UBC Theses and Dissertations
Static and dynamic testing of MIDPLY TM shear wall system Buitelaar, Marlen
The work documented in this thesis constitutes the second year of the three-year MIDPLY™ project. The MIDPLY™ shear wall system is a new invention for strengthening new and existing light frame timber buildings against earthquakes and high ' winds. The system needed to be tested before its implementation in the field (US Patent US5782054: Wood Wall Structure). As part of an ongoing research project undertaken by Forintek Canada Corp. and the University of British Columbia, the MIDPLY™ shear wall system was designed, tested, and developed in order to procure an improved product over the conventional shear wall presently used in construction. The objective of this project was three-fold: 1. Improve the behaviour of timber shear walls by utilizing conventional timber products combined with new technology - the MIDPLY™ wall. 2. Quantify the improvements though full-scale static and dynamic testing of the MIDPLY™ shear walls. 3. Determine failure modes and load-displacement characteristics of the MIDPLY™ walls. The work in this thesis comprises of static testing, dynamic testing, structural modeling, and shear wall connection design and implementation. Several configurations of 2.44m x 2.44m walls were tested statically at Forintek Canada Corp., where from three configurations were chosen to be tested dynamically at the Earthquake Engineering Laboaratory at UBC. The configurations of MIDPLY™ walls were tested under two different earthquake records. In total, 40 static tests, which include monotonic and reversed cyclic tests, and 6 dynamic tests were performed as part of the scope of this thesis. Throughout the testing, the parameters that were varied were lumber size, stud spacing, lumber type, loading protocol, hold down connection type, and vertical loading. The results of the testing clearly showed the strengths and weaknesses of the MIDPLY™ shear wall system. Two strengths were that the MIDPLY™ wall could withstand higher loads and displacements than the conventional light frame timber shear wall used in most buildings in North America. Also, some common failure modes from other walls were eliminated. The weakness was that the wall sometimes failed in a brittle manner through end-stud failure. The future plans of the MIDPLY™ project include new connection designs to further improve racking performance.
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