STRUCTURAL REHABILITATION OF OPERATING INDUSTRIAL FACILITIES: AN INTRODUCTION

by Merle E. Brander, P.E., ASCE

Overview

Unlike construction of new facilities that are unoccupied until substantial completion, structural modifications often require that work be done while operations continue in the facility. While there are risks associated with any building project, in new construction or rehabilitation of an unoccupied structure, the on-site workers are responsible for, aware of, and prepared for safe operation in a construction environment.

The risks associated with rehabilitation of operating industrial facilities, however, are greater than normal because occupants are the people driving lift trucks, delivering papers, meeting, eating lunch, etc. in the facility. These people prepare for the risks associated with their specific jobs, but may not necessarily for the risks associated with construction. For that reason, rehabilitation work must be done with the assumption that the building is always ready for final occupancy, with personnel and equipment in place and operating.

Approaching the Operating Industrial Facility

The building sciences have evolved over the centuries, allowing people trained in construction related activities to complete greater and more complex construction projects, and the structural rehabilitation of an operating industrial facility may be the most demanding task faced by today’s construction community. Such rehabilitation requires continual accommodation of the non-construction workers within the facility and, frequently, management of harsh physical conditions.

When a building owner decides to rehabilitate an industrial facility, through modification, repair, or demolition, his primary concern will understandably be the operations of the facility. Certainly he will recognize the importance of maintaining a sound structure both during and after the rehabilitation, but he will generally not realize the number of variables that can affect structural integrity, rehabilitation costs, facility service life, and the safety of personnel both during and after rehabilitation. With rehabilitation of operating facilities, variables not clearly defined and addressed can be the origins of failures of existing structures, temporary structures, or new structural components.

Planning Facility Rehabilitation

During each stage of a rehabilitation project, the strength, stability, and durability of all affected structures must be understood and accounted for if the facility is to remain safe and fully operational. Ultimately, it is the Owner who will bear the consequences of the project, both positive and negative, but the Owner generally does not have the knowledge or training needed to plan a rehabilitation project in detail. He needs someone to take responsibility for ensuring that buildings, platforms within buildings, and access structures are free of hazards; when new building configurations are being proposed, he needs someone who can design to account for the required strength, stability, and durability; and when the components of the structure are removed or altered to make way for new building configurations, he needs someone who understands how loads are redistributed.

Effective rehabilitation of operating industrial facilities requires the supervision of a Qualified Structural Engineer at all phases. It is generally understood that Competent people can construct a project, choosing the means and methods of construction and consulting a Qualified person when unknown loading conditions arise. However, in the case of rehabilitation of operating industrial facilities, the level of analysis required to achieve acceptable levels of predictability and safety increases dramatically. The structural and operational integration of the work site with other parts of the facility increases the base level of risk associated with the work, and the rational, moral response of the owner would be to proportionately augment risk-reduction measures by placing a Qualified Structural Engineer in charge from beginning to end.

Risk and Responsibility

All to often, though he shoulders the increased risk, the owner does not commensurately enhance his strategy to prevent accidents and failures. He may attempt to do so by paying a high price for rehabilitation services, trusting that the high cost of the services will lead to an adequate factor of safety, but unless the strength, stability, and durability of each structure is understood for each stage of the project, the risk of damage or injury remains high. Alternatively, a contractor performing the rehabilitation without the benefit of specifications for Means and Methods from a structural engineer may provide an unnecessarily high degree of support for some parts of the building, leading to higher costs and lost time for the owner.

Planning for the redistribution of load, and designing the new structure accordingly, is the most critical aspect of the rehabilitation of an operating industrial facility. The owner may not understand the forces at work within the structural members of his building, but still he bears the responsibility of their performance. If he unwittingly authorizes the modification of his facility structures by a person who does not fully understand load redistribution, he sets himself up for costly failures. The owner can not safely redirect his attention to facility operations until he transfers both the responsibility and the authority for structural modification to a party that can properly accept them.

The Structural Engineer has the professional liability insurance as well as the professional training that enable him to confidently direct the rehabilitation of an operating industrial facility. With so many more variables to consider during the work, as compared with new construction, this is an excellent example of a project requiring the input of a Qualified Structural Engineer regarding Means and Methods.

Conclusion

Building science has evolved to the point where traditionally high-risk, high-cost rehabilitation projects can be executed quickly, safely, and without interruption of on-site industrial operations. An increased number of relevant calculations and structural analyses, resulting from an expanded role for the Structural Engineer in structural modification, leads directly to less downtime, fewer accidents, and lower overall costs.

Structural Engineering in the 21st Century, ASCE

Proceedings of the 1999 Structures Congress

April 18-21, 1999

New Orleans, Louisiana