Engineering and Technology Journal

An exact solution for the bending attributes of a thick rectangular plate under transverse loading is modeled herein using three-dimensional (3-D) elasticity plate theory and fourth-order polynomial shear deformation function. Precluding coefficients of shear correction, this model captured the effect of shear deformation along with the transverse normal strain stress. The expression for total potential energy was derived from a 3-D kinematic and constitutive relation the equilibrium equation was developed and employed from the energy functional transformation to get the relationship between slope and deflection. Exact polynomial functions were obtained from the outcome of the equilibrium equation and with the aid of the direct variation approach, the coefficient of deflection of the plate was generated from the governing equation. The expression for computing the displacement, bending moments, and stress components along the three axes of the plate was established from these solutions for the assessment of the bending characteristics of a rectangular plate. The result of a simply supported at one edge, free at one edge and clamped at the two outer edges (SCFC) was evaluated using the obtained functions in this study. The report of this study confirms the exactness and consistency of the 3-D model unlike the refined plate theories applied by previous authors in the available literature. The value of 8.05% is the comprehensive average percentage variation of the values for center deflection obtained by Onyeka and Okeke (2020) and Gwarah (2019). It is established that at the 92 % confidence level, this model is worthy of adoption for safe, cost-effective and accurate bending analysis of thick plates of any support condition.

Reinforced concrete beams are the most generally used structural parts in building, bridges, and many other structures. In the past two decades, many investigations have been conducted using various fiber-reinforced polymer (FRP) material types /steel bars to reinforce concrete beams under flexural test. The purpose of this paper is to review the flexural performance of concrete beams reinforced with hybrid FRP and steel bars to better understand their behavior. The main parameters addressed by researchers were dimensions of beams, FRP bar material type, and hybrid reinforcement ratio. The researchers established that the use of the combination between steel and FRP reinforcement bars improves the performance of the concrete beams. Moreover, the studies showed that the ductility of the hybrid reinforced beams increased compared to that of conventional steel reinforced beams, however, it decreased when the ratio of (Af/As) increased. The application of using hybrid FRP/steel bars in reinforcing concrete beams will further increase upon utilizing techniques for reducing the brittleness and higher cost of FRP bars. The general structure of this paper consists of presenting the formulas offered by ACI 440.1R-15 building code relating to the flexural strength calculation of concrete beams reinforced with FRP/steel bars. The paper also details some of the current experimental tests and analytical works published for concrete beams reinforced with hybrid system, and outlines research directions and identifies gaps required for additional research.

This scientific research was carried out within the framework of contributing to the recovery different of natures of waste, and making it possible to minimize using of natural aggregates in the field of construction, in order to place an eco-self-consolidating concrete (eco-SCC). Crushed demolition waste mainly of concrete had been studied as a substitute for natural sand. As well as the effect of replacing fines with crushed eggshell waste was assessed. So this present work fits in these contexts. Therefore the main objective of this study is to improve current knowledge on the behavior of studied concretes in the fresh state: slump-flow test, and hardened state: mechanical resistances in compression and in bending, as well as water absorption by capillarity test, absorption by total immersion, and porosity accessible to the water of SCCs designed from different types of waste, recycled sand, and eggshell fines. Also, the method of assessing mixes were affected by the sort of chemical attack, namely the (NaCl) attack was investigated. In light of the obtained results, it was found that the addition of eggshell fines in adequate quantity, can improve the properties of SCCs, in this study a volume of 30% was sufficient, increasing the volume added to 60% introduced an opposite effect. Using recycled sand in this study did not contribute to a significant effect on the mechanical properties of the mixtures studied, although an improvement in workability was observed.

Foundations of various construction projects usually can be either shallow or deep foundations. A mat foundation is one of the common shallow foundations typically utilized for various types of buildings. Foundations construct on various types of soils, which might be essential to understand the interaction scenario between them as they are two different types of materials. This study aims to discover the characteristics of the soil-foundation interaction for the suitable areas for the resettlement process in focus on a certain foundation type with a dimension of 10m x 10m x 0.5m, applied on twelve areas rich with fine-grained soil types in Sulaimaniyah governorate, northern Iraq, which suffer from some geotechnical problems such as building cracks. Application of loads was conducted in three stages; 35 tons, 70 tons, and 140 tons were directly applied on the utilized soils. The obtained results of the study prove that the 3D Plaxis is quite capable to predict the settlement of each foundation modeled on each utilized soil type. In addition, the modeling work achieved that the utilized foundation center stresses are notably smaller than the obtained foundation corner stresses. The obtained soil settlement values are not dependent on the soil-bearing capacity.

Statistical methods such as Scheffe’s and Osadebe’s models are commonly employed for the optimization of concrete properties. Despite their prediction suitability, attention is drawn to their drawback. Ibearugbulem’s model has been developed to address these shortcomings. In this study, Ibearugbulem’s optimization method was employed to formulate a mathematical model for prediction and strength-optimization of nanostructured cassava peel ash (NCPA)-cement composite. The variation of 28 days compressive strength and initial and final setting time of NCPA-concrete was evaluated. Based on the establishment of a spatial domain for each concrete mixture variable, the response function is expressed as a multivariable function for the proportions of the constituent materials. Applying the variational approach, the response function was developed within the specified spatial domain and was optimized. There were 51 observation points. Twenty-six observation points were used to formulate the model and the remaining twenty-five points were used to test the adequacy of the formulated model. The observation points on the odd serial number are the ones selected for the formulation of the model. The ones on the even serial numbers are the ones used for testing the adequacy of the model. Fisher’s statistical tool was used in the analysis and the calculated value of fisher of 1.11 was lower than the fisher value of 1.94 derived from the statistical f-distribution table. This result proved that there was no significant difference between the laboratory compressive strength values and the modeled strength values at a 95% confidence level. This shows that the formulated model is reliable, safe, and recommended for concrete producti

The desideratum of determining the behavior of the underlying soil on which the foundations will be laid is indisputable. This study evaluates the strength characteristics of lateritic soil material at a new construction site opposite College of Engineering and Engineering Technology (CEET), Michael Okpara University of Agriculture, Umudike (MOUAU). A trail pit was dug taking disturbed soil samples at a depth of 1m, 2m, and 3m for experimental analysis. Laboratory tests on specific gravity, grain size distribution, moisture content, atterberg limits, and triaxial tests were carried out on each sample by the procedure highlighted in BS1377 1990. Inspecting visually, the soil profile was observed to consist of three layers; light reddish, reddish, and whitish at the top, middle, and bottom respectively. The natural water content of the soil samples varied as 9.06+0.00 %, 7.98+0.00 %, and 9.32+0.03 %, while the specific gravity obtained from the test results was 2. 630+0.00 %, 2.634+0.00 % and 2.647+0.00 % at depths 1m, 2m, and 3m respectively. Using the unified soil classification system (USCS), the top, middle and bottom layers were classified as cloud sand (SC). The soil samples have a liquid limit (LL) of 24.5%, 28.8%, 31.0%; plastic limit (PL) of 19.4%, 17.2%, 18.5%; and plasticity index (PI) of 5.1%, 11.6%, and 12.5% at depths 1m, 2m, and 3m respectively. It was observed that the soil index properties vary and are enhanced as the depth of the excavation increases. Furthermore, the value of the cohesion property of the soil is 74.62 kN/m2, 29.70 KN/m2, and 24.65 KN/m2 for samples at 2m, 3m, and 3m depth respectively. The greatest and least cohesion value was noted to be 74.62 kN/m2 and 24.65 kN/m2 for samples at 2m and 3m depth respectively; the maximum and minimum angles of internal friction were 25.52o and 13.67o at depths 1m and 2m respectively. The outcome of this paper showed that the analyzed soil samples are suitable for civil engineering works.

The present study assesses the pollution level and health risk of heavy metal (Cr) in the area surrounding the tanning factories’ soil in Baghdad city-Iraq. Chromium concentration, mean, and median values were calculated. The geoaccumulation index (Igeo), the enrichment factor (EF), and the integrated pollution index (IPI) have been used in the assessment of pollution. The lowest value of (Igeo) at the surface to the north of the factory was (2.36), and the highest value of (Igeo) at a depth of 100 cm from the surface to the south of the factory was (94.94). All values of (EF) were greater than 40. The values of (IPI) at the surface and a depth of 100 cm from the surface of the soil are considered to cause an extreme level of contamination. A depth of 50 cm from the surface of the soil to the north of the factory is considered to have a high level of contamination. In addition, the estimated health risk was assessed by calculating the values of hazard quotient (HQ), health index (HI) for non-carcinogenic, lifetime average daily dose (LADD) for carcinogenic heavy metals, and lifetime cancer risk (R). The values of HI were found at a safe level (<1). Moreover, carcinogenic risks were estimated by the exposure results, where the highest value of R was 51.9, and the lowest value was 0.231.

This study aims to predict the effect of climate change on net irrigation water requirements (NIWR) and agricultural productivity from five common crops (wheat, barley, summer maize, and sorghum) in the Al-Najaf Governorate in Iraq. GFDL-ESM2M mode was used to predict the lower and upper temp and precipitation for two time periods (2020-2080) with 30 years for two periods (P1 and P2) under representative concentrations paths (RCP 2.5, RCP6, and RCP8.5). The CROPWAT model is used to determine NIWR, and the extreme learning model was used to estimate agricultural yields using previous crop yield production and weather data, supported vectors machine (SVM) is executed as a Machines Learns algorithm. Results showed NIWR increment to consider cropping owing to climate change. Barley is the crop most affected by climate change under the (RCP2.5, RCP6, and RCP8.5) scenarios, with increasing crop water requirements (NIWR) of (22%, 23%, and 24% ) for P1 and (23%, 24%, and 29%) for P2, respectively. Summer maize is the crop least affected by climate change under all climate change scenarios, with increasing crop water requirements of (1%, 2%, and 4%) for P1 and (1%, 2%, and 5% for P2. Climate change negatively affects the crop yield of all crops under the different climate change scenarios. The findings of this study could be used as a guide to developing adaptation strategies for dealing with potential changes in water availability and agricultural water productivity due to climate change.

The compaction of soil is a pivotal matter in almost every earthwork to achieve the densest possible state of the soil. The suitability of soil for earthworks is largely decided by compaction characteristics such as Optimal Moisture Content (OMC) and Maximum Dry Density (MDD). Identifying the compaction characteristics of a large volume of soil in the laboratory requires a while. As a result, determining compaction characteristics from physical soil properties is critical for initial soil assessment. To predict the compaction characteristics of the soil, three different models of the Artificial Neural Network (ANN), M5P-tree, and Multiple Linear Regression (MLR) are used in this work. Particle size and plasticity properties of soil are combined in the models, and seven input parameters consist of gravel, sand, silt, and clay contents, plastic limit, liquid limit, and plasticity index. 1038 datasets are compiled and processed in order to develop the models. To evaluate the effectiveness of the proposed models, several statistical analyses are harnessed, including coefficient of determination (R2), scatter index (SI), root mean squared error (RMSE), mean absolute error (MAE), and Objective (OBJ) value. Overall, the ANN model outperformed the MLR model in predicting OMC, while the MLR model outperformed it in predicting MDD. Besides this, the sensitivity analyses revealed that the plastic limit has a greater influence on the value of OMC, whereas both sand content and the plasticity index are important in predicting MDD.

Dam safety is an important issue as it directly influences environmental and life losses. Embankment material and embankment core are important factors that contribute to determining the size and hydraulic characteristics of the breach that occurs due to dam failure. The current topic is to present the analysis of the impact of the dam materials properties and hydraulic characteristics on breach dimensions due to overtopping failure using 2D-HEC-RAS software with the aid of RAS-Mapper. The analysis was made by Digital Elevation Model (DEM) conversed to a Triangular Irregular Network (TIN), then the 2D area of the dam was determined and the storage area boundary was calculated. Mosul dam in Iraq, considered one of the big dams that consist of different materials in the core and body, was selected as a case study to simulate the dam breach development due to overtopping failure. Six scenarios of dam failure were carried out for three types of dam materials (dam with corewall, concrete-face dam, and homogeneous zoned fill dam), each with high and medium erodibility. All scenarios were made for the reservoir elevation of 341 m which is considered the probable elevation for failure occurrence. The results showed that the minimum and maximum values of breach width were found to be 542 m and 1118 m, respectively in both cases of concrete-face dam type with a high erodibility and homogeneous zoned fill dam with medium erodibility rate. It has been illustrated that the medium erodibility in each scenario gives a smaller width for a long time, especially in homogeneous zoned fill dam type which is a good indication in engineering design. The analysis of sensitivity was carried out to examine the impact of pool volume at failure on breaching time and width of the breach. It showed that the breach width is more sensitive to reservoir fill capacity and there is a linear relationship between water volume reduction ratios and the breach width. Finally, tests of the six cases reveal that the proposed model is sensitive to soil conditions.

Roller Compacted Concrete Pavement (RCCP) is one type of concrete poured and compacted with the same machines utilized to construct heavy-duty pavements, log sorting, and parking. In this work, a combination of three factors was optimized to produce a sustainable RCCP. These factors were densified silica fume, ground granulated blast-furnace Slag, and mixing water contents. By weight, sulfate-resistant Portland cement was substituted with cementitious materials such as silica fume and slag in the amounts of (5, 7.5, and 10%) and (25, 27.5, and 30%), respectively. In addition, various percentages (5, 6, and 7%) of water content were utilized. Using the Taguchi approach, the impact of these factors was investigated based on the results of compressive strength and bulk density. The cubic specimens of compressive strength and bulk density, with 100 mm length, were tested at 7, 14, and 28 days. According to the results, the optimum percentages of silica fume, slag, and water contents were (5, 27.5, and 6%), respectively. Comparing the optimal mixture to the reference, the compressive strength enhancement was about 13.9%. According to Taguchi's study, water content has a most significant influence on the characteristics of RCCP than silica fume content. The slag content has the least impact on RCCP.

The experimental program evaluated the fresh properties of self-consolidating lightweight concretes (SCLC) produced from expired cement EC cold-bonded lightweight coarse aggregates (ALA) with silica fume (SF) and fly ash (FA). Twelve mixtures of SCLC were prepared, the binder in the control mix was just Portland cement (PC), whereas other mixes included binary and ternary of (PC), 20% of (FA), and/or (10%) of (SF) with (0%, 50%, and 100%) as partial replacement of (ALA) with coarse natural aggregates. Fresh features of (SCLC) were evaluated by measuring their slump flow diameter, T500 slump flow time, V-funnel flow time L-box height ratio, and column segregation, (SCLC) with and without mineral admixtures have their fresh characteristics compared. It was found that increasing the quantity of ALA replacement resulted in a reduction in the amount of superplasticizer required to obtain a constant slump flow diameter of SCLC. Combining (SF) and/or (FA) lowered both the V-funnel flow time and the slump flow time, whereas the L-box height ratio increased from (0.82) to (0.86) with the addition of fly ash for reference mix. With the combined action
of mineral admixtures, the percentage of column segregation decreases by
(16.7%) compared with the reference mix. The maximum slump flow was (792)
mm with a mix of (M6).