Anticipating the Compressive Strength of Hydrated Lime Cement Concrete Using Artificial Neural Network Model

In this research work, the levernberg Marquardt back propagation neural network was adequately trained to understand the relationship between the 28th day compressive strength values of hydrated lime cement concrete and their corresponding mix ratios with respect to curing age. Data used for the study were generated experimentally. A total of a hundred and fourteen (114) training data set were presented to the network. Eighty (80) of these were used for training the network, seventeen (17) were used for validation, and another seventeen (17) were used for testing the network's performance. Six (6) data set were left out and later used to test the adequacy of the network predictions. The outcome of results of the created network was close to that of the experimental efforts. The lowest and highest correlation coefficient recorded for all data samples used for developing the network were 0.901 and 0.984 for the test and training samples respectively. These values were close to 1. T-value obtained from the adequacy test carried out between experimental and model generated data was 1.437. This is less than 2.064, which is the T values from statistical table at 95% confidence limit. These results proved that the network made reliable predictions. Maximum compressive strength achieved from experimental works was 30.83N/mm2 at a water-cement ratio of 0.562 and a percentage replacement of ordinary portland cement with hydrated lime of 18.75%. Generally, for hydrated lime to be used in making structural concrete, ordinary portland cement percentage replacement with hydrated lime must not be up to 30%. With the use of the developed artificial neural network model, mix design procedure for hydrated lime cement concrete can be carried out with lesser time and energy requirements, when compared to the traditional method. This is because, the need to prepare trial mixes that will be cured, and tested in the laboratory, will no longer be required

Physico-mechanical behaviour of sandcrete produced with different proportions of sand grain sizes

The physical and mechanical properties of sandcrete produced with various blended proportions of sand grain sizes were investigated. River sand was sieved into three portions with distinct grain sizes. These were: sand containing only grains with diameters less than 1 mm (fine sand), 1-2 mm (medium sand) and 2-4 mm (coarse sand). Seven different combinations of grain sizes were proportioned by weight, with each combination containing 50% fine sand. Five cement/sand mix ratios, 1:4, 1:5, 1:6, 1:7 and 1:8, were used for moulding 150 × 150 × 150 mm sandcrete cubes. The results revealed that an increased proportion of coarse sand tended to increase the bulk density and compressive strength of sandcrete cubes after 28 days of curing. The grain size combination which gave the optimum compressive strength of sandcrete contained 50% fine sand, 10% medium sand and 40% coarse sand

Plastic buckling of thin flat rectangular isotropic plates under uniaxial in-plane loads

This study presents the analysis of plastic buckling of thin flat rectangular isotropic plates. To actualize this, the deformation theory of plasticity by Stowell’s approach is used in expressing the governing differential equation, and this equation is modified by adopting the method of work principle based on the principle of conservation of energy. Taylor-Maclaurin series functions truncated at the fifth term is used in estimating the deflection functions. The analyzed plates are subjected to uniform uniaxial in-plane compression and the direction of the loading is in the longitudinal direction (x-axis). The three plate boundary conditions considered in this study are: four simply supported edges (SSSS); four clamped edges (CCCC); and two clamped edges along the x-axis and two simply supported edges along the y-axis (CSCS). The Taylor-Maclaurin series formulation satisfied each of the plate boundary conditions and resulted to a distinct deflection function for each plate. These deflection functions are substituted into the governing equation to obtain the critical plastic buckling loads. Values of the buckling coefficient, k, which is derived from the critical plastic buckling load equation, are calculated for aspect ratios, p, ranging from 0.1 to 1.0 in steps of 0.1, using values of moduli ratio, Et/Es, equal to 0.6, 0.7, 0.8, and 0.9. The results are compared with those of a previous investigation. The percentage differences of k with plastic buckling solutions for the different values of p and Et/Es of the plates ranged from −4.685% to 6.276%. It is shown that the technique proposed in this study is an alternative approximate method for analyzing the plastic buckling of thin rectangular isotropic plates under uniform uniaxial in-plane loads

Study on Vibration and Stability Analysis of Thick Rectangular Plates Section

This paper is the second part of free vibration and stability analysis of thick isotropic and orthotropic plates. The support condition CCCC and CCFC support was considered by applying the alternative II theory based on polynomial shape function. The work was based on the application of the formulation earlier derived using Ritz method. The frequency values of the first mode and critical loads obtained were compared with those obtained using first order shear deformation theory. For span to depth ratio of 10, the fundamental linear frequency for orthotropic CCFC plate corresponding to modulus of elasticity ratios (E1/E2) of 10, 25 and 40 were 0.00312Hz, 0.00373 Hz and 0.00398Hz.  &nbsp

The Effect of Coordinate and Boundary Conditions on Displacement and Strain of Thin Rectangular Plate with Large Deflection

<p>The objective of this research is to investigate the impact of coordinate and boundary conditions on the displacement and strain properties of a thin rectangular plate subjected to substantial deflection. The formulas for nonlinear displacement and nonlinear strain were found by utilising the Von-Karman strain-displacement equation. The Von-Karman equations were mathematically integrated with regard to the variables x and y, resulting in the determination of the nonlinear displacement in both the x and y directions. The nonlinear displacements were further differentiated with respect to both the x and y coordinates, leading to the derivation of the nonlinear strain-displacement equations. The researchers in the study conducted by Ibearugbulem et al. (2020) employed the total potential energy functional of a thin rectangular plate in their investigation of pure bending. The functional was minimised with respect to displacement, resulting in the derivation of a governing equation and two compatibility equations. The aforementioned equations were subsequently solved in order to obtain the in-plane displacements as a function of deflection. The energy functional was further minimised to determine the coefficient of deflection and produce the various formulas employed in the analysis of plates exhibiting considerable bending. The utilisation of polynomial displacement functions was employed in the analysis of pure bending. The load characteristics that were established were compared to those obtained by Levy and Ibearugbulem, revealing a maximum discrepancy of 21.53% and 18.9% respectively. This supports the current methodology. The nonlinear displacement and strain values for thin rectangular plates of SSSS and CCCC were obtained in two distinct coordinate systems. The initial set of coordinates is characterised by the values (0.5, 0.5, 0.5), whereas the subsequent set of coordinates is defined by the values (0.25, 0.25, 0.5). A comparison was made between the findings obtained from the SSSS and CCCC plates.</p><p>Keywords:- Von-Karman; Nonlinear Kinematic; Coordinate and Boundary Conditions.</p&gt