Why are DuraFuse Frames the “Resilient” seismic solution?
How does the repairability of DuraFuse Frames compare to other lateral systems?
DuraFuse Frames are less likely to require repair after a severe earthquake than traditional moment frames. If residual drifts make repair necessary, DuraFuse Frames are less expensive to repair because damage is limited to the fuse plate located at the bottom flange, which can be unbolted and replaced. In an independent study by Haselton Baker Risk Group, DuraFuse Frames reduced expected losses due to excessive residual drift by a factor of ten. For more information, please refer to Technical Bulletins 10 and 22.
How can DuraFuse Frames be lighter than special moment frames with other connections?
When compared to another proprietary system, DuraFuse Frames have about half of the connection plate weight. This is the primary reason that DuraFuse Frames can have lower overall frame weight. See Technical Bulletin 27.
In addition, since DuraFuse Frames do not have yielding beams, several prescriptive requirements for other special moment frame connections do not apply. For example, beams are not required to be highly ductile, there are no beam span-to-depth limitations, and seismic lateral bracing is not required.
When compared to non-proprietary special moment frame connections, DuraFuse Frames are up to 18 percent lighter, primarily due to enhanced panel zone stiffness. For more information, please refer to Technical Bulletins 10, 14, 19, and 22.
Are DuraFuse Frames as stiff as other proprietary frames?
Yes. DuraFuse connections are considered a fully restrained (FR) moment connection and can be modeled as such. DuraFuse Frames provide the same panel zone stiffness as other connections with cover plates while requiring less plate weight. In addition, the DuraFuse frame achieves stiffness by minimizing column and connection weight by putting the steel back in the beam, where other connections remove weight from the beams and add it to plates and connections. The total weight of a DuraFuse frame to achieve a desired stiffness will be comparable-to or less-than the total weight (beams, columns, and plates) of other connections. For more information, please refer to Technical Bulletins 17 and 18.
How do DuraFuse Frames compare to other special moment frames for residual drift performance?
DuraFuse Frames have higher post-yield stiffness than other special moment frames because of the patented fuse yielding mechanism. This higher post-yield stiffness has been shown to reduce residual drifts and the likelihood of needing repair. For more information, please refer to Technical Bulletin 22.
Are DuraFuse Frames code-approved special moment frames?
Is DuraFuse Frames approved for HCAI (OSHPD) or DSA?
DuraFuse Frames has submitted a Design Guide, Typical Drawings, and Typical Calculations to HCAI (OSHPD) and is in the review process. Please contact us for the most current information.
DSA references AISC 358 for prequalified connections that can be used for steel special moment frames (SMF). Since AISC 358-22 has not yet been adopted by the CBC, the use of DuraFuse Frames is permitted through an Alternative Means and Methods request. A template for Form 1-AMM is available on our website.
How much experimental validation has been done on the DuraFuse Frames connection?
Over 30 qualifying tests have been completed with a full range of beam and column sizes (see testing video). Testing was performed at Brigham Young University and at the University of California, San Diego. The connection is qualified per AISC 341-16 Section K for beams up to 40 inches deep and 529 lbs/ft. The DuraFuse connection is the only prequalified connection in AISC 358 that has been validated with full-scale shake table testing, (Technical Bulletin 25).
Have any DuraFuse Frames buildings been through any earthquakes?
The Salt Lake Community College Student Center was under construction during the 2020 Magna, UT earthquake (MW = 5.7). Following the event, the frame was inspected and no damage was found. For more details, please see Technical Bulletin 11.
DuraFuse Frames have been validated through shake table testing. A three-story frame was subjected to more than ten strong earthquake motions and performed as designed. The three-story frame experienced yielding of the fuse plates, which were easily removed afterwards and the frame recentered. For more details, please see Technical Bulletin 25 and the testing video.
What is the R factor for DuraFuse Frames?
DuraFuse Frames are pre-qualified as special moment frames and have the same seismic design coefficients and factors (R = 8, Ω0 = 3.0, Cd = 5.5).
Is DuraFuse Frames a fully restrained connection?
Yes. The connection stiffness, determined from full-scale experiments, is 2.2 to 4.6 times greater than the minimum connection stiffness required to be considered fully restrained (AISC 360). For more information, please refer to Technical Bulletin 4.
Do DuraFuse Frames require continuity and doubler plates in the column?
No. The DuraFuse connection plates eliminate the need for internal continuity and doubler plates.
When can you model the Panel Zone as rigid and when do you need to include the Panel Zone stiffness?
ASCE 41-17 Section 18.104.22.168.1.3 provides guidance for modeling a panel zone explicitly or as rigid. DuraFuse panel zones, with cover plates proportioned for strength requirements, generally have more-than-sufficient stiffness per the guidance in ASCE 41-17. When a rigid panel zone is assumed, DuraFuse Frames will confirm that the cover plates have sufficient thickness to meet the guidance in ASCE 41-17. For more information, please refer to Technical Bulletin 17 and 18.
What are the requirements for beam bracing for DuraFuse Frames as compared to other special moment frames?
Traditional special moment frame beams are designed to form plastic hinges under seismic loading. AISC 341 specifies prescriptive beam lateral bracing requirements for those beams to mitigate instability caused by the plastic hinges (AISC 341 D1.2b and E3.4b). In contrast, DuraFuse Frames do not form plastic hinges in the beam. DuraFuse Frames have been tested without lateral bracing and are prequalified without seismic bracing per AISC 341. However they are braced per AISC 360 for the maximum expected demands. This results in approximately 70% fewer beam lateral brace points than other special moment frames. For more information, please refer to Technical Bulletin 19.
What is the protected zone on a DuraFuse Frames connection?
The only protected zone on a DuraFuse connection is the fuse plate located at the bottom flange of the beam.
Can DuraFuse Frames be used for biaxial conditions?
Can DuraFuse Frames be used in a sloped beam or column condition?
Yes. DuraFuse connections can accommodate slope. For more information, please refer to Technical Bulletin 1.
Can DuraFuse Frames be used in a skewed beam condition?
Yes. DuraFuse connections can accommodate skewed conditions with limitations on geometry. Please contact us for more information.
Can the DuraFuse Frames connection be used in a retrofit scenario?
Are DuraFuse Frames bolts slip-critical?
DuraFuse bolts are not classified as “slip-critical” or “pre-tensioned”, but they are tensioned during installation. All bolt tensioning methods in the RCSC specification are permitted.
Who engineers the DuraFuse Frames connection?
DuraFuse Frames provides assistance with the connection design (stamped calculations, details, and schedules) at no cost to the engineer. The Engineer of Record is responsible for beam and column sizes.
How can I model the DuraFuse Frames connection for my building in commercial structural analysis software?
The DuraFuse connection can be modeled in any structural analysis software. RAM Structural System has the DuraFuse connection fully integrated, so the user can simply apply the connection to specific beams and the program calculates the frame stiffness automatically. For other software, the user can enter specific parameters that capture the frame stiffness. For more information on modeling the DuraFuse connection in RAM or ETABS, please refer to Technical Bulletins 7 and 8, respectively.
How can we work with DuraFuse Frames?
Is there a license fee to use DuraFuse Frames?
Who pays the license fee and how much is it?
The license fee is included in the fabrication cost and paid by the fabricator. The fee is available during the design phase for budgeting purposes. The license fee is typically a small portion of the cost savings achieved by using DuraFuse Frames.
Is the DuraFuse Frames connection proprietary?
Yes. But the cost is typically less than non-proprietary connections, even when the license fee is included.
Does DuraFuse Frames fabricate any of the materials/parts for the connections and who can fabricate the connections?
No. DuraFuse Frames is not a fabricator. Any fabricator can produce the frames, although we recommend using an AISC certified facility. DuraFuse engineers provide support to steel fabricators, especially those working with DuraFuse Frames for the first time.
Is there any field welding required for DuraFuse Frames connections?
No welding is required during erection. DuraFuse Frames are a field-bolted special moment frame connection.
What projects have used DuraFuse Frames?
Here is a sample of DuraFuse projects that have been built:
- Clearfield Public Library, Clearfield, UT
- Salt Lake Community College Student Center, South Jordan, UT
- China Lake Naval Base Chapel and Recreation Facility, Ridgecrest, CA
- Durango Culinary Health Center, Las Vegas, NV
- Sharp Innovation and Education Center, San Diego, CA
- UC Davis Engineering Student Design Center, Davis, CA
- UCSD Shake Table Modular Test-Bed Building, San Diego, CA
- Salt Lake Community College Juniper Building, Herriman, UT