Papers by Keyword: Beam

Abstract: This paper presents theory, experiments and numerical approaches suitable for the solution of straight plane beams rested on an elastic (Winkler's) foundation, including nonlinearities. The nonlinear dependence of the reaction force on displacement in the foundation (i.e. the experimental data) can be described via bilateral linear or bilateral linear + cubic or bilateral linear + cubic + quintic approximations, or by unilateral approximation (i.e. by using the Least Squares Method). These applications lead to linear or nonlinear differential 4^th-order equations. For solutions of nonlinear problems of mechanics, the Finite Difference Method (i.e. the Central Difference Method) and boundary conditions are applied. The solution and its evaluation is performed in second part of this article.

Abstract: Various higher order shear deformation theories of Levinson, Touratier, Karama are utilized to calculate the natural frequencies of functionally graded beams. The governing differential equations are solved by an analytical method. The present results are compared with the results of Aydogdu which demonstrate the accuracy of various theories.

Abstract: Most of the signal in the communication system have the cyclostationary property. Many algorithms based on the cyclostationary of the signal in the array signal processing have been exploited. They can well work without knowing the steering vector of interested signal, thus they all belong to the blind algorithms. When there is cycle frequency error, a mathematical analysis of gradient decent-based algorithm is provided in this paper. It pointed out that due to the zero point effect of the sinc function, the above approach have periodic deterioration as the number of snapshot increasing. Hence, in this paper a novel robust algorithm based on conjugate gradient, which can be used to extract signals with cyclostationarity with the cycle frequency error, is proposed. Because of its fast convergence, periodic nulls can be circumvented, and the steering vector of interested signal is estimated. Then we use traditional beamformer to avoid the influence of cycle frequency error. Simulation experiments show that our new algorithm performs well under cycle frequency mismatches.

Abstract: The article discusses the application of differential equations to solve large deformations of the designed slender structural elements. The structural element under design has a variable circular cross-section in longitudinal direction. It is made of a composite material based on carbon fiber and is capable of large deformations. In the solution it was necessary to consider the nonlinear deformation theory, which led to the solution of a nonlinear differential equation of second order. The creation of the differential equation describing the line of elastic deformation of a significantly curved structural element required the formulation of input equations and boundary conditions for its solution. The results obtained by means of a differential equation were compared with the numerical solution applying the finite element method. The solution presented and methodology can be used for practical application in the engineering design of fishing rods.

Abstract: Analysis of inhomogeneous residual stress (RS) fields in bodies is one of the major problems of the mechanics of deformable solid bodies. In the present research the new techniques of identification of inhomogeneous RS in bodies are developed on the basis of surface displacement measurement in a set of points under vibrating sounding load. Corresponding nonlinear ill-posed inverse problems (IP) are formulated and solved numerically by means of iterative regularization. Based on computational experiments, the most advantageous sounding load types and frequency ranges providing the best reconstruction accuracy are revealed. The examples for a cantilever, a plate, a layer, and a cylindrical tube are presented.

Abstract: With the application of computer technology in civil engineering more and more widely, it is important to find new methods suitable for computer programming to solve the engineering problems. In this paper, a new method based on differential equation group is introduced to analyze statically determinate beam and rigid frame. Firstly, the division method of member system is given and differential equation group is established. Secondly, the determination of boundary conditions is discussed in different situations. And the approximate analytical solution of internal force of statically determinate beam and rigid frame is obtained. At last, two calculating examples are given. The result shows that this method is easy to be programmed and suitable for application in engineering and teaching.

Abstract: Based on the fatigue test of 6 stainless steel reinforced concrete beams, number of stress cycles, dropping-coefficient of stiffness and crack width are studied. This paper mainly discussed, under different stress states and reinforcement ratio, the influence of the reinforced concrete beam with stainless steel rebar on crack development, deflection and fatigue life. It can be concluded that, the fatigue life of the stainless steel reinforced concrete beam will go up as the stress decreases. Based on the analysis of the test results, the S-N curve can be deduced.

Abstract: This paper focuses on the assessment of the shear strength prediction established in the brazilian concrete code, NBR6118/2007[1], for reinforced concrete beams without web reinforcement. The values obtained by using the brazilian code equation are compared with a significant number of available experimental data and with those predicted by the expressions of other national and international codes, such as CEB-FIP MC90[2] and ACI-318/11[3]. The brazilian concrete code regarding shear capacity of reinforced concrete elements are explicitly assumed to be valid only for concrete strengths up to 50 MPa. It is shown that the code equation may be unconservative in a large number of cases. This discrepancy increases with increasing concrete strength, decreasing longitudinal reinforcement ratio and increasing beam depth.

Abstract: This paper focuses on research of prestressed I-beams made of ultra-high performance concrete (UHPC), which are designed to be structural elements in small and medium span railway bridges. Prestressed concrete I-beams are designed with ten prestressing cables in the bottom flange. The prestressed beams are laid close together in the actual structure, with panels inserted between them. The entire structure will subsequently become monolithic. At the present time, I-beams made of rolled steel are commonly used as structural elements in this type of structure. The advantage of these types of structures lies in their having low construction height. This paper presents a computer and experimental analysis of loading of UHPC prestressed I-beams. For the purpose of the experiments, three specimens of 12 m span were made. The specimens were subsequently tested in the laboratory in four-point bending tests. The paper presents the process and results of the experiments. Simultaneously with the experiments, computer analyses were created in which optimization of the material and geometric parameters of the beams were carried out. The paper demonstrates the correspondence of the experimental and computer-simulated load test results.

Abstract: This paper focuses on research into prestressed I-beams made of ultra-high-performance concrete, which are designed to be structural elements in small and medium span railway bridges. Prestressed concrete I-beams are designed with ten prestressing cables in the bottom flange. The prestressed beams are laid close together in the actual structure with panels inserted between them. The entire structure will subsequently become monolithic. At the present time, I-beams made of rolled steel are commonly used as structural elements in this type of structure. The advantage of these types of structures lies in their having a low construction height. This paper presents a computer and experimental analysis of the loading of UHPC prestressed I-beams. For the purpose of the experiments, several specimens of 7 m span were made. The specimens were subsequently tested in the laboratory in four-point bending tests. The paper presents the process and results of the experiments. Simultaneously with the experiments, computer analyses were created in which optimization of the material and geometric parameters of the beams were carried out. The paper demonstrates the correspondence of the experimental and computer-simulated load test results.