Cyclic response of wood framed shear walls with sturdy end studs and strong hold down anchorages

Abstract

Ten 2470 mm height wood framed shear walls of different lengths (1200, 2400 and 3600 mm) were tested to know their cyclic response under in-plane shear loads. The walls have five 2×6” end studs, and strong hold-down anchorages. The main objectives of this research are to evaluate the cyclic response of these shear walls and to see how well code expressions (Special Design Provisions for Wind and Seismic, SDPWS) fit with the measured behaviour of shear walls with strong end-studs, which would be used in mid-height timber buildings (up to 6 stories high). Also, as comparison, results from typical shear wall configurations previously tested by three different authors, are compared with those expressions. Reasonable agreement is found between the measured lateral strength of previously tested walls and SDPWS (10 to 30% smaller); however, the strength of the shear walls tested here were 67% larger than the values calculated for walls with nails at 100 mm in sheathing edges, too conservative. Deformation capacity was analysed and was concluded that nail spacing was not significative in the ultimate displacement capacity of the walls, and short walls present higher ultimate displacements. The observed drift levels at 40% of peak load varied between 0.0040 and 0.0075, at which the walls were undamaged, and therefore, that the walls can be assumed in elastic regime. Stiffness were calculated for the tested walls and was observed that SDPWS expression for deflection overestimate the lateral stiffness. It may be necessary to use new expressions or testing results for the design of shear walls with strong end elements.