The study was conducted to evaluate the experimental and theoretical shear strength of a simply s... more The study was conducted to evaluate the experimental and theoretical shear strength of a simply supported reinforced concrete beam with and without shear reinforcement in accordance with Eurocode 2 design criteria. Fifteen (15) reinforced concrete beams of dimension 750mm x 150mm x 150mm reinforced with diameter 12mm size bars were cast at various reinforcement ratios (i.e. 1.0%, 1.5%, 2.0%, 2.5%, and 3.0%), while preliminary and mechanical tests were conducted on the materials (i.e. cement, fine and coarse aggregate, and reinforcement bars) in accordance with relevant codes and standards. The outcome from the findings showed that the cement, fine aggregate and coarse aggregate used to cast the reinforced concrete beam were well graded and satisfies the requirement of code specification. More results showed that the average diameter of the reinforcement bars are 11.67mm, the mean tensile and ultimate strength of the reinforcement bars are 389.73N/mm 2 and 640.80N/mm 2 respectively, while the mean reinforcement steel elongation is 14.23% which mostly met code requirement indicating suitability of the reinforcement bars usage in concrete. Furthermore, the result from the findings showed that the Eurocode 2 (EC2) design criteria of beams without shear reinforcement were lower than the experimental value, while EC2 design criteria for beams with shear reinforcement was close to the experimental value.
Zenodo (CERN European Organization for Nuclear Research), Jun 30, 2021
Timber is a natural material from matured trees that can be used for structural applications. Mat... more Timber is a natural material from matured trees that can be used for structural applications. Material properties of timber such as light weight to strength ratio, good durability, good insulation against heat and sound impact makes it suitable for use as material for constructing roofing system, pedestrian or bicycle bridges and framing of other load-bearing structures, where strength is the major factor in its selection and usage. Unfortunately, time-dependent deformation affects the strength and stiffness of timber in service. The process of creep in timber, which is affected by variables such as temperature, moisture, species type, grain direction, loading influence, and timber's natural variability causes excessive deformations and even collapse of an entire construction. This paper reviews the work presented by various researchers on creep prediction/investigation models devised for timber. From the available literature reviewed, creep prediction models were developed for small timber species that are not widely used for construction/structural applications and do not undergo large moisture fluctuations, therefore mechano-sorptive creep effects are minimal. Looking at local content, there is need to develop mathematical models that would be used to predict/investigate long term creep for Nigerian grown timber species. There is no record of an existing unified or generalized creep prediction model that could be used for estimating long term creep of all timber species, because each of the mathematical models developed contain a great variety of constants that can only be determined by rigorous and large experimental sample tests.
There is no doubt that construction and building industries are the main energy and materials con... more There is no doubt that construction and building industries are the main energy and materials consumers of any country. In sustainable development, both the immediate and imminent needs are adequately taken into consideration. Sequel to the fact that concrete is weak in tension, reinforcement is inevitable to compensate for the deficiency. This paper purposes to comparing the flexural properties of concrete beams reinforced with bamboo strips and steel bars. Bamboo strips were found to be a close replacement to steel for light-weight constructions. This research consists of 100 x 100 x 450mm reinforced concrete beams with varying percentages of steel served as reference. Three beams were cast for each bamboo/Steel reinforcement ratio for each curing age making a total of Ninety-Six beams for flexural properties test. Three cubes were prepaid for every curing age summing up to Twenty-Four cubes for compressive test. The area of Bamboo reinforcement equivalent to steel was calculated via the equivalence of the force that could withstand the bending stresses which was also resisted by corresponding bamboo area. Steel stirrups were used to carter for shear in the beams. Flexural and compressive strengths at 7-, 14-, 21-and 28-days have been taken into consideration for comparison purpose. The graphs from the results were plotted and the suitability of bamboo reinforced beam was discoursed regarding the failure types. Results from the research reveal that bamboo can be used in lowcost constructions.
FUDMA JOURNAL OF SCIENCES - ISSN: 2616-1370, Dec 31, 2019
Geopolymer concrete (GPC) has no mix design code to guide in the choice of material proportions f... more Geopolymer concrete (GPC) has no mix design code to guide in the choice of material proportions for specific compressive strengths, its properties have not been fully understood especially in Nigeria despite being blessed with abundant geopolymer Al-Si source material (Kaolin). This study presents the properties of Kankara kaolin before and after treatment. Minitab 18 factorial design was used to design a Metakaolin based Geopolymer Concrete (GPC) with target compressive strength of 25 N/mm 2 (Suitable for Reinforced concrete). After kaolin treatment XRF results indicate a marginal difference in Oxide composition with the kaolin before treatment, but FTIR results showed more of the difference because the transmittance of the band between 3619 and 3690 cm -1 which is typical of kaolin increased when treated to 94.484 % from 74.825 % when untreated and quartz interference at 1114.5 cm -1 and Si-O quartz at 674.6 and 752.9 cm -1 were no more after the treatment. A factorial design with four factors having 9 experimental runs recoded 39.5 N/mm 2 (Run No 7) as highest compressive strength and 4.1 N/mm 2 (Run No 2) as the lowest. Results indicated that mixes with low alkaline liquid and low Molar concentration content exhibits lower strength than those with high alkaline liquid content and High Molar concentration. Re-analysing laboratory results and targeting a strength of 25 N/mm 2 ; a mix (M1) with 14M proposed for the validation attained 38.7 N/mm 2 , another mix (M2) with 8 M also attained 30 N/mm 2 , Both M1 and M2
Quality timber species are declining due to over-exploitation in Nigeria. This has propelled the ... more Quality timber species are declining due to over-exploitation in Nigeria. This has propelled the utilisation of low-grade timbers species that are considered for low-end constructions in the past which called for concern. This study establishes the viability of a typical beam made from locally sourced non-durable Obeche (Triplochiton scleroxylon) with highly durable Opepe (Nauclea diderrichii) timber specie in a combined glulam form, using polyvinyl acetate (PVA) adhesive which serves the impact of environmental sustainability and reduced cost of engineering construction. Seasoned timber samples and PVA adhesive were all obtained locally in Nigeria. Beam specimens were tested in the Department of Civil Engineering, Ahmadu Bello University, Zaria according to EN 338 (2009). Based on tests, it is evident that solid Opepe and Obeche timber specimens exhibited more durable characteristics than their homogenous glulam when fabricated with PVA adhesive. The combined Opepe/Obeche (GLc OP/OB) glulam beam specimen was proposed into GL18c strength class according to EN 338 based on minimum constraints which it satisfies, reflecting a 41 % greater Modulus of Elasticity (MoE) in comparison with EN 338 experimental value. This study recommends the enhancement of the bending strength, density and modulus of elasticity of a typical non-durable solid Obeche timber beam by 38 %, 47 % and 35 % respectively with 40 % durable Opepe timber in a combined glulam form using PVA adhesive for engineering construction purposes.
This paper presents evaluation of a 67.12m high telecommunication tower with the objectives of ap... more This paper presents evaluation of a 67.12m high telecommunication tower with the objectives of applying the Finite Element Method (FEM) in modelling it, analysing it under Nigerian wind loads from five different wind zones (Zone 1, Zone 2, Zone 3 Zone 4 and Zone 5 with basic wind speeds as 42m/s, 45.8m/s, 50m/s, 55m/s and 56m/s respectively). The collapse mechanism of the tower was predicted using the Mechanism Method. The tower was modelled and wind load was calculated on it and analysis shows that there is mechanism for the tower to collapse under dynamic wind loads as plastic hinges are developed at the joints and along bracing members. The most severe wind load was used in the plastic analysis conducted and it shows that when the plastic hinges developed at the lower section of the tower, the three mechanisms are more critical compared to when it develops at other sections of the tower. Also, using such load as the collapse load, when the plastic hinges developed at any section of the tower, combine mechanism is more critical and hence the tower is likely to collapse due to failure of both leg members and bracing members.
Mathematical model of compression creep for Terminalia ivorensis (Black Afara) timber were develo... more Mathematical model of compression creep for Terminalia ivorensis (Black Afara) timber were developed and presented in this paper. One-year creep test was performed in this process on Terminalia ivorensis timber samples. The creep data were fitted to linear, exponential and logarithmic regression models. The coefficients of determination for each of the model was determined. The coefficients of determination of the linear, exponential and logarithmic models were determined as 0.689, 0.650 and 0.941 respectively. Since the logarithmic model has the highest correlation with coefficient of determination of 0.941, it gave the best compression creep prediction model for the Terminalia ivorensis timber.
The deterioration of reinforced concrete bridge deck that has been damaged as a result of load ac... more The deterioration of reinforced concrete bridge deck that has been damaged as a result of load action can affect the durability, safety and function of the structure. In this paper, a reliability time-variant fatigue analysis and uncertainty effect on the serviceability of reinforced concrete bridge deck was carried out. A simply supported 15m bridge deck was specifically used for the investigation. Mathematical models were developed and the uncertainties in structural resistance, applied loadings as well as the structural components were accommodated using probabilistic method. The limit state functions were evaluated using the First Order Reliability Algorithm and the entire process was implemented using a developed MATLAB program called Rayswit.m. Failure in the deck shear region gave the most critical effect with a reliability index range of 6.95 to-12.38 when compared to flexure region with an index of 8.58 to-10.53.
The purpose of this paper was the determination of the uncertainty models of reference material p... more The purpose of this paper was the determination of the uncertainty models of reference material properties and [1] strength class of Nigerian Grown Terminalia ivorensis timber, so that it can be used in structures designed based on the Eurocode 5. The test data were analysed using Easyfit® statistical package. The uncertainty models (Coefficients of Variation and Distribution models) of the reference material properties (density, bending strength and modulus of elasticity) were determined. The coefficient of variation of the density, modulus of elasticity and bending strength were found to be 15%, 21% and 16% respectively. The mean values of the density, modulus of elasticity and the bending strengths were determined at moisture contents of 17.93%. The values were adjusted to 12% moisture content for the determination of the strength class according to [1]. Five standard probability distribution models (Normal, Lognormal, Gumbel, Weibull and Frechet) were fitted to each of the three reference material properties using Kolmogorov Smirnov probability distribution fitting technique. The best fit theoretical distribution models were found to be Normal distribution for Density, Lognormal distribution for Modulus of Elasticity and Weibull for Bending Strength. The Terminalia ivorensis timber specie was also classified as D18 in accordance with [1] specification. The uncertainty models will facilitate the application of reliability based approach in the design of timber structures with Terminalia ivorensis. Also Terminalia ivorensis can now be used for construction of structural timber designed based on Eurocode 5 since its strength class is now established.
One of the problems of optimization of concrete is to formulate a mathematical equation that show... more One of the problems of optimization of concrete is to formulate a mathematical equation that shows the relationship between the various constituents of concrete and its properties. In this work, modelling of the compressive strength of concrete admixed with metakaolin was carried out using the Gene Expression Programming (GEP) algorithm. e dataset from laboratory experimentation was used for the analysis. e mixture proportions were made of three different water/binder ratios (0.4, 0.5, and 0.6), and the grades of concrete produced were grade M15 and M20. e compressive strength of the concrete was determined after 28 days of curing. e parameters used in the GEP algorithm are the input variables which include cement content, water, metakaolin content, and fine and coarse aggregate, while the response was designated as the compressive strength. e model was trained and tested using the parameters. e R-square value from the GEP algorithm was compared with the use of conventional stepwise regression analysis. With a coefficient of determination (R-square value) of 0.95, the GEP algorithm has shown to be a good alternative for modelling concrete compressive strength.
system-based time-dependent reliability analysis was carried out over the service life of a reinf... more system-based time-dependent reliability analysis was carried out over the service life of a reinforced concrete bridge using a MATLAB program, BRELA (BRidge RELiability Analysis). Component reliability analysis for the bridge members was evaluated using a built-in MATLAB based sub program in BRELA and the system reliability index “βsys” calculated over time using the system reliability analysis component of the main program. The bridge was modelled as a hybrid/combined system (series-parallel subsystems). Nineteen (19) failure modes for the bridge components were identified and their limit state functions incorporating load growth and deterioration models of the steel reinforcement due to corrosion were developed. The result of the system reliability analysis shows a system performance loss of 25.65–100% as corrosion rate increased from 0–0.06 mm/year for a load growth rate of 0.5%. Considering several realistic preventive maintenance options and their associated costs, the reinforc...
The failure of conventional concrete to have classical mechanical properties, reduced permeabilit... more The failure of conventional concrete to have classical mechanical properties, reduced permeability and lead to sustainability in concrete production called for the use of supplementary Cementitious Materials (SCM) in concrete to improve its performance. This study investigates the effect of adding optimal dosage of an SCM called nanosilica (nS) on the tensile and compressive strengths, microstructural properties and cement hydration reaction for grade 30 concrete. The optimal dosage of the nS was determined to be 1.5% by weight of cement using compressive strength test. The influence of optimal nS dosage on the concrete properties was investigated using compressive strength test, splitting tensile strength test, Scanning Electron Microscopy (SEM) and Energy Dispersion Spectroscopy (EDS). Results revealed that optimal nS addition led to 30% and 23.3% respective increase in compressive and tensile strengths of conventional concrete at 7days of curing. SEM micrographs show better packi...
In this study, experimental research is carried out to assess the flexural performance of RC beam... more In this study, experimental research is carried out to assess the flexural performance of RC beams strengthened with different amount of CFRP laminates at the tension face. Twelve rectangular RC beams were fabricated and three are un-strengthened and used as reference beams and the remaining nine are strengthened with different amount of CFRP varying from single to triple layers and all are tested to failure under three points bending test. The increase of ultimate strength provided by the bonded CFRP laminates is assessed and failure modes is identified and compared to the un-strengthened RC beams. The results indicated that the flexural capacity of the beams was significantly improved as the amount of the laminates increases that ranged from 20% to 52% increased for single to triple layers laminates. It is concluded that the attachment of CFRP laminates has substantial influence on the performance of CFRP strengthened RC beams. Based on the observed results, recommendations are ma...
The effect of ground-rubber used as aggregate on the impact resistance of concrete when partially... more The effect of ground-rubber used as aggregate on the impact resistance of concrete when partially replaced volume of mineral coarse aggregate (granite) was investigated. A total of six mix batches (using a mix ratio of 1:2:4 and a watercement ratio of 0.45) of concrete containing 0%, 5%, 10%, 15%, 20% and 25% ground-rubber aggregate by volume of granite were subject to impact resistance test using the Repeated Drop-weight Test method on circular concrete disc samples (150mm x 64mm). Fifty four (54) circular disc samples were cast for the impact resistance test after 14, 21 and 28 days of standard curing in water. The test results show that the density of the specimens at 28 days reduced by about 16%, having a value of 2072kg/m 3 at 25% ground rubber content when compared to the control mix at 0%. The results also reveal that the incorporation of ground-rubber aggregate in concrete enhanced the impact resistance of the concrete greatly with the average no of blows to indicate failure ranging from 189-409 blows for 5-20% ground rubber content as compared to the control mixes, which had no ground rubber required an average of 106 blows at 28 days. The application could be practical if the rubber content is limited to a range of between 5-20% (Average of 13%) for structures which are exposed to impact loads in other to mitigate, minimize and dampen its effect on the structure. It is recommended for use in the construction of industrial floors.
This paper presents the results of safety assessment of timber columns laminated with aluminium u... more This paper presents the results of safety assessment of timber columns laminated with aluminium using the First Order Reliability Methods. Three failure modes were considered in the studies: bending failure, buckling failure, and flexural buckling failure modes. The results show that the column is safer for compression failure mode which has safety index values of 4.3 and 9.68 for imposed load and dead-to-live load parameters respectively without laminates, and progressive safety indices of up to 12.4 and 20.87 respectively for columns with laminates of 20mm thickness. The study showed that the most critical failure mode for the column is the flexural buckling mode. It is therefore deduced that from the results of the critical failure mode, laminate thickness of 10mm should be used to withstand any variation in load ratios of 0.6, 0.8 and 1.0 and a maximum imposed load of 15kN be used to ensure a safe column design.
Neem Seed Husk is a by Neem Seed Husk is a by Neem Seed Husk is a by Neem Seed Husk is a by-produ... more Neem Seed Husk is a by Neem Seed Husk is a by Neem Seed Husk is a by Neem Seed Husk is a by-product obtained during industrial processing of Neem Seed to extract oil and produce product obtained during industrial processing of Neem Seed to extract oil and produce product obtained during industrial processing of Neem Seed to extract oil and produce product obtained during industrial processing of Neem Seed to extract oil and produce fertilizer fertilizer fertilizer fertilizer.. .. Laboratory tests on Laboratory tests on Laboratory tests on Laboratory tests on Neem seed husk ash Neem seed husk ash Neem seed husk ash Neem seed husk ash concrete concrete concrete concrete strength strength strength strength and workability and workability and workability and workability.. .. Tests including slump Tests including slump Tests including slump Tests including slump scanning electron microscope (SEM) were scanning electron microscope (SEM) were scanning electron microscope (SEM) were scanning electron microscope (SEM) were and 25 and 25 and 25 and 25% % % %NSHA NSHA NSHA NSHA and presented. and presented. and presented. and presented. The test results indicate that concrete The test results indicate that concrete The test results indicate that concrete The test results indicate that concrete replacement replacement replacement replacement by by by by increase in the slump at 5% and 10% replacements. But it decreases the slump at 15%, 20% and increase in the slump at 5% and 10% replacements. But it decreases the slump at 15%, 20% and increase in the slump at 5% and 10% replacements. But it decreases the slump at 15%, 20% and increase in the slump at 5% and 10% replacements. But it decreases the slump at 15%, 20% and 25% replacements. 25% replacements. 25% replacements. 25% replacements. At 28 days curing, only the control (0 At 28 days curing, only the control (0 At 28 days curing, only the control (0 At 28 days curing, only the control (0 compressive strength compressive strength compressive strength compressive strength and therefore can be used for non and therefore can be used for non and therefore can be used for non and therefore can be used for non most of the cubes partially replaced with NSHA are generally higher than that of the control concrete most of the cubes partially replaced with NSHA are generally higher than that of the control concrete most of the cubes partially replaced with NSHA are generally higher than that of the control concrete most of the cubes partially replaced with NSHA are generally higher than that of the control concrete supported by the SEM. supported by the SEM. supported by the SEM. supported by the SEM. which indicates that NSHA act as filler and occupy the voids between the aggregates, thereby which indicates that NSHA act as filler and occupy the voids between the aggregates, thereby which indicates that NSHA act as filler and occupy the voids between the aggregates, thereby which indicates that NSHA act as filler and occupy the voids between the aggregates, thereby making the concrete more compact and having higher densities. making the concrete more compact and having higher densities. making the concrete more compact and having higher densities. making the concrete more compact and having higher densities. requirement of B requirement of B requirement of B requirement of British standard ritish standard ritish standard ritish standard for normal for normal for normal for normal
Arid Zone Journal of Engineering, Technology and Environment, Jun 1, 2021
Introduction Concrete is a construction material composed of cement, fine aggregates (sand) and c... more Introduction Concrete is a construction material composed of cement, fine aggregates (sand) and coarse aggregates mixed with water which hardens with time. Portland cement is the commonly used type of cement for production of concrete. Concrete technology deals with study of properties of concrete and its practical applications. In a building construction, concrete is used for the construction of foundations, columns, beams, slabs and other load bearing elements (Naus, 2005). Concrete is a sustainable construction material which is widely used all over the world as it provides superior fire resistance, gains strength over time, gives an extremely long service life and capable of being moulded into different shapes (Neville, 2011). The major components of concrete are cement paste and inert materials. Cement is an important constituent in the concrete composite. However, its cost is relatively very high. This has impacted in the cost of concrete production and by extension on the cost
International journal of engineering research and technology, Nov 18, 2021
This paper shows the results of the safety assessment of Mansard steel roof truss using the First... more This paper shows the results of the safety assessment of Mansard steel roof truss using the First Order Reliability Methods. Four failure modes were considered in the studies: compression, bending, tension, as well as, combined compression and bending failure modes; From the results obtained from the First Order Reliability Method, the safety index values range between 0.076 to 11.90 for the members, while the values for the joints range from 0.677 to 1.89. A careful study of the results shows that the safety index values decreased as the load ratio increased and the safety index values at a particular load ratio are generally higher for the members than the joints. These results point to the fact that failure will be initialized at joint before progression to other members.
The study was conducted to evaluate the experimental and theoretical shear strength of a simply s... more The study was conducted to evaluate the experimental and theoretical shear strength of a simply supported reinforced concrete beam with and without shear reinforcement in accordance with Eurocode 2 design criteria. Fifteen (15) reinforced concrete beams of dimension 750mm x 150mm x 150mm reinforced with diameter 12mm size bars were cast at various reinforcement ratios (i.e. 1.0%, 1.5%, 2.0%, 2.5%, and 3.0%), while preliminary and mechanical tests were conducted on the materials (i.e. cement, fine and coarse aggregate, and reinforcement bars) in accordance with relevant codes and standards. The outcome from the findings showed that the cement, fine aggregate and coarse aggregate used to cast the reinforced concrete beam were well graded and satisfies the requirement of code specification. More results showed that the average diameter of the reinforcement bars are 11.67mm, the mean tensile and ultimate strength of the reinforcement bars are 389.73N/mm 2 and 640.80N/mm 2 respectively, while the mean reinforcement steel elongation is 14.23% which mostly met code requirement indicating suitability of the reinforcement bars usage in concrete. Furthermore, the result from the findings showed that the Eurocode 2 (EC2) design criteria of beams without shear reinforcement were lower than the experimental value, while EC2 design criteria for beams with shear reinforcement was close to the experimental value.
Zenodo (CERN European Organization for Nuclear Research), Jun 30, 2021
Timber is a natural material from matured trees that can be used for structural applications. Mat... more Timber is a natural material from matured trees that can be used for structural applications. Material properties of timber such as light weight to strength ratio, good durability, good insulation against heat and sound impact makes it suitable for use as material for constructing roofing system, pedestrian or bicycle bridges and framing of other load-bearing structures, where strength is the major factor in its selection and usage. Unfortunately, time-dependent deformation affects the strength and stiffness of timber in service. The process of creep in timber, which is affected by variables such as temperature, moisture, species type, grain direction, loading influence, and timber's natural variability causes excessive deformations and even collapse of an entire construction. This paper reviews the work presented by various researchers on creep prediction/investigation models devised for timber. From the available literature reviewed, creep prediction models were developed for small timber species that are not widely used for construction/structural applications and do not undergo large moisture fluctuations, therefore mechano-sorptive creep effects are minimal. Looking at local content, there is need to develop mathematical models that would be used to predict/investigate long term creep for Nigerian grown timber species. There is no record of an existing unified or generalized creep prediction model that could be used for estimating long term creep of all timber species, because each of the mathematical models developed contain a great variety of constants that can only be determined by rigorous and large experimental sample tests.
There is no doubt that construction and building industries are the main energy and materials con... more There is no doubt that construction and building industries are the main energy and materials consumers of any country. In sustainable development, both the immediate and imminent needs are adequately taken into consideration. Sequel to the fact that concrete is weak in tension, reinforcement is inevitable to compensate for the deficiency. This paper purposes to comparing the flexural properties of concrete beams reinforced with bamboo strips and steel bars. Bamboo strips were found to be a close replacement to steel for light-weight constructions. This research consists of 100 x 100 x 450mm reinforced concrete beams with varying percentages of steel served as reference. Three beams were cast for each bamboo/Steel reinforcement ratio for each curing age making a total of Ninety-Six beams for flexural properties test. Three cubes were prepaid for every curing age summing up to Twenty-Four cubes for compressive test. The area of Bamboo reinforcement equivalent to steel was calculated via the equivalence of the force that could withstand the bending stresses which was also resisted by corresponding bamboo area. Steel stirrups were used to carter for shear in the beams. Flexural and compressive strengths at 7-, 14-, 21-and 28-days have been taken into consideration for comparison purpose. The graphs from the results were plotted and the suitability of bamboo reinforced beam was discoursed regarding the failure types. Results from the research reveal that bamboo can be used in lowcost constructions.
FUDMA JOURNAL OF SCIENCES - ISSN: 2616-1370, Dec 31, 2019
Geopolymer concrete (GPC) has no mix design code to guide in the choice of material proportions f... more Geopolymer concrete (GPC) has no mix design code to guide in the choice of material proportions for specific compressive strengths, its properties have not been fully understood especially in Nigeria despite being blessed with abundant geopolymer Al-Si source material (Kaolin). This study presents the properties of Kankara kaolin before and after treatment. Minitab 18 factorial design was used to design a Metakaolin based Geopolymer Concrete (GPC) with target compressive strength of 25 N/mm 2 (Suitable for Reinforced concrete). After kaolin treatment XRF results indicate a marginal difference in Oxide composition with the kaolin before treatment, but FTIR results showed more of the difference because the transmittance of the band between 3619 and 3690 cm -1 which is typical of kaolin increased when treated to 94.484 % from 74.825 % when untreated and quartz interference at 1114.5 cm -1 and Si-O quartz at 674.6 and 752.9 cm -1 were no more after the treatment. A factorial design with four factors having 9 experimental runs recoded 39.5 N/mm 2 (Run No 7) as highest compressive strength and 4.1 N/mm 2 (Run No 2) as the lowest. Results indicated that mixes with low alkaline liquid and low Molar concentration content exhibits lower strength than those with high alkaline liquid content and High Molar concentration. Re-analysing laboratory results and targeting a strength of 25 N/mm 2 ; a mix (M1) with 14M proposed for the validation attained 38.7 N/mm 2 , another mix (M2) with 8 M also attained 30 N/mm 2 , Both M1 and M2
Quality timber species are declining due to over-exploitation in Nigeria. This has propelled the ... more Quality timber species are declining due to over-exploitation in Nigeria. This has propelled the utilisation of low-grade timbers species that are considered for low-end constructions in the past which called for concern. This study establishes the viability of a typical beam made from locally sourced non-durable Obeche (Triplochiton scleroxylon) with highly durable Opepe (Nauclea diderrichii) timber specie in a combined glulam form, using polyvinyl acetate (PVA) adhesive which serves the impact of environmental sustainability and reduced cost of engineering construction. Seasoned timber samples and PVA adhesive were all obtained locally in Nigeria. Beam specimens were tested in the Department of Civil Engineering, Ahmadu Bello University, Zaria according to EN 338 (2009). Based on tests, it is evident that solid Opepe and Obeche timber specimens exhibited more durable characteristics than their homogenous glulam when fabricated with PVA adhesive. The combined Opepe/Obeche (GLc OP/OB) glulam beam specimen was proposed into GL18c strength class according to EN 338 based on minimum constraints which it satisfies, reflecting a 41 % greater Modulus of Elasticity (MoE) in comparison with EN 338 experimental value. This study recommends the enhancement of the bending strength, density and modulus of elasticity of a typical non-durable solid Obeche timber beam by 38 %, 47 % and 35 % respectively with 40 % durable Opepe timber in a combined glulam form using PVA adhesive for engineering construction purposes.
This paper presents evaluation of a 67.12m high telecommunication tower with the objectives of ap... more This paper presents evaluation of a 67.12m high telecommunication tower with the objectives of applying the Finite Element Method (FEM) in modelling it, analysing it under Nigerian wind loads from five different wind zones (Zone 1, Zone 2, Zone 3 Zone 4 and Zone 5 with basic wind speeds as 42m/s, 45.8m/s, 50m/s, 55m/s and 56m/s respectively). The collapse mechanism of the tower was predicted using the Mechanism Method. The tower was modelled and wind load was calculated on it and analysis shows that there is mechanism for the tower to collapse under dynamic wind loads as plastic hinges are developed at the joints and along bracing members. The most severe wind load was used in the plastic analysis conducted and it shows that when the plastic hinges developed at the lower section of the tower, the three mechanisms are more critical compared to when it develops at other sections of the tower. Also, using such load as the collapse load, when the plastic hinges developed at any section of the tower, combine mechanism is more critical and hence the tower is likely to collapse due to failure of both leg members and bracing members.
Mathematical model of compression creep for Terminalia ivorensis (Black Afara) timber were develo... more Mathematical model of compression creep for Terminalia ivorensis (Black Afara) timber were developed and presented in this paper. One-year creep test was performed in this process on Terminalia ivorensis timber samples. The creep data were fitted to linear, exponential and logarithmic regression models. The coefficients of determination for each of the model was determined. The coefficients of determination of the linear, exponential and logarithmic models were determined as 0.689, 0.650 and 0.941 respectively. Since the logarithmic model has the highest correlation with coefficient of determination of 0.941, it gave the best compression creep prediction model for the Terminalia ivorensis timber.
The deterioration of reinforced concrete bridge deck that has been damaged as a result of load ac... more The deterioration of reinforced concrete bridge deck that has been damaged as a result of load action can affect the durability, safety and function of the structure. In this paper, a reliability time-variant fatigue analysis and uncertainty effect on the serviceability of reinforced concrete bridge deck was carried out. A simply supported 15m bridge deck was specifically used for the investigation. Mathematical models were developed and the uncertainties in structural resistance, applied loadings as well as the structural components were accommodated using probabilistic method. The limit state functions were evaluated using the First Order Reliability Algorithm and the entire process was implemented using a developed MATLAB program called Rayswit.m. Failure in the deck shear region gave the most critical effect with a reliability index range of 6.95 to-12.38 when compared to flexure region with an index of 8.58 to-10.53.
The purpose of this paper was the determination of the uncertainty models of reference material p... more The purpose of this paper was the determination of the uncertainty models of reference material properties and [1] strength class of Nigerian Grown Terminalia ivorensis timber, so that it can be used in structures designed based on the Eurocode 5. The test data were analysed using Easyfit® statistical package. The uncertainty models (Coefficients of Variation and Distribution models) of the reference material properties (density, bending strength and modulus of elasticity) were determined. The coefficient of variation of the density, modulus of elasticity and bending strength were found to be 15%, 21% and 16% respectively. The mean values of the density, modulus of elasticity and the bending strengths were determined at moisture contents of 17.93%. The values were adjusted to 12% moisture content for the determination of the strength class according to [1]. Five standard probability distribution models (Normal, Lognormal, Gumbel, Weibull and Frechet) were fitted to each of the three reference material properties using Kolmogorov Smirnov probability distribution fitting technique. The best fit theoretical distribution models were found to be Normal distribution for Density, Lognormal distribution for Modulus of Elasticity and Weibull for Bending Strength. The Terminalia ivorensis timber specie was also classified as D18 in accordance with [1] specification. The uncertainty models will facilitate the application of reliability based approach in the design of timber structures with Terminalia ivorensis. Also Terminalia ivorensis can now be used for construction of structural timber designed based on Eurocode 5 since its strength class is now established.
One of the problems of optimization of concrete is to formulate a mathematical equation that show... more One of the problems of optimization of concrete is to formulate a mathematical equation that shows the relationship between the various constituents of concrete and its properties. In this work, modelling of the compressive strength of concrete admixed with metakaolin was carried out using the Gene Expression Programming (GEP) algorithm. e dataset from laboratory experimentation was used for the analysis. e mixture proportions were made of three different water/binder ratios (0.4, 0.5, and 0.6), and the grades of concrete produced were grade M15 and M20. e compressive strength of the concrete was determined after 28 days of curing. e parameters used in the GEP algorithm are the input variables which include cement content, water, metakaolin content, and fine and coarse aggregate, while the response was designated as the compressive strength. e model was trained and tested using the parameters. e R-square value from the GEP algorithm was compared with the use of conventional stepwise regression analysis. With a coefficient of determination (R-square value) of 0.95, the GEP algorithm has shown to be a good alternative for modelling concrete compressive strength.
system-based time-dependent reliability analysis was carried out over the service life of a reinf... more system-based time-dependent reliability analysis was carried out over the service life of a reinforced concrete bridge using a MATLAB program, BRELA (BRidge RELiability Analysis). Component reliability analysis for the bridge members was evaluated using a built-in MATLAB based sub program in BRELA and the system reliability index “βsys” calculated over time using the system reliability analysis component of the main program. The bridge was modelled as a hybrid/combined system (series-parallel subsystems). Nineteen (19) failure modes for the bridge components were identified and their limit state functions incorporating load growth and deterioration models of the steel reinforcement due to corrosion were developed. The result of the system reliability analysis shows a system performance loss of 25.65–100% as corrosion rate increased from 0–0.06 mm/year for a load growth rate of 0.5%. Considering several realistic preventive maintenance options and their associated costs, the reinforc...
The failure of conventional concrete to have classical mechanical properties, reduced permeabilit... more The failure of conventional concrete to have classical mechanical properties, reduced permeability and lead to sustainability in concrete production called for the use of supplementary Cementitious Materials (SCM) in concrete to improve its performance. This study investigates the effect of adding optimal dosage of an SCM called nanosilica (nS) on the tensile and compressive strengths, microstructural properties and cement hydration reaction for grade 30 concrete. The optimal dosage of the nS was determined to be 1.5% by weight of cement using compressive strength test. The influence of optimal nS dosage on the concrete properties was investigated using compressive strength test, splitting tensile strength test, Scanning Electron Microscopy (SEM) and Energy Dispersion Spectroscopy (EDS). Results revealed that optimal nS addition led to 30% and 23.3% respective increase in compressive and tensile strengths of conventional concrete at 7days of curing. SEM micrographs show better packi...
In this study, experimental research is carried out to assess the flexural performance of RC beam... more In this study, experimental research is carried out to assess the flexural performance of RC beams strengthened with different amount of CFRP laminates at the tension face. Twelve rectangular RC beams were fabricated and three are un-strengthened and used as reference beams and the remaining nine are strengthened with different amount of CFRP varying from single to triple layers and all are tested to failure under three points bending test. The increase of ultimate strength provided by the bonded CFRP laminates is assessed and failure modes is identified and compared to the un-strengthened RC beams. The results indicated that the flexural capacity of the beams was significantly improved as the amount of the laminates increases that ranged from 20% to 52% increased for single to triple layers laminates. It is concluded that the attachment of CFRP laminates has substantial influence on the performance of CFRP strengthened RC beams. Based on the observed results, recommendations are ma...
The effect of ground-rubber used as aggregate on the impact resistance of concrete when partially... more The effect of ground-rubber used as aggregate on the impact resistance of concrete when partially replaced volume of mineral coarse aggregate (granite) was investigated. A total of six mix batches (using a mix ratio of 1:2:4 and a watercement ratio of 0.45) of concrete containing 0%, 5%, 10%, 15%, 20% and 25% ground-rubber aggregate by volume of granite were subject to impact resistance test using the Repeated Drop-weight Test method on circular concrete disc samples (150mm x 64mm). Fifty four (54) circular disc samples were cast for the impact resistance test after 14, 21 and 28 days of standard curing in water. The test results show that the density of the specimens at 28 days reduced by about 16%, having a value of 2072kg/m 3 at 25% ground rubber content when compared to the control mix at 0%. The results also reveal that the incorporation of ground-rubber aggregate in concrete enhanced the impact resistance of the concrete greatly with the average no of blows to indicate failure ranging from 189-409 blows for 5-20% ground rubber content as compared to the control mixes, which had no ground rubber required an average of 106 blows at 28 days. The application could be practical if the rubber content is limited to a range of between 5-20% (Average of 13%) for structures which are exposed to impact loads in other to mitigate, minimize and dampen its effect on the structure. It is recommended for use in the construction of industrial floors.
This paper presents the results of safety assessment of timber columns laminated with aluminium u... more This paper presents the results of safety assessment of timber columns laminated with aluminium using the First Order Reliability Methods. Three failure modes were considered in the studies: bending failure, buckling failure, and flexural buckling failure modes. The results show that the column is safer for compression failure mode which has safety index values of 4.3 and 9.68 for imposed load and dead-to-live load parameters respectively without laminates, and progressive safety indices of up to 12.4 and 20.87 respectively for columns with laminates of 20mm thickness. The study showed that the most critical failure mode for the column is the flexural buckling mode. It is therefore deduced that from the results of the critical failure mode, laminate thickness of 10mm should be used to withstand any variation in load ratios of 0.6, 0.8 and 1.0 and a maximum imposed load of 15kN be used to ensure a safe column design.
Neem Seed Husk is a by Neem Seed Husk is a by Neem Seed Husk is a by Neem Seed Husk is a by-produ... more Neem Seed Husk is a by Neem Seed Husk is a by Neem Seed Husk is a by Neem Seed Husk is a by-product obtained during industrial processing of Neem Seed to extract oil and produce product obtained during industrial processing of Neem Seed to extract oil and produce product obtained during industrial processing of Neem Seed to extract oil and produce product obtained during industrial processing of Neem Seed to extract oil and produce fertilizer fertilizer fertilizer fertilizer.. .. Laboratory tests on Laboratory tests on Laboratory tests on Laboratory tests on Neem seed husk ash Neem seed husk ash Neem seed husk ash Neem seed husk ash concrete concrete concrete concrete strength strength strength strength and workability and workability and workability and workability.. .. Tests including slump Tests including slump Tests including slump Tests including slump scanning electron microscope (SEM) were scanning electron microscope (SEM) were scanning electron microscope (SEM) were scanning electron microscope (SEM) were and 25 and 25 and 25 and 25% % % %NSHA NSHA NSHA NSHA and presented. and presented. and presented. and presented. The test results indicate that concrete The test results indicate that concrete The test results indicate that concrete The test results indicate that concrete replacement replacement replacement replacement by by by by increase in the slump at 5% and 10% replacements. But it decreases the slump at 15%, 20% and increase in the slump at 5% and 10% replacements. But it decreases the slump at 15%, 20% and increase in the slump at 5% and 10% replacements. But it decreases the slump at 15%, 20% and increase in the slump at 5% and 10% replacements. But it decreases the slump at 15%, 20% and 25% replacements. 25% replacements. 25% replacements. 25% replacements. At 28 days curing, only the control (0 At 28 days curing, only the control (0 At 28 days curing, only the control (0 At 28 days curing, only the control (0 compressive strength compressive strength compressive strength compressive strength and therefore can be used for non and therefore can be used for non and therefore can be used for non and therefore can be used for non most of the cubes partially replaced with NSHA are generally higher than that of the control concrete most of the cubes partially replaced with NSHA are generally higher than that of the control concrete most of the cubes partially replaced with NSHA are generally higher than that of the control concrete most of the cubes partially replaced with NSHA are generally higher than that of the control concrete supported by the SEM. supported by the SEM. supported by the SEM. supported by the SEM. which indicates that NSHA act as filler and occupy the voids between the aggregates, thereby which indicates that NSHA act as filler and occupy the voids between the aggregates, thereby which indicates that NSHA act as filler and occupy the voids between the aggregates, thereby which indicates that NSHA act as filler and occupy the voids between the aggregates, thereby making the concrete more compact and having higher densities. making the concrete more compact and having higher densities. making the concrete more compact and having higher densities. making the concrete more compact and having higher densities. requirement of B requirement of B requirement of B requirement of British standard ritish standard ritish standard ritish standard for normal for normal for normal for normal
Arid Zone Journal of Engineering, Technology and Environment, Jun 1, 2021
Introduction Concrete is a construction material composed of cement, fine aggregates (sand) and c... more Introduction Concrete is a construction material composed of cement, fine aggregates (sand) and coarse aggregates mixed with water which hardens with time. Portland cement is the commonly used type of cement for production of concrete. Concrete technology deals with study of properties of concrete and its practical applications. In a building construction, concrete is used for the construction of foundations, columns, beams, slabs and other load bearing elements (Naus, 2005). Concrete is a sustainable construction material which is widely used all over the world as it provides superior fire resistance, gains strength over time, gives an extremely long service life and capable of being moulded into different shapes (Neville, 2011). The major components of concrete are cement paste and inert materials. Cement is an important constituent in the concrete composite. However, its cost is relatively very high. This has impacted in the cost of concrete production and by extension on the cost
International journal of engineering research and technology, Nov 18, 2021
This paper shows the results of the safety assessment of Mansard steel roof truss using the First... more This paper shows the results of the safety assessment of Mansard steel roof truss using the First Order Reliability Methods. Four failure modes were considered in the studies: compression, bending, tension, as well as, combined compression and bending failure modes; From the results obtained from the First Order Reliability Method, the safety index values range between 0.076 to 11.90 for the members, while the values for the joints range from 0.677 to 1.89. A careful study of the results shows that the safety index values decreased as the load ratio increased and the safety index values at a particular load ratio are generally higher for the members than the joints. These results point to the fact that failure will be initialized at joint before progression to other members.
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