Continuous Timber Diaphragms
Publication: Journal of Structural Engineering
Volume 111, Issue 5
Abstract
Current design assumptions for diaphragms assume support conditions which are either simple span or fully continuous. The building codes require a design based on the highest values for moment and shear obtained under either of these two support conditions. More practical criteria for assessing continuity conditions at supports for wood diaphragms are needed. This investigation is to determine experimentally the effects of continuity conditions on timber floor diaphragms with plywood sheathing subject to inplane loads. Previous testing programs have evaluated simply‐supported diaphragms subject to uniform loading; this study evaluates the effects of other support conditions and non‐uniform loads. Static loading conditions were used to evaluate the response of the diaphragm for both deflection and ultimate strength. Six 8 ft×16 ft (2.44 m×4.88 m) floor diaphragms typical of certain residential construction techniques with three different sets of boundary and loading conditions were tested in accordance with ASTM E72. The tests demonstrated that: (1) Continuity over a rigid support apparently does not increase the unit shear resistance values of the diaphragm; (2) concentrated loads on the diaphragm produce lower load factors than moment‐equivalent uniform loads at a given load level; (3) there is not an apparent direct relationship between relative panel displacement and overall diaphragm deflection for the size diaphragms tested; and (4) local panel buckling has a minimal effect on overall diaphragm failure patterns.
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References
1.
American Society for Testing and Materials, ASTM E72‐74a, “Standard Methods of Conducting Strength Tests of Panel for Building Construction,” ASTM, Philadelphia, Pa.
2.
Applied Technology Council, Proceedings of a Workshop on Design of Horizontal Wood Diaphragms (ATC‐7‐1), Applied Technology Council, Berkeley, Calif., Dec., 1980.
3.
Carney, J. M., “Bibliography on Wood and Plywood Diaphragms,” Journal of the Structural Division, ASCE, Vol. 101, No. ST11, Nov., 1975, pp. 2423–2436.
4.
Countryman, D., “Lateral Tests on Plywood Sheathed Diaphragms,” Laboratory Report 55, American Plywood Association, APA, Tacoma, Wash., 1952.
5.
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6.
International Conference of Building Officials, Uniform Building Code, 1979 Ed., ICBO, Whittier, Calif., 1979.
7.
Johnson, J. W., “Lateral Test on a 12‐by‐60 Foot Plywood‐Sheathed Roof Diaphragm,” Report T‐11, Oregon Forest Products Laboratory, OFPL, Corvallis, Oreg., Jan., 1955.
8.
Johnson, J. W., “Lateral Test on a 20‐by‐60 Foot Roof Diaphragm with Stapled Plywood Sheathing,” Report T‐13, Oregon Forest Products Laboratory, OFPL, Corvallis, Oreg., Dec., 1955.
9.
Thomas, D. J., “Effects of Continuity Conditions on Timber Diaphragms with Plywood Sheathing,” a thesis presented to the Graduate School of Vanderbilt University, in 1982, in partial fulfillment of the requirements for the degree of Master of Science.
10.
Tissell, J. R., “1966 Horizontal Plywood Diaphragm Tests,” Laboratory Report 106, American Plywood Association, APA, Tacoma, Wash., 1966.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 111 • Issue 5 • May 1985
Pages: 992 - 1002
Copyright
Copyright © 1985 ASCE.
History
Published online: May 1, 1985
Published in print: May 1985
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