Analysis Of Truss Structures Research Articles

Reliability analysis of truss structures considering complete failure paths and using the FLHB model

abstract: The study of progressive collapse of structures using numerical models requires accurate modeling of geometrical nonlinearity and material failure behavior. Numerical models must demonstrate stability, such that localized member failures do not trigger numerical instabilities. Also, algorithms should be efficient, to limit the computational burden of analyzing multiple responses when considering the effects of uncertain loads, geometric and material variables. In this scientific domain, a comprehensive non-linear ductile-damage truss-element model has been recently presented by the authors. The model accounts for the geometrical and material nonlinearities observed during progressive collapse of structural systems. In this paper, the Felipe-Leonel-Haach-Beck (FLHB) model is calibrated to describe the response of Ultra-High-Performance Fiber Reinforced Concrete (UHPFRC). Based on a limited number of UHPFRC experimental curves, statistics of FLHB model parameters are obtained. These are employed in the probabilistic analysis of failure paths of truss structures under progressive collapse. Monte Carlo Simulation and the First Order Reliability Method are employed in the probabilistic failure path analyses. Six application examples demonstrate the accuracy, robustness, and efficiency of the FLHB model in evaluation of failure paths of realistic structural systems.

Método rotacional para el análisis estructural de armaduras


 Objetivo: Proponer un método innovador y práctico para realizar el análisis estructural de armaduras con la intención de facilitar y simplificar el análisis estructural, y de esta forma constituirlo en una herramienta alterna de análisis de este tipo de estructuras. Metodología: Primero se presenta la fundamentación analítica y conceptual del tema. Seguidamente, se propone un procedimiento paso a paso, ejecutado sobre una nueva representación paramétrica, que simplifica el problema a resolver. Luego se desarrolla un ejemplo de análisis de una ménsula de concreto reforzado, la cual fue idealizada con el método de la biela. Finalmente, y con la intención de comparar la simplicidad y tiempo de solución del método propuesto, este es comparado con una solución analítica tradicional. Resultados: La metodología propuesta simplifica el análisis estructural de armaduras, además de ser eficiente, confiable y versátil. El método requiere, en concreto, un menor tiempo de solución y cálculos en comparación con los métodos analíticos tradicionales de solución de sistemas lineales de ecuaciones. Conclusiones: El método rotacional es apropiado para realizar el análisis estructural de armaduras, pues simplifica la solución analítica de este tipo de estructuras. El método rotacional es más versátil y eficiente, y puede usarse en el análisis estructural de armaduras estáticamente determinadas.

Plastic Limit Analysis of Truss Structures Subjected to Progressive Collapse

In this paper, a method to generate the required basic mechanisms in a plastic limit analysis of truss structures subjected to progressive collapse is presented. Rigid body motion of all members is introduced by constraint equations and at the same time releases are introduced. A set of basic mechanisms is obtained by solving the generated set of equations. Additional modification is necessary to put the mechanisms in the usual form of relative deformations for each member. The joint geometry of the structure and the member connectivity are the requirements of the proposed method. The method is thus applicable for programming and omits the hand generation process of the basic mechanisms in a limit analysis.

Vulnerability analysis of truss structure by an improved sensitivity index method

Vulnerability analysis of truss structure by an improved sensitivity index method

유전 알고리즘을 이용한 트러스 구조물 손상탐지

본 연구에서는 유전 알고리즘(GA, Genetic Algorithm)을 이용하여 트러스 구조물에서 부재의 특성변화에 의한 손상탐지를 확인하였다. 구조물의 손상 탐지를 위하여 트러스 구조물을 모델링하여 특정 부재의 탄성계수를 감소시킴으로써 구조물의 손상을 결정하였다. 트러스 구조물의 해석은 특정 하중이 가하여졌을 경우의 정적 해석을 통하여 수행하였으며, 구조물의 손상 위치와 정도는 손상을 입기전의 구조물과 손상을 입은 구조물의 각 부재 변형률의 차이를 마이크로 유전 알고리즘을 통하여 비교 분석하여 탐지하였다. 본 연구에서는 트러스 구조물의 수치 해석 예제를 모델링하여 마이크로 유전 알고리즘을 이용하여 손상 탐지를 수행하였으며, 이를 통하여 구조물의 손상 위치와 정도가 탐지되는 것을 확인하였다. This study identifies the damage detection of truss structures by using genetic algorithm(GA) from changed elements properties. To model the damaged truss structures, the modulus of elasticity of some specific elements is reduced. The analysis of truss structures is performed with static analysis by applying uniform load, and the location and extent of structural damage is detected by comparing the stain of each element of healthy truss structures with damaged truss structures using genetic algorithm. In this study, some numerical examples are presented to detect the location and extent of damage using genetic algorithm.

Artificial neural network-based response surface methods for reliability analysis of pre-stressed concrete bridges

Two artificial neural network (ANN)-based response surface methods for reliability analysis of pre-stressed concrete bridges are presented. The first method is the traditional ANN-based response surface method, originally introduced by Papadrakakis et al. in 1996 (Papadrakakis, M., Papadopoulos, V. and Lagaro, N., 1996. Structural reliability analysis of elastic-plastic structures using neural network and Monte carlo simulation. Computer Methods in Applied Mechanics and Engineering, 136, 145–163), which is applied here to the reliability analysis of pre-stressed concrete bridges. The second method is an improved ANN-based response surface method developed recently by the authors for the reliability analysis of truss structures, in which the key idea is that the uniform design method (UDM) is adopted to select training data for establishing an ANN model, thereby greatly improving the quality of training datasets for establishing an ANN model and dramatically reducing the required number of training datasets. There are two main objectives of the present work. Firstly, an attempt is made to extensively examine the performance of the traditional ANN-based response surface method since no detailed study has been carried out to investigate the effectiveness of this ANN-based response surface method on the basis of the reliability analysis of complicated structures such as pre-stressed concrete bridges. Secondly, the recently developed ANN-based response surface method is extended to the reliability analysis of pre-stressed concrete bridges. A detailed numerical investigation is carried out to compare the performance of the two methods.

Interval Finite Element Computation Based on INTLAB for Statical Analysis of Truss Structures with Large Uncertainties

Nondeterministic Linear Static Finite Element Analysis: An Interval Approach A Thesis Presented to The Academic Faculty By Hao Zhang School of Civil and Environmental Engineering Georgia Institute of Technology December 2005

Probabilistic and Interval Static Response Analysis of Truss Structures with Uncertain Parameters

This paper presents the random factor method (RFM) and interval factor method (IFM) for the static analysis of truss structures with uncertainty. From the static governing equations of finite element method, the computational expressions for the mean value and standard deviation of structural displacement and stress are developed by using the RFM. The computational expressions for the lower and upper bounds of structural static response are also derived by means of the interval operations when system parameters are interval variables. The effect of uncertainty of individual structural parameters and loads on structural static response is demonstrated by truss structures.

Interval dynamic response analysis of structures with interval parameters

Dynamic response analysis of truss structures with interval parameters under interval loads are investigated using a new method called the interval factor method (IFM). Using the IFM, the structural physical parameters, geometric dimensions, and loads can be considered as interval variables. The structural stiffness and mass matrices can then, respectively, be described by the product of two parts corresponding to the deterministic matrix and the interval factors of structural parameters. The computational expressions for the midpoint value, lower and upper bounds of the structural dynamic responses are derived by means of the mode superposition method and interval operations. The influences of the uncertainty of the structural parameters and loads on the structural dynamic responses are demonstrated by using truss structures.

Probabilistic dynamic analysis of truss structures

The problem of dynamic analysis of truss structures based on probability is studied in this paper. Considering the randomness of both physical parameters (elastic module and mass density) of structural materials and geometric dimension of bars respectively or simultaneously, the stiffness and mass matrixes of the elements and structure have been built. The structure dynamic characteristic based on probability is analyzed, and the expressions of numeral characteristics of inherence frequency random variable are derived from the Rayleigh`s quotient. The method of structural dynamic analysis based on probability is developed. Finally, two examples are given.

Sensitivity analysis of truss structures (virtual distortion method approach)

A novel approach to sensitivity analysis of frame structures based on the virtual distortion method (VDM) has been presented. The sensitivity analysis has been performed for elasto-plastic material behaviour with respect to selected structural parameters e.g. cross-sectional area, hardening/softening coefficient and yield stress. Advantages of applying the virtual distortion method to sensitivity analysis have been emphasised i.e. making use of the so-called influence matrix, constant for the whole analysis and solving only local sets of equations corresponding to plastic locations. Theoretical background as well as the whole variety of examples has been presented. Copyright © 2001 John Wiley & Sons, Ltd.

Analysis of truss structures using distributed object-oriented methods

Analysis of truss structures using distributed object-oriented methods

Analysis of truss structures using distributed object-oriented methods

Objected-oriented analysis methods are developed for distributed finite element analysis of truss structures. The method is based on distributed solution of finite element equations using the substructuring method. Objects for static analysis of truss structures are identified and presented in a pseudocode form. The developed techniques are implemented in a network of workstations. A software tool called the IDL-C++ (RPC) compiler has been developed to aid the programmer in constructing distributed object applications. The speedup/performance for moderate size problems is presented to illustrate the present approach for truss analysis using distributed object-oriented methods.

Design Sensitivity Analysis of Truss Structures with Elastoplastic Material*

ABSTRACT A continuum-based design sensitivity analysis (DSA) method is presented for configuration (or layout) design of nonlinear structural systems with rate-independent elastoplastic material. Configuration design variables are characterized by shape and orientation changes of the structural component. A continuum-based shape DSA method that utilizes the material derivative of continuum mechanics is extended to account for effects of shape and orientation variations. The incremental analysis method, with updated Lagrangian formulation, is used to derive the design sensitivity for the nonlinear structural system. To derive the design sensitivity, incremental energy and load forms are utilized. The first variations of energy and load forms and the static response with respect to configuration design variables are described using the material derivative. Direct differentiation is utilized to obtain the first variation of the performance measure explicitly in terms of variations of configuration design var...

Object-oriented approach to modeling and analysis of truss structures

Object-oriented structural and geometric analysis methods for truss structures are proposed. The methods are based on the iterative relaxation of nodal unbalanced forces by moving the nodes. The entities appeared in truss analysis are modeled as classes, and their class hierarchy is established. The knowledge about a truss node, a truss member, a material, and a sectional shape of the member are extracted and constructed as a knowledge base in an object-oriented manner. The object-oriented structural analysis is found to be valid for material and geometric nonlinearities, and the object-oriented geometric analysis where a kinematic problem is converted into a problem for a force equilibrium at the nodes is also found to be effective for determining the geometry of variable geometry trusses. The whole system is written in an object-oriented language, Smalltalk, and several results on structural and geometric analysis are presented. The speed of the computation is discussed along with the size of the structures and the over-relaxation factor. The extension of the knowledge base is also discussed.

Inelastic post‐buckling analysis of truss structures by dynamic relaxation method

AbstractThe paper presents the inelastic post‐buckling analysis of truss structures by the Dynamic Relaxation (DR) method. A simplified inelastic finite element formulation for truss element and new algorithms are proposed for Elastic Post‐Buckling (EPB) analysis and Inelastic Post‐Buckling (IEPB) analysis using the DR method. The post‐buckling paths for elastic, EPB and IEPB analyses are completely traced using the variable‐arc‐length method. Four numerical examples are presented to illustrate the application of the proposed algorithms.

Discussion of “ An Event‐to‐Event Strategy for Nonlinear Analysis of Truss Structures. I ” by A. Karamchandani and C. A. Cornell (April, 1992, Vol. 118, No. 4)

Discussion of “ <i>An Event‐to‐Event Strategy for Nonlinear Analysis of Truss Structures. I</i> ” by A. Karamchandani and C. A. Cornell (April, 1992, Vol. 118, No. 4)

Closure to “ An Event‐to‐Event Strategy for Nonlinear Analysis of Truss Structures. I ” by A. Karamchandani and C. A. Cornell (April, 1992, Vol. 118, No. 4)

Closure to “ <i>An Event‐to‐Event Strategy for Nonlinear Analysis of Truss Structures. I</i> ” by A. Karamchandani and C. A. Cornell (April, 1992, Vol. 118, No. 4)

Computation of Critical Initial Imperfection of Truss Structures

A method for computing the critical (worst) initial imperfection of elastic truss structures is presented, on the basis of a previous work of the writers. This method can deal with initial imperfections of various properties, including loading pattern vectors, nodal initial position vectors, initial member length, and the product of Young's modulus and cross‐sectional area. Imperfection sensitivity matrices, which express the effects of initial imperfections, are computed compatibly with the method of finite element analysis of truss structures. Critical initial imperfections of a reticulated elastic truss dome structure are investigated in detail as a numerical example. The effects of various kinds of initial imperfections are compared quantitatively. It is shown that the load‐bearing capacity computed for the critical initial imperfection gives the lower bound on the capacity for the imperfections chosen at random. The present method is less costly and more accurate than the method of random imperfections.

Sensitivity analysis of truss structures and its application to the fully stressed design

Based upon the theorems of structural variations this paper derives a set of expressions for calculating partial derivatives of internal forces, stresses and joint displacements with respect to bar areas for truss structures. Compared with the known formulas for finding the gradients of structural behaviours the calculation effort with the proposed expressions in this paper is usually smaller because the additional virtual loadings needed are relatively fewer. It is of practical significance to various optimization methods in which the calculation of gradients of behaviours is widely used. Moreover, applying the derived formulas to the fully stressed design (FSD), we obtain an improved iterative method for FSD. The numerical examples show that the new method considerably reduces the reanalysis number required to converge to an FSD in comparison with the simple stress ratio method.