A system which integrates architectural and structural design issues for timber connections will be developed for a limited number of connections and loading conditions which are dealt with in various national and international codes and standards. The scope of engineering issues relevant to connections will be expanded to include a wide range of timber connections and engineering solutions which are not covered by code procedures. This will include cases such as 3-dimensional loading configurations, dynamic analysis of connections and more rigorous analysis procedures. Progress on these objectives is described.
Work is underway to prepare a preliminary design of a 3-storey office building using this new modular construction system. This application is helping to understand and improve configurations of prefabricated column and beam modules proposed for the new construction system. The use of standardized prefabricated connections in modules and between modules will contribute to the quality of construction and ease of design. The development of a flexible modular prefabricated construction system based on engineered wood products will also simplify the conceptual design process. The conceptual design of a class of buildings will only require selection of a few specific prefabricated column and beam modules with predetermined load carrying capacities, which may be guaranteed by testing or analysis.
Building construction - Design - Computer simulation
The life cycle of a structure consists of a sequence of typical stages: conceptual design, final design, construction, maintenance, repair and eventual replacement. Decisions regarding durability of the structure made at one stage have certain implications in the following stages. Each stage may involve different people, therefore decision aids should be able to service different users: owners, specifiers, designers, and builders. The objective of this project is to develop computer-based decision aids which will assist specifiers, designers, and builders to satisfy durability requirements of a wood structure during its life cycle.
The complexity of the current timber connection design process is one of the major reasons preventing the wider use of wood products in low-rise non-residential and innovative residential construction. Connections of members in structures, particularly in timber buildings, require the combination of both quantitative and qualitative aspects of design to produce a safe and aesthetically pleasing structure. Knowledge-based expert systems offer designers access to the full range of design methods, allowing the connection design task to be completed with ease and confidence. This study investigates the expert system approach by constructing a framework for such a design aid - a framework that incorporates techniques from artificial intelligence, architecture, and engineering. The design aid has potential for industrial application, and could be developed into an educational tool for timber and wood product design courses at the university level.
Although wood buildings can be built to last, they are still perceived as lacking durability compared to buildings constructed with steel and concrete. Furthermore, in some cases, new materials, conflicts in building bylaws, inappropriate design approaches, poor construction practices and maintenance regimes have combined to cause premature failures in wood-based building systems. Other issues that promote problems include lack of quality control, shortages of trained personnel and attempts to cut construction costs. A major part of the problem appears to be that appropriate design solutions are not being applied either because the knowledge is not available to the people that need it or because customers or designers demand a new look. There is a need to make the existing knowledge available in a user-friendly format, to identify knowledge gaps and perhaps identify needs for improved material properties or innovative design solutions. A system is also needed for decisions made at each stage of the life cycle to be passed on to participants in subsequent stages, thereby facilitating the best possible series of decisions for the durability of the structure. This project will develop computer-based decision aids which will assist specifiers, designers, builders and owners to satisfy the durability requirements of a wood structure during its life cycle. A framework for modeling durability in wood construction has been developed. Three dimensions of the framework are: life cycle considerations, a durability risk assessment model and a performance evaluation model for the building assemblies. The research to date has focused on the first two of these. Ideas for the life cycle and knowledge on the factors affecting the performance of wood systems exposed to intermittent wetting have been assembled through literature review and consultation with experts in the field. Methods for qualifying or quantifying the effect have been developed where possible. A risk assessment model has thus been developed. The performance evaluation model will be used to predict the durability of buildings. It will consider the interaction between different assemblies and the interactions between the parts of each assembly in the context of the risk assessment model. A computer program called Kappa is being used as the platform on which to build the preliminary model. The life cycle of a building consists of conceptual design, final design, construction, maintenance/repairs and demolition. The major tasks, key issues to be considered and the required inputs have been identified for each stage. The risk assessment model considers the demand on durability, the degree of loss due to failure of the system and the durability capacity provided by the specifier, designer, builder and owners. Demand considers the required service life, climate, local conditions, assembly/component exposure, component hazard class (use category) and the impact of design causing durability problems. The degree of loss considers the consequences of failure and the effort required for maintenance and repair. The durability capacity can be controlled through the selection of the appropriate materials, material treatment, design detailing, construction quality, and a maintenance program. The performance evaluation model will be the next part of the project to be addressed. The project is still in progress but already there have been spin-offs in terms of an improved understanding of the interactions among factors impacting the performance of wood construction.