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 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.

Spreadsheet programming is presented as a new programming alternative for solving daily calculations in the engineering design office. Two spreadsheet programs with different applications are used to introduce the reader to this technique. A retaining wall template demonstrates the advantage of altering one design parameter and seeing the results propagate instantly, thus leaving the engineer with a very responsive tool. A prestressed bridge template organizes in separate windows the engineering design process involved in the prestress design. The template is written according to the design requirements of AASHTO. It allows the engineer to verify different alternatives in the design of the concrete girder, hence leading to a manually optimized section.

A finite element procedure is presented for the analysis of reinforced concrete shearwalls. The wall is idealized as a two-dimensional structure, and the global behavior of the wall under static loading conditions is emphasized. A combination of a new family of higher-order quadrilateral elements and beam elements is employed in the finite element discretization of the wall. Constitutive models of material behavior are based on the nonlinear elasticity. The main material nonlinear effects accounted for in the analysis are the tensile cracking, the biaxial compressive response of concrete, and the yielding of steel reinforcement. A smeared approach is used in the representation of concrete cracking and steel bars. Simplified uniaxial and biaxial material models for reinforced concrete are developed and presented in detail. The incremental-iterative nonlinear solution techniques employ both constant and variable stiffness with the option of selective updating of the stiffness matrix in the load increment. Numerical examples are presented and compared with other existing solutions.

Presents an algorithm for a program code for the analysis of concrete columns reinforced with nonprestressed reinforcement, prestressed reinforcement, or both. The algorithm can be used to generate the coordinates of the load-moment interaction diagram for the section chosen in terms of shape; material properties; and type, amount and location of nonprestressed and prestressed reinforcement. Three shapes--namely rectangular, T, and I--can be analyzed. Hollow-core wall panels can be analyzed by converting them to equivalent I-sections. The lateral reinforcement could be ties, spirals, or none. The program can also be coded to reanalyze the section for revised partial input. This capability aids the designer in generating the loads and moment for, say, a different compressive strength of concrete without reinputting the entire design data. The load-moment values can be printed to look like the load-moment interaction diagram. The various assumptions involved, the equations, and the sequence of calculations are explained using a number of flow charts. A procedure is outlined for using the program for design purposes. Example problems are provided to illustrate the input-output variables. The program code, written in BASIC for Apple desktop computer, can be obtained from the author. The algorithm deals with only the strength aspect. The serviceability aspect, especially for prestressed columns, should be checked separately.