Crossing the Creek
In Fairfield County, South Carolina, a new flat slab concrete bridge is replacing the existing Valencia Bridge over Dutchman’s Creek, a partially collapsed bridge of concrete piers, timber pile caps, timber decking, and timber wearing boards. In 2017, the Valencia Bridge closed due to a collapse of one of the spans caused by the excessive weight of logging trucks.
Fairfield County purchased property adjacent to Dutchman’s Creek with plans to bring large development to the area and deliver additional jobs to the county. The new bridge is 100-feet long and 39-feet wide, contains two caps and three spans, and will allow construction traffic to access the area with little impact to the surrounding community.
During construction of the new bridge, the project team was looking for a rentable formwork solution for work that traditionally would use bar joist trusses and custom pieces for one-time use. Add in the increase in the cost of steel and lumber through 2021, and the team needed an alternative that would remove custom, purchase-only components.
PERI’s engineering team designed a customized rented formwork solution to support the cap and slab formwork for the development of the flat slab, triple-span bridge. Traditionally, flat slab bridge designs do not have beams and girders, and loads are transferred directly to the supporting concrete columns.
This custom-engineered truss system was designed by the PERI engineering team with customer input to fine tune the design for its first-ever use on a flat slab bridge. Close collaboration between the contractor, Construction Resource Group, and PERI’s engineering team created a solution that will be used on future flat slab bridge projects.
“We’ve worked with PERI and knew we could incorporate it into this project to create a new system for flat slab construction,” said Emilio Valentin, vice president of Construction Resource Group. “The adaptability of PERI formwork and the engineering support we have from the PERI team made it unique and made the decision easy for us.”
The design of the PERI solution enabled formwork that supports the cap to be used to reinforce the slab formwork, providing a more streamlined construction sequence than the traditional method. VARIOKIT beams, spindles, and connectors created a truss system for temporary falsework supporting the new concrete slab.
RCS rails and SLS spindles connected with bolts and cotter pins to create trusses in the field. After the trusses were assembled and moved into place, GT 24 girders were added to prepare for plywood decking. Lastly, heavy-duty rollers – instrumental in the safe and efficient removal of truss units – were added for the removal of falsework once the new bridge deck was poured and reached adequate strength. This allowed falsework to be dismantled after being lifted away from the bridge.
VST Heavy Duty Shoring Tower is used in projects that require the central transfer of large loads. The VST shoring tower assembles quickly and adjusts with simple moving hydraulics. GT 24 formwork girders replaced the need for lumber and provided high load-bearing, durable girders, reducing the material usage and workload needed.
Using primarily standard components, this customized PERI formwork solution provided a more flexible system than the traditional method. PERI also provided the project team with the ability to rent all components needed and respond to field changes in a timely manner, saving projects costs on a large bridge build. With standard, rentable components, the solution can be reconfigured in an infinite number of ways to reuse parts for future truss designs.
The new Valencia Bridge opened in late November 2021 after three months of bridge construction.