Temporary Construction Structures Coursework

Neil D. Opfer and John A. Gambatese

University of Nevada, Las Vegas

Las Vegas, Nevada

This paper highlights the importance of temporary construction structures in the construction process and its need for curriculum inclusion. It states the major factors and issues involved in the development of this type of coursework.

Key Words: Construction curriculum, construction management, temporary construction structures, structures.

Introduction

Temporary construction structures comprise those elements of the construction process which include such items as formwork, falsework/shoring, scaffolding, rigging, braced cuts, runways, and platforms. Temporary construction structures can be a significant cost segment on many projects and in some cases exceeding the actual cost of the in-place construction item such as with concrete formwork. These temporary structures can pose substantial challenges for the contractor since they are very seldom addressed in the project documents by the project design professional. The lack of design plans and specifications to govern these structures leaves a large number of choices open to the project contractor. Since no plans and specifications typically govern in this area, contractors can make serious safety and other mistakes in delegating this work to field crews. The historical development in the main of temporary structures is that they were constructed of wood by carpenters with minimal construction equipment support such as crane assistance. Facilities have become more complex along with an increasingly competitive construction environment. This changing environment means more demands on temporary structures plus material choice variety and more capable construction equipment. The combination of these aforementioned factors dictates a high degree of focus by construction management personnel. Therefore, construction management students need a fundamental background in this area. Temporary structures require design decisions made in the context of not only cost but interrelated issues of project schedule/cycle times and equipment support.

Most construction programs contain coursework requiring the students to learn structural design principles. Oftentimes the students do not realize the future applications of the structural concepts covered in these courses. In some instances, course instruction emphasizes theory and abstract concepts that confuse rather than clarify structural principles for students. Students need both theory and applications. Some students may conclude from their own limited backgrounds that they will not be involved in the design of buildings and therefore this coursework is "irrelevant." Unfortunately, these same students fail to realize the construction importance of understanding structures plus such aspects as value engineering where this knowledge is useful. The benefit of temporary construction structures coursework is that students can apply structural principles to actual items that they may have responsible charge of in the field. Moreover, temporary structures are an item that they will have to design or have designed in the absence of furnished plans and specifications unlike the project’s design documents. Of course, some students answer every difficult technical subject area with the response, "I’ll hire a consultant or that will be the subcontractor’s job." The counterpoint to this line of reasoning is that who can predict the future? Someday, that student may be working for just that subcontractor.

Temporary structures provide a significant element of difference from standard structures course principles as taught to construction majors in that certain loads such as for construction equipment have a dynamic component. Other loads such as fresh concrete on concrete formwork systems can vary significantly depending on placement rate and temperature. Construction management personnel not understanding these issues can experience significant problems including serious site accidents when substandard practices lead to failure. Just a cursory review of OSHA standards governing construction provides numerous examples of regulations governing these structures.

Paper Objective

The prime objective of this paper is to describe the key elements of this course in temporary construction structures. For faculty at other institutions teaching in this area, the paper may provide ideas for course revision. A course outline is included in the appendix to the paper.

Construction Management Course Placement

At our institution, the course is listed as CEM 432 Temporary Construction Structures. The enrollment for the course is limited to seniors majoring in construction management that have had as course prerequisites CEM 251 Construction Equipment, CEM 252 Methods and Materials, CEM 330 Soils and Foundations, and ABS 341 Building Structures I. The Building Structures I prerequisite ensures that students have a fundamental understanding of statics and strengths of materials concepts. The Construction Equipment/Methods and Materials/Soils and Foundations prerequisites provide the applications background for temporary construction structures issues. Additionally, at the freshman/sophomore level, the students have been exposed to the basics of cost estimating and job scheduling methods.

Since construction management programs can vary widely in scope of course selections, the individual course will need to be tailored to this particular background. As a sidebar comment, course prerequisites are strictly enforced which means that the need for review of such items as structural principles is minimal. Students requiring further review are given library references that provide additional assistance.

Course Objective

The objective of this course is to provide construction management students with the capability and understanding to design and construct a variety of temporary construction structures. The student will be conversant with temporary construction issues including safety concerns and state-of-the art developments. The student will be able to design and analyze these structures in terms of live and dead loads (dynamic and static), other technical issues, managerial issues, and cost/schedule considerations. In addition, the student will understand the role of subcontractors, suppliers, design professionals, owners, and governmental agencies in this area. The student will be able to present temporary structures concepts clearly and professionally from both a quantitative and qualitative standpoint.

Course Format

The course design is that of combination lecture and discussion format. The course is offered on a 3-credit hour semester-length basis in the Fall semester. After the first few lectures, subsequent course sessions are devoted to a blend of lectures and discussions. Due to the wide variety of temporary structures, guest speakers are utilized to provide additional course perspectives. Examples of some of these guest speakers in the past have been a crane and rigging contractor, manufacturer’s formwork design engineer, and scaffolding contractor. These guest speakers further help in providing a "real-life" component for the course. Many of the students by the time of their senior year have been able to gain through part-time and summer employment some experience that may include utilization and construction of these items. This further aids class discussion due to student background.

Class discussion may include the pros and cons of various solutions. Trench box removal and placement by hydraulic backhoe may be evaluated against a standard trench shoring system. Aerial work platform application could be compared versus steel sectional scaffolding. Issues of design, assembly, process, and cost are examined in lecture/discussion. Students realize that decisions in temporary structures impact techniques for work, project schedule, and resource allocation. The emphasis is on decision making and problem solving.

Course Assignments

The workload for the course is comprised of a number of homework assignments plus text readings covering the essential and varied aspects of this subject area. Besides the quantitative homework assignments, students were individually given readings on temporary construction structures and required to provide a combination of written and oral reports in these areas. Some of these course readings contain extensive case studies on the catastrophic failure of temporary structures. Course enrollments are relatively small (15+ students) to allow the assignment of non-overlapping material forcing sole individual efforts on the verbal/written report element in this course segment. Two exams are given during the semester plus a comprehensive final examination.

The majority of course assignments require both a quantitative component and a qualitative component. The quantitative, as might be expected, encompasses structural load calculations and cost analysis. The qualitative explains why a particular solution was chosen beyond quantitative factors such as OSHA requirements. An example of this would be with a double ladder system due to craft personnel occupancy factors or a quick-disconnect precast tilt-up rigging system to enhance cycle times.

A term project with two-person teams has also been included with some success. Student teams are given a complete set of C-sized (11" x 17") plans of an involved and complex construction project. The task requires the development of a complete system of temporary structures (traffic control, formwork, shoring, scaffolding, and rigging) for the execution of the construction project. Summary load calculations and cost estimates are a part of this term project. Submission of the term project in written format is required along with a verbal presentation by the student teams. Part of the written portion of the assignment requires the production of shop drawings by the student teams for these structures. The shop drawing element of the term project is particularly important since unlike many forms of construction, no other drawings typically exist in the contract documents. This term project creates more work for the course instructor and students but gives students both a "real-world" type experience plus additional practice in verbal and written communications. The emphasis to the student teams is on providing a well-organized and professional format document that could be submitted to an owner and the owner’s respective design team or a governmental agency for review. Currently enough examples have been collected from job sites to provide non-repetitive term projects between course years. This means that term projects are unique from year-to-year that prevents students from relying on the submissions of past students.

An example of a more-involved course assignment during the course might be the selection of a concrete formwork system. The students would complete their calculations and analysis to make a decision based upon:

Upon completion and grading of this assignment, class discussion might concern student-ignored areas of the assignment. The work of other trades such as hoisting, reinforcing, and concrete can be impacted by the forming system. Concrete formwork is placed first and can thus hamper the work of other trades. Post-tension cable tendon stressing operations require support platforms. Openings in the formwork system may be required in ductile beam designs. Rebar placement and electrical construction must be sequenced into the operations. Therefore, these other trades’ operations limit formwork placement. Other trades are impacted by the speed with which a forming system can be cycled through the project. The size and weight of forming members chosen can impact crane capacity. Extensive form tables for flying deck forms can increase crane costs since now a tower crane with additional reach and capacity is necessary. Issues such as architectural concrete mean that the form system must be installed more carefully and more slowly. These architectural concrete issues thus mean a higher cost as heavier form systems are utilized producing less deflection and a lower number of repeat uses to maintain specified surface finishes.

As can be seen, effective course assignments expose the students to many realities in this area. Students learn that temporary structures must be designed to enhance the production process and not be a detriment. This is a demanding and complicated process at times. For the above-illustrated formwork system, these activities will be on the critical path for project completion. Thus the best system choice may be a more expensive formwork system requiring higher crane capacity but that reduces the overall building completion time. This system selection means overhead savings for the general contractor and subcontractors in reduced project completion time. Moreover the owner saves on capital interest costs and achieves improved income from faster occupancy. On negotiated work, this owner benefit can be a prime sales advantage for the contractor. Students often criticize structural design coursework for emphasizing design and de-emphasizing construction issues. Effective temporary structures assignments provide an integration of both design and construction issues.

The present challenge is to develop a number of challenging examples and assignments in each of the key areas covered in this course. The limitations are chiefly instructor time for further development in this area.

Computer Applications

At present, students are required to perform certain assignments with electronic spreadsheet and word processing software. Other assignments are submitted in written format on standard engineering graph paper. Some students conversant with CAD programs have submitted shop drawings of temporary structures in this format. This CAD presentation is the exception rather than the rule however since CAD is not a mandatory aspect of our curriculum. Potential future areas of course development that have been looked at include the utilization/development of basic expert systems in such areas as formwork system selection.

The current drawback to more computer utilization in this course is that other courses such as estimating, scheduling, and project management already consume significant computer time with their own specialized software packages. These other course demands mean limited machine time availability for other areas like temporary structures.

Course Text And References

For many courses in the construction curriculum, there exist a great variety of books for the instructor to choose from for course textbook selection purposes. Thus there are innumerable books on such standard subjects as construction management and cost estimating. There is not a comparably large number of choices in the temporary structures area. The textbook selected, Handbook of Temporary Structures in Construction, provided comprehensive coverage of the subject area. This subject text is comprised of twenty-two chapters each by an expert in the respective area including coverage of legal and safety aspects. Realistically, the material is more than can be adequately covered in a one-semester course thus allowing the instructor a high degree in latitute in topic choices. The drawback of this text and others that were examined is the lack of homework applications problems for the student. Thus the assigned homework problems in the course have had to be developed by the instructors. In certain areas such as rigging and formwork design, other reference materials have provided source materials for these homework assignments. Engineering News-Record (ENR) provides a timely and continual source of examples on innovative applications of temporary structures. ENR further furnishes examples of the failure of temporary construction structures. These real-life examples drive home the importance of the temporary construction structures to students. Manufacturer’s literature on formwork systems, scaffolding, and rigging systems such as for precast tiltup panels provide additional course supplements. Some manufacturers also provide videotapes of these applications which are used to supplement course lectures.

For faculty active in consulting work, certain course assignments can be developed from these sources. Area contractors on projects utilizing various temporary structures may be willing to share information such as shop drawings and calculations provided sensitive information (names, locations, costs) is eliminated from these documents.

A survey of over twenty university course catalogs for this paper found that many construction programs do not cover these temporary structures topics or if covered they are well hidden in existing courses. Many potential reasons for this lack of coverage may exist but one reason may be the perceived scarcity of course material. Certainly, for those looking to publish in an uncrowded segment of the construction field, the temporary structures area provides an excellent opportunity.

Student Reaction

The unfortunate reaction of some students to construction sciences areas (structures, soils, mechanical/electrical systems) is lack of interest since they want to be construction managers. The common refrain from these students is that they want to be managers rather than designers. These students fail to realize the importance of a fundamental understanding of construction science principles to execution of the construction project. To adequately manage a process, one must be able to relate to the participants in the process including design personnel. This should be reason enough for a background in design principles. Temporary construction structures coursework can show the construction student relevant aspects and applications of construction sciences. Comparison of student reaction to the temporary structures courses in student comments has generally been very positive. Still, some students feel that they don’t need this background such as the student that may be working for a landscape contractor or an electrical contractor. Incorporation of a wide variety of examples such as the rigging and placement of a 40-foot palm tree on the corner of a hillside or scaffolding for cable tray installation on an elevated pipe bridge can show even these students the "relevance" of this material. Inclusion of temporary structures failures from actual construction projects as mentioned before additionally stresses the importance of this material.

During some class sessions, the costs of one temporary structures choice versus an alternative have driven home to the students the value of this course. The course guest speakers have provided additional reinforcement. These speakers have provided actual examples of jobs won or lost on the basis of a temporary structures decision. Students learn that temporary structures are not just a fixed cost of doing business. Instead, they as construction managers have a high degree of control over these costs.

Alternatives

Upon review of their own curriculum, some construction programs many find that no room exists for the addition of a temporary construction structures course. The logical alternative would be to incorporate certain elements of temporary construction structures into existing coursework. Thus a soils and foundations course might contain elements of braced cuts and tieback excavations. A materials and methods course could cover formwork types. Estimating coursework could cover the types of temporary structures and calculate respective costs. Existing structures coursework could incorporate temporary structures problems. The problem in diffusing temporary structures concepts by making it the responsibility of many course instructors is that certain key elements may be ignored by these instructors. Conversely, the benefit of infusing these topics into many courses is that students gain various perspectives on temporary structures.

Incorporation of temporary structures elements into existing structures courses has some obvious practical constraints. For a number of construction programs, they do not control structures course content. Instead, the structures sequence is offered as a "service course" taken jointly by other majors such as architecture or engineering. As with other courses offered outside the construction program, some limited revision of course content may be possible through discussion of these issues. All construction programs must evaluate additional courses in view of limited resources. The danger is in stretching resources too thin by this course addition. Moreover, many four-year construction degree programs are at the practical limit for credit hours. Indeed, these programs are realistically four-and-one-half-year degree programs at present taxing the capabilities of most students. One alternative would be the replacement of a conventional structures course with temporary construction structures. Limited faculty resources can be supplemented by part-time instructors from industry.

Conclusions

Temporary construction structures coursework has an essential role in construction management programs. It is felt by this paper’s authors that the subject area is important enough along with providing the necessary scope and variety to justify an individual course. If an exclusive course is not possible, integration of this subject matter into existing construction courses provides an alternative. Available course instructional materials, while limited in comparison with some areas of construction education, are still substantial enough to provide the foundation for sound education. Reviews of OSHA fatalities and disabling injuries as well as numerous construction site failures provides ample justification for enhanced backgrounds in this area by construction personnel.

Success in construction has often been defined by some as how far away from the workface is one’s position. Thus a typical job hierarchy might be foreman-general foreman-superintendent-project manager. There are many problems with this mind set but one positive aspect of temporary construction structures coursework is that students realize that these important issues should be management decisions and not left to the craft personnel.

References

Ratay, R.T. (1996). Handbook of temporary construction structures in construction (2nd ed). New York: McGraw-Hill.

Hurd, M.K. (1992). Formwork for concrete SP-4 Detroit: American Concrete Institute.

Rossnagel, W.E., Higgins, L.R. & MacDonald, J.A. (1988). Handbook of rigging for construction and industrial operations (4th ed.). New York: McGraw-Hill.

Parker, H., & Ambrose, J. (1993). Simplified engineering for architects and builders (8th ed.). New York: Wiley Inter-Science.

Appendix A

Topical Outline for Temporary Construction Structures

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