International Concrete Abstracts Portal

With the aid of modern digital computers and sophisticated computational techniques such as the finite element method, it is now possible to simulate the structural behavior of an arbitrary reinforced concrete shell structure under general loading through its elastic, cracking, inelastic, and ultimate load ranges, taking into account nonlinear material, nonlinear geometry and time-dependent effects of creep and shrinkage. In this paper, a method of analysis and a computer program based upon a composite layered finite element displacement model are briefly described. The analysis recognizes the nonlinearities due to cracking, nonlinear stress-strain behavior in concrete, yielding of the steel reinforcement and the tension stiffening between cracks. The effects of the countinuously changing structural geometry are taken into account by an updated Lagrangian formulation. The time dependent effects of creep and shrinkage are also included by an initial strain procedure. Numerical results for reinforced concrete shells obtained with the computer program are presented which indicate that in some cases an increase and in other cases a large reduction in the calculated ultimate load occurs as each of the nonlinear factors is included in the computer analysis.

Presents a new computer design environment that allows the designer complete freedom in choosing design options. It combines three common tools--analysis, graphics, and a spreadsheet--into a completely integrated system. The environment allows the designer to take results directly from the analysis database, display them graphically, choose the values to be used for design, and then insert those values automatically into the spreadsheet environment. The spreadsheet can be customized, through the use of templates, to fit any design scheme. A template for the design of singly reinforced concrete beams is presented.

The computer-aided design field is expanding rapidly. There is an abundance of commercial and public domain software that is available. It is no longer necessary to write programs to introduce students to computer-aided design. The availability of spreadsheet programs has added a new dimension to computer-aided design. The principal advantage of a spreadsheet program is that it allows a series of relational steps to be programmed without having to know a programming language or having to write formal program statements. In addition, if a change is made in a particular step of a program, changes are automatically made in steps affected by that change. This can be a significant advantage in teaching reinforced concrete design. Students can use the templates created by the spreadsheet programs to answer "what if" questions about design. In this paper, several programs for the flexural design and shear design of reinforced concrete beams are described. These programs are not written in a programming language but are formulated with a spreadsheet program. The programs were run on a mainframe computer. The basic formulation of a spreadsheet program is described. Advantages of using spreadsheet programs in computer-aided design and their application in undergraduate courses in reinforced concrete design are discussed.

A model for the design of a computer system to support decision making for the design of reinforced concrete structures is proposed. The process of analysis-design-drafting is transformed into a series of integrated operations performed upon a relational database. The computer tools used in structural engineering today are evaluated, and a model for planning their data integration has been developed. Databases are the backbone for the process of systematically storing and retrieving data to accumulate knowledge and support decisions. The focus of the paper is on identifying the requirements of databases suitable for structural analysis and design of reinforced concrete structures. A primer objective for such a database structure is to include data from engineering codes to provide information throughout the design. The importance of incorporating the ACI 318 Code and Commentary is emphasized and its implementation through a relational database is proposed.

A large amount of specialized factual and heuristic knowledge on the relations between the design of concrete mixtures, including the constituents, and the durability of concrete has been gained through research and field experience. Effective dissemination of this knowledge should result in fewer incidents of premature deterioration of concrete. Expert systems appear to be an effective means for transferring the knowledge on the durability of concrete obtained through laboratory and field studies and experiences to engineers and designers responsible for the design, construction, and maintenance of concrete structures. Durcon is a prototype expert system being developed to give recommendations on the selection of constituents for durable concrete. The purpose of developing Durcon is to demonstrate the application of expert systems to improve the process of selecting construction materials. Four major deterioration problems are covered by Durcon: freezing and thawing, corrosion of reinforcing steel, sulfate attack, and alkali-aggregate reactions. This report discusses the approach being followed and the progress being made in developing Durcon. In addition, model systems for recommendations for concrete exposed to corrosive environments and for preventing alkali-aggregate reactions are presented.