A Look at Formwork & Falsework Design

Entuitive’s drive to deliver Uncompromising Performance throughout the full asset lifecycle includes the consideration of constructability in the design of our projects, with particular attention paid to the means and methods that may be required by a contractor to implement the design.

Below, we’ll discuss how our two-pronged, collaborative approach benefits our contractor clients through the lens of a few of the complex formwork and falsework challenges our team has solved. Our team is active in static formwork and falsework design and has successfully delivered hundreds of designs to our contractor clients for a variety of structural elements of varying sizes and complexities.

Formwork & Falsework Design the Entuitive Way: Collaboratively Delivering the Best Solutions at the Right Cost

One of the items in our comprehensive list of Construction Engineering services related to means and methods work is formwork and falsework design. Formwork and falsework designs are a component in almost all projects involving concrete construction.

Formwork is the mold into which fluid concrete is placed and is the total system of support that resists the lateral pressures of fluid concrete, including the sheathing, joists, walers, ties, and associated hardware. Falsework is the temporary system used to support a permanent structure, or portion of a permanent structure, until it can become self-supporting.

Typical Timber Pedestal Forms

Typical Timber Wall Forms

Entuitive’s Construction Engineering team collaborates with the contractor from the onset of the design process to understand the intended construction, materials, methods, and sequences to ensure that the right system is chosen for the application. The right choice may be either a custom design or the use of a proprietary system.

The construction of formwork and falsework systems is often a labour-intensive process and represents a significant portion of the overall concreting cost on a given project. In bridge and heavy civil work, for example, the forming and falsework components for a concrete price may represent up to 75% of the item’s total unit cost.To achieve efficiency and help maintain reasonable costs, we learn which systems our clients are familiar with and want to use, which materials are available and may be re-used from previous jobs, and we look for ways to make the current design suitable for re-use on future projects.

We believe this collaborative mentality is paramount on all our projects. It ensures we meet the unique needs of each project at the right cost.

Falsework for Shored Construction: Understanding the Complex Interplay Between Permanent & Temporary Structures

Our integration of Construction Engineering with our holistic suite of services provides our clients with unique insight into the potential impact our designs may have on the means and methods required by a contractor. Similarly, our experience with permanent structure design informs our work for our contractor clients when completing means and methods designs.

Falsework design for the construction of post-tensioned bridges is a prime example of where our abilities and experience with permanent structures can provide value to our clients in temporary works design.

The sequencing of a bridge’s construction in a shored condition can affect the finished structure. It is important for the falsework designer to understand how the permanent structure behaves in a partially complete condition, and how it interacts with the temporary support system. This often requires careful modelling and can require adjustment of reinforcement in the permanent structure design to suit the contractor’s preferred construction sequence.

For example, with staged pours in box-type structures the bottom slab and webs are often cast first. There is concern for potential cracking in the relatively stiff first pour elements when the deck is cast in the second pour. This was a consideration for the design of the falsework of the Highway 7 eastbound and westbound bridges over Highway 407ETR near Brock Road in Pickering, Ontario.

Highway 7 Bridge over Highway 407ETR near Brock Road in Pickering, Ontario

Additionally, the falsework design for these structures is significantly more complicated than structural design alone. The final geometry of the bridge must be respected through all phases of construction, including consideration of the road profile, deck crossfalls, skews, and curves.

Our integrated team, working together rather than as siloed units, understands the complex interplay between permanent and temporary designs.

Delivering Ahead of Schedule: Innovation in Formwork Design

Maintaining a collaborative mentality also yields innovative designs where necessary. Working with Crosslinx Transit Solutions Constructors on the Eglinton Crosstown LRT project in Toronto, Entuitive’s Construction Engineering team developed an innovative formwork design that contributed to a significant reduction in the construction schedule for the Forest Hill station’s roof slab.

The roof slab for the station was broken up into several segments with transverse contraction joints. Concrete on either side of the contraction joint is conventionally placed as two discrete pours to provide a deliberate separation.

Contraction Joints

With upfront planning and minor modifications to the reinforcement detailed on the contract drawings, a method was devised to allow fluid concrete to be placed simultaneously on both sides of the contraction joints. This was done by using a custom-shaped sheet of PVC to form the shear keys between the slab segments, creating a small structural frame with the slab reinforcement on one side of the joint to support the lateral concrete pressures, and setting minor placement restrictions for the fluid concrete on either side of the joint to minimize hydrostatic differentials.

It was estimated that there was a schedule savings of approximately two weeks with each contraction joint constructed this way, with a total savings of approximately four weeks in the construction of the roof slab. The method was deemed successful and later adopted for portions of the roof slab at the Chaplin Station site.

Emergency Issue Support: Partners Every Step of the Way

Site conditions can prevent formwork and falsework designs from being implemented exactly as intended. Our Construction Engineering team remains fluid and responsive throughout the entire construction phase to ensure that required design modifications are addressed expediently so as not to delay work on site.

We see ourselves as partners with our contractor clients, there, on site, every step of the way.

Construction Engineering the Entuitive Way

Construction Engineering the Entuitive Way is our approach to our relationship with our contractor clients. Its dual foundation – collaborating with our clients and listening to their needs and ideas; and integrating our permanent and temporary design expertise – is the key to a successful construction engineering project.

Formwork and falsework design is just one of our extensive Construction Engineering services that illustrates how we approach our work in what we believe is the most rewarding way for all involved.

We’d love to work with you on your next construction project. Reach out to Jason Jelinek to learn more.