scholarly works
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Item Appropriate Simulation Technique for Complete Single-Bolt Shear Connection Shear-Out Tensile Properties and Fracture Behavior Predictions (2(2019) Adewole K.K.; Ajagbe W.O.This paper presents the finite element (FE) predictions of the complete S235, S690, Q550D, Q690D and Q890D steel grades steel sheet single-bolt shear connections shear-out (SBSCSO) behavior (tensile properties and fracture behavior). This work reveals that the FE elastic–plastic simulations without the damage and fracture model generally employed in the literature for SBSCSO failure predictions cannot predict the post-ultimate-load damage behavior, fracture initiation by elements removal and sudden drops in load required for determining the SBSCSO displacement at fracture. Consequently, the FE simulation without the damage and fracture model cannot accurately predict the complete SBSCSO tensile properties and fracture behavior. In particular, the FE simulation without the damage and fracture model cannot predict the SBSCSO displacement at fracture required for the seismic and fracture-resistant designs needed for the prevention of the failure of single-bolt shear connections that exhibit the shear-out fracture under extreme loading. FE simulation with the elastic, plastic damage and fracture models represents the appropriate simulation technique for the complete SBSCSO tensile properties and fracture behavior predictions.Item Effect of aggregate type on properties of pervious concreteutajeet(2019) AGBEDE O.A.; AJAGBE W.O.Pervious concrete (PC) is a cheap and effective drainage system for reducing storm-water runoff in urban centers. This research aim to investigate the influence of different type of aggregate on PC properties. Three PC mixtures were prepared with different aggregate types [Granite, Gravel and Recycled Concrete Aggregate (RCA)]. Physical and strength characteristics of the aggregates were analyzed. Density, porosity, permeability as well as compressive strength of PC made with these aggregates were measured. Results showed that PC made from RCA has the highest porosity and permeability due to the porous nature of adhered mortar on RCA. However, highest density and compressive strength was obtained from granite PC followed by gravel and then RCA PC. The study concluded that aggregate type has significant influence on PC properties.Item Modelling the effect of burning temperature and time on chemical composition of sorghum husk ash for optimum pozzolanic activity(2018) AGBEDE O.A.; AJAGBE W.O.Sorghum Husk Ash (SHA) can be used as partial replacement for cement in production of concrete due its pozzolanic behavior. This will reduce the cost and environmental pollution associated with the use and production of cement. The aim of this paper is to model the effect of burning temperature and time on chemical composition of SHA for optimum pozzolanic activity. The testing was done at 2-factors, 5-levels using Central composite design of Response Surface Methodology (RSM). Independent variables considered were: burning temperature (500, 600, 700, 800 and 900oC) and time (1, 2, 3, 4 and 5 hours). Dependent variables (chemical constituents) include: Silicon dioxide (SiO ), Aluminum oxide (Al O ), Iron 2 2 3 oxide (Fe O ), Calcium oxide (CaO), Sulphur oxide (SO ), Sodium oxide (Na O), Magnesium oxide (MgO) 2 3 3 2 and Potassium oxide (K O); all determined using atomic absorption spectrophotometer analysis. The 2 results revealed that the ash content decreases as the burning temperature and time increases. Optimum combined percent of SiO , Al O and Fe O (76.047%) which is the criteria for a good pozzolana was 2 2 3 2 3 achieved at temperature of 700oC and time 3 hours.Item Result Validation Analysis of Steel Testing Machines(2018) AGBEDE O.A.; AJAGBE W.O.Structural failures occur due to a number of reasons. These may include under design, poor workmanship, substandard materials, misleading laboratory tests and lots more. Reinforcing steel bar is an important construction material, hence its properties must be accurately known before being utilized in construction. Understanding this property involves carrying out mechanical tests prior to design and during construction to ascertain correlation using steel testing machine which is usually not readily available due to the location of project. This study was conducted to determine the reliability of reinforcing steel testing machines. Reconnaissance survey was conducted to identify laboratories where yield and ultimate tensile strengths tests can be carried out. Six laboratories were identified within Ibadan and environs. However, only four were nfunctional at the time of the study. Three steel samples were tested for yield and tensile strengths, using a steel testing machine, at each of the four laboratories (LM, LO, LP and LS). The yield and tensile strength results obtained from the laboratories were compared with the manufacturer’s specification using a reliability analysis programme. Structured questionnaire was administered to the noperators in each laboratory to consider their impact on the test results. The average value of manufacturers’ tensile strength and yield strength are 673.7 N/mm2 and 559.7 N/mm2 respectively. The tensile strength obtained from the four laboratories LM, LO, LP and LS are given as 579.4, 652.7, 646.0 and 649.9 N/mm2 respectively while their yield strengths respectively are 453.3, 597.0, 550.7 and 564.7 N/mm2. Minimum tensile to yield strength ratio is 1.08 for BS 4449: 2005 and 1.15 for ASTM A615. Tensile to yield strength ratio from the four laboratories are 1.28, 1.09, 1.17 and 1.15 for LM, LO, LP and LS respectively. The tensile to yield strength ratio shows that the result obtained from all the laboratories meet the code requirements used for the test. The result of the reliability test shows varying level of reliability between the manufacturers’ specification and the result obtained from the laboratories. Three of the laboratories; LO, LS and LP have high value of reliability with the manufacturer i.e. 0.798, 0.866 and 0.712 respectively. The fourth laboratory, LM has a reliability value of 0.100. Steel test should be carried out in a laboratory using the same code in which the structural design was carried out. More emphasis should be laid on the importance of code provisions.Item Structural Investigation into the Causes of Cracks in Building and Solutions: A Case Study(2018) AGBEDE O.A.; AJAGBE W.O.Cracks are commonly found on and in structures and are usually undesirable features naturally occurring due to age, workmanship and other natural and environmental causes. This study is set to characterize cracks with the principal aim of recommending proper maintenance and efficient repair actions. Crack occurrence in an office building (storey with basement) was investigated as a case study. Reconnaissance survey was carried out to locate and note the tools that would be required for the investigation of the cracks. Visual examination and measurement of cracks to know the cause and type of each crack were performed. Strength test of all the structural members was done using Schmidt hammer to determine the residual strength of the members on which they appear and the results were analyzed. The results of the reconnaissance survey revealed that most of the cracks are located at the left side than at right side elevation of the building. The nature of the cracks showed that 91% are dormant cracks, while 9% are active cracks. Some of the cracks extended to the plastered surface, while the rest extended to the structural elements region. Therefore, the cracks in this building were found to be caused by the drying shrinkage at the wall section, the compressive force from the beams exceeding the ultimate strength of the affected blocks, foundation settlement at the courtyard was also discovered through topographical survey, due to underground erosion of the foundation wall footing. The results of the non-destructive test (NDT) indicated that, the average strength of the structural elements is within acceptable limit.Item Effects of Crude Oil Imparted Sand on the Durability of Concrete(2018) AGBEDE O.A.; AJAGBE W.O.A large percentage of soils in crude oil producing areas in Nigeria were contaminated to a varying degree. Past research showed reduction in the compressive strength of concrete made with crude oil impacted sand (COIS). The current effort aimed at assessing the durability of COIS concrete. Soil samples were contaminated with crude oil concentrated levels of 0, 2.5%, 5%, 10% and 15% by weight of sand to produce COIS. Concrete design mix of 1:1.8:2.7 were made with COIS at the different concentrations from which concrete specimen – 100 mm cubes; 100 x 200 mm, and 75 x 150 mm cylinders, were made. COIS concrete were then tested for chloride and sulphate resistance using Electrical Resistivity(ER) test on 100mm x 200mm concrete cylinders and Water absorption (WA) test on 75 x 150 mm cylinders, respectively The COIS concrete was tested for Fire Resistance(FR) by testing the compressive strengths of heated 100 mm cubes. The results showed that COIS concrete exhibited an increased in durability properties as the contamination level increases. The control sample has the lowest value of ER of 119 kohm-cm which indicates low resistance to chloride ion penetration. It also has the highest value of WA of 3.9% indicating low resistance to sulphate attack. However, COIS concrete experienced reduction in strength when exposed to fire as the concentration of crude oil increases. The better durability property of the COIS concrete compliments the strength reduction.Item Assessment of Fine Aggregates from Different Sources in Ibadan and Environs for Concrete Production(2018) AGBEDE O.A.; AJAGBE W.O.Assessment of natural sand being used as fine aggregate for concrete production in Ibadan and its environs was carried out. Ten sources (F1 – F10) were selected for the study; four (F5, F6, F7, F8) were river sand sources while six (F1, F2, F3, F4, F9, F10) were burrow pit sand sources. Samples from each source were subjected to sieve analysis, atterberg limit, bulk density, specific gravity, water absorption, sand equivalent, clay lumps and friable particles, amount of materials passing 75μm and organic impurities adopting ASTM standard procedures. Results revealed that sand from river sources met all the criteria for concrete production stated in ASTM standard while sand from burrow pits deviated from limits of the standard in some respects. F10 had water absorption of 2.6% which exceeded maximum 2% specified, F9 was not free from clay lumps and friable particles with a significant value of 6% as against 3% maximum specification. F1, F2, F3, F4, F9 and F10 have more amounts of materials passing the 75μm sieve ranging from 10.8% for F9 to 20.1% for F10 than maximum of 5% in standard specification while F1, F9 and F10 showed an indication of having organic impurities. It is recommended that performance test be conducted on concrete made from burrow pits sand before use for concrete production. The knowledge of this study can be used as a prospecting tool for selecting suitable sand for the production of quality concrete.Item Compressive Strength of Concrete Made from Aggregates of Different Sources(2018) AGBEDE O.A.; AJAGBE W.O.The use of substandard materials, particularly low quality concrete has been identified in literature as the leading cause of building collapse in Nigeria. The roadside artisans/bricklayers usually produce concrete for building construction without taking the aggregate source into consideration. This paper presents a comprehensive data on the compressive strength of concrete made from aggregates obtained from different sources in Ibadan, Nigeria. Experiments have been performed on 12 mixtures made up of fine aggregate from four sources and coarse aggregate from three different sources. The study utilize cement of the same strength (42.5R), coarse aggregate of the same size (10mm), the same water/cement ratio (0.6), and concrete mix (1:2:4) in order to determine the influence of aggregate source on concrete strength. Result revealed that only five mixtures had above the minimum cube compressive strength of 25N/mm2 recommended for the construction of the reinforced load-bearing building structural members. Three mixtures had above the cube compressive strength of 20N/mm2 recommended for use in plain concrete construction while the rest four mixtures had their cube strength between 19.3N/mm2 and 17.9N/mm2. Fine aggregate with higher compressive strength showed the lesser amount of deleterious materials. It was concluded that the compressive strength depend on aggregate source.Item Professionals view on the causes and effects of construction projects abandonment in ibadan metropolis, Nigeria(2016) AGBEDE O.A.; AJAGBE W.O.Engineering and geological properties of rocks from eight different quarries in Ibadan were evaluated to determine their suitability for concrete production. Samples from each quarry sites were subjected to grading, relative density, water absorption, bulk density, amount of materials finer than 75μm, flakiness and elongation Index, Aggregate Impact Value (AIV), Aggregate Crushing Value (ACV), Aggregate Abrasion Value (AAV), 10% fines value and petrographical analysis adopting BS testing methods. The relationship between engineering properties with one another and the petrographical characteristics were described by Pearson correlation coefficient and bar charts. The results of engineering analysis revealed that rocks from all the quarries are generally sound and good because of their possession of necessary characteristics for use in concrete production when compared with British (BS), Indian (IS) and American Society for Testing and Materials (ASTM) standards. Petrographical analyses revealed that samples which have performed better in all the engineering tests possess higher content of quartz mineral and finer texture. Statistically significant correlations were found among the tests performedItem Engineering and geological evaluation of rocks for Concrete production(2015) Agbede O.A.; Ajagbe W.O.Engineering and geological properties of rocks from eight different quarries in Ibadan were evaluated to determine their suitability for concrete production. Samples from each quarry sites were subjected to grading, relative density, water absorption, bulk density, amount of materials finer than 75μm, flakiness and elongation Index, Aggregate Impact Value (AIV), Aggregate Crushing Value (ACV), Aggregate Abrasion Value (AAV),10% fines value and petrographical analysis adopting BS testing methods. The relationship between engineering properties with one another and the petrographical characteristics were described by Pearson correlation coefficient and bar charts. The results of engineering analysis revealed that rocks from all the quarries are generally sound and good because of their possession of necessary characteristics for use in concrete production when compared with British (BS), Indian (IS) and American Society for Testing and Materials (ASTM) standards. Petrographical analyses revealed that samples which have performed better in all the engineering tests possess higher content of quartz mineral and finer texture. Statistically significant correlations were found among the tests performed.