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Al-Gburi, Majid
Publications (10 of 14) Show all publications
Al-Gburi, M., Jonasson, J.-E. & Nilsson, M. (2018). Prediction of Restraint in Second Cast Sections of Concrete Culverts using Artificial Neural Networks (ed.). European Journal of Environmental and Civil Engineering, 22(2), 226-245
Open this publication in new window or tab >>Prediction of Restraint in Second Cast Sections of Concrete Culverts using Artificial Neural Networks
2018 (English)In: European Journal of Environmental and Civil Engineering, ISSN 1964-8189, E-ISSN 2116-7214, Vol. 22, no 2, p. 226-245Article in journal (Refereed) Published
Abstract [en]

Estimation of restraint is very important for accurately predicting the risk of early thermal and shrinkage cracking in concrete structures. The stress in young concrete is affected by changes in its dimensions during hydration and the restraint imposed by adjoining structures. In concrete culverts, the restraints from existing structures acting upon the first and second casting sections to be cast are different, causing them to exhibit different early cracking behaviour. This work presents a new method for predicting restraint in complex concrete structures using artificial neural networks (ANNs). Finite element calculations were performed to predict restraint in 108 slabs, 324 walls and 972 roofs from second sections of concrete culverts, and the results obtained were used to train and validate ANN models. The ANN models were then used to study the effects of varying selected parameters (the thickness and width of the roof and slab, the thickness and height of the walls, and the length of the culvert section) on the predicted restraint. Mathematical expressions for predicting restraint values in slabs, walls and roofs were derived based on the ANN models’ output and implemented in an Excel spreadsheet that provides a simple way of predicting restraint in practical applications. Restraint values predicted in this way agree well with the results of finite-element calculations

Place, publisher, year, edition, pages
Taylor & Francis, 2018
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-13947 (URN)10.1080/19648189.2016.1186116 (DOI)000427321300006 ()d43d84f0-c1d2-4a54-9629-77677abf0d2c (Local ID)d43d84f0-c1d2-4a54-9629-77677abf0d2c (Archive number)d43d84f0-c1d2-4a54-9629-77677abf0d2c (OAI)
Note

Validerad;2017;Nivå 2;2017-12-04 (svasva)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-04-06Bibliographically approved
Al-Gburi, M., Jonasson, J.-E. & Nilsson, M. (2016). Reduction of Early Age Crack Risks in Concrete Walls by Using a New Casting Technique (ed.). Structural Engineering International, 26(3), 216-224
Open this publication in new window or tab >>Reduction of Early Age Crack Risks in Concrete Walls by Using a New Casting Technique
2016 (English)In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 26, no 3, p. 216-224Article in journal (Refereed) Published
Abstract [en]

Volumetric changes in early age concrete that are restrained might lead to cracks. The degree of restraint is influenced by the casting sequence and the dimensions of the castings. In the current study a new casting technique is proposed to reduce restraint in the newly cast concrete with a new arrangement of the structural joint to the existing old concrete. The proposed technique is valid for the typical structure wall-on-slab using one structural joint. This casting method means that lower part of the wall is cast together with the slab, and that part is called a kicker. Hereby, the behavior of the structure changes from a typical case wall-on-slab to a typical case wall-on-wall. It has been proven by the beam theory and demonstrated by numerical calculations that there is a clear reduction in the restraint from the slab to the wall using kickers. In the paper different kicker heights are studied with the aim of determining the minimum restraint in the upper part of the wall cast in contact with the kicker. The technique using kickers is compared with common measures used in the field to avoid cracking, such as cooling pipes in the new casting and/or heating cables in the adjoining old concrete. The presented method is both cost and time effective, as it opens the possibility to use larger structural length of each casting sequence.

Place, publisher, year, edition, pages
International Association for Bridge and Structural Engineering, 2016
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-9105 (URN)10.2749/101686616X14555429843960 (DOI)000386695500004 ()2-s2.0-85021095055 (Scopus ID)7ac04418-9d63-4c95-b719-af26f19330d0 (Local ID)7ac04418-9d63-4c95-b719-af26f19330d0 (Archive number)7ac04418-9d63-4c95-b719-af26f19330d0 (OAI)
Note

Validerad; 2016; Nivå 2; 2016-11-25 (andbra)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Hamodi, H., Lundberg, J., Al-Gburi, M., Ahmadi, A. & Ghodrati, B. (2015). Model for economic replacement time of mining production rigs including redundant rig costs (ed.). Paper presented at . Journal of Quality in Maintenance Engineering, 21(2), 207-226
Open this publication in new window or tab >>Model for economic replacement time of mining production rigs including redundant rig costs
Show others...
2015 (English)In: Journal of Quality in Maintenance Engineering, ISSN 1355-2511, E-ISSN 1758-7832, Vol. 21, no 2, p. 207-226Article in journal (Refereed) Published
Abstract [en]

Purpose - This paper presents a practical model to determine the economic replacement time (ERT) of production machines. The objective is to minimise the total cost of capital equipment, where total cost includes acquisition, operating, maintenance costs and costs related to the machine’s downtime. The costs related to the machine’s downtime are represented by the costs of using a redundant machine. Design/methodology/approach - Four years of cost data are collected. Data is analysed, practical optimisation model is developed and regression analysis is done to estimate the drilling rigs ERT. The artificial neural network (ANN) technique is used to identify the effect of factors influencing the ERT of the drilling rigs.Findings - The results show that the redundant rig cost has the largest impact on ERT, followed by acquisition, maintenance and operating costs. The study also finds that increasing redundant costs per hour have a negative effect on ERT, while decreases in other costs have a positive effect. Regression analysis shows a linear relationship between the cost factors and ERT. Practical implications - The proposed approach can be used by the decision maker in determining the economic replacement time of production machines which used in mining industry.Originality/value - The research proposed in this paper provides and develops an optimisation model for economic replacement time of mining machines. This research also identifies and explains the factors that have the largest impact on the production machine’s ERT. This model for estimating the ERT has never been studied on mining drilling rigs.Keywords Decision support model, Life cycle cost, Optimisation, Replacement timePaper type Research paper

National Category
Other Civil Engineering
Research subject
Operation and Maintenance
Identifiers
urn:nbn:se:ltu:diva-15537 (URN)10.1108/JQME-07-2014-0041 (DOI)000211515300005 ()2-s2.0-84929074579 (Scopus ID)f116c303-ba8e-43b6-9aff-48109010af18 (Local ID)f116c303-ba8e-43b6-9aff-48109010af18 (Archive number)f116c303-ba8e-43b6-9aff-48109010af18 (OAI)
Note
Validerad; 2015; Nivå 1; 20141016 (hasham)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Al-Gburi, M. (2015). Restraint Effects in Early Age Concrete Structures (ed.). (Doctoral dissertation). Paper presented at . : Luleå tekniska universitet
Open this publication in new window or tab >>Restraint Effects in Early Age Concrete Structures
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

One of the widespread issues in concrete structures is cracks occurring at early age. Cracks that appear in the young concrete may cause early start of corrosion of rebars or early penetration of harmful liquids or gases into the concrete body. These situations could result in reduced service life and in significantly increased maintenance cost of structures. Therefore it is important for construction companies to avoid these cracks.Volumetric deformations in early age concrete are caused by changes in temperature and/or the moisture state. If such movements are restrained, stresses will occur. If the tensile stresses are high enough, there will be a damage failure in tension and visible cracks arise. These stresses are always resulting from a self-balancing of forces, either within the young concrete bodyalone, i.e. without structural joints to other structures, or from the young concrete in combination with adjacent structures through structural joints.The decisive situation within a young concrete body alone is typically high stresses at the surface when the temperature is near the peak temperature within the body. This situation occur rather early for ordinary structures, say within a few days after casting for structures up to about some meters thickness, but for very massive structures like large concrete dams, it might take months and even years to reach the maximum tensile stresses at the surface. Usually this type of cracks is denoted "surface cracks", and in some cases only a temperature calculation may give a good perception to make decisions of the risk of surface cracking.On the other hand, the decisive situation within a young concrete body connected to adjacent structures, might include both risk of surface cracking at some distance away from the structural joint and risk of through cracking starting in the neighborhood of the structural joint. If the young concrete body is small in accordance to the adjacent structure, or, in other words, if thereis an overall high restraint situation in the young concrete, the risk of early surface cracking might be out of question. So, restraint from adjacent structures represents one of the main sources of thermal and shrinkage stresses in a young concrete body.This study is mainly concentrated on establishing the restraint inside the young concrete body counteracted by adjacent structures, and how to estimate the risk of through cracking based on such restraint distributions. The restraint values in the young concrete are calculated with use of the finite element method, FEM. Any spatial structure may be analyzed with respect to the level of restraint. Calculations of risk of cracking are demonstrated with use of existing compensation plane methods, and a novel method denoted equivalent restraint method, ERM, is developed for the use of restraint curves. ERM enables the use of both heating ofthe adjacent structure and/or cooling of the young concrete, which are the most common measures used on site to reduce the risk of early cracking.In a design situation many parameters are to be considered, like type of cement, different concrete mixes, temperature in the fresh concrete, surrounding temperatures, temperature in the adjacent structure, measures on site (heating/cooling/insulation), sequence order of casting.Therefore, in general a lot of estimations concerning risks of cracking are to be performed. The main objective with the present study is to develop methods speeding up and shorten the design process.Furthermore, established restraint curves have been applied to the method of artificial neural networks (ANN) to model restraint in the slab, wall, and roof for the typical structure Tunnel. It has been shown that ANN is capable of modeling the restraint with good accuracy. The usage of the neural network has been demonstrated to give a clear picture of the relative importance of the input parameters. Further, results from the neural network can be represented by a series of basic weight and response functions, which enables that the restraint curves easily can be made available to any engineer without use of complicated software.A new casting technique is proposed to reduce restraint in the newly cast concrete with a new arrangement of the structural joint to the existing old concrete. The proposed technique is valid for the typical structure wall-on-slab using one structural joint. This casting method means that the lower part of the wall is cast together with the slab, and that part is called a kicker. It hasbeen proven by the beam theory and demonstrated by numerical calculations that there is a clear reduction in the restraint from the slab to the wall using kickers.Restraint is affected by casting sequence as well as boundary conditions and joint position between old and new concrete elements. This study discusses the influence of different possible casting sequences for the typical structure wall-on-slab and slab-on-ground. The aim is to identify the sequence with the lowest restraint to reduce the risk of cracking.

Place, publisher, year, edition, pages
Luleå tekniska universitet, 2015. p. 190
Series
Doctoral thesis / Luleå University of Technology 1 jan 1997 → …, ISSN 1402-1544
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-18705 (URN)9f072c77-0c63-4e2e-9b12-466b8ee68c88 (Local ID)978-91-7583-374-3 (ISBN)978-91-7583-375-0 (ISBN)9f072c77-0c63-4e2e-9b12-466b8ee68c88 (Archive number)9f072c77-0c63-4e2e-9b12-466b8ee68c88 (OAI)
Note
Godkänd; 2015; 20150817 (majali); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Majid Al-Gburi Ämne: Konstruktionsteknik/Structural Engineering Avhandling: Restraint Effects in Early Age Concrete Structures. Opponent: Professor Björn Engström, Avd för Konstruktionsteknik, Institutionen för Bygg- och miljöteknik, Chalmers tekniska högskola, Göteborg. Ordförande: Professor Jan-Erik Jonasson, Avd för Byggkonstruktion och produktion, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet, Luleå. Tid: Torsdag 17 september 2015, kl 10.00 Plats: F1031, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Al-Gburi, M., Jonasson, J.-E. & Nilsson, M. (2015). Using Artificial Neural Network to Predict the Restraint in Concrete Culvert at Early Age (ed.). Paper presented at . Structural Engineering International, 25(3), 258-265
Open this publication in new window or tab >>Using Artificial Neural Network to Predict the Restraint in Concrete Culvert at Early Age
2015 (English)In: Structural Engineering International, ISSN 1016-8664, E-ISSN 1683-0350, Vol. 25, no 3, p. 258-265Article in journal (Refereed) Published
Abstract [en]

Estimation of restraint is very important for accurate prediction of the risk of concrete cracking at early age. The present study predicts the restraint in 324 walls and 972 roofs for a concrete culvert. A parametric study included the thickness and width of the roofs, thickness and height of the walls, thickness and width of the slab, and length of the structures. Each parameter increased or decreased the restraint in the walls and the roofs. The calculation of the restraint was done elastically by the finite-element method (FE). The results were used by an artificial neural network (ANN) tool, where firstly an influential percentage was investigated as input parameters on the restraint prediction. Equations have been derived by the ANN model to calculate the restraint in the walls and the roofs. It was then used in an Excel sheet to calculate the restraint and compare the result with the result from the finite-element calculations giving high accuracy between the ANN model and the FE calculations

National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-13425 (URN)10.2749/101686614X14043795570570 (DOI)000370775600003 ()2-s2.0-84941962665 (Scopus ID)ca62ce25-6bf8-45cf-8228-03e331ee8dfe (Local ID)ca62ce25-6bf8-45cf-8228-03e331ee8dfe (Archive number)ca62ce25-6bf8-45cf-8228-03e331ee8dfe (OAI)
Note
Validerad; 2015; Nivå 2; 20150316 (majali)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-07-10Bibliographically approved
Al-Gburi, M., Jonasson, J.-E. & Nilsson, M. (2014). Effect of casting sequences on the restraint in slab-on-ground (ed.). Paper presented at Concrete Innovation Conference : 11/06/2014 - 13/06/2014. Paper presented at Concrete Innovation Conference : 11/06/2014 - 13/06/2014.
Open this publication in new window or tab >>Effect of casting sequences on the restraint in slab-on-ground
2014 (English)Conference paper, Oral presentation only (Refereed)
Abstract [en]

One of the widespread issues in concrete structures is cracks occurring at early age. Cracks that appear in the young concrete may cause early start of corrosion of rebars or early penetration of harmful liquids or gases into the concrete body. These situations could result in reduced service life and in significantly increased maintenance cost of structures. Therefore it is important for construction companies to avoid these cracks. Restraint represents one of the main sources of thermal and shrinkage stresses at early age concrete. The casting sequence is affected by the restraint from adjacent structures. The present study discusses the influence of five casting sequences for the typical structure slab-on-ground. The aim is to map restraints for a number of possible casting sequences, and to identify the sequence with the lowest restraint. The study covers both continuous and jumped casting sequences, which include one, two and three contact edges. The result shows that the best casting sequence is the continuous technique with one contact edge

Keywords
Restraint cracks, through cracking, early age concrete, casting sequence, slab-on-ground., Civil engineering and architecture - Building engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-27959 (URN)1952cb57-ba4e-470c-99d8-1bc91a56dafa (Local ID)1952cb57-ba4e-470c-99d8-1bc91a56dafa (Archive number)1952cb57-ba4e-470c-99d8-1bc91a56dafa (OAI)
Conference
Concrete Innovation Conference : 11/06/2014 - 13/06/2014
Note
Godkänd; 2014; 20140618 (majali)Available from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-03-26Bibliographically approved
Al-Gburi, M., Jonasson, J.-E. & Nilsson, M. (2014). Effect of the boundary conditions on the crack distribution in early age concrete (ed.). Paper presented at Nordic Concrete Research Symposia : 13/08/2014 - 15/08/2014. Nordic Concrete Research, 50, 347-351
Open this publication in new window or tab >>Effect of the boundary conditions on the crack distribution in early age concrete
2014 (English)In: Nordic Concrete Research, ISSN 0800-6377, Vol. 50, p. 347-351Article in journal (Refereed) Published
Abstract [en]

Restrained movement in early age concrete may cause cracking. The boundary conditions – restraint – influence the possible crack distribution. This study aims at highlighting the effect of such restraint on the crack distribution. This is done by using the “Cracking Model for Concrete” in ABAQUS/Explicit simulating the non-linear behaviour under and after cracking. In the study the typical case wall-on-slab was in focus using a structure previously been tested in laboratory with both fixed and free bottom slab. The result of the modelling shows fairly good agreement with the cracks observed in the tests.

National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-35902 (URN)aa1a1048-666a-411e-8f71-de9393198743 (Local ID)aa1a1048-666a-411e-8f71-de9393198743 (Archive number)aa1a1048-666a-411e-8f71-de9393198743 (OAI)
Conference
Nordic Concrete Research Symposia : 13/08/2014 - 15/08/2014
Note
Godkänd; 2014; 20140812 (majali); Konferensartikel i tidskriftAvailable from: 2016-09-30 Created: 2016-09-30 Last updated: 2018-03-26Bibliographically approved
Al-Gburi, M. (2014). Restraint Calculation in Concrete Culvert First Casting (ed.). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Restraint Calculation in Concrete Culvert First Casting
2014 (English)Report (Other academic)
Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2014. p. 71
Series
Technical report / Luleå University of Technology, ISSN 1402-1536
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-22002 (URN)119f46d6-711a-4264-bae4-2bbe16498c49 (Local ID)978-91-7439-882-3 (ISBN)119f46d6-711a-4264-bae4-2bbe16498c49 (Archive number)119f46d6-711a-4264-bae4-2bbe16498c49 (OAI)
Note

Godkänd; 2014; 20140317 (majali)

Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2018-08-17Bibliographically approved
Al-Gburi, M. (2014). Restraint Calculation in Concrete Culvert Second Casting (ed.). Paper presented at . : Luleå tekniska universitet
Open this publication in new window or tab >>Restraint Calculation in Concrete Culvert Second Casting
2014 (English)Report (Other academic)
Place, publisher, year, edition, pages
Luleå tekniska universitet, 2014. p. 156
Series
Technical report / Luleå University of Technology, ISSN 1402-1536
Keywords
Restraint cracks, second casting, culvert, Civil engineering and architecture - Building engineering, Samhällsbyggnadsteknik och arkitektur - Byggnadsteknik
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-24047 (URN)96f7034d-b339-4466-8ab4-0a7d40c9ffcd (Local ID)978-91-7583-075-9 (ISBN)96f7034d-b339-4466-8ab4-0a7d40c9ffcd (Archive number)96f7034d-b339-4466-8ab4-0a7d40c9ffcd (OAI)
Note
Godkänd; 2014; 20141103 (majali)Available from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
Al-Gburi, M. (2014). Restraint in structures with young concrete: Tools and estimations for practical use (ed.). (Licentiate dissertation). Paper presented at . Luleå: Luleå tekniska universitet
Open this publication in new window or tab >>Restraint in structures with young concrete: Tools and estimations for practical use
2014 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

One of the widespread issues in concrete structures is cracks occurring at early age. Cracks that appear in the young concrete may cause early start of corrosion of rebars or early penetration of harmful liquids or gases into the concrete body. These situations could result in reduced service life and in significantly increased maintenance cost of structures. Therefore it is important for construction companies to avoid these cracks. Restraint represents one of the main sources of thermal and shrinkage stresses at early age concrete. Paper I, deals with both the compensation plane method, CPM, and local restraint method, LRM, as alternative methods studying crack risks for early age concrete. It is shown that CPM can be used both for cooling and heating, but basic LRM cannot be applied to heating. This paper presents an improved equivalent restraint method, ERM, which easily can be applied both for usage of heating and cooling for general structures. Restraint curves are given for two different infrastructures, one founded on frictional materials and another on rock. Such curves might be directly applied in design using LRM and ERM.In Paper II, existing restraint curves have been applied to the method of artificial neural networks (ANN) to model restraint in the wall for the typical structure wall-on-slab. It has been proven that ANN is capable of modeling the restraint with good accuracy. The usage of the neural network has been demonstrated to give a clear picture of the relative importance of the input parameters. Further, it is shown that the results from the neural network can be represented by a series of basic weight and response functions. Thus, the results can easily be made available to any engineer without use of complicated software.Paper III, discusses the influence of five casting sequences for the typical structure slab-on-ground. The aim is to map restraints from adjacent structures for a number of possible casting sequences, and to identify the sequence with the lowest restraint. The paper covers both continuous and jumped casting sequences, which include one, two and three contact edges. The result shows that the best casting sequence is the continuous technique with one contact edge.

Place, publisher, year, edition, pages
Luleå: Luleå tekniska universitet, 2014. p. 106
Series
Licentiate thesis / Luleå University of Technology, ISSN 1402-1757
National Category
Infrastructure Engineering
Research subject
Structural Engineering
Identifiers
urn:nbn:se:ltu:diva-16816 (URN)028c9586-d47e-4e26-9b00-e6f74242891c (Local ID)978-91-7439-976-9 (ISBN)978-91-7439-977-6 (ISBN)028c9586-d47e-4e26-9b00-e6f74242891c (Archive number)028c9586-d47e-4e26-9b00-e6f74242891c (OAI)
Note
Godkänd; 2014; 20140623 (majali); Nedanstående person kommer att hålla licentiatseminarium för avläggande av teknologie licentiatexamen. Namn: Majid Al-Gburi Ämne: Konstruktionsteknik/Structural Engineering Uppsats: Restraint in Structures with Young Concrete - Tools and Estimations for Practical Use Examinator: Professor Jan-Erik Jonasson, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Diskutant: Ph.D, Consulting Engineer Carsten Vogt, Projektengagemang, Anläggningsunderhåll, Stockholm Tid: Måndag den 1 september 2014 kl 10.00 Plats: F1031, Luleå tekniska universitetAvailable from: 2016-09-29 Created: 2016-09-29 Last updated: 2017-11-24Bibliographically approved
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