Search results

Timoshenko deformation calculation theory is suited to open section beam, which is not suited to closed section beam due to the difference stress distribution between the open and the closed section beam. This study aims to modify the deflection formula for prestressed concrete hollow slab (closed section beam) based on the Timoshenko theory.

(1) The deflection curves of the prestressed concrete hollow slab beam were obtained under a single point force; (2) linear phases of the deflection values, which were calculated by Timoshenko theory and ABAQUS, were compared with the measured values; (3) a modified coefficient related to the loading location was obtained to modify the Timoshenko theoretical formula in calculating the deflection of the prestressed concrete hollow slab.

(1) There is a large difference between the calculated values and the measured values at 4.3 < a/H < 7.7, and the differences are between 24 and 33 percent; (2) the Timoshenko deflection formula has been modified to fit for the calculation of the prestressed concrete hollow slab. The mean of f/ft is 1.01, and the variation coefficient is 0.09 after modification. Therefore, the modified formula can be better applied in the deflection calculation of the prestressed concrete hollow slab.

The Timoshenko theory is the most classical theory, which is often used to calculate the deformation of beams. The modified deflection formula for prestressed concrete hollow slab based on the Timoshenko theory is reliable and convenient, which can help engineers to calculate the deflection for closed section beam quickly.

The purpose of this paper is to consider divergence of composite plate wings as well as slender wings with thin-walled cross-section of small-size airplanes. The main attention is paid to establishing of closed-form mathematical solutions for models of wings with coupling effects. Simplified solutions for calculating the divergence speed of wings with different geometry are established.

The wings are modeled as anisotropic plate elements and thin-walled beams with closed cross-section. Two-dimensional plate-like models are applied to analysis and design problems for wings of large aspect ratio.

At first, the equations of elastic deformation for anisotropic slender, plate-like wing with the large aspect ratio are studied. The principal consideration is delivered to the coupled torsion-bending effects. The influence of anisotropic tailoring on the critical divergence speed of the wing is examined in closed form. At second, the method is extended to study the behavior of the large aspect ratio, anisotropic wing with box-like wings. The static equations of the wing with box-like profile are derived using the theory of anisotropic thin-walled beams with closed cross-section. The solutions for forward-swept wing with box-like profiles are given in analytical formulas. The formulas for critical divergence speed demonstrate the dependency upon cross-sectional shape characteristics and anisotropic properties of the wing.

The following simplifications are used: the simplified aerodynamic theory for the wings of large aspect ratio was applied; the static aeroelastic instability is considered (divergence); according to standard component methodology, only the component of wing was modeled, but not the whole aircraft; the simplified theories (plate-lime model for flat section or thin-walled beam of closed-section) were applied; and a single parameter that defines the rotation of a stack of single layers over the face of the wing.

The simple, closed-form formulas for an estimation of critical static divergence are derived. The formulas are intended for use in designing of sport aircraft, gliders and small unmanned aircraft (drones). No complex analysis of airflow and advanced structural and aerodynamic models is necessary. The expression for chord length over the span of the wing allows for accounting a board class of wing shapes.

The derived theory facilitates the use of composite materials for popular small-size aircraft, and particularly, for drones and gliders.

The closed-form solutions for thin-walled beams in steady gas flow are delivered in closed form. The explicit formulas for slender wings with variable chord and stiffness along the wing span are derived.

Gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view. The range of applications of FEMs in this area is wide and cannot be presented in a single paper; therefore aims to give the reader an encyclopaedic view on the subject. The bibliography at the end of the paper contains 2,025 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1992‐1995.

Python codes are developed for the versatile structural analysis on a 3 spar multi-cell box beam by means of idealization approach.

Shear flow distribution, stiffener loads, location of shear center and location of geometric center are computed via numpy module. Data visualization is performed by using Matplotlib module.

Python scripts are developed for the structural analysis of multi-cell box beams in lieu of long hand solutions. In-house developed python codes are made available to be used with finite element analysis for verification purposes.

The use of python scripts for the structural analysis provides prompt visualization, especially once dimensional variations are concerned in the frame of aircraft structural design. The developed python scripts would serve as a practical tool that is widely applicable to various multi-cell wing boxes for stiffness purposes. This would be further extended to the structural integrity problems to cover the effect of gaps and/or cut-outs in shear flow distribution in box-beams.

This study aims to analyse slender thin-walled anisotropic box-beams. Fiber-reinforced laminated composites could play an important role in the design of current and future generations of innovative civil aircrafts and unconventional unmanned configurations. The tailoring characteristics of these composites not only improve the structural performance, and thus reduce the structural weight, but also allow possible material couplings to be made. Static and dynamic aeroelastic stability can be altered by these couplings. It is, therefore, necessary to use an accurate and computationally efficient beam model during the preliminary design phase.

A proper structural beam scheme, which is a modification of a previous first-level approximation scheme, has been adopted. The effect of local laminate stiffness has been investigated to check the possibility of extending the analytical approximation to different structural configurations. The equivalent stiffness has been evaluated for both the case of an isotropic configuration and for simple thin-walled laminated or stiffened sections by introducing classical thin-walled assumptions and the classical beam theory for an equivalent system. Coupling effects have also been included. The equivalent analytical and finite element beam behaviour has been determined and compared to validate the considered analytical stiffness relations that are useful in the preliminary design phase.

The work has analyzed different configurations and highlighted the effect of flexural/torsion couplings and a local stiffness effect on the global behaviour of the structure. Three types of configurations have been considered, namely, a composite wing box configuration, with and without coupling effects; a wing box configuration with sandwich and cellular constructions; and a wing box with stiffened panels in a coupled or an uncoupled configuration. An advanced aluminium experimental test sample has also been described in detail. Good agreement has been found between the theoretical and numerical analyses and the experimental tests, thus confirming the validity of the analytical relations.

The equivalent beam behaviour that has been determined and the stiffness calculation procedure that has been derived could be useful for future dynamic and aeroelastic analyses.

The article presents an original derivation of the sectional characteristics of a thin-walled composite beam and a numerical/experimental validation.

A bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view is given. The bibliography at the end of the paper contains 1,726 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1996‐1999.

This paper gives a bibliographical review of the finite element methods (FEMs) applied for the linear and nonlinear, static and dynamic analyses of basic structural elements from the theoretical as well as practical points of view. The bibliography at the end of the paper contains more than 1330 references to papers, conference proceedings and theses/dissertations dealing with the analysis of beams, columns, rods, bars, cables, discs, blades, shafts, membranes, plates and shells that were published in 1999–2002.

Anti‐static Liquid Announced by a London firm is the introduction of their C.S.L. anti‐static liquid. It is claimed that plastic surfaces wiped over with this liquid will remain free from dust for several months. CT 1681

The purpose of this paper is to develop, for use in everyday design, a procedure that incorporates the effect of concrete cracking in reinforced concrete (RC) beams at service load and requires computational efforts which is a fraction of that required for the available methods. Further for ease of use in everyday design the reinforcement input data is minimized. The procedure has been demonstrated for continuous beams and is under development for tall building frames.

The procedure is analytical at the element level and numerical at the structural level. A cracked span length beam element consisting of three cracked zones and two uncracked zones has been used. Closed form expressions for flexibility coefficients, end displacements, crack lengths, and mid-span deflection of the cracked span length beam element have been presented. In order to keep the procedure analytical at the element level, average tension stiffening characteristics are arrived at for cracked zones.

The proposed procedure, at minimal computation effort and minimal reinforcement input data, yields results that are close to experimental and finite element method results.

The procedure can be used in everyday design since it requires minimal computational effort and minimal reinforcement input data.

A procedure that requires minimal computational effort and minimal reinforcement input data for incorporating concrete cracking effects in RC structures at service load has been developed for use in everyday design.

The purpose of this paper is to introduce a closed-form analytical solution to evaluate the nominal moment capacity and associated deflections of steel-FRP beam systems. The proposed solution takes into consideration the partial composite behavior resulting from the interfacial contact and slip between the subcomponents of the system.

The partial composite action theory was used to develop an elastic analytical solution for the deflection of simply supported composite steel-FRP beams subjected to a mid-span point load. The solution takes into consideration the partial composite behavior of the system that arises from the interlayer slip at the steel-FRP interface.

The developed analytical model is used to predict the nominal moment capacity of the composite beam and the load value at the onset of yielding in the steel subcomponent of the section. The distribution of shear forces induced in the steel fasteners due to the interfacial slip is also obtained analytically. A comparative study is conducted by comparing the analytical results to their counterparts resulting from finite element modeling of the composite steel-FRP system. The agreement between analytical results and finite element predictions validates the accuracy of the derived analytical solution for partial composite steel-FRP beams.

The proposed solution applies only to the FRP strips and 6 mm steel bolts used in the study.

Recent studies revealed a promising efficiency of using mechanically fastened hybrid FRP sheets in strengthening steel beams. A major advantage of this technique is the ductile behavior of the steel-FRP system. The current paper introduces a closed-form analytical solution to evaluate the nominal moment capacity and associated deflections of steel-FRP beam systems. Forces developed at the steel-FRP interface due to the relative slip between both components are considered in the proposed analytical solution.