ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00410.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00411.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:The paper examines constraint strategies appropriate for modeling three‐dimensional geometry in civil engineering design. Despite potential advantages, computer based geometric models are seldom used from the early stages of design since they are difficult to modify; this is because conventional models describe the results of design decisions rather than the intent. To support powerful modification operations, a model must incorporate constraints describing geometric intent; this allows geometric modifications to be propagated through an assembly so that the constraints are maintained. During the past decade, there has been significant research in geometric constraints. The paper reviews this research and identifies three basic constraint approaches: (1) the algebraic approach, which represents constraints as equations; (2) the deductive approach, which represents constraints as logical predicates; and (3) the constructive approach, which represents constraints as geometric operations. Since much of this research is oriented toward machine design, the paper compares modeling issues in machine design and civil engineering design in order to identify important research areas. These areas include the following two aspects of constraint organization: (1) hierarchical constraints, creating and manipulating constraints in meaningful groups; and (2) assembly constraints, defining constraints on the overall geometry of an assembl

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00412.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:Analysis is one of the key issues in realizing complex large structures. In spite of the tremendous accumulation of methods and theories in the field of structural analysis, there is still a need to include newly developed methodologies into analysis codes for production use. This paper describes the initial development of a platform to accommodate the future needs in this area. The system being developed is a knowledge‐based system which first accepts the user's description of an analysis problem, comes up with a suitable analysis method and a corresponding computational algorithm, then develops a program along with input data to solve the problem, and finally gives a result to the user. Program generation is done by selecting appropriate building‐block codes from a program database. To construct a prototype system, a problem solving model called an ‘organizational model’ is introduced, which is developed to imitate the problem solving in a real life. The main part of the system, which functions as described above, is written in CLOS (common LISP Object System), while generated codes are written in either FORTRAN or C++. The performance of the prototype system shows that this approach can be ef

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00413.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:In this paper, a support system of optimum aseismic design is proposed on the basis of fuzzy set theory and a graphical representation method. In optimum aseismic design of buildings, it is necessary to take account of subjective evaluation of users. In this system, a hierarchical model is employed to idealize and model the decision process of optimum aseismic design. By applying fuzzy set theory, this system can take account of subjective evaluation of users. The system is a prototype of an expert system for optimum aseismic design, and its knowledge is compiled interactively as numerical values by the fuzzy confluence rule and membership functions in fuzzy set theory in accordance with the hierarchical model given by users. Knowledge, which is necessary to perform the inference on optimum aseismic design, is acquired interactively. Optimization is performed by fuzzy multiobjective maximizing decision, and the maximum evaluation values of the top attribute can be found. Furthermore, distributions of the grade of membership value in maximizing the decision process are graphically represented, so the user can understand this process easily and intuitively. A case study is carried out for a reinforced concrete typical high school building in Kobe City.

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00414.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:This paper introduces the application of a robot to CO2gas shielded arc welding in the construction of steel structures. In shop welding, using horizontal position welding makes the construction process easier and more efficient. Technically, however, horizontal position welding is more difficult than the flat position one. So we have developed a horizontal position multilayer welding system by introducing a robot to the CO2gas shielded arc welding of steel structures where semiautomatic welding has been used. The situation where we can use this welding robot is in a single beveled horizontal position butt weld in a steel structure. In this paper, first we explain the structure of a welding robot system, followed by the results of a mechanical property test consisting of a tensile, impact test (based on the Japan Industrial Standard) and a full‐size three‐point bending test. These results were as good as those for semiautomatic welding. Using this horizontal position multilayer welding robot system, the burden of the welding operator will be reduced, and we will be able to obtain more easily constant high‐performance horizontal position we

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00415.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:Recently, designs of high‐rise buildings have become more complex. Various types of buildings result, such as buildings with a semicircular plan, and buildings in which the upper floors are larger than the lower floors.The authors have developed a three‐dimensional (3‐D) dynamic analysis system, ‘Super DYNAMICS’, which considers the nonlinear behavior of each structural member in order to analyze the structural behavior of such complex steel buildings under severe earthquakes.This system is mainly operated on a supercomputer because of the large number of calculations required for the member level dynamic analysis.This paper first describes the general concepts of the system and the 3‐D dynamic response analysis methods, based on the nonlinear behavior of each member under axial force and biaxial bending moments, and then examines and demonstrates the precision of the yield surface of steel members created by multispring models, and the ability of the system to trace the behavior of members and frames after yielding. It shows, in addition, actual examples of a static and a dynamic analysis by three‐direction ground motion applied to a 19‐story steel‐frame

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00416.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:A computational model that simulates human behavior under fire and earthquake emergencies has been developed, using the object‐oriented language Smalltalk‐80. The present model consists of a space model, a scenario model and a human model. In the space model, the spaces in which people can move are represented by nodes connected by links. The nodes incorporate exit, guidelight and staircase facility data. Also, they feature environmental data including the darkness of the lighting system and the density of smoke. Seismic hazards such as a power failure and occurrence and expansion of fire and smoke are represented in the scenario model. This kind of information is then furnished from the scenario model to the space model as obstruction information. In the human model, a suitable knowledge‐based model has been constructed for representing evacuation behavior: people choose the evacuation path based on the production rules with certainty values, and move to the target exit along the evacuation links. The present simulation model is experimentally applied to examine the behavior which masses of people take in an underground structure under an emergency condition caused by an earthquake, and the results obtained confirm that the model is able to simulate correctly the principal human behavior enacted in an emergency evacu

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00417.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:Acquisition of structural design knowledge for knowledge‐based systems is difficult because humans acquire their design knowledge through years of experience, resulting in a diverse, unstructured and implicit body of knowledge. Research and development of knowledge bases for structural design have identified distinguishing characteristics of design knowledge. One approach to acquiring design knowledge using machine learning techniques is to transform design examples into a generalized representation of design knowledge. In this paper, we suggest the use of a dependency network as the generalized representation. A four‐step learning process is presented: grouping design variables into skeletal concepts, learning default values and values ranges for each variable, deriving relationships among numerical valued variables, and learning patterns among nominal valued variables. The resulting representation provides a basis for producing an initial design given a set of design requireme

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00418.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

Abstract:This paper presents a computer‐aided construction process program based on a heuristic research knowledge‐based system, logical procedures for constraints propagation, as well as on operational research algorithms. The system is interactive: it is the user, not the program, who controls the heuristic research. Furthermore, it is graphics oriented: a reflexive architecture between the knowledge‐based system and a geometrical modeller allows permanent graphic visualization of the work in progress. The application presented includes a variety of operations, ranging from the geometric modelling of the architectural project to the intelligent analysis of its structure, its division into component types (e.g. shuttering posts, beams, floors, walls) and the planning of the construction process (production cycles, tasks scheduling).Tested by engineers of a private international building company, the system has now received new implementations, which allow us to simulate different technologies and modify very rapidly many various parameters, thus giving to the users a real computer‐aided construction process envi

ISSN:1093-9687    

DOI:10.1111/j.1467-8667.1992.tb00419.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY