Application of Groyne as a Sustainable Solution to Agulu-Nanka Erosion Problem

The paper aims at highlights the natural and anthropogenic impact in gully-erosion geo-structural failures. The application of groyne model-placement as sustainable solution which minimizes the control cost and guaranttees bed load as well as suspended load sediment transport. Keywords: Erosion model sediment, groyne, sustainable-solution, contro

INFLUENCE OF MIX DESIGN METHODS ON THE COMPRESSIVE SRENGTH OF CONCRETE

ABSTRACT Concrete mixes are designed to achieve a defined workability, strength and durability. The design is geared towards the selection and proportioning of constituents to produce a concrete with pre-defined characteristics both in fresh and hardened states. This study investigates the variation of concrete compressive strength with mix designed methods. Four common mix design methods were used namely: American Concrete Institute (ACI), Department of Environment (DOR), Road Note 4 (RN4) and CPIIO. The Ibeto brand of Portland cement was used in the research and a characteristic strength of 20N/mm 2 was designed for using the first four mix design methods. The concrete components used were tested for specific gravity; moisture content and grading were found suitable. Four sets of concrete cubes (150 x 150 x 150 mm) each were casted using four mix designs. Compressive strengths were evaluated at 7, 14, 21, and 28 days of curing. The 28 th day strengths of the four sets of concrete were found to be 30.7 N/mm 2, 33.7 N/mm 2, 33.0 N/mm 2, and 35.1 N/mm 2 for ACI, DOE, RN4, and CP110 mix design methods, respectively

Nonlinear free vibration analysis of levy plates using weak-form variational principle in polynomial displacement functions

This paper evaluates nonlinear free vibrations of Levy plates using Weak-Form variational principle in algebraic polynomial displacement functions. The energy functional of the plate problem was formulated using Weak-Form variational technique on the integral function of the Von Karman thin plate differential equations. The displacement functions were developed based on static deflection configurations of orthogonal beam network. The process of repeated direct integration on compatibility equation was used to determine the algebraic expressions for stress function. The amplitude of deflection which directly influences the geometric nonlinearity of the plate was determined using integration process on energy functional based on static equilibrium equations. The modal combination method was used to develop the stiffness and mass matrices respectively from the expressions of energy functional based on dynamic equilibrium equations. The numerical values of amplitudes of deflection at various aspect ratios were computed. Also, the first four nonlinear natural frequencies at various aspect ratios were numerically computed. The validation of the present study’s results using the results from previous work found in literature shows satisfactory convergence, with an absolute mean error of 0.186 %. Conclusively, the application of Weak-Form variational principle in polynomial displacement functions provides satisfactory approximation to nonlinear dynamic analysis of Levy plates

Free vibration analysis of all round clamped thin isotropic rectangular plate by Ritz Direct Variational Method

This paper developed polynomial comparison functions for the free vibration analysis of clamped thin rectangular plates using the Ritz Direct Variational Method. The polynomials were derived systematically from a predefined formula, which could generate any number of trial functions for any set of plate’s classical boundary conditions. The method was implemented by means of a Mathematica computer programme developed by the authors. The frequency parameters so obtained agreed excellently with those available in the literature. The numerical values of the frequency parameters increased with the aspect ratio irrespective of the mode considered. In addition, the study showed that the more the number of polynomial coordinate functions in the shape function, the better the accuracy of the results. The convergence study corroborated the fact that a one-term approximation yields sufficient accuracy. The convergence was best for square plates, even though acceptable percentages of convergence were obtained for the other side ratios