Progress 12/01/00 to 08/31/04
Outputs
Based on the load test results (two M.S. theses are still in progress) the following preliminary observations were made. Based on analytical modeling, major improvements were made to past devices used to conduct interlayer slip tests. Using the new device, interlayer slip tests of 35 connection specimens were conducted for a mix of ambient dry (6 7.5% moisture content) and conditioned wet (13-16% moisture content) specimens and each under either ramp (linearly changing load level) or repeated (cyclic load range) loading. Connections were very significantly stiffer than anticipated from past testing, but consistent with analytical predictions made prior to the tests. Under ramp load, dry specimens and wet specimens performed similarly. Under repeated loading, the wet specimens exhibited about a 60% reduction in stiffness, compared to the dry specimens, but were still very stiff compared to expectations. Testing of 36 beam specimens (some ambient dry at 6-7.5% moisture
content, some conditioned wet at 12-16% moisture content) was conducted for ramp, repeated loading and creep loading and combinations of these effects. Repeated loading (4000 and 21,000 cycles) and creep each reflected about a 9-15% drop off in flexural stiffness of the beams under subsequent ramp loading, compared to those only ramp loaded. A full scale wood concrete floor/deck specimen was tested under a "shake down" sequence of ramp load 1, creep load (load of 6% of estimated ultimate capacity), ramp load 2, repeated load (4000 cycles of 500-5000 lbs range), and ramp load 3. Compared to in ramp load 1, in ramp load 2 the deck exhibited a 16% lower flexural stiffness. Compared to in ramp load 1, in ramp load 3 the deck exhibited 24.5% lower flexural stiffness. Compared to in ramp load 2, in ramp load 3 the deck exhibited 11% lower flexural stiffness. Additional publications are planned subsequent to completion of two ongoing M.S. theses by graduate research assistants.
Impacts
Commercial floor construction, primarily made of cast-in-place reinforced concrete slabs, in offices, hotels etc. is a largely untapped market for wood products. A reinforced concrete slab is highly wasteful of materials. The tensile zone cracks and about half the depth is ineffective and can allow moisture to enter, leading to corrosion, spalling and other deterioration. Exposed rebar is a potential fire protection problem, too. The aim is to show that the cracked concrete and expensive rebar can be replaced by a structurally effective, solid wood deck. Low added cost should result as half the concrete and most of the rebar are eliminated and replaced by lower cost wood. The scientific goal of the research was to examine the influence of moisture, creep and repeated loading on the load- displacement behavior of the interlayer connection, full-scale beam specimens and a full-scale floor/deck test specimen. The objective was to assess the long term structural adequacy
of full scale layered wood/concrete systems. A successful system would contribute to the possible future use of a renewable resource (wood) to replace non-renewable concrete and steel. No use of such composite construction in commercial buildings in the U.S. is occurring, so potential economic savings and environmental benefits are enormous.
Publications
- Gutkowski, R., J. Balogh, M. Wieligmann, C. Rogers and P. Haller. 2003. Analysis and Testing of Composite Wood Concrete Floor/Deck Systems. Proceedings of CMEM 2003, Eleventh International Conference on Computational Methods and Experimental Measurements, Halkidiki, Greece, WIT Press, Wessex Institute of Technology, UK.
- Fast, R.S, Durability Studies of Layered Wood-Concrete Composite Connections and Beams. M.S. Thesis, Colorado State University, Fall 2003.
- Balogh, J. Wieligmann, M., Gutkowski, R., P. Haller. 2002. Stress Strain Behavior of Connections for Partially Composite Wood Concrete Floors and Deck Systems, Proceedings-2nd Material Specialty Conference of the Canadian Society of Civil Engineering, Montreal, Quebec, Canada.
- Gutkowski, R.M., J. Balogh. Refined Modeling of Composite Wood-Concrete Beam and Deck Specimens. Proceedings, 9th International Conference and Exhibition in Structural Faults and Repair- 2001, ASCE, London, UK
- Gutkowski, R., Balogh, J. Rogers, C., SaRibeiro, R. 2002. Laboratory Tests of Deep Composite Wood-Concrete Beam and Deck Specimens, Proceedings-4th Structural Specialty Conference of the Canadian Society of Civil Engineering, Montreal, Quebec, Canada
- Balogh, J., Gutkowski. R. M., Wieligmann, M., and Haller, P. 2002. Mechanics behavior of dowel connectors for partially composite wood concrete beam. Proceedings, The 7th World Conference on Timber Engineering, Selangor, Malaysia, Mara University of Technology, Vol. 4.
- Gutkowski, R., Balogh, J., Rogers, C, and Shigidi, A.M.T. 2002. Load test of composite wood concrete deep beam specimen. Proceedings, The 7th World Conference on Timber Engineering, Selangor, Malaysia, Mara University of Technology, Vol. 3.
- Cecotti, A., Fragiacomo, M. and Gutkowski, R. 2002. Design of timber concrete composite structures according to EC5-2002 version. Proceedings of 35th Meeting of Working Commission W18-Timber Structures, Kyoto, Japan. International Council for Research and Innovation in Building and Construction, Lerhstuhl fur Ingenieurholzbau und Baukonstructionen, Universitat Karlsruhe, Germany.
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Progress 01/01/03 to 12/31/03
Outputs
Results and Conclusions: A fire destroying the control panel of the environmental chamber in Year 1 backed tasks up (and others needing the facility) for nearly 9 months. A 1 year no cost extension was approved for the 2 year project. Belated testing of beams was conducted for ramp, repeated loading and creep loading. The latter two each reflected about a 10 15% drop off in stiffness of the beams under subsequent ramp loading. A M.S. thesis was done on that topic. Belated slip tests of connections under ramp and repeated loading were conducted with mixed results, and some were included in the thesis. Connections appear considerably stiffer than thought, a positive. Some significant modifications in the conventional test device used are suggested as a breakthrough finding. Development of a computer model was ongoing simultaneously and a graduate student is doing thesis work on that. Aside of that a Visiting Scientist who assisted in the studies, is conducting (via his
own funding) load tests of connections and beams at INPA, a national research laboratory in Brazil. We are cooperating. A visiting student (self supported) did mechanics studies of the connection and completed a diploma thesis for his home institution, which was not previously reported. This helped understand the need for modification to the connection test set up compared to the conventional one being used. Plans for Coming Year: A floor/deck specimen remains, as its configuration was dependent on findings of the connection and beam tests. It is configured but needs to be constructed and tested after repositioning our load frame. A small number of follow up additional connection tests (in a revised device) and beam tests will be done, funds available dictating the number, consequent to the past results and early analytical modeling. Another thesis and additional publications will result as well as final report. One has been submitted already, a second is nearly ready to submit.
Impacts
Commercial low to high rise construction in offices, hotels etc. is a largely untapped domestic market for wood products. In such applications, floors are primarily made of cast in place reinforced concrete. A reinforced concrete slab is highly wasteful of materials. The tensile zone cracks and about 40 60% of the depth is ineffective and can allow moisture to enter, leading to corrosion, spalling and other types of deterioration. Exposed rebar is a potential fire protection problem, too. The aim is to show that the cracked concrete and expensive rebar can be replaced by a structurally effective, solid wood deck. The wood deck is a low added cost and half the concrete and all rebar are eliminated, resulting in substantial savings. The outcome will be a determination of the long term structural adequacy of full scale layered wood concrete specimens. A successful outcome will contribute to the possible future use of a renewable resource (wood) to replace non renewable
concrete and steel. Even a modest change from concrete and steel to more wood construction can substantially reduce energy requirements and carbon dioxide emissions. No use of such composite construction in commercial buildings in the U.S. is occurring, so potential economic savings and environmental benefits are enormous.
Publications
- Gutkowski, R.M., K. Brown, A. Shigidi and J. Natterer. 2003. "Investigation of Notched Composite Wood Concrete Connections. Accepted for publication in the Journal of Structural Engineering, ASCE, Reston, Va.
- Wieligmann, M. 2003. "Stress Strain Behavior of Dowel Connections for Partially Composite Wood Concrete Floors and Decks." Diploma Thesis Technical University of Dresden, Dresden, Germany.
- Fast, Ryan S., 2003. "Durability Studies of Layered Wood Concrete Connections and Beams," M.S Thesis, Department of Civil Engineering, Colorado State University,Ft. Collins, CO.
- Gutkowski, R. M., Balogh, J., Wieligmann, M., Rogers, C. and Haller, P., 2003, "Analysis and Testing of Composite Wood Concrete Floor/Deck Specimens," Proceedings Eleventh International Conference on Computational Methods and Experimental Measurements, WIT Press, Wessex Institute of Technology, Southhampton, UK.
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Progress 10/01/01 to 09/30/02
Outputs
Due to an electrical fire destroying the control panel of the environmental chamber in Year 1. Nearly all experimental work had to be delayed but computer modeling proceeded and load test frames were also setup. A requested 1 year nocost extension was approved for the 2 year project. Since that time, all but one conditioned beam tests have been completed. Companion sliptest connection specimens are prepared and ready for testing. The test apparatus has been fabricated and the test setup will be done after testing the last beam test. Comparison of the analytical results was ongoing simultaneously. Remaining experimental and computer modeling should be completed before the extended termination date.
Impacts
Commercial low to high rise construction in offices, hotels etc. is a largely untapped domestic market for wood products. In such applications, floors are primarily made of castinplace reinforced concrete. A reinforced concrete slab is highly wasteful of materials. The tensile zone cracks and about 4060% of the depth is ineffective and can allow moisture to enter, leading to corrosion, spalling and other types of deterioration. Exposed rebar is a potential fire protection problem, too. The aim is to show that the cracked concrete and expensive rebar can be replaced by a structurally effective, solid wood deck. The wood deck is a low added cost and half the concrete and all rebar are eliminated, resulting in substantial savings. The outcome will be a determination of the long term structural adequacy of fullscale layered wood concrete specimens. A successful outcome will contribute to the possible future use of a renewable resource
(wood) to replace nonrenewable concrete and steel. Even a modest change from concrete and steel to more wood construction can substantially reduce energy requirements and carbon dioxide emissions. No use of such composite construction in commercial buildings in the U.S. is occurring, so potential economic savings and environmental benefits are enormous.
Publications
- Balogh, J., Gutkowski. R. M., Wieligmann, M. and Haller, P. 2002. Mechanics behaviour of dowel connectors for partially composite woodconcrete beam. Proceedings,The 7th World Conference on Timber Engineering, Selangor, Malaysia. Mara University of Technology, Vol 4..
- Gutkowski, R., Balogh, J., Rogers, C, and Shigidi, A.M.T. 2002. Load test of composite woodconcrete deep beam specimen. Proceedings, The 7th World Conference on Timber Engineering, Selangor, Malaysia. Mara University of Technology, Vol 3.
- Cecotti, A., Fragiacomo, M. and Gutkowski, R. 2002. Design of timberconcrete composite structures according to EC52002 version. Proceedings of 35th Meeting of Working Commission W18Timber Structures, International Council for research and Innovation in Building and Construction, Kyoto, Japan. Lerhstuhl fur Ingeniieurholzbau und Baukonstructionen, Universitat Karlsruhe, Germany.
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Progress 10/01/00 to 09/30/01
Outputs
In February 2001, an electrical fire destroyed the control panel of the environmental chamber needed for the project. After a 5-6 month period, an insurance claim was accepted by the university insurer. The manufacturer of the chamber prepared and installed a replacement. The compressor system was also inoperative and was subsequently repaired. The chamber is now operational and safe to use. Nearly all experimental work had to be delayed. Progress was made on the computer modeling task. Load test frames were also set-up. The first sets of test specimens have been cast and will be put into the chamber in January 2002. A request for about a 1-year no cost extension is anticipated.
Impacts
Commercial low to high rise construction in offices, hotels etc. is a largely untapped domestic market for wood products. In such applications, floors are primarily made of cast-in-place reinforced concrete. A reinforced concrete slab is highly wasteful of materials. The tensile zone cracks and about 40-60% of the depth is ineffective and can allow moisture to enter, leading to corrosion, spalling and other types of deterioration. Exposed rebar is a potential fire protection problem, too. The aim is to show that the cracked concrete and expensive rebar can be replaced by a structurally effective, solid wood deck overlaid with and interconnected concrete layer. The wood deck is a low added cost and half the concrete and all rebar are eliminated, resulting in substantial savings. The outcome will be a determination of the long-term structural adequacy of full-scale layered wood concrete specimens. A successful outcome will contribute to the possible future use of a
renewable resource (wood) to replace non-renewable concrete and steel. Even a modest change from concrete and steel to more wood construction can substantially reduce energy requirements and carbon dioxide emissions. No use of such composite construction in commercial buildings in the U.S. is occurring, so potential economic savings and environmental benefits are enormous.
Publications
- In January 2001, an abstract for a technical paper was accepted for an August 2000 IABSE Conference on "Innovative Wooden Structures and Bridges" but had to be withdrawn when the project experimental work was delayed. In August 2001, abstracts for two technical papers were submitted and recently accepted for the World Conference on Timber Engineering to be held in August 2002.
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