SR220 BRANZ test and evaluation method EM3-V3 for bracing rating of walls to NZS 3604 (2010)
Product Description
This report presents the basis for changing the current BRANZ test and evaluation procedure used to establish wall bracing ratings. This is known as the BRANZ P21 test method and is used to obtain the bracing ratings of sheet-sheathed timber-framed wall systems for houses and other low-rise structures to meet the wind and seismic demand stipulated in the timber-framed building standard NZS 3604:1999.
The demand loads in NZS 3604 were based on the loadings specified in the New Zealand loadings standard NZS 4203:1992, but are expected to be revised to be compatible with NZS 1170.5:2004. The revised wind and earthquake test and evaluation method (EM3-V3) was derived from engineering analysis to ensure the as-built house strength from walls assessed by EM3-V3 will achieve the NZS 1170.5 intent in a reliable but economical manner.
In the EM3-V3 method, the design seismic bracing strength of a test wall is obtained by factoring a selected peak resisted racking load by a two parameters, referred to as F1 and F2. The relationship between F1 and wall deflection was determined by computer simulation, using typical test hysteresis loops, and design level earthquake records. Factor F2 is called the systems factor and was selected to represent the reliable strength enhancement of a total house compared to the sum of the racking strengths of individual bracing walls when isolated from the house and tested separately.
Product Information
Publication date | 2010 |
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Author | SJ Thurston |
System number | SR220 |