OBJECT-ORIENTED APROACH TO MODELING AND ANALYSIS OF TRUSS STRUCTURES

Wind resistant size optimization of geometrically nonlinear lattice structures using a modified optimality criterion method

An energy balancing strategy for solution of combined geometrical and material nonlinearity problems

A new reduced formulation for modeling elastic structures or structural components with geometric nonlinear- ities is presented. This formulation is obtained as a generalization of the concept of foreshortening, which has been successfully used by other authors to model beams. Some examples are provided that illustrate the generality and validity of this formulation. The proposed theory is compared to previous work related to foreshortening, variable reduction in nonlinear elastic problems, and the use of a geometric stiffness matrix. Some guidelines are also given to implement the proposed method and to interpret the concepts that it involves. The reduction method presented is general, but a corotational approach is followed to simplify the exposition. The use of the foreshortening 9 is another method that has been proposed to solve this problem. This interesting concept provides certain importantcalculation advantagesdespitethat,unfortunately, it has been impossible to generalize structural members other than cantileverbeams.Thepresentpaperdevelopsa generalizationofthe concept of foreshortening that can be applied to any type of struc- ture or structural component with elastic behavior and geometric nonlinearities. The result is a method of structural analysis with variable reduc- tion that provides considerable savings in calculation times, as well as an interesting theoretical model for the purpose of studying these types of problems analytically. In addition, the presented deriva- tion allows a better understanding of the relationships between the different approaches that are used to solve the geometric stiffening problem. 9 Thispaperisorganizedasfollows.First,abriefintroductiontothe foreshortening concept is presented (Sec. II). This is followed by a second-order corotational formulation of elastic structural analysis includinggeometric nonlinearities thatprovideaneasy introduction to the ideas presented (Sec. III). Next, foreshortening is redee ned and generalized in the framework of the structural formulation just mentioned, up to a new reduced formulation of the nonlinear prob- lem (Sec. IV). This derivation is subsequently ree ned, and relevant terms are identie ed and interpreted (Sec. V). A brief description of the particularization of the proposed formalism in the case of a planar cantilever beam (Sec. VI) and the key steps of the numerical algorithmofthestaticproblem (Sec.VII)aresubsequentlyincluded. InSec.VII,itis also explained howto usethepresented formulation togeneratereducedcomponentmodelsvalidformultibodyanalysis. In the succeeding section, the most relevant connections with other derivations where foreshortening or variable reduction are applied are discussed. Finally, some examples are provided that illustrate the potential of this theory (Sec. IX).

Object-oriented technology, including object-oriented analysis (OOA), object-oriented design (OOD), and object-oriented programming (OOP), is a new promising approach to developing software systems to reduce software costs and to increase software extensibility, flexibility, and reusability. Software metrics are widely used to measure software complexity and assure software correctness. This paper proposes a metric to measure object-oriented software. Also, an important factor called URIs, is conducted to build the metric. This approach describes a graph-theoretical method for measuring the complexity of the class hierarchy. The proposed metric shows that inheritance has a close relation with object-oriented software complexity and reveals that misuse of repeated (multiple) inheritance will increase software complexity and be prone to implicit software errors. >

Smart City is one of the Smart Initiatives that tries to provide solutions to parking problems that are found in big cities. The growth of the vehicle population is not matched by the growth of parking infrastructure, which raises various problems such as illegal parking, traffic jams, and driving safety. Thanks to the massive evolution of the Internet of Things, the Smart Parking idea became a breakthrough in solving the growing parking problem. In this paper, we explain the prototype development of the Smart Parking System using the Internet of Things which has three subsystems, namely embedded systems, as well as Android and web-based applications. Smart Parking System’s software was developed using the Object-Oriented Analysis and Design (OOAD) method and has been tested using black-box testing with 41 test cases that were successfully received.

This study aims at improving the constructability of design solutions by inte grating site construction problems, which are related to the design, with the design's main functions. A full process analysis was carried out on the design functions of concrete framed office buildings whereby site problems were traced back to the relevant design stages. Design processes that significantly contribute to these problems were highlighted, along with their data flows. An object‐oriented analysis (OOA) method was then applied to model those processes. Proceedings through the five major activities of Coad & Yourdon's OOA method, a complete OOA model was developed. This technique has proved to be very effective in producing a well structured data model with the consequence of being easily mapped into an object‐oriented development environment. An integrated object‐oriented system was also developed, which attempts to use essential design information, at an early stage of the design process, to improve the constructability of the design.

An object-oriented architecture for extensible structural design software

In recent years, there has been a demand for Web applications with complex functions. In addition, most web applications efficiently manage data based on databases. While the key and critical dimension of developing these Web applications is analysis and design, most object-oriented analysis and design methods do not have a consistent view of the database. In addition, Java Enterprise Edition (EE) -based technologies are used in Web application implementations, but they do not provide any correlation with the database. On the other hand, as users' demands for security increase, security becomes more important. To this end, Java EE and database systems provide security solutions. However, it does not provide any correlation with object-oriented analysis and design methodology. As a result, it is difficult to develop secure web applications in a consistent way from analysis to implementation. In this paper, we propose a consistent software development methodology from analysis to implementation of secure web applications. The proposed software development methodology for web application development uses UMLsec, a security-emphasized modeling language, and object-relational (O-R) mapping for relational database design. It also uses Java servlets and SQL to implement analysis and design results based on role-based access control (RBAC). The software development methodology for the secure web application proposed in this paper has been applied to the development of the online banking system, from the design stage of the user's requirements analysis to the implementation of the web application.

Change Vector Analysis (CVA) is an important change detection method for remote sensing imagery with medium and low resolution. Traditional CVA is a pixel-based method, which is insufficient for high-resolution (HR) imagery. An object-oriented change vector analysis method (OCVA) is proposed in the paper. Image segmentation method was used to get image objects. The object histogtam was extracted as the feature of the image object at different bands. G statistic was employed to measure the distance between the object histograms at two times. Change vector of the object was built by the histogram distance at different bands. The heterogeneity of the object was measured by the magnitude of the object change vector. The threshold to detect change/no change objects was decided by Otsu method which maximizes the variance between change objects and unchanged objects. The experimental results on QuickBird images show that OCVA can make full use of the spatial information in HR images and get higher accuracy than pixel-based CVA.

Object-oriented finite element analysis and programming in VC++

PurposeThis paper aims to present an adaptive approach of the generalized finite element method (GFEM) for transient dynamic analysis of bars and trusses. The adaptive GFEM, previously proposed for free vibration analysis, is used with the modal superposition method to obtain precise time-history responses.Design/methodology/approachThe adaptive GFEM is applied to the transient analysis of bars and trusses. To increase the precision of the results and computational efficiency, the modal matrix is responsible for the decoupling of the dynamic equilibrium equations in the modal superposition method, which is used with only the presence of the problem’s most preponderant modes of vibration. These modes of vibration are identified by a proposed coefficient capable of indicating the influence of each mode on the transient response.FindingsThe proposed approach leads to more accurate results of displacement, velocity and acceleration when compared to the traditional finite element method.Originality/valueIn this paper, the application of the adaptive GFEM to the transient analysis of bars and trusses is presented for the first time. A methodology of identification of the preponderant modes to be retained in the modal matrix is proposed to improve the quality of the solution. The examples showed that the method has a strong potential to solve dynamic analysis problems, as the approach had already proved to be efficient in the modal analysis of different framed structures. A simple way to performh-refinement of truss elements to obtain reference solutions for dynamic problems is also proposed.

Recent successes using object-oriented analysis methods to develop software systems suggest exploiting these techniques for systems engineering of large, complex systems. Unfortunately, object-oriented analysis methods are limited in their ability to model systems performance, one of the key components of the systems engineering process. To overcome these limitations, this paper proposes a systems engineering discipline that involves the integration of object-oriented models (which include information, state transition, and process models) with queueing-based performance simulation models. We discuss several techniques that promote performance modeling of hardware components as shared physical resources accessed by logical software objects. These techniques allow in-depth analysis of functionality, performance, and partitioning early in the requirements and design process which, in turn, reduces the risk, cost, and time involved in building and deploying computer-based systems.

An analysis is described that models the behavior of planar prestressed concrete cable‐stayed bridges up to failure taking into account geometric and material nonlinearities. The geometric nonlinearities arise from cable sag, large deformations of the system, and from the shift of the centroid of the deck section caused by the material or by cracking of the concrete. The effect of the axial forces on the stiffness of the members is also considered. Material nonlinearities are encountered when one or more of the structure components, namely the stay cables, prestressing tendons, the reinforcement, or the concrete, exceed their elastic limits. Parametric studies are made on cable‐stayed bridges with the following cable arrangements: fan, semifan and harp‐type cable arrangement. To demonstrate the influence of the different types of nonlinearity on the internal forces and reactions three analyses were performed—namely elastic, geometric nonlinear, and geometric and material nonlinear analyses—and the results...

The monograph is devoted to the study of differential equations (DEs) describing wave processes in inhomogeneous media, properties of families of curves and surfaces using group and geometric analysis. The equivalence group of the eikonal equation and other differential equations and its differential invariants are studied. On this basis, a group stratification of a wide DE class, new differential identities, a new description of the kinematic seismic problem, exact solutions, relationships between different DEs, differential conservation laws for the eikonal equations, hydrodynamics, families of curves and surfaces, etc. are obtained. These results reveal a number of new possibilities of group and geometric analysis. The monograph is intended for specialists, graduate and undergraduate students specializing in the methods of mathematical physics, group and geometric analysis and their applications.

CALEB is a nonlinear finite element program for geometric and material nonlinear analysis of offshore platforms and general framed structures. The finite element formulations implemented in CALEB assumes large displacements and small strain. Geometric nonlinearity is taken into account by means of an updated Lagrangian formulation. Material nonlinearity is taken into account by means of an elastic perfectly plastic model derived from plastic hinge theory. Capabilities of CALEB version 1.4, the current release of CALEB, include: pre-processor for mesh refinement, problem-oriented language input, distributed member loads, automatic generation of environmental loads, joint failure check, save/restart procedure, eigenvalue buckling analysis, nonlinear stress analysis, and graphical post- processing. In this paper a brief description of CALEB version 1.4 and of its main features is presented.