Dear Andres,
I will be glad to share verbally with you and the ASCE Community what I can on the results information out of the testing that was done some years ago at NJIT, New Jersey Institute of Technology under the direction of late Dr. C.T. Thomas Hsu who sadly passed away recently. You may want to start doing a search in Google on Technical Papers that may had been published on this work or reach out to the NJIT CEE Department that owns the Technical Research Papers of the testing that was done at NJIT testing facilities years ago and also the rights and copyrights to all technical information done at NJIT. The US Patent document is a public document that can be downloaded by anyone from the US Patents Office website, a copy is attached for your reference.
Manly the key concept is the use of a continuous cold formed steel hat channel which is securely attached to the top flange of the cold formed steel joists with self tapping screws that go through the metal deck and produce an interlocking action that allows to achieve some degree of composite action between the cold formed steel joists, metal deck, continuous shear connector, shear screw connectors, wire mesh, and concrete deck slab to form a Composite Cold Formed Steel Floor System (CCFSFS).
The continuous cold formed steel hat channel serve two purposes, one a continuous bonding action between concrete slab, metal deck, and for support of the wire mesh up high for the negative bending moments that could develop at the points of supports of continuous concrete slabs on cold formed joists. The shear transfer mechanism between the concrete slab deck and the supporting cold formed steel joists can be achieved by different methods of different types of SHEAR CONNECTORS, perhaps you could come up and devise one that can be very practical to install and very effective to do the shear transfer mechanism. Options are out there ... thinking of Power Actuated Fasteners can also be an option, the key here is that we are dealing with cold formed steel sections which naturally are thinner that the conventional structural steel hot rolled steel WF members.
I am sure that with the appropriate modifications and ratios of thickness to web and flange dimensions of the cold formed steel sections and considering that having double of cold formed steel web sections and top flange is mainly continuously restrained then some of the basic concepts of the AISC can be adapted to be used for composite floor systems using double cold formed steel sections of the appropriate thickness that could meet the ratios of AISC Composite Floor Systems Design. Something that still the AISI have not addressed in the Standard for Cold Formed Steel Design, but here is work for the Structural Research Groups of Universities and Testing Manufacturers. Hope you can carry on with this research effort. If needed see if you could come up with some other creative methods to achieve the shear transfer mechanism that will be appealing to the AISI community and Cold Formed Steel Manufacturers.
There are plenty of applications for medium span and low rise buildings for residential multifamily, hospitality, hotels, etc. Please share with us your thoughts about it.
Civil Engineering | New Jersey Institute of Technology
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| Civil Engineering | New Jersey Institute of Technology |
| Civil Engineering is the fusion of engineering, design and aesthetics. Civil Engineers call upon science and engineering principles to plan, design and construct infrastructure such as buildings; roads and highways; tunnels, bridges and rail systems; airports and seaports; water reservoirs; and storm water drainage and control plants. They also maintain this infrastructure. |
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Pedro Munoz Ph.D., P.E., M.ASCE
Principal
PRM Engineering, LLC
Methuen MA
(978)7388001
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Original Message:
Sent: 12-10-2018 19:42
From: Andres Guzman
Subject: AISI S100-16 - COLD FORMED STEEL COMPOSITE FLOORS
Dear Pedro, thanks for sharing and congratulations on your patent! Can you share information about how the tests that support Fig. 2 were performed? We worked with a similar configuration to achieve a composite section, but it will be interesting to replicate international studies to compare with our studies (we have to deal with welding conforming sections).
Regards,
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Andres Guzman Ing., M.ASCE
PROFESSOR
UNIVERSIDAD DEL NORTE
Barranquilla
573004284680
Original Message:
Sent: 11-15-2018 11:11
From: Pedro Munoz
Subject: AISI S100-16 - COLD FORMED STEEL COMPOSITE FLOORS
Dear Professor Guzman,
Glad to hear a Colleague from Barranquilla is taking the effort to work on updating Steel Construction Standards for Colombia in South America. You see this subject of Composite Floor Systems using cold formed steel joists, concrete slab, metal deck and shear connectors had been neglected to be incorporated into the AISI for years even though specific formulations have been in the AISC Steel Standard for many years for hot rolled steel wide flange beams. Cold Formed Steel is Steel, thinner than hot rolled steel but still when selected of proper thickness over depth dimensions may still provide enough capacity to perform well under composite floor action. Perhaps this may be a subject that may require a comprehensive documentation from AISI in terms of State of the Art on this type of composite cold formed steel floor systems.
Back in the 2000's at New Jersey Institute of Technology some research and testing was done by late Dr. C.T. Thomas Hsu (RIP) of a system that used some type of continuous channel screwed together to the top flange of the cold formed steel joists to achieve some degree of composite action. At the time this research was done, I was glad to participate with the NJIT team to develop and test a composite floor system using cold formed steel hat channels screwed to CFS joists which at the same time served as support of the rebars of the concrete slab.
Perhaps this is an excellent topic for more comprehensive R&D by Universities in collaboration with Cold Formed Steel Manufacturers to come up with some reliable type of shear connectors that can be comfortably and safely used by Engineers to design this type of lightweight floor system for a multitude of economical medium span building applications. Try searching by Google NJIT Research on Composite Floor systems. Best Wishes.
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Pedro Munoz Ph.D., P.E., M.ASCE
Principal
PRM Engineering, LLC
Methuen MA
(978)7388001
Original Message:
Sent: 11-15-2018 07:32
From: Andres Guzman
Subject: AISI S100-16 - COLD FORMED STEEL COMPOSITE FLOORS
Greetings, In Colombia we are updating our construction regulations. I am involved in the Chapter referring to Steel construction. One concern is related to the best choice for shear connectors and how to evaluate their performance. Do you know studies related to these subject, specifically channel type connectors?
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Andres Guzman Ing., M.ASCE
PROFESSOR
UNIVERSIDAD DEL NORTE
Barranquilla
573004284680
Original Message:
Sent: 11-12-2018 14:14
From: Pedro Munoz
Subject: AISI S100-16 - COLD FORMED STEEL COMPOSITE FLOORS
Mr. Chen, that is great news for the Cold Formed Steel Engineering community. Having a Standard by AISI for composite floor systems using single or double CFS joists will allow some type of common standard guideline for the analysis and design of this type of composite floor system. Having that standard then the software companies can comfortably incorporate the methodology into the algorithms for automatic analysis and design check which will certainly open the doors for some other options of composite floor systems for a variety of typical medium span composite CFS systems for multifamily, light commercial, hospitality, assisted living facilities, college dormitories, residential condominiums, hotels, apartments, townhouses, military and government housing, and some other similar floor systems. I LOOK FORWARD TO SEE THIS STANDARD SPECIFICATION FOR COMPOSITE FLOOR SYSTEMS WITH CFS IN NEXT RELEASE OF AISI. Thank You for listening and taking on this suggestion for future incorporation into the AISI Standard, I am sure there will be many applications for this composite floor system! Cold Formed Steel Joists with web openings can easily accommodate the type of mechanical and ventilation (HVAC) systems that can pass through the joists. Fire Ratings and Sound Transmission Ratings are issues that will need to be addressed as well, but it appears that they can be somewhat achieved at this time for most common residential buildings.
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Pedro Munoz Ph.D., P.E., M.ASCE
Principal
PRM Engineering, LLC
Methuen MA
(978)7388001
Original Message:
Sent: 11-12-2018 11:36
From: Hong Chen
Subject: AISI S100-16 - COLD FORMED STEEL COMPOSITE FLOORS
Mr. Pedro Munoz,
Thank you for your comments! AISI Committee on Specifications plans to develop composite design provisions for cold-formed steel members. The provisions are expected to be included in the future edition of AISI S100.
Sincerely,
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Hong Chen P.E., M.ASCE
Manager of Construction Standards Development
Washington, DC 20001
(202) 452-7134
Original Message:
Sent: 11-10-2018 14:05
From: Pedro Munoz
Subject: AISI S100-16 - COLD FORMED STEEL COMPOSITE FLOORS
Recently an updated version of AISI S100-16 has been published for Analysis and Design of Cold Formed Steel. In looking at the summary of the updated chapters it is noted that there are no provisions for the Analysis and Design of Composite Cold Formed Steel-Concrete floor systems and there are no references up to how a designer can address the design of composite floor systems using concrete slab, metal deck,shear connectors, and single or double cold formed steel joists with or without holes, similar to the Design Provisions for Composite Floor Systems using steel beams from AISC. Apparently the available commercial software for cold formed steel joists does not include the composite floor analysis and design using cold formed steel joists. Is it somehow appropriate to use the methodology included in the AISC for composite floor systems of hot rolled steel with some modification or adjustment factors to design cold formed steel composite floor systems? Or can AISI include in the next updated Standard some provisions for composite floor systems using cold formed steel and shear connectors? Perhaps this could be an area of R&D that can be sponsored by CFS manufacturers in coordination with some Universities for any required testing of appropriate shear connectors similar to what was done by AISC years ago.
Updated AISI S100-16
| Structuremag |
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| Updated AISI S100-16 |
| In 2016, AISI S100, North American Specification for the Design of Cold-Formed Steel Structural Members (or Specification), was updated with an entirely new layout which is parallel in format with ANSI/AISC 360, Specification for Structural Steel Buildings. Also, the Direct Strength Method has been integrated into the body of AISI S100, which enables engineers to design cold-formed steel members with unconventional cross-sections. |
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Pedro Munoz Ph.D., P.E., M.ASCE
Principal
PRM Engineering, LLC
Methuen MA
(978)7388001
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