Ali S Alnuaimi - Academia.edu (original) (raw)

Papers by Ali S Alnuaimi

Journal of construction engineering, technology & management, May 24, 2013

The aim of this paper was to identify the problems resulting from the delays in completion of con... more The aim of this paper was to identify the problems resulting from the delays in completion of construction projects in Oman. A field study was conducted on a number of construction projects in Muscat area to collect data required for analysis. Two groups of projects were studied, the first group included projects constructed during the period 2007–2008 and the second group studied comprised projects constructed during the period 2009–2010. It was found that 40 per cent of the projects constructed during the periods of both groups have experienced delays in completion with slight differences in the length of delay between the two groups. Another finding was that the causes of delay are changing with the time in a pattern depending on different variables. Owner related causes were found to be the dominant reason for delay and contrarily the first to seek solutions. Keywords: delay, construction projects, Oman, contracts

The Journal of Engineering Research, May 9, 2019

Due to the advantages of Fiber Reinforced Polymer (FRP) materials, they have been utilized to str... more Due to the advantages of Fiber Reinforced Polymer (FRP) materials, they have been utilized to strengthen several reinforced concrete (RC) elements such as slabs, beams and columns. In this paper, five RC beams (200 mm width, 300 mm height, and 2750 mm length) were constructed. Four of these beams were strengthened with CFRP sheets whereas the last beam was used as a reference. Test parameters include the amount of FRP and the strengthening technique. Three strengthening techniques were used including the externally bonded technique (EB), the near surface mounted (NSM) technique using folded CFRP sheets inserted in near surface grooves, and a hybrid technique. All beams were tested under four point bending setup until failure. The control beam failed by the yielding of the tension steel followed by concrete crushing. The strengthened beams failed by steel yielding followed by either rupture or debonding of CFRP sheets at higher loads compared to the reference one. The stiffness after steel yielding and the ultimate capacity increased as the amount of CFRP increased. The strengthening technique affected the ultimate capacity of the strengthened beams. The NSM beam showed the lowest increase in the ultimate capacity (25.2%) whereas the hybrid beam showed the best performance with the highest increase in the ultimate capacity (58%) compared to the reference beam.

The Hong Kong Institute of Steel Construction eBooks, 2009

This paper presents an artificial neural networking (ANN) model developed to predict the behaviou... more This paper presents an artificial neural networking (ANN) model developed to predict the behaviour of semi-rigid bare-steel joints at elevated temperature. Data for three flush end-plate and one flexible end-plate joints were considered. Sixteen parameters which included geometry of the joint's components, material properties of the joint, joint's temperature and the applied moment were used as the input variables for the model whilst the joint's rotation was the main output parameter. Data from experimental fire tests were used for training and testing the model. In total, fifteen different test results were evaluated with 331 and 61 cases were used for training and testing the developed model, respectively. The model predicted values were compared with actual test results. The results obtained indicated that the model can predict the moment-rotation behaviour in fire with very high accuracy. The coefficients of determination (R 2) for training and validation of the model were 0.964 and 0.956, respectively.

Structural Engineering and Mechanics, Dec 20, 2007

ABSTRACT Tests were conducted on two partially pre-stressed concrete solid beams subjected to com... more ABSTRACT Tests were conducted on two partially pre-stressed concrete solid beams subjected to combined loading of bending, shear and torsion. The beams were designed using the Direct Design Method which is based on the Lower Bound Theorem of the Theory of Plasticity. Both beams were of cross-section and 3.8 m length. The two main variables studied were the ratio of the maximum shear stress due to the twisting moment, to the shear stress arising from the shear force, which was varied between 0.69 and 3.04, and the ratio of the maximum twisting moment to the maximum bending moment which was varied between 0.26 and 1.19. The required reinforcement from the Direct Design Method was compared with requirements from the ACI and the BSI codes. It was found that, in the case of bending dominance, the required longitudinal reinforcements from all methods were close to each other while the BSI required much larger transverse reinforcement. In the case of torsion dominance, the BSI method required much larger longitudinal and transverse reinforcement than the both the ACI and the DDM methods. The difference in the transverse reinforcement is more pronounce. Experimental investigation showed good agreement between design and experimental failure loads of the beams designed using the Direct Design Method. Both beams failed within an acceptable range of the design loads and underwent ductile behaviour up to failure. The results indicate that the Direct Design Method can be successfully used to design partially prestressed concrete solid beams which cater for the combined effect of bending, shear and torsion loads.

Advances in Structural Engineering, Aug 1, 2006

Tests were conducted on three hollow partially prestressed concrete beams subjected to combined l... more Tests were conducted on three hollow partially prestressed concrete beams subjected to combined loading in bending, shear and torsion. The beams were designed using the Direct Design Method which is based on the Lower Bound Theorem of the Theory of Plasticity. All beams were of 300 × 300 mm cross-section, 3.8 m in length, and possessed a 200 × 200 mm hollow core and 50 mm wall thickness. The two main variables studied were the ratio in the web of the maximum shear stress due to the twisting moment, to the shear stress arising from the shear force, which varied between 1.09 and 6.85, and the ratio of the maximum twisting moment to the maximum bending moment which varied between 0.35 and 2.62. Good agreement was found between design and experimental failure loads. All beams failed near the design loads and underwent ductile behaviour up to failure. The results indicate that the Direct Design Method can be successfully used to design partially prestressed concrete hollow beams which will cater for the combined effect of bending, shear and torsion loads.

A field study was conducted on a number of construction projects in Muscat area to identify probl... more A field study was conducted on a number of construction projects in Muscat area to identify problems resulting from delays in completion of construction projects. The collected data was classified into two groups of projects, the first group included projects constructed during the period 2007-2008 and the second group comprised projects constructed during the period 2009-2010. It was found that 40 per cent of both groups have experienced delay in completion. Another finding was that the causes of delay are changing with the time in a pattern depending on different variables. Owner related causes were found to be the dominant reason for delay and contrarily the first to seek solutions.

WIT transactions on modelling and simulation, Jun 3, 2005

This paper presents a finite element model for idealisation of partially prestressed concrete hol... more This paper presents a finite element model for idealisation of partially prestressed concrete hollow beams using 2D plane elements. The method of ensuring compatibility between the plates using a two-dimensional model to analyze this type of structures is discussed. Cross-sectional distortion is minimised by incorporating end diaphragms in the finite element model. Experimental results from three partially pre-stressed concrete hollow beams are compared with the non-linear predictions produced by a 2D in-house finite element program. The beam dimensions were 300x300 mm cross section with 200x200 mm hollow core and 3800 mm length. The beam ends were filled with concrete to form solid end diaphragms to prevent local distortion. The beams were subjected to combined bending, torsion and shear. It was found that the two-dimensional idealisation of hollow beams is adequate provided that compatibility of displacements between adjoining plates along the line of intersection is maintained and the cross-sectional distortion is reduced to a minimum. The results from the 2D in-house finite element program showed a good agreement with experimental results.

Building and Environment, Sep 1, 2007

A controlled low strength material (CLSM) is a self-compacted, cementitious material used primari... more A controlled low strength material (CLSM) is a self-compacted, cementitious material used primarily as a backfill. It is also known as a flowable fill which is usually a mixture of fine aggregates, small amount of cement, fly ash, and water. To be classified as a CLSM, the mixture must have a compressive strength between 345 and 8400 kPa. This paper evaluates the potential use of cement bypass dust, incinerator ash and copper slag as a CLSM. Mixtures were designed to produce a CLSM, with a low compressive strength (less than 1034 kPa), that can be excavated without using any mechanical equipment. Slump, unit weight and unconfined compressive strength tests were conducted on various mixtures. Cubical and cylindrical specimens were prepared and cured at room temperature and in sealed plastic bags. Results indicate that with a good mix design it is possible to produce a CLSM with good mechanical properties to meet design requirements. Mixing these materials with cement and sand produced better results than using them alone due to their low pozzolanic activity. Curing method and period can have considerable effects on the strength of a CLSM.

Biochemical Engineering Journal

Open-graded friction course (OGFC) or porous mixtures consist of an open gradation, mostly of coa... more Open-graded friction course (OGFC) or porous mixtures consist of an open gradation, mostly of coarse size aggregate with little fines. The benefits of an OGFC mixture are typically increased surface friction, increased surface permeability, and noise reduction. This paper presents the results of an on-going study investigating four different OGFC mixes containing: (1) no additives, (2) cellulose fibers, (3) styrene butadiene rubber (SBR) polymer, and (4) a combination of both fibers and SBR polymer. Mix designs were performed according to the design procedure proposed by the National Center of Asphalt Technology (NCAT) for a range of 4.5 to 6.5 percent asphalt content. The results showed that the addition of SBR polymer has a more significant effect on the reduction of unaged abrasion compared to cellulose fibers. The polymer and fiber have the same effect on aged abrasion reduction, while a combination of both has a higher effect on the abrasion reduction. The fibers have a signifi...

The Journal of Engineering Research [TJER], 2019

This paper reports findings of a study that captures cost estimation practices and techniques pre... more This paper reports findings of a study that captures cost estimation practices and techniques prevalent in the construction industry in Oman. It also identifies the success and risk factors that are encountered in the cost estimation process. Eighty structured questionnaires were distributed to some professionals working in construction projects, selected randomly from large and medium size enterprises across the Sultanate. A response rate of 56% was achieved. The results showed that the unit rate method, the use of historical data and benchmarking are the most common methods used for cost estimation. Success and risk factors as reported by respondents were analyzed and ranked accordingly. The main sources of risk were reported by respondents as “Unclear reading and understanding of specifications”, “Lack of clear documents of the project scope of work”, and “Unavailability of Resources”. This study provides an insight understanding of revealed practices and techniques and globally...

Sultan Qaboos University Journal for Science [SQUJS], 2003

The aim of this study is to illustrate the problem of fire accidents in the Sultanate of Oman and... more The aim of this study is to illustrate the problem of fire accidents in the Sultanate of Oman and their causes in order to find out how the existing data could be used as a base to improve fire resistance, to detect the weak points (vulnerability to fire) in existing structures, and to minimize fire occurrences in places where it is high. This will also provide useful recommendations with regard to fire safety including causes, people’s awareness and education, etc. Fire data in Oman were collected from two sources: The Directorate General of Civil Defence (Public Relations Department) and Sultan Qaboos University library. The collected data represent the number of fires in Oman during the last decade. It also includes fire distribution by type and averages. The analysis shows that there is a linear increase in the number of fire accidents in the last decade with time. Many factors are included as potential sources, which are explained in the paper, and suggestions are made for ...

Structural Engineering and Mechanics, 2009

ABSTRACT This paper presents experimental results on the behaviour and ultimate load of fifteen p... more ABSTRACT This paper presents experimental results on the behaviour and ultimate load of fifteen pipes and six roof panels made of ferrocement. Additional results from three roof panels, carried out by others, are also compared with this research results. OPC cement, natural sand and galvanised iron wire mesh were used for the construction of 20 mm thick specimens. The pipe length was 2 m and roof panel length was 2.1 m. The main variables studied were the number of wire mesh layers which were 1, 2, 3, 4 and 6 layers, the inner pipe diameter which were 105, 210 and 315 mm, cross sectional shape of the panel which were channel and box sections and the depth of the edge beam which were 95 mm and 50 mm. All specimens were simply supported and tested for pure bending with test span of 600 mm at mid-span. Tests revealed that increasing the number of wire mesh layers increases the flexural strength and stiffness. Increasing the pipe diameter or depth of edge beam of the panel increases the cracking and ultimate moments. The change in the pipe diameter led to larger effect on ultimate moment than the effect of change in the number of wire mesh layers. The box section showed behaviour and strength similar to that of the channel with same depth and number of wire mesh layers.

Construction and Building Materials, 2016

This paper investigates the use of FRPs for the flexural strengthening of RC beams. All strengthe... more This paper investigates the use of FRPs for the flexural strengthening of RC beams. All strengthened beams showed a capacity increase ranging between 31 and 133%. The CFRP strengthened beams gave greater capacities than the GFRP strengthened ones. The GFRP strengthened beam, however, showed much better ductile behavior. The ACI 440-2R gave reasonable predictions of the ultimate capacities of the beams.

5th Brunei International Conference on Engineering and Technology (BICET 2014), 2014

Cement, Concrete and Aggregates, 2002

Résumé/Abstract Flowable fill is a self-compacted, cementitious material used primarily as a back... more Résumé/Abstract Flowable fill is a self-compacted, cementitious material used primarily as a backfill in lieu of compacted fill. It is generally a mixture of sand, small amount of cement, fly ash, and water. Sand is the major component of most flowable fill mixes. Waste materials such as fly ash, ground granulated blast furnace slag, and foundry sand are commonly used to ensure low maximum compressive strength. Cement by-pass dust (CBPD) is considered a waste material of the production of cement. An estimated 25,000 tons of CBPD are ...

WIT Transactions on The Built Environment, Vol 85, 2006

This paper presents the experimental results of nine roof panels made of Ferrocement. Two types o... more This paper presents the experimental results of nine roof panels made of Ferrocement. Two types of channel sections and one type of box section were tested. All panels were 2m long, 470mm wide and 20mm thick. Channel type A had side edge beams 95mm deep and channel type B had side edge beams 50mm deep. The depth of the box section was 95mm. Thin hexagonal wire mesh was used as reinforcement. The number of wire mesh layers was varied between two to six. The wires were impregnated midway through the thickness of the panels. The panels were tested for bending moment with simple supports. The main variables studied were the number of wire mesh layers, the cross sectional shape of the panel and the depth of edge beam. Tests revealed that all panels showed acceptable strength for roofing systems. The increase in the number of wire mesh layers leads to an increase in the flexural strength. The box section showed strength similar to that of the channel section with 95mm edge beam. The channels with 50mm deep edge beams showed strength much less than the ones with 95mm edge beam and box section.

Proceedings of the Institution of Civil Engineers - Structures and Buildings, 2006

Higher experimentally measured load resistance of a solid beam than a hollow one, with similar re... more Higher experimentally measured load resistance of a solid beam than a hollow one, with similar reinforcement, led to theoretical and experimental investigations on how the concrete core participates in stress resistance. Stress analysis was carried out on solid beams subjected to combined load of bending, shear and torsion. The beams were 300 × 300 mm in cross-section and 3800 mm in length. A three-dimensional in-house non-linear finite-element program was used for numerical analysis. From this analysis, a stress distribution was selected and used in computational experiments. It was found that the concrete core participates in the beams' behaviour and strength and cannot be ignored when combined loads of bending, shear and torsion are present. Its participation depends partly on the ratio of the torsion-to-bending moment and the ratio of shear stress caused by torsion to the shear stress caused by shear force. This computational study was followed by experimental testing of thr...

Journal of Materials in Civil Engineering, 2009

This paper presents the results of an investigation to study the possibility of developing concre... more This paper presents the results of an investigation to study the possibility of developing concrete blocks using waste materials. The blocks were produced from three waste materials: vermiculite and polystyrene beads, which were used as lightweight aggregates with different proportions in the mix, and cement kiln dust (CKD), which was used as a partial replacement for cement. The strength of the three types of blocks and the strength of masonry columns constructed from the blocks were compared with another two types of ...

Construction and Building Materials, 2008

In the last few years, extensive research has been done on the strengthening of concrete structur... more In the last few years, extensive research has been done on the strengthening of concrete structures using fiber reinforced polymers (FRP) as externally bonded sheets or plates. A limited number of studies have also been performed on the strengthening of steel and steel–concrete composite structures. Constructing and testing steel–concrete composite beams is not only time consuming but also expensive. Following a successful experimental study by the authors on strengthening steel–concrete composite girders using carbon fiber ...