Structural Timber Shearwalls, the Alternatives and the ICC Evaluation Service

摘要

Structural analysis and design of timber framed structures with timber shearwalls or their alternate components have become more refined in the past 14 years since the 1994 Northridge Earthquake. Or have they? This presentation explores the nature, analysis, design and construction of timber shearwalls and variations that occur in their construction and compare those variations with the tolerances of the structural design.rnThis presentation will include the effects of construction variations, differences and omissions from the construction of structurally designed timber shearwalls in residential "production" tract buildings. Also included are the implied and stated tolerances of the building code and that of the construction industry. Discussion includes assumptions that the structural designer makes while generating and distributing building code prescribed loads between systems, assemblies and components.rnIncluded in the presentation is whether these assumptions are understood by the construction industry, the structural designers and/or the plan checkers and inspectors. Sensitivity of the mis-installation and defective construction is examined to demonstrate the effects of careless or unsupervised construction that is provided.rnThe presentation includes a discussion of the recent additions to lateral force resisting systems family in timber structures, manufactured "shearwall" alternatives. Manufactured timber shearwalls, steel webbed shearwall panels and welded braced frames are among the list of alternates to on-site constructed timber shearwall. Discussion in the presentation covers the procedures to create a "level playing field" for the different shearwall alternatives.rnDiscussion includes the adequacies of the criteria that are intended to create the "level playing field" and whether the level of engineering in this criterion is equal to, above or below the level of engineering understanding of on site constructed timber shearwalls and their performance.