Tilt-up construction continues to grow as a wide-spread building solution due to its advantages of efficiency, economy, and effectiveness. In fact, tilt-up construction has grown at an annual volume of more than a quarter billion square feet of wall, outperforming the general building industry during the past decade. Market growth, however, means that people are entering this field at a rapid rate, requiring increased attention to safety—another long-recognized benefit of tilt-up.
While gaining an understanding of safe tilt-up practices may be important for a newcomer to the industry, even veterans should periodically review safety guidelines. After all, lifting 8-inch-thick, load-bearing concrete wall panels weighing 60,000 pounds or more and measuring 30 feet wide and 50 feet tall leaves no margin for error, especially when it comes to safety.
Despite the obvious safety considerations of erecting massive concrete wall panels with large mobile cranes, tilt-up construction offers great safety for crews. The floor slab is cast first as it is the primary casting surface for the wall panels, creating a solid, dry work area. In addition, constructing the framework on the ground eliminates the need for scaffolding, further increasing worker safety. Overall, site-cast tilt-up construction is recognized as a reliable and safe building method, if used in conjunction with good planning and a solid safety program.
For tilt-up crews to take advantage of the benefits of speed and economy inherent in the site-cast tilt-up process, safety programs and guidelines must be enforced. Since a comprehensive safety program goes well beyond what to do and not do in the field, it must begin in the office before any workers even go to the field. For example, your safety program should include a review of all subcontractors, contracts, and purchase orders—allowing you to address safety concerns and attribute responsibilities. Ongoing training is essential, which means bringing the training to the crews in the field.
Before a Project Begins
During the design phase, another important safety consideration is the floor slab and its load capacity. If the lot size or other factors require that the panel erection be completed on the floor slab, careful consideration and planning is needed to ensure that the floor slab thickness and reinforcement can withstand the panel and crane weight. The designer must consider the concentrated weight on a crane's outrigger or track during panel raises. If erection stresses—the weight concentration effect on a floor slab—are not taken into consideration, the result is usually a cracked or broken floor slab.
The crucial decision as to whether or not the crane will erect the panels from the floor slab or the perimeter also affects the project plan. Although perimeter erections can cost more than an on-slab erection, they often present a great advantage in terms of reducing risks to the floor slab during panel lifting. The contractor or engineer should advise the owner of the pros and cons of on-slab versus off-slab panel lifts.
Design and Testing Considerations
In addition to the management planning, analysis, and awareness training, safety should be addressed in the design and testing process. Key considerations for review between the design and construction team include the following:
- Alleviating tripping concerns: Since panels contain much reinforcing, ensure that no protrusions exist that may impale a worker who stumbles.
- Proper installation of lifting hardware and inserts: Ensure these products are tested and verified for performance.
- Concrete strength: Ensure that the concrete strength is tested for field, not merely lab, strength. Also make sure the floor slab has been properly designed for the bracing loads.
Coordination of Personnel
A significant contribution to a safe tilt-up construction site is the coordination of personnel. When a site is cluttered with people who are not actively and intelligently working, accidents are more likely to happen. For this reason, it is appropriate for construction crews to have a pre-tilt walk-through and safety meeting. This serves to identify potential job-site hazards, to assign each individual a specified task, and to review pertinent onsite safety issues.
Prior to erection day, many contractors recommend a safety meeting for everyone on the jobsite. At the meeting, all crew members should sign a safety checklist for documentation of the meeting. Review the lifting safety checklist provided by the Tilt-Up Concrete Association (TCA) and address all concerns such as proper attire, how to look out for other crewmembers, and where to stand during the lift.