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UBC Theses and Dissertations

Testing and analysis of Midply(TM) Shear Wall System Lungu, Dan


The thesis details a six-month period of experimental studies of the structural properties of the MIDPLY™ Wall System, which has being developed through a three-year testing program. The MIDPLY™ shear wall was invented by Dr. Erol Varoglu, formerly with Forintek Canada Corp. and Prof. S.F. Stiemer (University of British Columbia), US Patent US5782054: Wood wall structure. The system provides greater lateral resistance to earthquakes and high winds loads. The name MIDPLY™ refers to its configuration: the plywood or OSB panel is placed between the studs. The improved performance is due to this special rearrangement of wall framing components and sheathing used in standard shear walls. The new fabrication system uses typical building methods and standard building materials, but a prefabricated production may be desirable to ensure the quality of the product. The objective of the project is to establish the proof-of-concept for the MIDPLY™ Wall System, design and construction method. The structural properties are being developed through testing of full-scale specimens subjected to monotonic (ramp), cyclic and dynamic displacement schedules. Several anchoring techniques and hold-down connectors have been developed and tested. The tests were performed mainly on 2.44m x 2.44m and 1.22m x 2.44m MIDPLY™ shear walls. In the investigations covered by this thesis, were designed and tested 30 walls and were primarily studied: • Alternate hold-down connections that prevent the fracture of the end studs of the MIDPLY™ wall by using MSR lumber or inverted-triangle hold-downs with different bolt spacing, bolt diameters, hold-down length and placement along the stud. • Alternate hold-down connectors: steel rods and double shear hold-downs. • The performance of MIDPLY™ walls under pseudo-dynamic tests. • The performance of MIDPLY™ walls used as insert segments in standard shear walls. • The performance of MIDPLY™ walls with openings. Special attention was given to the connection details between header and MIDPLY™ walls to achieve desired pinor moment-connection. • The performance of MIDPLY™ walls affected by shrinkage. • The performance of repaired MIDPLY™ walls. One can conclude that, there are many real-life applications of the system, using the superior structural performance of the MIDPLY™ walls. Thus, future studies will conduct to a final package of design values needed for structural engineers, architects and designers.

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