INACOF—A computer program for the inelastic analysis of reinforced concrete framed structures

The paper presents a general-purpose computer program for the inelastic analysis of reinforced concrete frames based on the method of imposed rotations. The program is capable of calculating the response of the structure to a given loading and also capable of performing collapse load analysis of the given structure. The program has been tested for a variety of problems and has been found to be extremely efficient compared to the other existing routines with much more limited capabilities. Complete listing and information for using the program has been presented.     

Damped second-order Rayleigh-Timoshenko beam vibration in space—an exact complex dynamic member stiffness matrix

A uniform linear beam in a uniform linear ambient medium is studied. The beam performs stationary harmonic damped nonsynchronous space vibration in simultaneous tension, torsion, bending and shear in the presence of a large static axial load. Hysteretic and viscous dampings of the beam material and ambient medium are considered. Generalized complex Kolou?ek functions are derived. A 12 × 12 complex symmetric stiffness matrix is established for a supported beam member excited at its ends by prescribed harmonic translations and rotations which have the same frequency but may be out of phase. This matrix allows for an exact analysis of nonproportionally damped built-up beam structures, thus avoiding assumed mode shapes and lumped or consistent masses. A general notation is suggested. Numerical examples are given, including applications of the computer program SFVIBAT-DAMP.     

A spline wavelets element method for frame structures vibration

A spline wavelets element method that combines the versatility of the finite element method with the accuracy of spline functions approximation and the multiresolution strategy of wavelets is proposed for frame structures vibration analysis. Instead of exploring orthogonal wavelets for specific differential operators, the spline wavelets are applied directly in finite element implementation for general differential operators. Although lacking orthogonality, the two-scale relations of spline functions and its corresponding wavelets from multiresolution analysis are employed to facilitate the elemental matrices manipulation by constructing two transform matrices under the constraint of finite domain of elements. In the actual formulation, the segmental approach for spline functions is provided to simplify the computation, much as conventional finite element procedure does. The assembled system matrices at any resolution level are reusable for the furthur finer resolution improvement. The local approximation and hiararchy merits make the approach competitive especially for higher mode vibration analysis. Some examples are studied as verification and demonstration of the approach.     

RADS — a computer package for refrigeration analysis, design and simulation

A commercially available computer package for refrigeration analysis, design and simulation is described. Its main applications are heat load determination, multi-stage compression plant layout design, and simulation of the interactions between refrigerant plant, applications and control systems.     

A lanczos-based technique for exact vibration analysis of skeletal structures

This paper presents and discusses a Lanczos-based eigensolution technique for evaluating the natural frequencies and modes from frequency-dependent eigenproblems in structural dynamics. The new solution technique is used in conjunction with a mixed finite element modelling procedure which utilizes both the polynomial and frequency-dependent displacement fields in formulating the system matrices. The method is well suited to the solution of large-scale problems. The new solution methodology presented here is based on the ability to evaluate a specific set of parameterized non-linear eigenvalue curves at given values of the parameter through an implicitly restarted Lanczos technique. Numerical examples illustrate that the implicitly restarted Lanczos method with secant interpolation accurately evaluates the exact natural frequencies and modes of the non-linear eigenproblem and verifies that the new eigensolution technique coupled with the mixed finite element modelling procedure is more accurate than the conventional finite element models. In addition, the eigenvalue technique presented here is shown to be far more computationally efficient on large-scale problems than the determinant search techniques traditionally employed for solving exact vibration problems.     

平面钢框架在撞击荷载作用下的抗连续倒塌分析

各种自然灾害和人为因素都可能造成结构连续倒塌,抗连续倒塌研究经常抛开引起倒塌破坏的原因,直接拆除关键柱,研究剩余结构的抗倒塌性能.该研究以平面框架受撞击荷载为例分析具体灾害对框架结构抗倒塌性能的影响,提出一种撞击力简化模型,分析结构体系对撞击力的激励反应,并将撞击拆柱法模拟结果与传统直接拆柱法结果对比,分析两种方法对结...     

Coupled vibrations of beams—an exact dynamic element stiffness matrix

A uniform linearly elastic beam element with non-coinciding centres of geometry, shear and mass is studied under stationary harmonic end excitation. The Euler-Bernoulli-Saint Venant theory is applied. Thus the effect of warping is not taken into account. The frequency-dependent 12 × 12 element stiffness matrix is established by use of an exact method. The translational and rotational displacement functions are represented as sums (real) of complex exponential terms where the complex exponents are numerically found. Built-up structures containing beam elements of the described type can be analysed with ease and certainty using existing library subroutines.     

Finite-element time-domain modelling of plane wave scattering by a periodic structure using an exact boundary condition

A two-dimensional singly-periodic structure, at plane wave oblique incidence, is modelled using the finite-element time-domain method. Over the non-periodic boundaries of the computational domain, an exact Floquet modal absorbing boundary condition is developed, in detail, for the finite element method in the time domain. The proposed formulation is validated by comparing its results with that of the finite-element frequency-domain method and with independently obtained published results. Very accurate numerical results, over a wide frequency range and incident angle range, are obtained for both transverse electric and transverse magnetic polarised plane wave illuminations     

A computer program for repetitive strain gauge rosette analysis

A system is described with which the signals from a strain gauge rosette can be used to compute principal stresses and their orientation, the results being plotted on a VDU screen and updated continuously.     

A multiharmonic method for non-linear vibration analysis

A multiharmonic method for analysis of non-linear dynamic systems submitted to periodic loa conditions is presented. The approach is based on a systematic use of the fast Fourier transform. The e linearization of the resulting equations in the frequency domain allows to obtain full quadratic converg rate.     

Experimental analysis of vibration characteristics of an edge- cracked composite plate by ESPI method

In this paper, the amplitude fluctuation (AF) electronic speckle pattern interferometry (ESPI) method was adopted to investigate the vibration characteristics of a composite plate containing an edge crack. The change of the modal shapes was discussed. In addition, the stress intensity factors (SIFs) induced by the resonant vibration were evaluated. This revised version was published online in August 2006 with corrections to the Cover Date.     

A generalized computer program for analysis of mixture refrigeration cycles

The growing interest in non-azeotropic refrigerant mixtures for heat pumps and appliances has led to the need for a method of analysing the refrigeration cycle properties of such mixtures. Thermodynamic property tables are not sufficient, because they give no information about the two-phase region, where temperature and vapour and liquid compositions are not constant at constant pressure. This paper describes the computer program CYCLE, which can perform thermodynamic property calculations for subcooled, two-phase, and superheated non-azeotropic mixtures and can analyse a simple refrigerating cycle.     

An exact method for solving logical loops in reliability analysis

This paper presents an exact method for solving logical loops in reliability analysis. The systems that include logical loops are usually described by simultaneous Boolean equations. First, present a basic rule of solving simultaneous Boolean equations. Next, show the analysis procedures for three-component system with external supports. Third, more detailed discussions are given for the establishment of logical loop relation. Finally, take up two typical structures which include more than one logical loop. Their analysis results and corresponding GO-FLOW charts are given. The proposed analytical method is applicable to loop structures that can be described by simultaneous Boolean equations, and it is very useful in evaluating the reliability of complex engineering systems.     

Damped second-order Rayleigh-Timoshenko semi-infinite beam vibration—an exact complex dynamic member stiffness matrix

A uniform linear semi-infinite beam in a uniform linear ambient medium is studied. The beam performs stationary harmonic damped non-synchronous space vibration in simultaneous tension, torsion, bending and shear. Hysteretic and viscous dampings of the beam material and ambient medium are considered. Four new generalized complex Kolousek functions are derived. A 6 × 6 complex symmetric stiffness matrix is established for a semi-infinite beam member excited at its end by prescribed harmonic translations and rotations which have the same frequency but may be out of phase. This matrix extends the range of application of the so called ‘exact analysis’ of non-proportionally damped built-up beam structures as described in a previous paper by Lundén and Åkesson.¹ Numerical examples are given, including applications of the computer program SFVIBAT-DAMP. Power flows are studied.     

框架结构爆破震动响应的时程预测

对岩石爆破地震动作用下框架结构进行了动力分析,建立了爆破地震波作用下框架结构的空间非线性时程分析方法.利用选用二组实测典型爆破地震波,对一栋七层钢筋混凝土框架结构进行了实例分析,通过与天然地震波作用下结构的动力反应的对比,为框架结构在爆破地震波作用下的安全评估及推广应用提供了有效途径.从位移反应来衡量,爆破持时对框架结构有比较大的影响,持时达到一定时间后(约为1/4倍结构自振周期),持时对最大位移基本没影响.     

Plate bending for frame analysis by coupling method of singular integral operators method with finite elements

The coupling of the Singular Integral Operators Method (SIOM) and the Finite Element Method (FEM) is proposed and investigated for the solution of plate bending problems. Such combination of the above two numerical methods gives more accurate results for the solution of plate bending problems in structural analysis. The plates are basic units of building frame structures, as well as to underground structures and thus the determination of bending moments around the plates is very important for the analysis of all kinds of structures. An application of plate bending problems is finally given to the determination of the bending moments in a rectangular plate with a rectangular hole in the center of the plate.     

On a progressive simultaneous iteration method for vibration analysis of gyroscopic systems

This paper presents details of an eigenproblem solution procedure for the efficient and accurate free vibration analysis of gyroscopic systems such as spinning structures. The procedure enables computation of the first few roots and vectors without having to compute any other. While structural discretization is achieved by the standard finite element method, eigenproblem solution of the resulting equations is effected by a newly developed progressive simultaneous iterative (PSI) method. Numerical solution of relevant example problems re presented which are compared to those obtained by ther existing analysis techniques, testifying to substantial gains in the efficacy of the newly developed solution algorithm. Copyright © 2001 John Wiley & Sons, Ltd.     

Free vibration analysis of functionally graded conical shell panels by a meshless method

A free vibration analysis of metal and ceramic functionally graded conical shell panels is presented using the element-free kp-Ritz method. The first-order shear deformation shell theory is used to account for the transverse shear strains and rotary inertia, and mesh-free kernel particle functions are employed to approximate the two-dimensional displacement fields. The material properties of the conical shell panels are assumed to vary continuously through their thickness in accordance with a power-law distribution of the volume fractions of their constituents. Convergence studies are performed in terms of the number of nodes, and comparisons of the current solutions and those reported in literature are provided to verify the accuracy of the proposed method. Two types of functionally graded conical shell panels, including Al/ZrO₂ and Ti–6Al–4V/aluminum oxide, are chosen in the study, and the effects of the volume fraction, boundary condition, semi-vertex angle, and length-to-thickness ratio on their frequency characteristics are discussed in detail.