Progress 10/01/05 to 10/01/09
Outputs
OUTPUTS: During the past year, experimental tests were performed on an economically viable alternative shear connector and focus was placed on Task III - analysis and summary of results of Task I and II (performed in the previous year) in a Masters thesis. Three series of experimental tests were conducted to investigate the viability of MT-20 steel truss plates manufactured by MiTek as possible wood-concrete composite shear connectors. In the first series of tests, a total of 70 MT-20 plates were tested in shear with Spruce-Pine-Fir (SPF) members and Laminated Veneer Lumber (LVL) members in 90 degree and 180 degree orientations. The number of specimens tested ranged from 17-19 for the four possible combinations. The proportional limit and slope was established for each configuration. Cross comparisons using ANOVA f-tests indicated that SPF and LVL in the 90 and 180 degree truss plate orientations have no significant difference in proportional limit but that LVL has significantly higher shear stiffness than SPF. In the second series of tests, 5 LVL-concrete shear specimens were prepared and tested using MT-20 steel truss plates as the shear connector. All of the specimens performed in an ideal ductile manner, with peak load ranging from 57427.684 to 69758.997 N - a pleasing result. In the third series of tests, a 9ft long LVL-concrete beam (with a T shaped cross section) using MT-20 steel truss plates as shear connectors was fabricated and tested in 4-point bending. The initial performance of the beam was recorded, but data on failure of the specimen was lost due to testing machine malfunction. Follow up tests will be performed in the spring of 2010. PARTICIPANTS: Mr. John Michalski. Masters of Science student. Mr. Michalski prepared all specimens and measured and tested the specimens in this study. He performed statistical analysis on the experimental data and is writing his masters thesis on the topic. Mr. David Posluszny. Senior undergraduate student. (independent study project) Mr. Posluszny helped in the fabrication and testing of the full size T-shaped bending specimen. Mr. Jimmy Nguyen. Senior undergraduate student. (independent study project) Mr. Nguyen helped in the fabrication and destructive testing of 5 LVL-concrete shear specimens. Mr. Dmitry Solovyov. Senior undergraduate student. (independent study project) Mr. Solovyov helped in the fabrication and destructive testing of the MT-20 plate shear specimens. TARGET AUDIENCES: The target audience consists of design and building professionals who are working on mill restoration; they include architects, engineers, builders and building officials. PROJECT MODIFICATIONS: It was decided that investigation into readily available MT-20 steel truss plates would prove to be an economically viable alternative to the epoxy with aggregate connection previously studied in this project. For this, additional experimental tests were conducted.
Impacts
The knowledge gained this year is that readily available MT-20 steel truss plates are a mechanically viable option as a wood concrete shear connector. More tests are required, however, before the connection can be promoted and adopted by commercial contractors. The research findings and deliverables from this study will help designers and builders create more environmentally responsible buildings by restoring and re-purposing old structures. This green building strategy will mitigate resource extraction and reduce the burden of construction waste on landfills.
Publications
- No publications reported this period
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Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: OUTPUTS: 10/01/2007 TO 09/30/2008 During the past year, a total of twenty specimens were tested and statistically compared to evaluate the load-displacement behavior of 4 shear connector types: nails, concrete shear keys, glued-in steel plates and epoxy with aggregate. The properties examined were safety, predictability, composite efficiency, strength, and cost. The data collected from these tests were bending stiffness, slip, yield point, ultimate strength type of failure (brittle, quasi brittle, or ductile), and material in which failure occurs concrete, wood, steel, adhesive. A weighted scale analysis of these properties indicated that the epoxy with aggregate was the most viable option so the follow up task (Task II) focused on this connector. As part of Task II, low-frequency cyclic four-point bending tests were conducted on 5 full size specimens (i.e. 2.4m long with the same cross section as in the previous testing) to gauge long-term behavior of the epoxy with aggregate connection. DISSEMINATION: 10/01/2007 TO 09/30/2008 A new website was established www.millrenovation.org to help engage and train professionals on mill renovation techniques by providing a collection of redevelopment case-studies. As a result of visiting the website, several design firms from across the US have contacted me to investigate how to incorporate wood-concrete technology in their projects. PARTICIPANTS: Dr. Peggi Clouston. Principal investigator. Dr. Clouston trains, directs and supervises students in conducting the activities of the study. She consults and counsels the design community on uses of wood concrete composites. Mr. John Michalski. Masters of Science student. Mr. Michalski prepared all specimens and measured and tested the specimens in this study. He performed statistical analysis on the experimental data and will write his masters thesis on the topic. Mr. Tyler Bolte. Senior undergraduate student. (independent study project) Mr. Bolte helped in the fabrication of full size bending specimens. Mr. Alexander Schreyer. Senior lecturer in the Building Materials and Wood Technology program. Mr. Schreyer created and maintains the millrenovation.org website. He also co-authored the most recent publication from this study. TARGET AUDIENCES: The target audience consists of design and building professionals who are working on mill restoration; they include architects, engineers, builders and building officials. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
OUTCOMES/IMPACT: 10/01/2007 TO 09/30/2008 The knowledge gained in this year is that the epoxy with aggregate option is the most viable of the four connections investigated. This is a significant publishable finding; the novel connection offers a new strategy for upgrading old wood floors. The results from the cyclic bending tests will be needed to gauge long-term behavior however, before the system can be adopted by commercial contractors. The research findings and deliverables from this study will help designers and builders create more environmentally responsible buildings by providing design strategies for restoring and re-purposing old structures. This green building technology will mitigate resource extraction and reduce the burden of construction waste on landfills.
Publications
- Clouston, P., Schreyer, A. (2008). Design and Use of Wood-Concrete Composites, American Society of Civil Engineers (ASCE) Practice Periodical on Structural Design and Construction, 13(4): 167-175.
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Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: In the past year, a new series of experimental tests were prepared (but not yet tested) to evaluate the mechanical behavior of 4 shear connector types specifically for use with mill floor planking. This is distinct from the previous year which focused on connectors for mill floor beams. The change was made based upon surveys from common mill construction practices. It was decided that connecting the concrete to existing planking (which lays on top of floor beams) would be a more efficient method to create the composite floor. Twenty new specimens were prepared (five per connector type) which consisted of nominal 3x8 inch pine decking that was salvaged from an old local mill connected to a concrete slab and tested in three point bending. The new connection types to be evaluated are: nails, shear keys, glued in steel plates and epoxy with aggregate. Another output of the study was consulting and counseling work by the PI to extend and implement the wood-concrete technology
into real-life application. Work is currently in progress to renovate an old pulp and paper mill in Turners Fall, MA using wood-concrete composites. Also, recent research findings on wood concrete connectors systems was the topic of one presentation at the Annual UMass Wood Structures Symposium - founded and organized by the PI.
PARTICIPANTS: Dr. Peggi Clouston. Principal investigator. Dr. Clouston trains, directs and supervises students in conducting the activities of the study. She consults and counsels the design community on uses of wood concrete composites. Mr. John Michalski. Masters of Science student. Mr. Michalski prepared all specimens and measured and tested the specimens in this study. He performed statistical analysis on the experimental data and will write his masters thesis on the topic. Mr. Nick Cacciotti. Senior undergraduate student. (independent study project) Mr. Cacciotti conducted experimental push out tests on three connector types and summarized the data in a technical report. Mr. Harrison Oura. Senior undergraduate student. (independent study project) Mr. Oura conducted experimental push out tests on one connector type and summarized the data in report form.
TARGET AUDIENCES: Structural designers: Architects, Engineers and Builders
PROJECT MODIFICATIONS: It was decided that the study would change its focus on the performance of connectors attached to floor planking as opposed to floor beams. For this, additional experimental tests were conducted on composites made from wood planking connected to concrete. The reason for this change was to make implementation of the technology on existing mill floors easier; given that the planking rests on top of the floor beams, they are more accessible.
Impacts
Interest in wood-concrete composite technology is growing. Local design firms (Werner-Sobek Corporation, NY and Grace Construction Products, MA) have shown interest to incorporate this novel and efficient technology in construction projects. The research findings from this study will contribute knowledge to help designers re-use old buildings and thereby reduce the impact of building on the environment. By restoring and re-purposing old structures, designers can reduce resource extraction and burden on landfills.
Publications
- No publications reported this period
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Progress 10/01/05 to 09/30/06
Outputs
Significant headway was made towards completion of Task I this past year. A series of experimental tests were conducted to compare the mechanical performance of 4 different wood-concrete shear connectors: glued-in perforated plates, shear keys, SFS Intec screws (a proprietary product) and standard common nails. The connectors joined a 90mm x 300mm x 300mm Glulam beam to a 90mm x 300mm x 300mm concrete slab. A total of 20 specimens were fabricated (five per connector type) and statically tested using a one-sided push-out test set-up with general conformance to ASTM D 5652. Mean shear strength and stiffness values were computed from the test data. The perforated plate provided the highest strength and stiffness values. The test results also provided important information on the shear behavior of the connectors. The perforated plate and nail connectors both failed in a ductile fashion; whereas, the shear key and the SFS Intec screw connectors failed in an undesirable
brittle manner. The perforated plate provided the highest strength and highest ductility, making it the preferred connector ensuring the most safe and reliable performance.
Impacts
The information collected in this study will provide a basis upon which to decide the usefulness and appropriateness of wood-concrete composite technology in the restoration of old industrial buildings. The impact of this knowledge is both economic (if found to be a structurally feasible option as hypothesized, it will allow for the preservation of existing timber beams - a cheaper alternative to demolition) and environmental (it will enhance the use of the only renewable, recyclable and biodegradable building material - wood).
Publications
- No publications reported this period
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