Assessment and Retrofit of Timber Diaphragms in URM Buildings
Principal Researcher: Associate
Professor Jason Ingham
Students involved: Razak Abdul Karim, Aaron Wilson, Ronald Lumantarna.
Typical multi-storey unreinforced masonry (URM) construction in New Zealand consists of solid perimeter walls and straight-sheathed timber floor diaphragms. It is widely recognised that the behaviour of these flexible diaphragms is crucial to the seismic response of the complete URM building. Lively in-plane shear rotation caused by their flexibility has been observed to cause significant corner damage to the URM walls in past earthquakes. There is often an absence of sufficient positive connection to the out-of-plane walls, which significantly increases the likelihood of out-of-plane wall failure.
A problem currently exists that researchers and practitioners must predict building response and formulate retrofit solutions based on limited laboratory data and inadequately validated modelling techniques. Practitioners have communicated the need for improved in-plane performance characteristics of heritage timber diaphragms in order to improve the accuracy of their seismic assessments. Of particular interest is diaphragm strength, stiffness, damping, hysteretic response, degradation, and displacement capacity.
The current study forms an integral component within the scope of the wider Seismic Retrofit Solutions program, with the specific task of determining the performance characteristics of heritage timber floor diaphragms typical of New Zealand URM buildings. Using an integrated experimental and modelling approach, these performance characteristics will be established, as well as the influence that diaphragm parameters have on these performances. Testing will include both new and salvaged specimens from existing URM buildings in New Zealand.
Knowledge generated from this research will be embodied as a set of simplified ‘desktop’ assessment procedures that engineering practitioners can use during the seismic assessment of URM buildings. In addition, a set of finite element modelling guidelines will be provided for a commercially available structural analysis software package to be used during unique non-linear time-history URM building analyses.
More information can be found here.
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