USE OF COMPUTERS FOR DEVELOPMENT OF MANAGEMENT SKILLS IN A REINFORCED CONCRETE DESIGN COURSE

INTRODUCTION

Much discussion has been directed at the problem of teaching design courses and specifically at the problem of teaching structural courses in construction degree programs. Criticism aimed at courses in concrete, steel, timber and foundations cite an overemphasis on design and a lack of a construction management perspective. In response to concern for building communication skills, some construction educators increased requirements for oral and written reports in construction science courses. A similar approach utilizing computers as the tool may be used to enhance teaching of management skills in structural design courses. By designing computer solutions to problems, students are forced to clearly understand basic concepts of design. Designing a computer solution to a problem requires planning the appropriate calculations, properly sequencing the calculations and anticipation of possible answers for different given values. The management, decision-making and productivity skills learned may be applied in other courses and in future management careers in construction.

The construction degree program at Northeast Louisiana University includes a computer application course taught by the computer science department which includes BASIC programming language, a spreadsheet, word processor and a database program. Students are expected to gain a working knowledge of current software. Incorporating software usage into construction science classes increases opportunities for students to build management skills in problem solving while receiving instruction from an expert on the topic.

The computer spreadsheets included in the Appendices perform tedious calculations in reinforced concrete design. The work was assigned to students in a reinforced concrete design course taught at the School of Construction, Northeast Louisiana Univer­sity in Monroe, Louisiana.

TEACHING METHOD

 Selected problems called Management Skill Builders (MSBs) were assigned. The problems selected were beam analysis, bar development length, column analysis and beam deflections. The MSBs were developed on personal computers using Lotus 1-2-3T^M spreadsheets. Spreadsheets are generally easier to learn than high level computer languages and have built-in printing, formatting, editing and file handling utilities. A hard copy example of an acceptable solution format was provided to show students the required information and a reasonable format for display of the solution. Corresponding homework assignments with calculations performed by hand were assigned and graded. Comparison with the hand calculations provided additional help in development of MSBs. Students were required to turn in diskettes and hard copy solutions to the problems. One class period was used for computer orientation. Students were encouraged to seek help from a manual and from other students.

The MSBs described in this paper draw largely from reference [1]. This paper is not intended as a primer on reinforced concrete. Symbols used are the same as found in ACI 318 and most basic texts on reinforced concrete design except for special symbols used in reference [1]. A legend of symbols is included. For a more detailed explanation of the problems see references [1] and [2].

THE MANAGEMENT SKILL BUILDERS Appendices A, B, C and D are output of the MSBs. User supplied information is surrounded by a double box.

Basic Development Length

The MSB created a table for manual "look-up" of information. The table shown in Figure 1 is for non-top bars in tension and normal density concrete. The students were required to use "IF' statements in the spreadsheet to select the correct equation among four choices for calculation of the tabulated data. The management skill taught was production of tabular reference materials. Possible variations on the MSB are tables for Class A, B and C splice lengths, top bars, bars in compression and deformed wire.

Singly-Reinforced Rectangular Beam

Producing the beam analysis MSB (Figure 2) required application of equations for flexural design by the load factor method for a simple, singly-reinforced concrete beam. Steel ratios that violated American Concrete Institute (ACI) code requirements were "flagged". By substitution, the flexural capacity of beam cross sections may be checked. The management skill taught was development of a design aid for use as an alternative to traditional methods developed for slide rules and hand calculators. Variations of the MSB could include a "look-up" table to check rebar spacing or a MSB for doubly reinforced beams and tees.

Column Anal,

The column analysis MSB (Figure 3) analyzes short rectangular columns with symmetrical cross-sections in strong-axis bending. The balanced failure condition, column load capacity and failure mode were determined. Possible failure modes are: (1) compressive failure, (2) tension failure with yielding of compression steel and (3) tension failure with yielding of tension steel. Traditional manual solution methods treat cases l, 2 and 3 separately. Simplifying assumptions allow direct solutions for cases 1 and 2. Case 3 may only be solved by a tedious trial and error solution because of a cubic equation for the location of the neutral axis. However, the trial and error solution for case 1 also solves case 2 and 3. By varying the column eccentricity, column interaction diagrams may be manually constructed. Development of the MSB requires planning and sequencing of calculations. The management skill taught was reduction of tedious trial and error calculations to manageable problems. Variations of the MSB could include biaxial bending and rebar spacing checks.

Beam Deflection

The beam deflection MSB (Figure 4) calculates maximum dead and live load deflections for simply supported rectangular, singly-reinforced concrete beams with uniform dead and live loads. A major difficulty in beam deflection calculations is likely to be accurate determination of loads. A notable difference between reinforced concrete beams and steel or timber beams is that reinforced concrete beams crack. While the same basic deflection equations for elastic bending are used, the moment of inertia may vary due to beam cracking under load. The MSB must be designed to determine the correct moment of inertia to use with the load under consideration. The management skill taught was allowance for varying conditions in analysis. Variations of the MSB could include doubly-reinforced beams, deflections at varying locations on the beam and comparison of deflection calculations to ACI limits. The dead load (DL) given for the beam in Figure 4 corresponds to the beam weight. The live load (LL) is zero. The given beam was built in the laboratory portion of the course to verify the deflection calculations.

FUTURE DEVELOPMENT

Additional MSB units in reinforced concrete may be developed for shear, torsion, crack control and footings. The MSB method has been used by the author in estimates (quantity take-off), statistics, strengths of material, surveying and concrete mix design.

DISCUSSION

Construction management students in structural design courses have different expectations and goals than design students. Construction managers must learn to communicate effectively with design professionals on a wide variety of topics and an appropriate level of technical detail in order to increase quality and productivity of work.

When judgment is required in making a management decision, memorized solution procedures are not as valuable to construction management students as an understanding of basic design principles.

In order to develop the appropriate algorithm for problem solutions with a computer spreadsheet, students must thoroughly understand problem solution procedures. Students must anticipate the possible range of answers and build in necessary checks for possible errors.

Spreadsheets are easy to learn and have many desirable built-in utilities that increase productivity. Students may use spreadsheets to perform "what if' analysis in structural design. Spreadsheet problem solving skills may be applied in other management areas such as estimating.

Design professionals may choose from a variety of commercial software packages. Customized computer programs are frequently written in high-level computer languages such as BASIC, PASCAL, FORTRAN, C or database languages. These programs may be the most efficient tools for design professionals, but do little to reinforce understanding of basic principles when used by students. MSBs could be written in high-level languages, but high-level languages generally take longer to learn and require greater programming time. A construction manager can rarely justify the use of management time for development of software. For the manager, spreadsheets are the medium of choice.

CONCLUSIONS

1. The MSB units are an effective method for incorporating computer and management skills into a construction science course in reinforced concrete. 2. The exercises used in the class are best suited for solution with computer spreadsheets such as Lotus 1­

2-i^rm or Quattro.

 3. Depending on students' computer skills and facilities available, one to four MSBs could be used in a first course in reinforced concrete design.

REFERENCES

LEGEND

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