades (32.5) and (42.5) that were used in the studied buildings. A comparison of the compressive strengths obtained in-situ was established in relation to the normative values according to the cement grade used. The reliability of the obtained results was confirmed by the correlation between the results obtained in the laboratory conditions on the reinforced concrete experimental samples. Results. This study showed that in Burundi up to 100% of collapses are caused by privately built structures. It was proved that the compressive strengths of 100% of the columns, 82% of the beams and 82% of the slabs that were made with a low-grade cement (32.5) had compressive strengths lower than the normative value (25MPa). In addition, the compressive strengths of 50% of the columns, 50% of the beams and 84% of the slabs made with a high-grade cement (42.5) were also proved to have compressive strengths lower than the normative values (35MPa).
Discussion and conclusion. In this study, the reliability of the results obtained by sclerometer test in-situ on the reinforced concrete buildings has been proved. Concrete has been shown to be a factor in the collapse of privately built reinforced concrete buildings in Burundi. Low-grade cement was observed to have a high impact in the collapse of reinforced concrete structures than the high-grade one. Therefore, as a recommendation, the process of building reinforced concrete buildings in Burundi needs to be regulated and controlled.
KEYWORDS: concrete, reinforced concrete structures, factors of structures collapse, buildings collapse in Burundi.
The article was submitted 11.11.2021; approved after reviewing 10.03.2022; accepted for publication 12.04.2022.
The authors have read and approved the final manuscript.
Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.
For citation: Mikerego E., Ndikumana J.Concrete as a factor in reinforced concrete buildings collapse in Burundi. The Russian Automobile and Highway Industry Journal. 2022; 19 (2): 300-306. https://doi.org/10.26518/2071-7296-2022-19-2-300-306
© Mikerego E., Ndikumana J., 2022
Content is available under the license Creative Commons Attribution 4.0 License.
INTRODUCTION
In Burundi, architectural and structural design are the mainly documents required to obtain a building permission. These are issued by the urban planning authorities. Thereafter, no measures are planned by the competitive authority for the verification of the material quality, technology and workforce involved in the construction works specifically for structures erected by individuals. Usually, the collapses happen during the construction process. For example, some known cases of collapse of reinforced concrete buildings are the Tankoma, Kinindo, Winterekwa and Buterere cases. In general, the causes are not known.
Buildings collapse in cities is a real risk in town planning in developing countries [1, 2]. That is why there exist a number of norms that gives a protocol of procedures for non-destructive approaches in order to conduct assessments on the mechanical performances of the concrete in-situ or on the precast-concrete12 [3, 4]. These are used to identify whether the concrete is or not one of the factors of the collapse of reinforced concrete buildings. In foreign literature, a number of assessments have been conducted on the causes of the collapse of reinforced concrete structures [5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18].
b
c
Figure 1 - Experimental samples preparation (a) and compression testing under hydraulic press (b)
and sclerometer (c) used in the laboratory and in-situ study Source: compiled by the authors.
b
c
Figure 2 - Random example of source of construction materials (a) used in manufacturing concrete (b) used in individual reinforced concrete buildings (c) in Burundi
Source: compiled by the authors.
a
а
1 ГОСТ 22690-88 «Бетоны. Определение прочности механическими методами неразрушающего контроля. Поправка ИУС № 5 1989».
2 CTO 56947007-29.240.55.269-2019. Требования к качеству конструкций, материалов и выполненных работ при строительстве (реконструкции) ВЛ 35 - 750 кВ. ПАО «ФСК ЕЭС» 2019.
Figure 3 - Designation of the type of the investigated bearing elements (column, beam and slab) on the seventeen (17) three-storey buildings Source: compiled by the authors.
However, these assessments cannot totally be related to Burundi because they do not take into consideration the local conditions.
MATERIAL AND METHODS
The main instrument that was planned to be used in the investigation of the studied structures was the sclerometer «SCHMIDT 2000». Thus, the first step of the research was to identify the correlation between the results obtained from the compression test under the hydraulic press and the results given by the sclerometer on the same experimental samples of the ordinary concrete (Fig.1). Two cement grades were considered for the concrete: low-grade cement (32.5) and highgrade cement (42.5).
The next step was to visit the construction sites in progress in order to observe visually the quality of the construction materials, technology and workforce used in the execution of reinforced concrete constructions (Fig. 2).
The study continued by the analysis of the reports provided by the staff from the civil protection agency about building collapse in Burundi. Finally, in-situ experimental tests on compressive strengths were carried out with the sclerometer on the columns, beams and slabs of the first floor (Fig.3) of seventeen (17) three-storey buildings under construction in Bujumbura Mairie, Bujumbura Rural and Gitega. The tests were performed according to the European norm [3].
The in-situ measurements were recorded in tables designed for further processing according
to the cement grade (32.5 or 42.5) used for the concrete of the investigated buildings.
RESULTS
To start with, the results obtained show a good correlation between the tests obtained under the hydraulic press and the sclerometer (Fig.4; Fig.5).
As the results show (Fig.4, Fig.5), for concretes aged 28 days, the compressive strengths obtained by crushing under the hydraulic press are lower than those determined by the sclerom-eter with a maximum difference of 7%.
Furthermore, tests in-situ showed that there may be remarkable difference between the compressive strengths of the concrete for columns, beams and slabs for a given reinforced concrete building. That difference was found to be more accentuated for buildings with concrete made with high-grade cement (42.5) than those with concrete made with low-grad cement (32.5) (Fig.6).
Thus, a detailed analysis of the previous results (Fig.6) show that a 100% of the columns, 82% of the beams and 82% of the slabs of the reinforced concrete buildings made from cement grade (32.5) had compressive strengths lower than the required normative compressive strength (25MPa). In addition, it was also found that 50% of the columns, 50% of the beams and 84% of the slabs of the reinforced concrete buildings made with cement grade (42.5) had compressive strengths lower than the required normative compressive strength (35MPa) (Fig.6).
Hydraulic press i
Sclerometer
ÖU
<l) <я KT О
g
о
ет
ВЭ BIO Bll В12 Blî B14 BIS B16
Experimental samples (B1...B16) of concrete made with cement grade 32.5
Figure 4 - Comparative results of compressive strengths obtained under t he hydraulic press and the sclerometer on the same experimental concrete samples with cement grade (32.5)
Source: compiled by the authors.
Hydraulic press i
■ Sclerometer
гЧ 70 00
ùL бо.оо —i
50.00
и 40.00 tu сз
Si 30.00
«
U — 20.00
О
U
10.00 0.00
Hilm
SI
B2
вз
В4
BS
В6
В7
Experimental samples (B1...B7) of concrete made with cement grade 42.5
Figure 5 - Comparative results of compressive strengths obtained under the hydraulic press and the sclerometer on the same experimental concrete samples with cement grade (42.5)
Source: co m piled by the authors.
1 ? $ 4 5 6 7 8 9 10 11 \2 13 14 IS 16 17
Figure 6 - Compressive strengths determined by sclerometer test in-situ for concrete from columns,
beams and slabs of the investigated reinforced concrete buildings
Source: compiled by the authors.
Cement grade 32.3 Cement grade 42.3
Figure 7 - Concrete bearing elements whose compressive strengths are under normative compressive strengths in studied
individual's reinforced concrete buildings in Burundi Source: compiled by the authors.
DISCUSSION AND CONCLUSION
In this study, the reliability of the results obtained by sclerometer test in-situ on the reinforced concrete buildings has been proved. It is demonstrated that the concrete is one the factors of the collapse of reinforced concrete buildings constructed by individuals in Burundi. Low-grade cement is observed to have a high impact in the collapse of reinforced concrete structures than the high-grade one. Therefore, as a recommendation, the process of building reinforced concrete buildings in Burundi needs to be regulated and controlled.
БИБЛИОГРАФИЧЕСКИЙ СПИСОК
1. Boateng F. G. Building collapse in cities in Ghana. A case for a historical-intitutional grounding for building risk in developping countries. International Journal of Disaster Risk reduction. Volume 50, Nove-meber 2020, 101912.
2. Francis O. Okeke, Chinwe G. Sam-amobi, Francis I. Okeke. Role of local town planning authorities in building collapse in Nigeria: evidence from Enugu metropolis. Heliyon. xxx (xxxx) xxx.
3. NF EN-12504-2 (2003) Essai pour béton dans les structures. Partie 2: Essais non destructifs - Détermination de l'indice de rebondissement.
4. NF EN 13791 (2007). Assessment of concrete compressive strength in structures or in precast concrete products.
5. Конухин В. П., Смирнов Ю. Г., Орлов А. О. Оперативный контроль прочностных свойств бетона неразрушающим методом при возведении ответственных железобетонных конструкций в условиях Арктики // Арктика: экология и экономика. 2012. № 4 (8).
6. Ayadeji O. (2011). An examination of the causes and effects of Building Collapse in Nigeria. Journal of design and Built environment, 9, 2011.
7. ESIRIS. Identification, investigation et diagnostic des défauts d'un bâtiment existant. Annales du bâtiment et des Travaux publics, vol.66, 2014. pp. 206-211.
8. Nguyen N. T. Apport de l'étude de la variabilité spatiale des mesures non destructives en vue d'un meilleur diagnostic des ouvrages en béton armé. 32èmes Rencontres Universitaires de Génie Civil (AUGC 2014), Orléans, 4-6 juin 2014. 8 p.
9. Ngoc Tan NGUYEN. Évaluation non destructive des structures en béton armé. Étude de la variabilité spatiale et de la combinaison des techniques. Thèse de Doctorat à l'Université de Bordeaux, juin 2014.
10. Oloyede S., Omoogun C. and Akinjare O. (2010). Tackling Causes of Frequent Building Collapse in Nigeria. Journal of Sustainable Development, 3, 2010.
11. Ngugi H. N., Mutuku R. N. and Gariy Z. A. (2014). Effects of Sand Quality on Compressive Strength of Concrete: A Case of Nairobi County and Its Environs, Kenya. Open Journal of Civil Engineering, 2014. Pp. 255-273.
12. Olanitori L. M. (2006). Mitigating the effect of Clay content of sand on concrete stregnth.31st conference on Our world in concrete and structures, Singapore. August 2006.
13. J. Gora Piasta W. Impact of mechanical resistance of aggregate on properties of concrete. Elsevier. Case studies in construction materials 13 (2020).
14. Machuki O.V. (2012). Causes of collapse of Building in Mombasa County. A case of Mombasa City - Kenya. Departement of extra Mural Studies. University of Nairobi. Kenya 2012.
15. Hong L., Gu X., Lin F. Influence of aggregate surface roughness on mechanical properties of interface and concrete, Constr. Build. Mater. 65 (2014).
16. Mansur Hamma-Adama. Causes of Building Failure And Collapse In Nigeria: Professionals «View» American Journal of Engineering Research (AJER). 2017. vol. 6, no. 12. pp. 289-300.
17. Olajumoke A, Oke I, Fajobi A, Ogedengbe M. Engineering failure analysis of failed building in Osun State, Nigeria. Journal of failure analysis and prevention. 9 (1). 2009.
18. Gulay F. G., Kaptan K., Bal E. I., Tezcan S. S. Scoring Method for the Collapse Vulnerability Assessment of R/C Buildings. The Twelfth East Asia-Pacific Conference on Structural Engineering and Construction. Procedia Engineering 14 (2011) 1219-1228.
REFERENCES
1. Boateng F. G. Building collapse in cities in Ghana. A case for a historical-intitutional grounding for building risk in developping countries. International Journal of Disaster Risk reduction. Volume 50, Novemeber 2020, 101912.
2. Francis O. Okeke, Chinwe G. Sam-amobi, Francis I. Okeke. Role of local town planning authorities in building collapse in Nigeria: evidence from Enugu metropolis. Heliyon. xxx (xxxx) xxx.
3. NF EN-12504-2 (2003) Essai pour béton dans les structures. Partie 2: Essais non destructifs - Détermination de l'indice de rebondissement.
4. NF EN 13791 (2007). Assessment of concrete compressive strength in structures or in precast concrete products.
5. Konuhin V. P., Smirnov Ju. G., Orlov A. O. Opera-tivnyj kontrol' prochnostnyh svojstv betona nerazrusha-jushhim metodom pri vozvedenii otvetstvennyh zhele-zobetonnyh konstrukcij v uslovijah Arktiki. [Operational control of concrete strength properties by nondestructive method during erection of critical reinforced concrete structures in Arctic conditions]. Arktika: jekologija ijekonomika. 2012; 4 (8). (in Russ.)
6. Ayadeji O. (2011). An examination of the causes and effects of Building Collapse in Nigeria. Journal of design and Built environment, 9, 2011.
7. ESIRIS. Identification, investigation et diagnostic des défauts d'un bâtiment existant. Annales du bâtiment et des Travaux publics, vol.66, 2014. pp. 206-211.
8. Nguyen N. T. Apport de l'étude de la variabilité spatiale des mesures non destructives en vue d'un meilleur diagnostic des ouvrages en béton armé. 32èmes Rencontres Universitaires de Génie Civil (AUGC 2014), Orléans, 4-6 juin 2014. 8 p.
9. Ngoc Tan NGUYEN. Évaluation non destructive des structures en béton armé. Étude de la variabilité spatiale et de la combinaison des techniques. Thèse de Doctorat à l'Université de Bordeaux, juin 2014.
10. Oloyede S., Omoogun C. and Akinjare O. (2010). Tackling Causes of Frequent Building Collapse in Nigeria. Journal of Sustainable Development, 3, 2010.
11. Ngugi H. N., Mutuku R. N. and Gariy Z. A. (2014). Effects of Sand Quality on Compressive Strength of Concrete: A Case of Nairobi County and
Its Environs, Kenya. Open Journal of Civil Engineering. 2014. Pp. 255-273.
12. Olanitori L. M. (2006). Mitigating the effect of Clay content of sand on concrete stregnth.31st conference on Our world in concrete and structures, Singapore. August 2006.
13. J. Gora Piasta W. Impact of mechanical resistance of aggregate on properties of concrete. Elsevier. Case studies in construction materials 13 (2020).
14. Machuki O.V. (2012). Causes of collapse of Building in Mombasa County. A case of Mombasa City - Kenya. Departement of extra Mural Studies. University of Nairobi. Kenya 2012.
15. Hong L., Gu X., Lin F. Influence of aggregate surface roughness on mechanical properties of interface and concrete, Constr. Build. Mater. 65 (2014).
16. Mansur Hamma-Adama. Causes of Building Failure And Collapse In Nigeria: Professionals «View» American Journal of Engineering Research (AJER). 2017. vol. 6, no. 12. pp. 289-300.
17. Olajumoke A, Oke I, Fajobi A, Ogedengbe M. Engineering failure analysis of failed building in Osun State, Nigeria. Journal of failure analysis and prevention. 9 (1). 2009.
18. Gulay F. G., Kaptan K., Bal E. I., Tezcan S. S. Scoring Method for the Collapse Vulnerability Assessment of R/C Buildings. The Twelfth East Asia-Pacific Conference on Structural Engineering and Construction. Procedia Engineering 14 (2011) 1219-1228.
ВКЛАД СОАВТОРОВ
Микерего Э. Концептуализация, методология, обработка данных, написание статьи, научное редактирование текста.
Ндикумана Ж. Методология, сбор и обработка данных.
COAUTHOR'S CONTRIBUTION
Emmanuel Mikerego - Conceptualization, methodology, data processing, writing of the article, scientific editing of the text.
Justin Ndikumana - Methodology, data collecting and processing.
ИНФОРМАЦИЯ АБ АВТОРАХ
Микерего Эммануэль - канд. техн. наук, преподаватель факультета инженерных наук, кафедры строительства.
Ндикумана Жистэн - магистрант факультета инженерных наук, кафедры строительства.
INFORMATION ABOUT AUTHORS
Emmanuel Mikerego - Dr. of Sci., Lecturer, University of Burundi, Engineering Sciences Faculty. B.P. 2700 Bujumbura - Burundi.
Justin Ndikumana - Graduate student; University of Burundi; Engineering Sciences Faculty; Department of Civil Engineering, B.P 2700 Bujumbura - Burundi.
