Performance of Plywood and Composite Panels Under Concentrated and Impact Loads

The American Plywood Association program related to impact and concentrated load performance of plywood and veneer particleboard composite panels had three stages: defining the minimum load limits and stiffness levels applicable to roof sheathing, subfloor, and single floor applications; testing plywood for the strength levels developed; and defining market acceptance levels for stiffness. Two types of composite panels were subjected to concentrated and impact tests to determine whether they met the performance limits established. Preliminary research indicated a target minimum test load value for single floors of 550 lbs. applied through a 1-inch disk, 300 lbs. applied through a 3-inch disk for subfloors, and 350 lbs. applied through a 3-inch disk for roof sheathing. Test results for concentrated loads are discussed. The limit for roof sheathing was easily met by both 3/8-inch and 1/3-inch plywood. Two thicknesses and two types of composites were tested with comparable load values to plywood sheathing. For stiffness, plywood test information was used to define a target level, since market acceptance has established minimums. Composite panels easily met the requirements. For single floor construction, both plywood and the composites easily met the minimum target of 550 lbs. applied through a 1-inch disk. For subflooring the average deflection of a plywood subfloor was about 1/8 inch, while the average for the same thickness of composite panels was about 1/10 inch. Strength test values indicate that for subfloors both the plywood and the composite met the 300 lb. minimum target test value. Development of an impact test included determining the impact of persons jumping from several heights, and an attempt to reproduce this effect with a 30 lb. bag of lead shot. Floors were tested not only for the initial effect of the impact but for degradation due to the impact that would affect future performance. Results of the tests on plywood and composite floor panels are shown. In general plywood was shown to meet construction and long-term performance requirements in home construction, and in some cases appears to have greater capabilities than needed. Composite panels in the same thicknesses as plywood can also meet minimum concentrated and impact load performance requirements.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member