Articles in This Issue
Abstract
In this paper, a practical method of analysis of the pile displacements is proposed on the basis of the theory of load-transfer curves widely used in pile design and analysis. The parameters of the load-transfer curves for piles under axial load (called t-z, q-z curves) or lateral load (called P-Y curves) were correlated with the number of blows Nspt measured during the standard penetration test (SPT). Well documented case histories of full-scale axial or lateral loading tests on single piles in sand were collected, and the analysis of the experimental results led to define the parameters of the load-transfer curves. Two practical methods of computation of a single pile under an axial load or a lateral load were proposed to be used within the scope of a pile foundation project. At last, a validation process of the load-transfer curves was undertaken by direct comparison of the predicted pile displacements to those measured during other pile loading tests, which showed a good predictive capability of the two proposed methods
Abstract
Thin plate bending analysis is an important research subject due to the extensive use of plates in the different fields of engineering and the need for accurate solutions. This article uses the Ritz variational method and a superposition of trigonometric and polynomial basis functions to solve the Kirchhoff-Love plate bending problems (KLPBPs). The unknown displacement function in the Ritz variational functional (RVF) to be minimized is sought as linear combinations of basis functions Fm(x) and Gn(y) that are found by superposing sine series and third degree polynomial functions with the polynomial parameters determined such that all boundary conditions of deformation and force are satisfied. The displacement is thus expressed in terms of unknown displacement parameters Amn which are found upon minimization of RVF with respect to Amn. The minimization process gave a matrix stiffness equation in Amn with the stiffness matrix and force matrix found from Fm(x) and Gn(y) and their derivatives. The algebraic equation is solved, and the deflection and bending moments obtained. The problems considered were clamped (CCCC) plates under uniform and hydrostatic distribution of loads and plates with opposite edges clamped, the rest simply supported (CSCS) under uniformly distributed loading. Comparison of the solutions by Generalized Integral transform method, Levy-Nadai series method, and symplectic eigenfunction superposition confirms that the present results are accurate.
Abstract
Free transverse vibration frequency analysis of Euler-Bernoulli beams on Winkler foundation (EBBoWF) is a significant part of their analysis for averting failures by resonance. Resonant failure of EBBoWF occurs when the loading frequency exciting the vibration coincides with the least natural frequency. This study aims at using the Stodola-Vianello iteration method (SVIM) for the natural transverse vibration analysis of EBBoWF. Generally, the problem is governed by a non-homogenous partial differential equation (PDE) for forced vibrations, but simplifies to a homogeneous PDE for free vibrations where excitation forces are absent. For harmonic vibrations, and harmonic displacement response u(x, t), the equations are decoupled in terms of the independent spatial and time variables, resulting in a fourth order ordinary differential equation (ODE) in the displacement modal function for u(x, t). The study’s focus is on homogenous, prismatic, isotropic thin beams leading to ODEs with constant parameters. SVIM was used to express the ODE as Stodola-Vianello iteration equations with four constants of integration, determinable via the boundary conditions. Specific application of SVIM to the EBBoWF with simple end supports used exact sinusoidal shape functions and boundary conditions to determine the integration constants. Convergence criterion at the nth iteration was used to find the eigenequation which was solved for the eigenvalues. The natural transverse vibration frequencies at the nth modes were found in terms of frequency parameters . Values of calculated for the first five modes n = 1, 2, 3, 4, 5, and for values of showed that the present SVIM gave exact results compared to other previous results. The exact solutions were obtained because exact shape functions were used in the SVIM equations resulting in satisfaction of the governing equations at the domain and the boundaries.
Abstract
ABSTRACT This research models the relationship between traffic characteristics and lane position on a six-lane divided highway. Both macroscopic and microscopic models were developed to analyze speed-density, speed-flow, and flow-density relationships for each lane, using linear and nonlinear approaches. Additionally, microscopic models were created to investigate speed-spacing, speed-headway, and headway-spacing relationships. Data was gathered using video recordings and radar speed guns, and traditional methods were applied to calculate density and spacing distance, which are typically challenging to measure in the field. Microsoft Excel and SPSS ver.26 software were utilized for analysis. The coefficient of determination (R-square) and the chi-square test were employed to assess the goodness of fit for the models. The results indicated no significant differences between the predicted and observed data, demonstrating critical traffic characteristics and providing insights into vehicular and driver behavior. These models can be utilized to identify various parameters of traffic characteristics in future studies on the examined highway.
Abstract
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.
Abstract
One of the most important aspects of the developing any area is creating a viable road network and defining the relationship between landscape use and road networks. Proper communication and direction are essential to the proper construction of any network. In addition to providing chances for production and consumption, resource extraction, and social cohabitation, the road network also functions as a hub for these activities. As a consequence, this contributes to the development of cities and the improvement of the level of living. However, Ramadi's road network has not received much attention and evaluation. To identify Ramadi road network transportation indicators, the researchers used geospatial information systems. Connectivity was assessed using the alpha, beta, gamma, and eta indices to describe and analyse the network. The data was collected in the first quarter of 2024. The Alpha, the beta, the gamma, and the eta indexes show weak Al-Ramadi road network connections. Indexes are 0.197, 1.26, 0.43, and 0.82. The research indicates a loss in network connectivity in the study region, necessitating the prioritization of new the roads and a city plan to mitigate network shortages.
Abstract
Concrete is produced from millions of tons of Cement, which emits a significant amount of carbon dioxide from cement mills and contributes to global warming. Therefore, it is important to seek out less expensive and more environmentally friendly substitutes for OPC. While various substitutes are available, such as recycled glass, marble, silica fume fly ash, or agricultural waste like rice husks or wheat straw, the performance of concrete is significantly affected when bentonite is used as a replacement for Cement. This study aims to evaluate Jhelum bentonite, which is located at 32°56′ north and 73°44′ east longitude, as a replacement for Cement in different ratios (0:100, 10:90, 20:80, 30:70, and 40:60) to improve the durability of the system as more bentonite is used to replace conventional Portland cement, the workability, density, and water absorption of the new concrete all decrease. Compressive Strength, Tensile Strength, and flexural Strength of blocks and cylinders were tested after being cured for 7 and 28 days. Analysis of these strength tests revealed that the mixes containing bentonite were weaker after 7 days compared to 28 days, and the Strength of blocks was reasonable compared to cylinders.Keywords: Bentonite, Concrete, Compressive Strength, Tensile Strength.
Abstract
Microbial-induced carbonate precipitation (MICP) is a fast-evolving technology for cementing sandy soils, improving ground, repairing concrete cracks, and remediating contaminated land. The current work thoroughly reviews various factors that can impact the effect of the MICP technology on geomaterials. These factors include the type and strain of the microbes, concentration of bacterial solution, cementation solution composition and concentration, environmental factors (temperature, pH level, and oxygen dissolved), and soil properties. It was found that the type and strain of bacteria, concentration of bacterial suspension, pH value, temperature, and the reaction solution properties are the most affecting factors in controlling the characteristics of the produced calcium carbonate, which in turn affects the degree of bonding between geomaterials particles. For an optimal implementation of the MICP in soils treatment, it appeared that for the most commonly used bacterial strains a temperature between 20 and 40 °C, a pH between 6.5 and 9.5, and a cementation solution concentration of 0.5 mol/L, are typically recommended.
Abstract
A study examined the ductility and toughness properties of beams made of reinforced concrete, including foamed, normal, and hybrid beams. Nine reinforced concrete beams were produced: three foamed concrete beams, three normal concrete beams, and three hybrid concrete beams. Each beam possessed identical rectangular cross-sectional dimensions of 1500 mm × 250 mm × 150 mm. The flexural parameters (ultimate load, ductility, deflection, and durability) were assessed for each type of concrete utilized. The study's results showed that the load-bearing capacity of hybrid concrete beams was comparable to that of normal concrete beams, whereas foamed concrete beams exhibited slight improvement in their ability to carry loads. The ductility of reinforced foamed concrete beams was lesser than that of normal concrete. For over-reinforced beams, the ductility of hybrid concrete beams showed a significant improvement of 61% compared to foamed beams and an even more significant increase of 91.7% compared to normal beams. Furthermore, the hybrid concrete beam with over-reinforcement had a flexural toughness of 18.7% greater than the normal concrete beam. Suggested that a hybrid section comprising conventional and foamed concrete be utilized to decrease ductility and improve stiffness.
Abstract
A voided slab is an innovative type of reinforced concrete slab system developed recently, that has proven its excellence in terms of its structural, environmental, and economic benefits. The self-weight of a slab can be considerably reduced using different shapes of void formers like spherical, cubical, and donut. All researchers confirm that the self-weight of the slab decreases by up to 40%. Various researchers have carried out experimental and numerical studies for studying one-way flexural strength and punching shear strength of voided reinforced concrete slabs. However, the one-way or two-way flexural strength of the voided slab still needs to be acutely investigated. This paper deals with the survey on many titles of selected high impacted journals to illustrated almost criteria of investigations of these types of slabs. The main outcomes of this paper are the term environmental protection, sustainable and plastic waste reduction had a role not a little in this research, as 16% of the research on this topic were studied. Also, the plastic material governs the subject of the raw materials used to make the voids;43% of researches used this material.
Abstract
The performance of the structural materials (concrete and steel reinforcement) and the behavior of the structural members after they were exposed to high temperatures have been considered the main topics of the current literature review. All varieties of concrete mixtures lost their compressive strength after 300˚C, even though there was no discernible strength loss between 150 and 300˚C. It was also discovered that the heating time had no appreciable impact on the strength loss when the exposed to heat less than 300 ˚C. Above 300 ˚C. Concrete begins to lose strength after being exposed for longer than one hour; the greatest loss of strength occurs during the first and second hours of exposure. Both the cured cement paste and the aggregates undergo chemical and physical changes at temperatures ranging from 600 °C to 900 °C. The 5% weighted rice husk ash (RHA) blended concrete still had an advantage in compressive strength, over the concrete when subjected to temperatures up to 700 C for two hours. Adding more recycled glass and ceramic particles to regular concrete increases its overall compressive and tensile strengths. Concrete becomes more durable and has fewer cracks when there is a higher replacement rate for ceramic and glass particles. The splitting tensile strength decreased with increasing temperature, changing from 60% to 70% of its initial strength after 600 °C. In this review, the better performance of concrete than the other concrete in terms of mechanical, physical, and durability properties at both room temperature and high temperature were concrete with 10% waste glass powder (WGP) substitution as a partial of cement and 10%–20% crushed glass (CG) substitution as a partial of aggregate .
Abstract
Despite the importance of plates in structural analysis the flexural analysis of plates under parabolic load has not been extensively studied. This paper presents single finite sine transform method for exact bending solutions of simply supported Kirchhoff plate under parabolic load. The governing equation of equilibrium is a fourth order non-homogeneous differential equation in terms of the deflection The considered thin plate problem has Dirichlet boundary conditions at all the edges. This recommends the use of the finite sine integral transform method whose sinusoidal kernel function satisfies the boundary conditions. The sinusoidal function of x used for the sine transform kernel in this paper satisfies the Dirichlet boundary conditions along edges. The transformation simplifies the problem from a partial differential equation (PDE) to an ordinary differential equation (ODE) in the transformed space. The general solution, obtained using methods for solving ODEs is found in terms of unknown constants of integration which are found by using the finite sine transform of Dirichlet boundary conditions along the and edges. The solution in the physical domain space variables is then found by inversion as a rapidly convergent single series with infinite terms. A one term truncation of the single infinite series yields center deflection solution that is only 2% greater than the exact solution. A three term truncation of the infinite series for gave exact center deflections. Bending moments are found using the bending moment deflection relations as convergent single series with infinite terms.