Abstract In this study, a theoretical analysis is presented to estimate the in-plane large displacement elastic stability behavior of structures having non-prismatic members of linearly and nonlinearly varying sections resting on elastic foundation (Winkler type) and subjected to static loads applied at joints only. The analysis adopts the beam-column approach and models the structural members as beam-column elements resting on distributed springs. The formulation of beam-column element is based on Euler approach allowing for the influence of the axial force on bending stiffness. Changes in member chord length due to axial deformation and flexural bowing are taken into account. The stability and bowing functions are estimated using methods of finite differences and finite segments. Also, approximate results have been obtained by using approximate stability and bowing functions of linearly and nonlinearly tapered members resting on elastic foundation. A computer program has been coded in QB language to carry out the proposed analysis of structures with prismatic or non-prismatic members of linearly and nonlinearly varying sections resting on elastic foundation. As a result of this study; the only difference between the analysis of non-prismatic members resting on elastic foundation and those which are not, when adopting the beam-column approach, is represented in the stability and bowing functions, and this is reflected directly on the tangent stiffness matrix.
The buckling analysis of Euler-Bernoulli beam resting on two-parameter elastic foundation (EBBo2PEF) has important applications in the analysis and design of foundation structures, buried gas pipeline systems and other soil-structure interaction systems under compressive loads. This study investigates the buckling analysis of EBBo2PEFs. The governing differential equation of elastic stability (GDiES) is derived in this work using first principles equilibrium method. In general, the GDiES is an inhomogeneous equation with variable parameters for non-prismatic beams under distributed transverse loadings. However, when transverse loads are absent and the beam is prismatic the GDiES becomes a fourth order ordinary differential constant parameter homogeneous equation. General solution to GDiES is obtained in this work using the classical trial exponential function method of solving equations. Two cases of end supports were considered: simply supported ends and clamped ends. Boundary conditions (BCs) were used to obtain the characteristic buckling equations whose eigenvalues were used to determine the critical buckling loads for two cases of BCs considered. It was found that the method gave exact solutions for each of the BCs. The critical elastic buckling load coefficients for dimensionless beam-foundation parameter and ranging from for simply supported EBBo2PEFs were identical with previous results that used Stodola-Vianello iteration methods and finite element method. Similarly, the critical buckling load coefficients for and are identical with previous results that used Ritz variational method.
Recycling the old paving waste and reusing it in the construction of new highways was resorted to, and this is a good step from an economic point of view, as well as from an environmental and health point of view, as it reduces carbon emissions and eliminates a large amount of disposable reclaimed asphalt pavement materials (RAP). This study aims to evaluate the best layer of pavement structure; base, binder, and surface layers for inclusion (RAP) materials based on stability and indirect tensile strength. In addition, highlight the best percentage that can be added from RAP to achieve positive results and better than that associated reference mixture in terms of Marshall test and Indirect tensile strength test RAP materials collected from different sources Karbala and Fallujah, were adopted in this study at percentages of 20%, 30%, and 40% by weight of the asphalt mixture. Two scenarios of incorporating RAP materials have been adopted : The first is considered that RAP as a black rock in which the effect of aged binder surrounding the aggregate of RAP is neglected while the second is not considered RAP as black rock and the influence of aged binder in RAP materials has been taken into consideration. Dora bitumen has been adopted in the current study which is used commonly in Iraq. It has been highlighted that the best layer in which RAP can be incorporated is the base layer, with a percentage up to 40% that RAP without considering RAP black rocks regardless of the sources of RAP
AbstractThe aim of this study is to analyze the slope stability for sections in Al-Furat River where engineering construction build on it, when a sudden decrease in the river water level happens. Two sections were chosen from the river in the area located about 35 km away from Ramadi city called Tel Aswad where undisturbed samples are taken and laboratory tests are done to obtain the soil parameters which are used in Geo-Slope program. The finite element method was applied in this study with elastic-plastic soil model. The analysis results show that the sections slope chosen from the river are stable. The second purpose of this analysis to reduce the risk of using earth structures when engineering construction build on it. Also, it is clear that the values of factor of safety calculated by the FEM are low compared with limit equilibrium methods.
The analysis of the least compressive load that cause buckling failures of Euler-Bernoulli beams resting on two-parameter elastic foundations (EBBo2PFs) is vital for safety. This article presents Ritz variational method (RVM) for the stability solutions of EBBo2PFs under in-plane compressive loads. The Ritz total potential energy functional, was derived for the problem as the sum of the strain energies of the thin beam, the two-parameter lumped parameter elastic foundation (LPEF) and the work potential due to the in-plane compressive load. Ritz functional was found to depend upon the buckling function w(x) and its derivatives with respect to the longitudinal coordinate. The principle of minimization of was implemented for each considered boundary condition to find the w(x) corresponding to minimum Three cases of boundary conditions investigated were: clamped at both ends, clamped at one end and free at the other, simply supported at both ends. For each case, w(x) was found in terms of unknown generalized buckling parameters ci, and buckling shape functions satisfying the boundary conditions. Thus was expressed in terms of the parameters ci. The Ritz functional was subsequently minimized with respect to the parameters yielding an algebraic eigenvalue problem. The condition for nontrivial solutions of homogeneous algebraic equations was used to find the characteristic buckling equations that were solved to find the eigenvalues. The eigenvalues were used to find the buckling loads and the critical buckling load. It was found that a one-parameter RVM solution for the EBBo2PF with both ends clamped, and with one clamped and one free end gave similar critical buckling load solutions to those presented in the literature. It was also found that an n-parameter RVM solution for the EBBo2PFs with both ends simply supported yielded exact buckling load solutions because exact sinusoidal buckling shape functions were used.
Scour around bridge piers is a well-known threat to bridge stability worldwide. It can cause losses in lives and the economy, especially during floods. Therefore, an artificial intelligence approach called artificial neural network (ANN) was used to predict the scour depth around bridge piers. The ANN model was trained with laboratory data, including pier width, flow velocity, particle diameter, sediment critical velocity, flow depth, and scour depth. The data was divided into 70% for training, 15 for validation, and 15% for testing. Besides, the ANN model was trained using various training algrthins and a single hidden layer with 20 neurons in the hidden layer. The results showed that the ANN model with Bayesian regularization backpropagation training algorithm provides a better predicted scour depth with a correlation coefficient (R) equal to 0. 9692 and 0.926 for training and test stages, respectively. Besides, it showed a low mean squared error (MSE), which was 0.0034 for training and 0.0066 for the test. These results were slightly better than the ANN with Levenberg-Marquardt backpropagation with R training equals 0.9552 (MSE training = 0.0047), and R test equals 0.838 (MSE test = 0.007).On the other hand, the ANN model with a scaled conjugate gradient backpropagation training algorithm showed worse predictions (R training = 0.7407 and R test = 0.6409). Besides, the ANN model shows better outcomes than the linear regression model. Finally, the sensitivity analysis has shown that the pier width is the most crucial parameter for estimating scour depth using the ANN model.
This study is the second stage of the paper “Study the Effect of Rubber Silicon on Physical Properties of Asphalt Cement”. This study took the effect of additives on asphalt mixture performance. Asphalt mixture has been designed by Marshall method for determining the optimum asphalt content and geophysics properties of mix according to ASTM (D- 1559 ). Rubber silicon at different percentage (1%, 2%, 3% and 5%) was added to asphalt binder and three specimens of asphalt rubber silicon mixture (ARSM) are prepared and evaluating according to Marshall method. Diametric tensile creep test ASTM (D-1075) at 60 Co used to evaluating permanent deformation and modulus of elasticity for ARSM. The study shown that the Rubber-Silicon has more effects increasing the marshal stability, air voids, and reducing the flow and bulk density compared with the original mix.. Increase the flexibility properties of the mix and this appear from reducing the permeate deformation at test temperature (60C), the reduction percent is about (30 to 70)%
ABSTRACT:The gypseous soils are distributed in many regions in Iraq and other countries. Therefore, it is necessary to study the behavior of such soils due to the large damages that affects the structures founded and constructed in or on it.This research is concerned with studying the effect of leaching soil process on the stability of an embankment erected on foundation gypseous soil. The finite element method is adopted in this research. The analyses carried out using a nonlinear, increment, and stress-dependent finite element computer program. The hyperbolic stress-strain parameters used in the finite element analyses are estimated by the data collected from triaxial compression tests of some researchers. The analysis of the embankment problem carried out, shows that the leaching process for foundation gypseous soil increases the displacements and deformations of the embankment and its foundation. Finally, this research necessitate the success using of the finite element method in design and analyses of the important structures and buildings erected on gypseous soils that may expose to the effect of leaching process. This means that there is possibility to predicate the behavior of structure by a powerful means to establish the suitable solutions for any problems that may be occurred as a result of the present gypseous soil.