2 The Journal of Policy Engagement

The Journal of Policy Engagement is published six times a year by the Ontario Centre for Engineering and Public Policy. The council of Professional Engineers Ontario (PEO) established the centre in June 2008 to enhance the engagement of the engineering profession in the development of public policy to better serve and protect the public interest. The centre’s mandate also includes out-reach to members of the engineering profession, the academic community, policy-makers and others interested in advancing the public interest. The views expressed here are those of the authors and do not necessarily reflect those of PEO or any other organization.

Contact: Donald Wallace, Executive DirectorOntario Centre for Engineering and Public Policy1000-25 Sheppard Avenue WestToronto, Ontario M2N 6S9 416-840-1078dwallace@ocepp.ca

eONTARIO CENTREFOR ENGINEERINGAND PUBLIC POLICY

Vol 1 • No 3 | July 2009

Making the right connections

By Carlos de Oliveira, M.A.Sc.

Executive summaryThis paper presents an innovative technology borne from academic engineering research and its suc-cessful commercialization through the formation of a new Canadian business enterprise. The technology, developed at the University of Toronto under the auspices of the Natural Sciences and Engineer-ing Research Council of Canada (NSERC) and the Ontario Centres of Excellence (OCE), improves the safety and simplifies the design and construction of buildings that must resist earthquakes. The case study is presented as a positive example of how government and institutional support of research, talent and commercialization efforts can result in the development of innovative technologies and the creation of new businesses that have the potential to make significant contributions to the economic and social landscapes of Canada.

IntroductionA successful marriage of academe and government support has led to the birth of a new technology that promises to revolutionize the steel fabrication indus-try. Developed by University of Toronto (U of T) civil engineering professors Jeffrey Packer, P.Eng., and Constantin Christopoulos, P.Eng., along with gradu-ate student-turned entrepreneur Carlos de Oliveira, EIT, this breakthrough focuses on replacing existing individually designed and fabricated structural steel connections with standardized components. The particular components the trio developed will make buildings in earthquake-prone regions safer and easier to design and construct.

Ontarians, particularly Ontario engineers, can take pride in the fact that this “disruptive technol-ogy,” one that has the potential to forever change current industry practices, was developed in Ontario and is gaining traction in the construction indus-try. And although Cast ConneX Corporation, the company de Oliveira now heads, is still very young, the company’s early success demonstrates that the right mix of research, talent, industry pull, financial support and political will can lead to success in the innovation economy of the 21st century.

BackgroundOver the past 50 years, an entire industry has been built around the design and fabrication of structural steel connections, the welded or bolted “details” that

connect any two or more structural steel elements in the buildings we all occupy. These connections are critical because they facilitate the transfer of forces among structural elements (joists, beams, columns, etc.) and are thus a part of a building’s overall integrity system.

Although the producers of structural steel sections–the building blocks that form the backbone of every steel building–have moved towards the standardization of the shapes they manufacture (wide-flange sections, angles, channels, hollow structural sections, etc.), the fabrication sector of the industry has been able to remain competitive while still being based on manual fabrication of “one-off” connections.

This individual detailing and manual fabrication has led regulatory authorities to develop numerous codes, guides and standards on steel connection design. It has also led to the evolution of weld-ing certification procedures and qualifications that are meant to ensure a uniform quality and safety factor for typical welded details (some examples include CSA [2005], CSA [2008], AISC [2005] and AWS [2008]).

But new demands on the building construction industry are changing past fabrication practices. Recently, authorities around the world have been insisting on stricter requirements for connections that must resist earthquake-induced (seismic) load-ing. Based on the devastation caused by recent earthquakes around the world, it has become ap-parent that the connections and structural systems that were once considered the most ductile and favourable for resisting seismic loading are not adequate to withstand powerful quakes.

These findings have led to increasingly stringent requirements for earthquake-resistant connections with every reissue of design codes and standards. As a consequence, the steel fabrication industry is having trouble keeping up with the ever-changing re-quirements. At the same time, responsibility, liability and performance issues are becoming part of every discussion on earthquake-resistant connections.

Recent research at U of T by professors Packer and Christopoulos, along with graduate student de Oliveira, has focused on addressing the aforemen-tioned industry developments. Backed by the OCE Centre for Materials and Manufacturing and NSERC, the researchers developed a standardized cast steel

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3Volume 1 • No 3 | July 2009

connector to connect hollow section brace members to resist earthquake-induced loading in “braced-frame” building structures.

Traditional earthquake-resistant brace connectionsUp to now, most buildings have been constructed with individually designed, detailed and fabricated connections that anchor hollow brac-ing members to the structure’s frame. While these brace connections can resist typical lateral forces, such as wind, they are susceptible to fractures during earthquakes, putting a building’s structural integrity, and the lives of those in the building, at risk.

Braced frames provide lateral stability to building structures by transmitting lateral loads (i.e. wind or seismic loads) to the founda-tions through tension or compression of diagonal brace members as illustrated in Figure 1.

As hollow structural sections (HSS) are the most efficient members for carrying compression forces, they are commonly used in braced-frame

structures. The usual way of connecting HSS bracing elements to the steel frame involves cutting a slot in the HSS member, fitting a gusset plate into the slot and subsequently welding the HSS element to the plate (Figure 2).

Such a connection induces a phenomenon referred to as “shear lag” in the HSS member. To better understand the effects of shear lag on the capacity of a connection, it is helpful to consider an analogy to a related localized failure in something that is more tangible–like a sheet of paper.

If one pulls a sheet apart from both ends, localized loading causes the paper to tear at one of the ends rather than at its centre. Extending the analogy, think of an HSS brace member as a piece of paper that is rolled into a tube. The welds between the tube and the plate serve as hands, holding on to the “cross-sections” at their ends.

Figure 2: Shear lag in common slotted brace connections and an analogous failure in a sheet of paper pulled from each end

Figure 1: How lateral loads impact traditional braced structures

“Pinned” structure collapses with the application of lateral load

Lateral load is transferred to the foundation through compression in the brace

Lateral load is transferred to the foundation through tension in the balance

4 The Journal of Policy Engagement

As is evident from this analogy, it is difficult to make the connection strong enough to ensure failure does not occur if the member is overloaded. Thus, the general essence of shear lag is that the full cross-section of the member is not engaged at its ends. This phenomenon may cause a localized connection failure at loads that are lower than the full cross-sectional strength of the member.

Typical steel connections are designed only to be stronger than the expected forces that may develop during the service life of the building, including safety factors against overload and to account for material variability. In most cases, providing connections that are actually as strong as the member itself is neither necessary nor pragmatic. Hence, in the majority of applications, shear lag in structural connections is acceptable.

However, the structural response to earthquake-induced loading is very different. During an earthquake, the inertia of the structure induces cyclic tensile and compressive forces in the brace members of a braced steel frame. In a strong earthquake, provided the connections are stronger than the brace members themselves, the braces will actually yield in tension and buckle in compression, thereby safely dissipating the seismic input energy. In these extreme loading conditions, if the connections at the ends of each brace are not stronger than the brace members, the connections will fracture and the building may collapse. The crux of the problem is making the brace end connections stronger than the brace member. As described above, this is difficult with typical slotted HSS connections because of shear lag (Figure 3).

Unfortunately, as with most seismic design-related issues, the severity of the problem went unnoticed until several high-magnitude earthquakes struck California and Japan in the 1990s. It was during post-disaster recon-naissance that engineers noted a disproportionately large number of brittle failures in welded connections. With laboratory testing, the propensity of connection failure was confirmed (AIJ; Tremblay et al.; Bonneville and Bartoletti; Yang and Mahin; Fell et al.).

These findings led to the immediate adjustment of provisions in North American steel design codes. Now, all seismic-resistant HSS brace con-nections must be reinforced in the vicinity of the slot that is cut into the member ends. This connection reinforcement is meant to reduce the likelihood of a localized connection failure.

Not only must these earthquake-resistant connections now be re-inforced, field welding is typically used to fasten these brace members in place during construction. In comparison to bolting, field welding is expensive and requires substantial on-site inspection to ensure the welds are sufficiently sound to perform the critical function of transferring primary structural forces.

As a result, connection designers have struggled with developing ways to design seismic-resistant brace members that can accommodate bolted field installation, further complicating design, detailing and fabrication of bracing connections. Figure 4 shows one example of a particularly clever seismic-resistant brace connection that accommodates field bolting through the use of a “spliced” connection. The complex engineering involved with the connection shown in the figure, in addition to the

Figure 3: Typical connection failure modes in gusset plate-to-slotted HSS welded connections [Photos: Packer, University of Toronto]

5Volume 1 • No 3 | July 2009

complexities of fabrication and installation, led the U of T research team to question the industry’s overall approach to the earthquake-resistant brace connection dilemma.

The innovationThe Packer-Christopoulos-de Oliveira research team realized early on that what the industry needed was a connection detail that would eliminate shear lag, minimize the deformations that occur in the connection region and, simultaneously, accommodate on-site field bolting of the brace as-sembly. In response, the group developed a specially designed cast-steel connector that could meet both the demanding structural, as well as the practical, requirements (Figure 5).

Although other industries, such as rail, marine, mining, agriculture, energy and military, make significant use of steel castings in structural applications, the North American steel construction industry has been slow to embrace their benefits. The use of a steel casting to address the brace connection issues is a part of what made the U of T research both innovative and practical.

At one end of the connector, there is a circular shape and preparation, which allows it to be welded to a round HSS brace. The tapered prepara-tion on the nose of the connector accommodates any brace of a given outer diameter (shown as “D” in Figure 5), regardless of the brace’s wall thickness. In this way, standardization of the connector is achieved (i.e. one size of connector fits various sizes of round HSS members). Further,

Figure 5: The innovative Cast ConneX® High-Strength Connector

Figure 4: The reinforced and spliced connection approach is one way to produce a seismic-resistant brace connection. Exploded view (left); installed in field (right) [Photo: Canam Group]

6 The Journal of Policy Engagement

this weld detail eliminates shear lag as the full cross-section of the brace is engaged and with a “complete joint penetration” (CJP) weld, the connection is inherently as strong as the brace itself.

At the connector’s other end, the shape permits a “double-shear” bolted connection to be used for attaching the shop-welded, brace-connector assembly to the gusset plate in the field. This halves the number of bolts that would otherwise be required in a spliced connection (see Figure 4).

In this way, the researchers’ solution exploited the geometric free-dom provided by steel-casting manufacturing and leveraged the same

manufacturing process’s inclination towards mass production to provide a technologically sound and commercially viable product. Substantial full-scale testing of brace assemblies fitted with these novel connec-tors, carried out both at U of T and at École Polytechnique in Montreal, proved that the connectors do indeed provide the capacity required to withstand design-level earthquakes (de Oliveira et al.; Tremblay et al.) (Figures 6 and 7).

By casting the connection’s complexity into the connectors, their use vastly simplifies the design and fabrication of seismic-resistant brace connections. Moreover, because the connectors can be standardized

Figure 6: How the cast steel connector works during an earthquake (top left); brace configuration in field (bottom left); brace configuration in test (right)

Figure 7: Full-scale testing of a six-metre-long brace assembly equipped with high-strength connectors (left to right): undeformed assembly; brace in buckled configuration; closeup of end connection; desirable ductile rupture of the brace at its midpoint, not at an end connection [Photos: de Oliveira]

7Volume 1 • No 3 | July 2009

and subjected to testing to prove their effectiveness in an earthquake (unlike the one-off connections currently used), buildings equipped with these connectors should benefit from improved safety.

CommercializationThe next step was to move the research from the laboratory to the field. Working with The Innovations Group, the U of T technology transfer department, the researchers filed Canadian, US and international patents for their technology. Because the connectors are produced using casting manufacturing, the natural option would have been to license the technol-ogy to an existing steel foundry, which would then market, produce and sell the connectors to the steel construction industry.

Unfortunately, even the largest steel foundries in North America have almost no exposure or experience with the structural steel construction industry and lack the technical expertise to market such a specialized product to structural engineers who, of course, must specify the com-ponents prior to their use in construction.

Although steel fabricators have the requisite industry experience and exposure, they lack the impetus to market a technology that may be seen as disruptive to their core business. Thus, creating a new corporate entity to market and sell the connectors was the most operable solution.

In early 2007, de Oliveira co-founded the Cast ConneX Corporation to do just that. The business plan he developed to bring the technology to market won him the Heffernan/Co-Steel Innovation Fellowship. Later that same year, Cast ConneX secured seed financing, partnered with leading steel foundry producers and, with funding provided by the Ontario Centres of Excellence through their Market Readiness Program, developed and tested a full line of market-ready Cast ConneX® High-Strength Connectors based on the U of T research. Now CEO of Cast Connex Corporation, de Oliveira received the prestigious Ontario Centres of Excellence Martin Walmsley Fellowship for Technological Entrepreneurship in 2007.

With a full product line of validated connectors, Cast Connex Corpo-ration secured its first commercial sale in 2008 to the Canam Group of Saint-Georges, QC, Canada’s largest steel contractor. The first project to feature the innovative high-strength connectors was a four-storey seismic-resistant office building constructed in a suburb of Montreal that, along with much of the St. Lawrence lowlands region, is a moderate seismic zone (Figure 8).

The project, representing years of investigation and commercialization efforts, helped make the researchers and Cast Connex Corporation the inaugural winners of the Canadian Society for Civil Engineering’s Excel-lence in Innovation in Civil Engineering Award in 2009. This prestigious award, presented by peers in the civil engineering community, recognizes outstanding innovation in civil engineering that has the potential for significant and far-ranging beneficial impact on the prosperity and well-being of society.

Lessons for policy-makersThe Ontario Centres of Excellence played a critical role in the early suc-cess of Cast Connex Corporation, from funding the initial U of T research and supporting the company’s commercialization efforts through their Market Readiness Program and their support via the Martin Walmsley Fellowship. The U of T Innovations Group also played a key role in men-toring, supporting the researchers through the process of protecting the intellectual property they developed, and providing incubator space during the company’s first year of operation.

Without the support of both U of T and of the Ontario Ministry of Research and Innovation through the Ontario Centres of Excellence, the research may only have materialized in technical publications instead of making building structures in earthquake-prone regions safer and easier to construct, potentially saving lives.

Figure 8: The first commercial application of the Cast ConneX® High-Strength Connectors, the Sandoz building in the Montreal suburb of Boucherville [Photos: de Oliveira]

8 The Journal of Policy Engagement

The Cast Connex template demonstrates how public policy can stimulate engineering innovation for the benefit of society. As a result, this Ontario company has the potential to become a major global player in the steel construction industry.

Job creation and wealth generation, in addition to the potential de-velopment of peripheral technology or manufacturing businesses, are the obvious economic benefits of new technology start-ups such as this. But beyond that, with engineering based on the practical application of scientific principles, research in this field has the ability to improve every aspect of our everyday lives, whether it’s the food we eat, the water we drink, the buildings we inhabit or even the air we breathe.

Policy-makers have the ability to stimulate the movement of important engineering innovations into the public domain through continued and increased funding of academic research and through the support of the commercialization efforts of technology-based start-ups and young entre-preneurs. The goal should be to replicate the Cast Connex story for both its economic and social benefits, especially in this time of economic crises.

Unfortunately, governments don’t always make the right decisions, particularly when times are tough. Recent cuts to federal funding of programs such as the NSERCl are alarming. That said, with initiatives like the “innovation agenda,” the Ontario government and its ministry of research and innovation clearly understand that the province’s economic and social prosperity is dependent on our ability to leverage the high-quality research being carried out in our province’s universities.

ReferencesAmerican Institute of Steel Construction. Specification for Structural

Steel Buildings, ANSI/AISC 360-05. Chicago: American Institute of Steel Construction. 2005.

American Welding Society. Structural Welding Code–Steel, ANSI/AWS D1.1/D1.1M:2008. Miami: American Welding Society. 2008.

Architecture Institute of Japan. Reconnaissance Report on Damage to Steel Building Structures Observed from the 1995 Hyogo Ken-Nanbu (Hanshin/Awaji) Earthquake. Tokyo: Architectural Institute of Japan Steel Committee of Kinki Branch, 1995.

Bonneville, Davice and Stacy Bartoletti. Case Study 2.3: Concentrically Braced Frame, Lankershim Boulevard, North Hollywood. 1994 Northridge Earthquake; Building Case Studies Project; Proposition 122: Product 3.2, SCC 94-06. Seismic Safety Commission. State of California: 305-324. 1996.

Canadian Standards Association. Limit States Design of Steel Struc-tures. CAN/CSA-S16-01 and CAN/CSA-S16S1-05. Toronto: Canadian Standards Association. 2005.

Canadian Standards Association. Welded Steel Construction (Metal Arc Welding). CAN/CSA-W59-08. Toronto: Canadian Standards Associa-tion. 2008.

de Oliveira, J.-C., J.A. Packer and Constantin Christopoulos. “Cast steel connectors for circular hollow section braces under inelastic cyclic loading.” Journal of Structural Engineering. March 2008: 374-383.

de Oliveira, J.-C., C. Christopoulos, J.A. Packer, R. Tremblay and M.G. Gray. “Full-scale experimental validation of standardized seismic-resistant cast steel brace connectors.” Proceedings, 14th annual World Conference of Earthquake Engineering. Beijing. October 2008.

Fell, Benjamin et al. Buckling and Fracture of Concentric Braces Under Inelastic Loading. Steel Tips Technical Information and Product Service. Moraga, CA: Structural Steel Educational Council. 2006.

Tremblay, Robert et al. Quasi-Static Cyclic Testing of Individual Full-Scale Circular Steel Tubular Braces Equipped with Cast ConneX™ High-Strength Connectors. Joint École Polytechnique de Montréal and University of Toronto Publication. 2008.

Tremblay, Robert et al. “Seismic design of steel buildings: Lessons from the 1995 Hyogo Ken-Nanbu earthquake.” Canadian Journal of Civil Engineering. June 1996: 727-756.

Yang, Frances and Stephen Mahin. Limiting Net Section Fracture in Slotted Tube Braces. Steel Tips Technical Information and Product Service. Moraga CA: Structural Steel Educational Council. 2005.

Carlos de Oliveira is a co-founder and the chief executive officer of Cast Connex Corporation. He received his B.A.Sc. in civil engineering with a certificate in structural engineering from the University of Waterloo, graduating on the Dean’s honours list with distinction in 2004. He received his M.A.Sc. from the department of civil engineering from the University of Toronto in 2006. He is the inaugural co-recipient of the 2009 CSCE Excellence in Innovation in Civil Engineering Award and the winner of the 2008 CIDECT President’s Award for Research, the 2007 OCE Martin Walmsley Fellowship for Technological Entrepreneurship, the Heffernan/Co-Steel Innovation Fellowship, and received honour-able mention at the 2007 NSERC Innovation Challenge Awards. He has authored and co-authored several articles and conference papers and is a co-inventor on pending Canadian, US and international patents.

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