Many owners of manufacturing facilities are faced with the twin challenges of outdated, even perhaps substandard, physical plants and aging infrastructures. When building a new facility is financially prohibitive and moving operations during renovations is impractical, the building must be repaired in real time. The design and engineering challenge is to upgrade the structure with minimal disruption of production.
Many lessons learned apply across the industry, but for the particular project that generated most of the examples in this study, architects and engineers were tasked with remediating the wood truss roof of a 1940s-era industrial plant. The roof had been rendered obsolete by new structural design standards. Each step in the solution required creative application of professional insights in both planning and technical solutions, strong relationships with good listening and communication, and abiding by the owner’s commitment to maintain production throughout the construction process.
Casing the client structure
Looking before you leap is as true in remediation design as it is in mountain climbing. Make sure the issues you include in the design scope are really there and not just in the documentation.
The designers in this case started the upgrade process by scoping the project. They first looked at the legacy drawings and blueprints of the facility. The plans had been accurate when the plant was built, but there had since been more than 70 years of renovations and changes in use of the building. Because recordkeeping had been a low priority over the decades, the old plans, though useful as a starting point, were now incomplete and inaccurate. Thus, the designers had to verify which parts of the plan were still valid. This exercise is almost always the first step toward remediation.
These circumstances can crop up in all kinds of plants. In a completely different project for another client — a renovation of and an addition to a large chemical plant — designers had to plan their work around the overhead pipelines that were shown in the original drawings. However, when they tried to corroborate this initial condition, the designers discovered that the lines had been abandoned at a time before any of the current employees could remember. No longer constrained to design around the lines, they were freed to plan much more efficiently.
Another tool gaining popularity is 3D laser scanning. This tool can scan an existing facility with accuracy as close as 1/8 in. and provide a point cloud that can either be modeled to provide an accurate 3D model of the facility or simply used to design existing elements around. It can be more expensive — although on complex projects or projects with a lot of overhead elements it may actually be less expensive — but its speed and accuracy are often worth the tradeoff.
An example project for Honda included an expansion of its assembly test plant, as well as an expansion and retrofit of an existing weld zone. Included in the scope was field verification of existing conditions and the requirement that the measurement process not interfere with ongoing production. By employing the use of laser scanning on the existing areas of the facility, the team was able to capture more detail in one day than would have been possible with an entire month of field work and measurements. When working within an existing space, a zero-errors-and-omissions policy makes it critical that the documentation of existing conditions be extremely accurate to avoid conflicts with new construction.
The cost of the project was $2,500 per day of laser scanning, which saved them from months of less-accurate manual field measurements. In addition, the lower cost of field measurements, to date zero errors have been recorded and therefore no financial impact has affected the project.
Multiple site inspections
“Many hands make light work” can, in the design world, be transformed into “many experiential backgrounds add to a project’s real-world feasibility.”
Back at the truss roof project, after the designers evaluated the surviving plans, they performed multiple site inspections, starting with a vision trip with the owner for a general site inventory. They asked the owner for three lists for the upgrade: the “have to” list, the “should do” list, and the “want to” list. The team included representatives from various departments, including facility maintenance.
The designers periodically toured the site with a contractor selected by the client that frequently performed work throughout the plant. The team’s combined backgrounds in hundreds of industrial structures enabled the team to provide accurate estimates on costs, scheduling sequences, material availability, and general project feasibility after a brief walkthrough. Diverse expertise plays a key role in both formal encounters, such as site inspections, and informal encounters, such as brainstorming and consultations in the designers’ offices. In the truss roof project, the team consisted of designers and architects, as well as structural, mechanical, and electrical engineers. All of these stated their professional opinions of what could and could not be accomplished.
At this early point in the process, designers normally compile a schedule and logistics for a remediation project, but in this case they were unable to build what the owner wanted for the budget. Throughout the preliminary stages, the project architects and engineers steered the owner toward a project vision that would match constructability. Leaders knew what they wanted for the end product but were not aware of schedule and cost implications. They put the project team in the driver’s seat and took a hands-off approach as long as the end product met expectations. They wanted a new roof. Initially, they thought the only way to do this was replace the entire roof. However, it was more cost-effective to provide an “umbrella” over the existing roof.
To achieve a holistic solution to a challenge that affects an entire organization requires outreach to all major segments of that organization. Architects and engineers know that they are not the only piece of the puzzle. When partnered with the owner’s team and with contractors and fabricators, they can, with good communication skills, form a seamless solution.
In the truss roof project, important questions remained to be answered. The designers conducted multiple site tours, observing the workflow and holding discussions with floor staff and maintenance personnel. They asked which design changes would make their jobs go more smoothly. In that way, designers solicited ideas about the least intrusive and most effective design solutions. Front line employees are happy to describe their solutions — such as which pieces of equipment are most easily moved — which the seasoned designers may find to be uniquely appropriate, even though such solutions may depart from conventional engineering approaches.
The architect or engineer also needs to solicit input from employees and should put on boots and a hardhat and get out on the production floor. It’s essential to observe work flow and traffic patterns, brainstorm, and think out loud with users, managers, owners and contractors. Ask about past history and, for any previous redesign projects, discuss what worked and what didn’t. Some of the best insights and solutions come from outside the architectural and engineering firm.
Not only can designers glean unexpected information from staff members; they may also discover unexpected and unforeseen benefits for the owner. For example, during a pre-construction inspection on the truss roof project, engineers found previously undiscovered leaks above new equipment, thanks to a plant worker highlighting the leaks during a walkthrough. This enhanced the firm’s value to the owner because it averted potentially costly water damage.
Team-oriented early planning comes into play throughout the course of a project. The key is getting the right people on board as soon as possible, including well-placed on-site decision makers who understand which construction methods are applicable. Those decision makers should have experience interacting with contractors because they will be approached by the contractors as issues arise. On the truss roof project, the designers and engineers eventually became the go-to people for the plant and were called on to consult in nonproject areas, such as providing fall protection on an unrelated plant platform.
Keep production running
In any remediation project, there is always pressure to maintain work flow as robustly as possible while reconstruction of an old facility is underway. Don’t pardon the interruption of work.
The wood truss roof plant had an irregular production schedule, which made careful coordination essential. Designers and engineers met with plant maintenance and production managers to plan work areas and staging areas and to coordinate their work with regularly scheduled plant downtime for minimal interruption to production.
Nonetheless, with any remediation project, many factors — including weather, varying and unpredictable production demands, and employee turnover — can force changes to even the best plan. If the plan changes, the result becomes the new plan, but it too will be subject to change. In these circumstances efficient teams rely as much as possible on voice communication. Although email leaves a valuable paper trail, digital communication unfortunately removes an important dimension — the sender’s nonverbal communication — creating the possibility for misunderstanding. The guideline should be to speak first and then, when necessary, confirm in writing.
For construction processes that are susceptible to unexpected changes, a streamlining technique is called “repetition equals speed.” Each new solution creates additional work for engineers, fabricators, and contractors. Therefore, in the truss roof project, engineers avoided unique fixes whenever possible. Instead, they identified a handful of solutions that were broadly applicable. Although that strategy resulted in greater upfront costs on some of the repairs, it produced a net savings for the owner through a quicker return to operational status and workflow schedules.
Take the example of a congested area of the plant that needed repair. The standard approach would have been to shut down the area and remove the workers and then complete the repair and replace the needed equipment. After talking with staff, the designers discovered that the portion of the plant they needed to work on was to be out of service in an upcoming month, and this timeframe fit conveniently within the window of the overall project. The obvious choice was to complete the work in the nonpopulated period, thereby eliminating any work stoppage. Bundling the repair with other standard maintenance avoided a special work stoppage and allowed this repair to fall into the repetitive pattern of preventive maintenance procedures.
Another streamlining strategy, one not limited to remediation projects, is using a color-coded matrix to organize large quantities of information. Conventional, language-based matrices have long been used in the construction industry. In contrast, the roof truss project used color-coded cells in an Excel spreadsheet to indicate one of three statuses for each truss: not repaired, being repaired, or completely repaired. The system allowed anyone to determine the project status with just a glance to see what needed attention, what was lagging, and what needed constructive intervention.
A unique solution was required in an isolated area of the plant above the basement. Reinforcing the existing trusses over the plant space required support for the new steel beam below the existing truss. The plant had a main floor above a 7-ft basement. Along one exterior wall, additional columns were needed under the main floor to support the channels below the beam that was supporting the truss. The under-floor columns were then hauled into place and installed. Because the basement was only accessible by a stairway, the under-floor support columns had to be positioned by hand, which required they be fabricated of steel members that were economically designed to minimize their weight.
Some of the columns in the plant needed to stand on individual concrete footings. The first step in preparing those foundations was to cut into the existing slab at each location. Due to the sensitive nature of the equipment, the contractor built a mobile tent to capture the concrete dust from the cuts. After each slab cut was removed, crews dug out an earth form for the column foundation, for which the designer specified a high-early-strength concrete. The entire sequence of steps allowed work to continue in the plant spaces with minimal interruption while a permanent solution was constructed around staff members.
Replacing the same design with newer structural elements is not necessarily the optimal method to remediate a legacy structure. Sometimes it is possible to fabricate a solution that achieves the same function by building around the older one.
One phase of the roof truss project required a customized solution because it was in a location where a conventional truss repair and upgrade would have been inefficient to support the winter snow load. To make matters even more interesting, that portion was over an office area, so it required a different approach because staff members could not work in cubicles with a roof replacement going on over their heads. As with all other areas in the facility, it was important that work continue in the office spaces throughout the construction process.
|Joel Kramer, PE is senior structural engineer at SSOE Group, a global engineering, procurement, and construction management (EPCM) firm in Troy, Michigan. He has 15 years of experience and is responsible for structural analysis, design, and the preparation of structural design documents. He can be reached at (248) 643-6222 or at firstname.lastname@example.org.|
In the affected area, project engineers determined they could reduce the roof loads on the existing wood roof trusses by installing steel joists and a wide flange beams to form an umbrella roof that spanned the existing roof — the so-called belt-and-suspenders fix. This design simply bypassed the trusses and relieved them of most of the load. The wood frame trusses could then remain in place with minimal demolition, as they were strong enough to support the remaining load.
Throughout the project, careful planning combined with creative engineering made all of the technical aspects of the roof upgrade successful. The owner was the most important person to satisfy, but the other stakeholders are equally pleased with the process and the ongoing effort. The plant staff, contractors, and fabricators, who had partnered with the planning team, all play active roles. Intentional team building had produced strong partnerships. Clear and mutually respectful communication had produced efficient workflow. Commitment to the owner’s production and workflow goals had maintained profitability. These were the outcomes that the clients expected, and these are the outcomes that any client in a competitive environment has a right to expect from project architects and engineers.