Global analysis of light-framed timber construction detailing and its performance during major contemporary earthquakes

Abstract

The seismic performance of hundreds of light-framed timber buildings (LFTB) during major contemporary earthquakes was analyzed in order to relate current timber framing construction detailing with damage level (DL) aftershock. The objective of this investigation being: (i) to identify and correlate most relevant parameters that dictate the DL of LFTB; (ii) to analyze current performance and resilience of LFTB under earthquakes with increasing destructive potential; (iii) to analyze DL of LTFB in a global context to assess potential risks and protection necessities for higher timber buildings. The investigation was based on hundreds of detailed forensic reports aftershock, including data from some of the most destructive earthquakes of United States, Chile and New Zealand recorded during the last two decades. In every case, the international Hazus damage scale was used for numerical analysis. The results indicate that low to mid-rise LFTB performed very well preventing collapse in most cases. Nonetheless, significant reparation costs – up to 90% of total costs – were involved with non-structural elements, especially with gypsum encapsulation, stucco and other finishes. In terms of structural damage, the most relevant parameters were first floor stiffness, irregular plan and shear wall percentage with damage correlations of R2=0.4, 0.5 and 0.6, respectively. The number of stories, and particularly the number of wood stories, also showed a large correlation factor of 0.5 with Hazus DL, which indicates a need to further developing seismic protection technologies for mid-rise timber buildings.