東京理科大学「火災安全科学研究拠点」
Tokyo University of Science “Research Center for Fire Safety Science”■研究成果概要報告書/ Report for Outline of Research Results
研

究 課 題

Research Topic
所属
研究代表者

Affiliation

Research

氏名LeaderNamee-mail

受入担当責任者

氏名

Organization

Name

Structural Fire Performance ofEarthquake-Damaged Cold Formed
Steel Framed Walls

実 施 年 度2016

Worcester Polytechnic Institute (WPI)
Brian Meachambmeacham@wpi.edu
Ken Matsuyama

１．研究の背景および目的/ Background and Aim of Research

Post-earthquake fire performance of buildings is a concern in earthquake prone zones across theglobe. In recent years, there has been an increased use of cold formed steel (CFS) framed building
assemblies in many countries, including the USA. CFS is known for its strength, durability,stability, sustainability, non-combustibility and cost effectiveness over conventional light woodframed construction. Due to its wide advantages, cold-formed steel is used as a preferred material
for construction in earthquake resistant structures. However, the performance of CFS framed
structures in fire remains unknown. However, multiple tests have been performed on CFS wall
frames in the recent past [1-7].
A project was successfully completed in summer 2016 with UC San Diego and WPI to investigate
the earthquake and post-earthquake fire performance of CFS framed construction. A series of 7
seismic tests were conducted on the large outdoor shake table at UCSD on a 6-story cold-formed
steel building. Given site restrictions, fire testing could not be conducted at a desired duration oruntil structural failure. In parallel to this effort, Individual CFS framed wall panel tests wereconducted on damaged specimens at the National Fire Research Laboratory (NFRL) at NIST,Gaithersburg, MD to assess the structural fire performance of individual panel systems. However,for comparison purposes, the duration of fire was matched with the short-duration of the fire tests
at the shake table site.
To complement those tests, WPI proposed to conduct CFS wall-floor configurations at Tokyo
University of Science (TUS), using the Multiple Horizontal Loading Full-Scale Furnace(MHLFSF), which can support a compartment-size specimen with provision to impart structural1

loading. The application to utilize the TUS MHLFSF was accepted, and plans were developed toconduct tests in November 2016. While the original intent was to test specimens from the USA
with induced damage, as representative of earthquake damage, this was ultimately not possible.
First, the CFS panel supplier cancelled their participation late in planning; meaning specimens
were not available for shipment to Japan. In addition, it was determined that the plannedearthquake loading (motion-induced damaged) could not be developed at TUS. As such, it wasdecided to test a representative CFS panel assembly, constructed of Japanese materials fabricatedclose to US specifications, without induced damage, as this was appropriate to investigate thefeasibility of structurally loaded full-scale fire test in MHLFSF.
[1]

W. Chen, J. Ye, Y. Bai, and X.-L. Zhao, "Full-scale fire experiments on load-bearing
cold-formed steel walls lined with different panels," Journal of Constructional Steel
Research, vol. 79, pp. 242-254, 2012.

[2]

W. Chen, J. Ye, Y. Bai, and X.-L. Zhao, "Improved fire resistant performance of load
bearing cold-formed steel interior and exterior wall systems," Thin-Walled Structures,vol. 73, pp. 145-157, 2013.

[3]

M. Feng and Y. Wang, "An analysis of the structural behaviour of axially loaded fullscale cold-formed thin-walled steel structural panels tested under fire conditions," Thinwalled structures, vol. 43, pp. 291-332, 2005.

[4]

M. Feng and Y.-C. Wang, "An experimental study of loaded full-scale cold-formed
thin-walled steel structural panels under fire conditions," Fire safety journal, vol. 40,
pp. 43-63, 2005.

[5]

S. Gunalan, P. Kolarkar, and M. Mahendran, "Experimental study of load bearing coldformed steel wall systems under fire conditions," Thin-Walled Structures, vol. 65, pp.
72-92, 2013.

[6]

P. Kolarkar and M. Mahendran, "Experimental studies of non-load bearing steel wall
systems under fire conditions," Fire safety journal, vol. 53, pp. 85-104, 2012.

[7]

L. Laím, J. P. C. Rodrigues, and L. S. da Silva, "Experimental analysis on cold-formed
steel beams subjected to fire," Thin-Walled Structures, vol. 74, pp. 104-117, 2014.

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２．利用施設及び利用日/ Facility and Schedule
・ ●●装置 （2016 年--月--日 ～ --月--日）
・ ●●装置 （2016 年--月--日 ～ --月--日）
We utilized the Multiple Horizontal Loading Full-Scale Furnace (MHLFSF) at TUS. With an external
dimension of 7 m (W) x 10 m (D) x 6 m (H), the MHLFSF is capable of offering an internal heatingarea of 3 m (W) x 4 m (D) x 3.5 m (H). This dominated the specimen size.
The overall test scheduled spanned over four weeks of November and early December 2016.
•The week of 11/07/2016 was used primarily for planning. A facility visit was undertaken for
better understanding the feasibility of testing a full-scale test specimen and instrumentation.
A meeting was held with the professional development company on 11/07/2016 to discuss
the fabrication of test specimen. In the absence of standard cold-formed steel ready-madechannel sections in Japan, a decision was made to produce studs, tracks and angle connectors(with the dimensions equivalent to standard US CFS sections) using 2.3 mm thick galvanizedsheet steel. Also, the sheet steel used for sheathing and drywall panels was 0.8 mm inthickness. This week was also utilized for shop fabrication of the studs and tracks as well as
redesigning the CFS frame to fit the actual furnace dimensions.

•During the week of 11/14/2016, a detailed instrumentation plan was worked out and the CFS
materials were delivered to the furnace warehouse.

•The week of 11/21/2016 was scheduled for preparation of thermocouples and field fabricationof CFS wall and roof panels. The end of the week was used for mounting thermocouples
alongside the specimen assembly.

•The week of 11/28/2016 was used for final assembly of wall panels, surface thermocouple
mounting and preparation of loading block and the load-spreader frame. The full-scale CFSframe was slated for loading and testing on 11/30/2016 and 12/01/2016. However, the testing
was delayed to 12/02/2016 due to a minor technical glitch with the gantry crane, which wasessential to lift the test specimen into the large furnace. The crane was also used to tether thestructural loading block in order to prevent the collapse of loading block and damage to thefurnace floor.

3３．実験方法・研究成果、および考察（申請時の計画に対する達成度合いも含む）※継続課題の場合は，前年度との関係性，進展度合いについても記載すること。
/ Method, results, and conclusions (degree of achievement compare to application)

The full-scale test specimen was constructed from light-gauge cold-formed steel (CFS) frame.
The assembly consisted of a CFS floor panel supported on two CFS wall panels. The assembly
was provided with two cross-braces for adding structural stability and constructed over a simple
platform made up of structural steel angles. This facilitated the easy lifting of specimen withoutcompromising its verticality. Cold-formed steel framed construction represents a stud-and track
system connected together using self-drilling, self-tapping sheet metal screws. The studs, tracks
and joist sections were custom fabricated using locally available galvanized sheet steel bent toresemble standard US CFS sections (152.4 mm x 51 mm). It should be noted that the floor panels
was fabricated using the same size tracks as studs. This is in contrast with the standard floor (orrim) track sections (254 mm x 51 mm). The CFS wall panels were built as shear walls, where one
side of the sheathing consisted of a single layer of sheet steel (0.8 mm thick) adhered to 12.5 mm
thick gypsum board using water-soluble adhesive. A second layer of 12.5 mm gypsum wallboard
covered the base layer. 2 layers of 12.5 mm gypsum wallboard represent a 1-hour fire resistance
rating.

The test specimen is comprised of two wall panels connected to a floor panel. The dimensions of thespecimens are carefully chosen to fit within the internal dimensions of the furnace. The overall wall
panel dimensions were 2540 mm (W) x 2400 mm (H). The roof panel was also 2540 (W) x 2400 mm(D) in dimension similar to the wall panels. Each wall panel was a combination of two separate panels,
joined at the center using fasteners The center connection represented a typical double stud connection
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arranged back to back and fastened using sheet metal screws with a spacing of 300 mm o.c..
Structural loads are very important in fire tests as they may govern the failure of structural systems
after the loss of their strength and stiffness in fire. Live loads are one of the major occupancy loads
considered in designing the structure. However, in the event of fire, only 50% of live loads areconsidered in a structure. This is due to the fact that the live load in a structure is significantly reduced
due to evacuation of the occupants. In the current test, 50% of the live load accounts to approximately
90 kg.m2. This was achieved by means of a solid loading block placed on top of a secondary load
spreader grid. The load spreader grid was constructed by orthogonal arrangement of cold form steelmembers. This supported a metal grillage, which facilitated the uniform distribution of load. This
arrangement was protected from high temperature inside the furnace by covering them with ceramic
fiber blankets. The loading block, which consisted of a stack of solid metal plates (30 kg each), wasplaced in the center of the roof over the load spreader. The loading block was tethered to the gantry
crane to protect it from causing damage to the furnace floor due to collapse.

Temperature at various locations was the main parameter of measurement in the current test. The test
frames was rigorously instrumented with Type-K thermocouples to measure the temperatures invarious points of interest. Temperature was measured on the gypsum wall board surface, at different
depths of the walls and diaphragm in between the components of the wall and diaphragm.
Thermocouples were also inserted in the stud and joist cavities. Measuring temperatures at theselocations will help in understanding the member temperature, which is an important parameter that
determines the loss of structural capacity. The temperatures may also be used to validate the structure5

fire and heat transfer modeling. 27 thermocouples were mounted on each wall: Wall A and Wall B(Total 54). 22 thermocouples were mounted on the diaphragm. Surface temperatures on each wall andthe ceiling were measured using plate thermocouples. Each wall consisted of 10 surface
thermocouples, 5 each on the interior and exterior face, whereas, the diaphragm was instrumented
with only 6 plate thermocouples. Beaded wire thermocouples were used for all other locations. The
center location on each panel was instrumented with thermocouples between all layers. An example

IN32

GYPSUM BOARD

GYPSUM BOARD

GYPSUM BOARD

STEEL SHEETGYPSUM BOARD

GYPSUM BOARD

GYPSUM BOARD

STEEL SHEETGYPSUM BOARD

GYPSUM BOARD

STUD1K7I

8J12004619512006619

7400

1619

21200

STUD619

34

OUT

OUT

INof thermocouple layout is shown below.

1964

9M

10Surface TC: Plate Thermocouple
TC between Gypsum Boards:
Bead Thermocouple (thin)
TC between Gypsum Board and Steel
Sheet: Bead Thermocouple (thin)L

TC on Stud Surface: BeadThermocouple (thin)
Bead Thermocouple in the void
space (thin)

For this project, the two design fire curves considered were ASTM E-119 and the Hydrocarbon FireCurve. The Hydrocarbon curve was deemed preferable for this study since a petrochemical fuel (nHeptane) was used for fire tests conducted in UCSD. The duration of fire recommended was 60
minutes, followed by natural convective cooling achieved by opening the furnace doors..Given thematerials used, the specimen was constructed to mimic 1-hour fire resistantconstruction, if tested against ASTM-E119. Exemplar furnace temperatures, developed
during the testing, are shown below.

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Results obtained by testing the cold-formed steel primarily consisted of temperature readings recordedby thermocouples instrumented at various locations of interest, as well as visual indication of failuremodes and times to failure.
Representative temperature profiles from walls / wall cavities and ceiling / ceiling cavities are shown
below. Individual temperature plots are specifically superimposed to compare the trends of heattransfer through the walls, which may then be corroborated with limited visual observations.

Temperature on Wall B: (a) Center (Location H)

Temperature on Wall B: (b) Stud Cavities

Temperature on diaphragm/roof: (a) Center

Temperature on diaphragm/roof: (b) Joist cavities

While difficult to see on this scale, gypsum wallboard started to fail within 10 minutes from the startof the test (top left figure). This is further evident by the temperatures measured in stud cavities (topright figure), where, a steep rise in temperature was observed following the loss of gypsum wallboard.
A similar behavior may was observed in the roof panels, where the loss of gypsum board resulted insteep rise in temperature in the joist cavities. Catastrophic failure occurred around the 42-minute mark.
The primary reason for failure was the yielding of connections at the wall to roof joint. The yieldingof connections at high temperature was further pronounced by the failure of connections at the two
individual panels, connected back to back. A quick post-fire investigation showed that the sheet metalscrews did not completely shear off, but were bent and the screw holes had widened with occasional
tearing. Thermomechanical buckling of steel studs and warping of sheet steel was also observed. Noteagain that the nominal fire resistance rating of this type of construction would be 60 minutes under an7

ASTM E119 (standard) fire curve.
Figure below shows the views from the viewport camera, which shows the separation of gypsum
wallboards as early as 10 minutes into the test. Dehydrated gypsum boards showed a shearing failure
originated near the fasteners. Dehydration was evident from visually observed numerous surface
micro-cracks. Also, loss of bond between the gypsum wall board and sheet steel was observed, whichis consistent with the CFS tests conducted in San Diego.

Figure below shows the collapsed roof panel and failure of the double stud connection.

8Conclusions
While the original intent was to test specimens with simulated earthquake damage (motioninduced damaged), such damage was not possible to be developed TUS. Nonetheless, it wasdeemed appropriate to investigate the fire performance of undamaged CFS construction as abenchmark. In this regard, the tests were successful. Also, the MHLFSF facility at TUS wassuccessfully found to enhance the capabilities for comprehensive, long-duration, full-scale
structure-fire furnace tests to structural failure. A large data-set of temperatures through the wallis generated, which may be used to further validate the numerical modeling.

9４．今後の展望（今後の発展性，見込み等についても記述）/ Future Perspectives
To collect additional data on fire performance of earthquake-damaged lightweight construction, anapplication for extending the joint usage research was submitted to TUS. The proposal was accepted.
Year 2 of this project will involve assessment of multiple wall-diaphragm configurations of timberand cold-formed steel framed construction, which are firstly seismically-loaded (damaged) at theBuilding Research Institute (BRI) in Tsukuba, and then transported to Centre for Fire Safety Scienceand Technology at TUS-Noda Campus, where, the damaged specimens will be tested to failure under
the load in the Multiple Horizontal Loading Full-Scale Furnace.
The specimens are envisioned to include at least one specimen each of the following: CFS
construction fabricated to US standards, lightweight timber construction to US standards, CFS
construction fabricated to Japanese standards (i.e., the Steel House), and lightweight timber
construction to Japanese standard. If possible with timing constraints, two experiments on each system
type will be tested. The specimens are to represent construction for residential housing.
The specimens have been designed so as to fit on trucks for transportation between BRI and TUS(Noda). Full-scale tests on assemblies are scheduled in the month of November/December 2017. It isenvisaged that the wall and floor panels will be prefabricated and shipped to Japan (BRI) by the panel
fabricator in the United States. The Japanese equivalent panels shall be fabricated and assembled at
BRI by Professional Development Company. A series of 8 tests are scheduled from 11/06/2017 to12/01/2017. Tentatively, the first two weeks will be utilized in simulated earthquake tests on traditional(or advanced) light-wood frame at BRI, thereafter followed by fire tests at TUS. One day is reserved
for transporting the specimen from Tsukuba to Noda-Shi. Similarly, in the following two weeks,
earthquake and fire tests on cold-formed steel frame will be carried out.

５．成果の公表状況（学会への発表，学術誌への投稿等を記述。予定も含む）/ Publishing (presentation, paper, etc. incl. plans in the future)
Since the tests are rather recently concluded, papers have not yet been prepared.
However, it is planned to submit abstracts to the following conferences, which haveproceedings, as well as to submit to a journal, such as Fire Technology or Fire Safety
Journal. Planned conferences include the 2018 SFPE International Conference on
Performance-Based Codes and Fire Safety Design, Structures in Fire (SIF), and the 2018
NFPA Annual Conference. It is planned to include the outcomes of the Year 2 testing aswell.

10６．経費の使用状況 / Usage of Budget
expendables・Meeting・Travel expense

Personnel expenses

Printing
Contents

Cost- Shipping Costfor Experimental
Samples

2,608- Materials forexperiment; e.g.,
flexible containerbags

10,585- Glass Coating
Thermocouples68,040- Materials for
Test Specimen

693,360- Disposal Fee of
Test Specimen

160,920

Subtotal

935,513

Contents

Cost- Air Fare

120,279- Accommodation

142,500

SubtotalContents- Fees forSpecimen
Production
SupportExperiment262,779

Cost
Test

788,400

andforSubtotal

788,400

Burden of Tokyo University of Science / Total Yen 1,986,692
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