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Gray M.G.,Cast Connex Corporation | Christopoulos C.,University of Toronto | Packer J.A.,University of Toronto
Journal of Structural Engineering (United States) | Year: 2017

The yielding brace system (YBS) is a seismic-resistant concentrically braced frame system that provides a fully symmetric hysteretic response via flexural yielding of cast steel triangular yielding fingers of a specially designed yielding connector. The behavior of the system is first reviewed, and a detailed discussion of the limit states design of a YBS braced frame is presented. Results of two full-scale yielding connector prototype tests, conducted in a braced frame configuration, are then presented. The test specimens were subjected to several quasi-static and dynamic load cycles, up to axial brace deformations of 120 mm (3.8% interstory drift). The proposed design limit states were validated through full-scale testing and the performance of a YBS yielding connector brace assembly in a typical braced frame with a bolted brace-to-gusset connection was demonstrated to be very similar to the performance of YBS yielding connectors tested in a purely axial configuration. © 2016 American Society of Civil Engineers.


De Oliveira C.,Cast Connex Corporation | Grant R.,Pacific Steel Casting Co. | Gonczy S.,Gateway Materials
Metal Casting Design and Purchasing | Year: 2010

Cast Connex Corp. worked with a metal casting supplier to produce a construction frame connector that met several design criteria. The steel connector casting developed by Cast Connex consists of a solid round section transitioning into two flat plates that are bolted to a gusset plate. Bolt attachment to a single gusset plate accommodates simple fabrication, construction and site erection. The heavy end of the connector is tapered to accept hollow round braces of different wall thickness for complete joint penetration welding. The Cast Connex design engineers originally considered three different steel casting alloys, as specified by ASTM standards: A27 Grade 70-40, A148 Grade 80-50 and A958 Grade 8620. In addition to selecting the appropriate alloy, the casting design team worked together to determine the best molding method, which affects the surface finish and dimensional tolerances of the finished casting. Quality assurance for these structural components is driven both by building codes and specifications and requirements.


Iwashita T.,Ariake National College of Technology | Packer J.A.,University of Toronto | Carlos De Oliveira J.,Cast Connex Corporation
Tubular Structures XIV - Proceedings of the 14th International Symposium on Tubular Structures, ISTS 2012 | Year: 2012

This paper describes defect tolerances for cast steel connections in braced frames and explores the possibility of brittle fracture from assumed defects in typical cast steel connectors.A parametric study, which investigates the sensitivity of brittle fracture to defect size, defect location and material mis-match effects, is described through cast steel connector models.A toughness scaling model is used for evaluating the occurrence of brittle fracture from assumed defects in the models. © 2012 Taylor & Francis Group, London.


Iwashita T.,Ariake National College of Technology | Iwashita T.,University of Toronto | Packer J.A.,University of Toronto | Oliveira J.-C.D.,Cast Connex Corporation
Journal of Structural Engineering (United States) | Year: 2012

During the last decade, various steel casting products for steel building structures have been developed, such as connectors between brace members and gusset plates in braced frames. Some casting products are welded to steel sections such as tubular members and I-section members in building structures, where these members are expected to develop their capacity during a large-scale earthquake. In this situation, brittle fracture can be another concern of the casting products if there are defects in the connections. A study of defect tolerance for cast steel connections is therefore very important to prevent brittle fracture from weld defects or casting defects. This paper describes defect tolerances for cast steel connections in braced frames and explores the possibility of brittle fracture from assumed defects in typical cast steel connectors. A parametric study, which investigates the sensitivity of brittle fracture to defect size, defect location, and material mismatch effects, is described through cast steel connector models. A toughness scaling model is used for evaluating the occurrence of brittle fracture from assumed defects in the models. © 2012 American Society of Civil Engineers.


Haque T.,Cast Connex Corporation | Packer J.A.,University of Toronto
Canadian Journal of Civil Engineering | Year: 2012

Elliptical hollow sections (EHS) are the newest steel shape to have emerged in the construction industry. They have been incorporated in a variety of structures around the world, including Canada, without structural design guidelines. To date, EHS are completely absent from Canadian codes and guides. A possible application of EHS is within truss-systems and, as such, a research project has been undertaken to investigate the behaviour of EHS-to-EHS welded connections. Twelve T and X connection tests have been performed to study the effect of connection angle, orientation type, and loading sense. Two methods to predict connection capacities and failure modes are investigated: an equivalent circular hollow section (CHS) approach and an equivalent rectangular hollow section (RHS) approach. The equivalent RHS approach proved to be more successful at capturing the actual failure mode of welded EHS-to-EHS connections and is therefore recommended at this time as a preliminary design method for EHS truss-type connections.


Herion S.,Gmb Competence Center Tubes and Hollow Sections | de Oliveira J.-C.,Cast Connex Corporation | Packer J.A.,University of Toronto | Christopoulos C.,University of Toronto | Gray M.G.,University of Toronto
Proceedings of the Institution of Civil Engineers: Structures and Buildings | Year: 2010

During the past three decades, steel casting technologies and processes have developed significantly, making way for the production of high-quality castings that are capable of meeting the rigorous demands of structural applications. As a result, the use of steel castings in construction is becoming increasingly more accepted and commonplace. This article presents the state-of-theart uses of steel castings in onshore construction and summarises recent publications to give an overview of the current status of research and use of cast steel in tubular structures in North America, Europe and Asia.


De Oliveira J.-C.,Cast Connex Corporation | Christopoulos C.,University of Toronto | Packer J.A.,University of Toronto | Tremblay R.,Ecole Polytechnique de Montréal | And 2 more authors.
Stahlbau | Year: 2011

Although concentrically braced frames are an efficient and popular choice for the lateral force resisting systems of mid- to low-rise steel frames, their bracing connections may be prone to premature failure unless complex design and fabrication procedures are undertaken. Frames utilizing Hollow Structural Section (HSS) braces, slotted to receive a concentric welded gusset plate, are particularly susceptible to connection fracture due to stress concentrations arising from the shear lag phenomenon at the net-section.To address this issue, a cast steel connector was developed at the University of Toronto that provides a bolted connection between a circular hollow section (CHS) brace and a typical corner gusset plate. Unlike standard, fabricated, slotted-tube type connections, the cast connector is designed such that shear lag in the brace member is virtually eliminated. Thus, there is no need for cumbersome reinforcing plates in the connection region. The connector was designed using solid modeling software and finite element analysis, and cast using ASTM A958 grade steel, which is very similar to most wrought grades. This paper presents the results of a series of full-scale brace tests in which four moderately slender, compact, cold-formed CHS brace assemblies were cyclically loaded to failure. Each of theWTce assemblies employed a different size of CHS and cast steel connector, with the latter in turn bolted to a typical corner gusset plate. Each of the tests followed the buckling restrained brace protocol specified in the American Institute of Steel Construction (AISC) Seismic Provisions. All of the braces survived several cycles beyond the protocol and failed in tension at the center of the brace. In each testthe cast steel connectors showed no sign of yielding, illustrating that the use of a cast steel connector is a viable means of connecting CHS brace members for seismic applications. © Ernst & Sohn Verlag für Architektur und technische Wissenschaften GmbH & Co. KG.


Gray M.G.,Cast Connex Corporation | De Oliveira J.C.,Cast Connex Corporation | Christopoulos C.,University of Toronto | Binder J.I.,University of Toronto
NCEE 2014 - 10th U.S. National Conference on Earthquake Engineering: Frontiers of Earthquake Engineering | Year: 2014

The cast steel Yielding Brace System is a non-buckling concentric bracing system that dissipates earthquake energy through the flexural yielding of elements of a specially designed Yielding Connector. The Yielding Connector's hysteretic response is characterized by an increase in stiffness at large (inelastic) displacements due to a second-order geometric effect. Results of a numerical study on building structures designed using Yielding Connectors are presented. A twelve-story sample structure designed with both buckling restrained braces and Yielding Connector-equipped braces was subjected to time-history analyses in an effort to examine the effect of post-yield stiffening on the collapse performance of buildings. The building designs were modeled with OpenSees and the Yielding Connectors were simulated with an experimentally validated phenomenological material model. The non-linear time-history analyses were performed with a suite of seven ground motions scaled to the Design Earthquake and Maximum Considered Earthquake seismic hazard levels. The effect of increased brace and brace connection strengths on collapse performance is also explored. The study confirmed that, when included in the capacity design of the braces and brace connections, post-yield stiffening and strengthening can decrease the likelihood of a structural collapse during a significant earthquake.


Gray M.G.,Cast ConneX Corporation | Christopoulos C.,University of Toronto | Packer J.A.,University of Toronto
Journal of Structural Engineering (United States) | Year: 2014

The Yielding Brace System is a highly ductile bracing system in which seismic energy is dissipated by the yielding fingers of a specially engineered cast steel connector. When the brace is severely loaded in tension and compression, the fingers yield in flexure, thus providing a full, symmetric hysteresis. Second-order geometric effects result in an increase in postyield stiffness at large displacements. The mechanics of the system are first presented, including several first principle equations used to predict a connector's response. These equations are then used to design a prototype connector. The geometry of this prototype is evaluated using nonlinear finite element analysis. Following this analysis, the results of full-scale axial component testing of the prototype are discussed. These results include tensile coupon tests from material taken directly from unyielded portions of the test specimens. The prototype design and testing program presented demonstrate that the Yielding Brace System is a ductile connector that can enhance the energy dissipation and displacement capacity of braced frames. Good agreement between predicted and experimental response showed that the mechanics of the connector were well understood and that the method used to design the prototype was effective in meeting the targeted performance. © 2013 American Society of Civil Engineers.


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Cast Connex Corporation | Date: 2016-12-28

steel elements, products, and components for construction; cast or forged steel elements, products, and components for construction; structural steel elements, products, and components for construction. design, consulting, manufacturing and fabrication services in the fields of structural engineering, casting, forging, and construction.

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