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STRUCTURE approached representatives of companies that offer different types of connections for structural engineering applications to talk about developing trends in materials, manufacturing, and resources. They stressed that when it comes to connections, connecting with fellow collaborators is key, and beyond product advancements, one of the biggest trends is developing tools to make it easier to communicate intention and specification with the rest of the team. ■
What manufacturing trends are you seeing for connection products, and what do they mean for structural engineers?
Jennifer Pazdon, Vice President, USA, Director, UK Division, Cast Connex: Use of cast steel connections has become increasingly popular as designers and construction professionals have identified the benefits to structural performance and bottom line. Demanding project delivery schedules and projects with ambitious structural demands call for reliable connections solutions that can be easily understood from a load path perspective, are straightforward to design, or are pre-engineered.
Ryan Smith, Vice President, Engineering, and Global Design Engagement, MiTek: As a company that is involved in the design and manufacturing of a variety of connection solutions, we have seen a particular interest in focusing on connections that speed up overall construction time. I believe manufacturers and designers are listening a lot more to the other project constituents. A couple examples from both our Timber Construction and Steel Construction supply chain partners are the MiTek Firewall Hanger and the SidePlate Bolted Moment Connection. Connections like these make it easier to install firewall assemblies and in the case of SidePlate, eliminate the need for expensive and time-consuming field welding.
RJ Angle, Senior Product Manager, Simpson Strong-Tie: As demand and costs have grown for skilled labor, manufacturing has become increasingly automated. Many production processes can now be performed entirely by robotic equipment, and some new means and methods of fabrication are due solely to the advances in the equipment. The advent of robotic equipment—like a new industrial revolution—continues to impact designs and project deliveries for the better.
One such change has been a shift away from welded connections. With new equipment and software making design, lay out, and drilling of holes faster and more accurate than ever before, bolted connections offer many unique benefits. Not only do bolted connections generally work through the production shop faster, but they also afford greater adjustment in the field, and require less skilled labor for installation. Solutions such as the Yield-Link Moment Connection and Strong-Link Moment Connection by Simpson Strong-Tie are fully-bolted connectors for LFRS moment frames. Quick and easy to install, these products eliminate costly welding and weld inspections.
As construction using mass timber and high strength steel evolves, how have their connections evolved? How can structural engineers adjust their connection designs to maximize constructability and efficiency with this design trend?
Michael Weinert, Senior Product Manager, Simpson Strong-Tie: Mass timber manufacturers, fabricators, and installers seek repeatable connection solutions that are easy to procure, cost-effective, and rigorously tested to meet project demands. Structural engineers can enhance constructability and efficiency by specifying readily available, code-listed connector products for standard applications, reserving custom-fabricated connection designs for unique or atypical portions of the structure. This approach leverages industry advancements in standardized connections, which have been developed and validated through extensive testing to support the growing adoption of mass timber.
Pazdon: Mass timber construction presents the opportunity to rethink how we design connections with consideration for how projects with this material will be delivered. The advantages of time-saving on site that can come from panelized CLT construction can be leveraged with careful consideration of the construction process when developing connection details.
The opportunity to expose mass timber to celebrate the warmth of the material is complimented by connection details that support aesthetic value. The ability to sculp sculptural steel in casting manufacturing can lead to lovely cast steel-timber hybrid connection details. Standardized connectors for cast steel-timber hybrid projects are aligned with the goals of reducing site time and cost.
Structural connectors are critical to a structure's ability to withstand seismic events, high winds, and more. What improvements or innovations have been made to further elevate their performance in extreme events?
Angle: Extreme events can cause significant damage to structural members and connectors in a Lateral Force Resisting System (LFRS). Often, the needed repairs to these systems come at significant costs and lead times. Moreover, until repairs are completed, structures are often uninhabitable, further disrupting communities and local economies. This issue has spurred innovation in building resiliency. The Yield-Link Moment Connection (YLMC) by Simpson Strong-Tie is a prequalified connection for Special (SMF) and Intermediate Moment Frame (IMF) type Seismic Force Resisting Systems (SFRS). Unlike most other IMF and SMF connection designs, the YLMC connector is the yielding mechanism in the frame which absorbs and dissipates the energy. The YLMC is also the sacrificial member (structural fuse) when the SFRS is pushed beyond the elastic state, salvaging the beam and column members. Similarly, the Yield-Link Brace Connection (YLBC) is an inelastic fuse connector for braced frames. The YLBC likewise deforms under large lateral loading, allowing the frame to dampen the energy. Inelastic deformation is isolated to the YLBC fuse components, salvaging the beams, columns, and braces. Designed for resiliency, the YLMC and YLBC are both fully field-bolted connections, which can be quickly replaced after a strong wind or seismic event.
In your discussions with structural engineers, what challenges are they facing (in terms of connections) that your company is specifically addressing?
Brad Fletcher, Sr. Engineer, Atlas Tube: Many of the questions relate to HSS connection design. Our most common piece of advice is to think about the connections during design to avoid miscommunication about intent, loads, and other variables that can lead to late changes during the construction phase.
In an effort to demystify these challenges, Atlas Tube launched the HSS Connections Hub. The HSS Connections Hub includes fabrication-friendly, fully code referenced, and reliable HSS connection tools to help engineers think through these things, even if they are delegating the connection design. The education and tools we provide are built to address the challenges that engineers face, from general knowledge of HSS connections to tools such as typical details and connection calculators. Our goal is to simplify and optimize HSS connection design, which can help the team avoid late changes and project delays.
Pazdon: Structural engineers come to us for solutions to geometrically complex and/or architecturally significant connections that would be difficult to design, fabricate and/or install using conventional methods. Delegation of connection design to a casting supplier ensures that structural performance is coordinated with manufacturing processes and delivery schedules are met in the interest of design and construction professionals.
Structural engineers may be well trained in connection design by codified equations, but they may not be as well versed in steel manufacturing methods nor in shop fabrication or field activities. As EOR, their scope of responsibility is extensive, and success relies on working with capable partners to achieve the final built project. With our attention specifically on connection design and manufacture, our scope is comparatively quite limited, but with potential for substantial impact. Our design process is akin to DFMA in that we develop products that provide value at every stage from design though construction while respecting manufacturing limitations and harnessing manufacturing capabilities to improve upon conventional solutions.
Time is always a challenge. Structural engineers come to us for pre-engineered solutions that save them time in design, development of design documents, and review of shop drawings.
Smith: When looking especially at timber construction, we have received feedback that many of the typical details being used have not been updated for quite some time. This can be very challenging if the goal is to advance connections to be more efficient and cost effective. Besides working to create more effective hardware, like top plate screws, and firewall hangers that make install easier, we are working to support our professional design customers in updating their details. MiTek, an innovator in timber construction, has substantial experience in how design decisions early in the process will affect productivity downstream. We are utilizing this supply chain knowledge and helping educate professional designers on the pros and cons of certain details. This should help professional engineers make good, informed decisions, and therefore I encourage professional engineers to reach out to their local MiTek Design Engagement Consultant to see what support we can provide.
What resources and tools do you recommend to structural engineers when they are designing and specifying connections in their projects?
Smith: I recommend that engineers develop a very good network of subcontractors and partners that specialize in connection designs. I encourage engineers to reach out to the field and specialized connection engineers, like those from MiTek’s SidePlate solution, anytime there is an abnormal condition. It is likely that these groups have experienced the condition before and can provide insight.
Angle: Connection design can be complex, but great resources are becoming more accessible. Simpson Strong-Tie offers design assist on our structural steel lateral connections SLMC, YLMC, and YLBC. With resources that include design guides, typical detail sheets, and personalized help—building safer, stronger, more resilient structures has never been easier.
Pazdon: Talk to your fellow engineers who are standing on the other side of the table at tradeshows! Connection product suppliers are generally trained as structural engineers and have spent time working in the same role you are in as a consultant. Now they are focused experts in the type of connections they design and supply with their company, and they are likely to have more exposure to other products and solutions available on the market.
We have developed 2D and 3D CAD assets and Revit families as well as sample specification language to help designers to describe standardized connectors and custom products in their contract documents. For the pre-engineered products we have data sheets or design manuals to provide the specifier with relevant technical information. “How to Specify” guides available on our website walk the structural engineer through each step of specification. This saves time in design and specification and sets the project up for success in the tender phase and beyond.
