Significance of Stiffness Assumptions on Lateral Force Criteria


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Title: Significance of Stiffness Assumptions on Lateral Force Criteria

Author(s): S. A. Freeman, R. M. Czarnecki, and K. K. Honda

Publication: Special Publication

Volume: 63


Appears on pages(s): 437-458

Keywords: building codes; concrete slabs; deflection; dynamic loads; earthquake resistant structures; earthquake; lateral pressure; loads (forces); mathematical models; multistory buildings; reinforced concrete; stiffness; structural analysis; structural design.

Date: 8/1/1980

The lateral force stiffness characteristics of structures cannot be represented by a single set of modeling assumptions. Measured data obtained from the study of full-sized buildings subjected to various sources of lateral displacements are compared to calculated results based on various modeling assumptions used in determining the stiffness characteristics of structures. Tentative recommendations are presented for use in the lateral force design of reinforced concrete buildings subjected to winds and/or earthquakes. Stiffness properties associated with effective concrete sections, concrete slab participation, and nonstructural materials are discussed. For both wind and earthquake design, it appears that the assumptions that apply to low amplitude motion should be different than the assumptions that apply to high amplitude motion. Therefore, it is recommended that modeling techniques and the cal-culation of stiffness characteristics be based on some form of a two-level approach.