International Concrete Abstracts Portal

A computational procedure is described for determining nonlinear response of a building system subjected to earthquake motion. The method is sufficiently simple for use with a microcomputer because system response is expressed in terms of a single generalized coordinate. Deflected shapes for the systems are assumed to be invariant for all amplitudes of motion. The equation of motion is integrated for each instant of response on the basis of a normalized relation between base shear and top-level deflection. The hysteretic relation is constructed for each new cycle using cubic segments to express a path from initial unloading through force and deflection reversals to the point of maximum deflection. The base motion is selected from a menu of earthquake records stored on diskette. Results displayed on screen consist of histories of acceleration at the top-level and maximum interstory drift, and the computed force-deflection relation.

The microcomputer and associated digital technology has changed the way things are done both in the structural laboratory and in the field. The impact of microcomputers on the science of field measurement is mainly with regard to cost and time. The many benefits of field monitoring of structures are now available at an acceptable cost. Cost is reduced due to automatic recording rather than manual methods. This paper discusses the benefits of field monitoring during construction and the life of the structure. Two proven measuring systems are described in detail. The paper also describes a system for dynamic analysis of structures. The reduced cost of determining the behavior of buildings and bridges is not the only benefit of these three new measuring systems. Data returned for analysis are in a form that can be quickly reduced and evaluated by computer. A short turn-around time means that the behavior data are available when needed.

Microcomputer applications are continually expanding into new fields, including the area of concrete construction. The dissemination of information concerning these applications promotes their growth and development and benefits the construction industry. When the Bureau of Reclamation began planning Upper Stillwater Dam, the largest roller-compacted concrete (RCC) dam to date in the U.S., due consideration was given to the management of the myriad of concrete test data that would be generated during this rapid method of construction. Using a microcomputer system to facilitate proper treatment of these data would serve several important purposes: 1) provide an overall view of quality control of the RCC, and act as a quality assurance tool; 2) provide a quick method for updating mix design quantities based on variations in materials; and 3) provide access to the data for a comprehensive review of this state-of-the-art method of construction. Both the programming structure and the capabilities of the program will be discussed. The qualifications for developing an RCC quality control system required that the program be user friendly so that it could be readily used by construction inspectors and laboratory technicians. The system provides record keeping for all RCC tests and RCC materials tests, including concrete unit weight, concrete consistency measurements by vibrating table, nuclear density readings, cylinder compressive brake strengths, and aggregate gradations and moisture contents. The program also calculates adjusted mix proportions based on moisture content and clean separation of the aggregate. The RCC quality control system is written in dBASE III, and the host is an IBM-XT microcomputer. The system is connected to a mainframe computer in Denver via modem so that data can be periodically reviewed by designers and for long-term storage.

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.