professor ben schafer's thin-walled structures research group - johns hopkins university

 

Experiments on Rotational Restraint of Sheathing

 

Note: The research reported on this page is motivated from a gift from the American Iron and Steel Institute. The research initiated in the Fall of 2006 and was completed in July of 2007. From August of 2007 to July of 2008 a JHU undergraduate continued research in this area resulting in the Supplemental report provided below.

 

Research Abstract

The objective of the proposed experimental testing program is to determine the elastic rotational restraint, kf, provided by sheathing to joists (studs, rafters, etc). This restraint, kf, serves to partially or fully restrict the distortional buckling failure mode. Given newly adopted AISI-Committee on Specifications (COS) provisions for distortional buckling (Ballot 227B) it is important to formally establish the system benefits of light-frame construction as embodied in kf. The proposed work plan is split into two phases. The first phase includes fabrication and shakedown of the testing rig, and performing the first 9 tests on 800S200 joists with thickness varying from 33 to 97 mils connected to plywood. These tests will provide initial insight on the potential rotational capacity of conventional floor systems, provide a means to assess the limitations of the AISI TS-1-02 testing protocol for examining distortional buckling rotational restraint, and will be compiled into an interim report for the AISI-COFS. Phase 2 testing, if agreed upon, focuses on completing a testing matrix that covers: sheathing type (plywood, OSB, gypsum board), joist spacing, fastener spacing, fastener type, flange width, and web depth. The complete results will be compiled into a report (as well as made available electronically) along with appropriate AISI-COFS Specification provisions and a design example.

 

Project Materials

Proposed Work (pdf) - Fall 2006

Project Final Report (pdf) - July 2007

ICTWS Conference Paper (pdf) - August 2007

Supplemental Report (pdf) - July 2008

 

last updated 07/21/08

 

 

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