Claude Bédard

Wind-induced interference effects on buildings - a review of the state-of-the-art

The evaluation of wind loads on buildings is carried out mainly by using codes and standards, whose specifications are generally based on wind tunnel tests performed on isolated structures in an open terrain. However, it has been shown by several researchers that wind loads on buildings in realistic environments may be considerably different from those measured on isolated buildings. Neighbouring structures may either decrease or increase the flow-induced forces on a building, depending mainly on the geometry and arrangement of these structures, their orientation with respect to the direction of flow and upstream terrain conditions. Therefore, this effect, commonly known as interference, must be properly assessed by designers and planners. This paper reviews and analyzes over six decades of work pertaining to interference effects. In addition to highlighting the seriousness of the problem, the analysis has found inconsistencies in the results and incoherence among various studies. A few attempts to provide general recommendations have not been successful, due to the complex nature of the problem and the large variation among various studies. It is, therefore, imperative to tackle the problem of interference in a systematic manner in order to propose a generalized set of guidelines that will be of practical use to building designers and planners.

Wind environment around buildings: A knowledge-based approach

Abstract Tall buildings may create inhospitable or even dangerous wind environmental conditions at street level. Reported in this paper are recent experimental results obtained from a boundary layer wind tunnel study for pedestrian-level winds around buildings. These data with additional literature information are generalized and organized to form the knowledge base for an expert system designed for evaluating wind environmental conditions at the pedestrian level around buildings. This study shows the knowledge-based approach is suitable to provide information about wind environmental conditions for preliminary building design and city planning.

Specifications for computer-aided conceptual building design

Abstract The relative absence of computer support in conceptual building design deprives designers of advanced capabilities for the manipulation, organization and representation of design data. Such capabilities would be highly beneficial to the design process, particularly when designers from different specialties must work together to provide the best possible design solution. We look into how designers work during conceptual design with particular attention on how information is manipulated and organized. We then draw specifications for the creation of a computer tool to support such an early design stage.

Modelling wind-induced interference effects using backpropagation neural networks

The modification of wind loads on a building due to adjacent buildings known as interference, can be quite significant. Interference effects depend mainly on the geometry and arrangement of adjacent buildings, their orientation with respect to the direction of flow and the upstream terrain conditions. Data collected through the literature on wind-induced interference effects on buildings has been analysed and compared in order to identify common points of agreement and areas of concern. Given the limited and sometimes inconsistent available data coupled with a large number of variables involved, empirical generalizations are difficult to obtain. In order to overcome these limitations the paper suggests a neural network approach for the assessment of wind-induced interference effects on design loads for buildings.

Knowledge-based system approach to building envelope design

Abstract Building envelope design is a decision-making process requiring expertise for the selection of materials and constructional systems. The number of alternatives and performance attributes to be considered in design is so large that the designer cannot efficiently evaluate them without computerized assistance in information handling and decision making. Developments in artificial intelligence and knowledge-representation methodologies have shown that computer programs can be constructed for solving ill-structured design problems. Following this approach, a building envelope design system has been developed to assist the designer in selecting materials and constructional systems. A knowledge base containing information on performance requirements and constraints from building codes is interfaced with a database of material properties to solve the information handling problem. Feasible design alternatives are thus synthesized following a ‘plan—generate—test’ strategy with multiple levels of constraint checking. The designer has the option of modifying or updating the knowledge base, adding more information to the material properties databse or defining preferences or performance attributes during the evaluation process. The designer-specified preferences can be used in ranking the alternatives to identify an overall best design alternative. This paper presents the methodology and implementation details of a knowledge-based design assistant for the selection of materials and constructional systems for the building envelope. A review of the building envelope design process, design alternative generation and evaluation methodologies is also presented.

Shared conceptual model for the building envelope design process

Abstract The lack of communication and co-ordination among designers during the building envelope design process results in sub-optimal solutions leading to inadequate performance. To reverse this trend and to achieve better performance of the building envelope, professionals must be provided with computer integrated design tools which facilitate communication between participants and improve the transfer of data throughout the design process. This article presents a shared conceptual model that would enable integration in the building envelope design process. The wealth of data is organized into major envelope entities which are then decomposed into cohesive sets of data called primitives to form the conceptual model. Such a conceptual model should facilitate data exchange between design tasks, improve communications among designers and support the growth of data as the design process unfolds. The resulting conceptual model is implemented as a shared central database in an object-oriented database management system to experiment with integration.

Functional analysis of the preliminary building envelope design process

Abstract Integration in the building envelope design process has the potential to reduce the number of envelope deficiencies since it can improve communication among participants and minimize the fragmentation inherent to the building industry. This paper presents the first mandatory steps in creating a computerized approach to support integrated building envelope design : the functional analysis. The envelope design process is described and the principal design requirements are explained and put in context.

On the adoption of computing and IT by industry: the case for integration in early building design

Civil engineers were among the first professionals to embrace computerization more than 50 years ago. However computing applications in construction have been in general unevenly distributed across the industry. The significance of such a situation cannot be overstated, particularly in the North American context where fragmentation plagues the structure and the mode of operation of the industry. The paper attempts first to characterize the adoption of computing and IT tools by the industry, to describe the current status of this penetration as well as factors that prevent the practice from embracing the new technologies. Integrative approaches may hold the key to the development of a new generation of computing and IT tools that counteract effectively fragmentation in the industry. An on-going research project is briefly described to illustrate recent developments in the area of collaborative work and integration across disciplines for the conceptual design of building structures.

Approximate methods of structural analysis and design in a knowledge-based system environment

Abstract A knowledge-based system (KBS) is developed for assistance at the preliminary stage of multistorey office building design. The system generates overall building configurations and then compatible structural system alternatives. The process of structural configuration is followed by an approximate design solution for structural sizing. The approach used in the implementation of approximate methods of structural analysis in a KBS environment is also illustrated by an example.

Interpolation function of a general triangular mid-edge finite element

Abstract An interpolation function for triangular mid-edge finite elements is developed using an algebraic interpolation approach. A convenient method for deriving shape functions of serendipity type directly and explicitly arises aslo from the interpolation function proposed above.